Wiley: Biological Journal of the Linnean Society: Table of Contents

Nuclear DNA based species delineations of Coccus scale insects in symbiosis with plants and ants, and the role of plant epicuticular wax in structuring associations

Fri, 09 Dec 2016 00:00:00 -0800

We undertook phylogenetic analysis of nuclear DNA to elucidate species boundaries in the symbiotic Coccus scale insects associated with mutualistic Crematogaster ants and Macaranga plants occurring in the ever-wet forests of Southeast Asia. The coccid specimens clustered into ten lineages, each corresponding to a morphospecies assignment. The lineage identified as C. secretus was separated from the Main Clade by an outgroup. We also examined all pairwise associations among the three symbiont guilds to understand how patterns of association were structured. The analyses revealed that each ant, plant or coccid operational (taxonomic) unit often associated with multiple O(T)Us of each of the other two guilds. However, where testing was feasible, a ‘preference’ for one or sometimes two partner O(T)Us of each guild was often detected. Mutual ‘preferences’ or ‘avoidances’ were relatively common among the symbionts, and no conflicts of interest were apparent. The network of preferred partners among all three guilds showed compartmentalization structured by the presence/absence of plant epicuticular wax, suggesting that this feature plays a fundamental role in how the symbionts select partners that best serve their needs. To a lesser degree, the network was also structured by whether the host plant stems were ant-excavated or hollowed naturally.

Colder environments may select for darker paper wasps

André R. Souza, Stefano Turillazzi, José Lino‐Neto, Giacomo Santini — Mon, 21 Nov 2016 00:00:00 -0800

Polistes paper wasps have striking and variable colour patterns. Although these colour patterns are known to function in communication, little is known about how they affect fitness in relation to the abiotic environment. In the present study, we used dried-preserved museum specimens, comprising male and female Polistes from all over the world, aiming to test for a correlation between the body luminance (assessed by digital photography) and environmental temperature (assessed by the available online environmental databases). We found that the female thorax and abdomen are darker (low luminance) in colder compared to warmer environments. In males, however, body luminance is not associated with environmental temperature. Theoretical and empirical evidence suggests that darker insects have an advantage in colder environments because they can heat faster than lighter ones (thermal melanism hypothesis). By showing that melanic Polistes inhabit cooler areas more than the brighter species, we presume that selection for effective heating may provide an adaptive explanation for the evolution of Polistes colour diversity.

Relationship between pre‐ and post‐copulatory traits in Salvator rufescens (Squamata: Teiidae)

Fri, 18 Nov 2016 00:00:00 -0800

Understanding pre- and post-copulatory mechanisms of sexual selection can provide insights into the evolution of male reproductive strategies. The phenotype-linked fertility hypothesis postulates that male sperm quality and secondary sexual characteristics will positively co-vary, whereas the sperm competition hypothesis predicts a negative association between those traits. Male reproductive traits often show variation throughout the reproductive period, suggesting that the relationship between pre- and post-copulatory sexual selection may vary temporally. Here, we evaluated the relationship between secondary sexual character and sperm traits and its temporal variation in Salvator rufescens, a south American lizard. We observed a negative relationship between jaw muscle and principal piece length of sperm and a variation in the relationship between pre- and post-copulatory traits throughout the reproductive period. Collectively, our results evidenced a trade-off between pre- and post-copulatory traits and a strong seasonal flexibility of male reproductive strategies in this lizard species.

Transition from monogyny to polygyny in Nephila senegalensis (Araneae: Nephilidae) is not accompanied by increased investment in sperm

Onno A. Preik, Jutta M. Schneider, Gabriele Uhl, Peter Michalik — Fri, 18 Nov 2016 00:00:00 -0800

A common male adaptation to prevent sperm competition is the placement of a mating plug. Such plugs are considered as an extreme investment if they comprise parts of the genital systems and render the male sterile. Genital mutilation occurs in monogynous spiders of several families and may co-occur with permanent sperm depletion, meaning that sperm production is terminated once males become mature. Within the orb-web spider genus Nephila, monogynous mating strategies are considered ancestral, although some species have reverted to a polygynous mating strategy. Although genital mutilation does not occur in these species, permanent sperm depletion (PSD) remained. We compared investment in sperm between an effectively plugging (Nephila fenestrata Thorell, 1859) and a closely-related nonplugging species [Nephila senegalensis (Walckenaer, 1841)]. Sperm investment should be higher in N. senegalensis because males are able to mate with several females, whereas N. fenestrata males can only achieve a maximum of two copulations, generally performed with the same female. The absence of a plugging mechanism in N. senegalensis and the inability to monopolize females by means of mating plugs results in a higher risk of sperm competition. Thus, we predicted higher investment in sperm producing tissue and larger sperm storage organs in males of N. senegalensis compared to N. fenestrata. We examined the testes and deferent ducts of both species for size and cell-quality differences using light and transmission electron microscopy and analyzed the volume of the sperm reservoir in the male copulatory organ (i.e. spermophor) using X-ray microcomputed tomography. In contrast to our prediction, the lumen of testes, deferent ducts, and spermophor of N. senegalensis males were significantly smaller than in N. fenestrata.

Toxin depletion has no effect on antipredator responses in common toad (Bufo bufo) tadpoles

Anikó Kurali, Katalin Pásztor, Attila Hettyey, Zoltán Tóth — Fri, 18 Nov 2016 00:00:00 -0800

Antipredator responses often involve changes in several phenotypic traits and these changes interactively influence fitness. However, gaining insight into how the overall fitness effect of the overall response comes about is notoriously difficult. One promising avenue is to manipulate a single defensive trait and observe how that modifies fitness as well as the expression of other inducible responses. In chemically-defended animals, toxins are likely to be costly to produce but it is still unknown how their depletion influences other characteristics. In the present study, we artificially depleted bufadienolide toxin stores in common toad (Bufo bufo) tadpoles, and assessed the effect of this with respect to the interaction with predator presence and limited food availability. We found that toxin depletion in tadpoles did not significantly affect any of the measured life-history traits. Tadpoles in the predator treatment exhibited an elevated development rate, although this was only apparent when food availability was limited. Also, body mass at metamorphosis was lower in tadpoles exposed to chemical cues indicating a predation threat and when food availability was limited. These results provide evidence that, in larval common toads, the expression of inducible defences may incur fitness costs, whereas chemical defences are either expressed constitutively or, if inducible, elevated toxin production has negligible costs.

Sexual dimorphism and sexual conflict in the diving beetle Agabus uliginosus (L.) (Coleoptera: Dytiscidae)

David T. Bilton, Jamie W. G. Hayward, Jonathan Rocha, Garth N. Foster — Fri, 18 Nov 2016 00:00:00 -0800

Sexual conflict can drive intersexual arms races, with female resistance and male persistence traits coevolving antagonistically. Such arms races are well documented in some diving beetles, although the extent of sexual conflict in this family remains unclear. The European dytiscid Agabus uliginosus has a strikingly dimorphic female; individuals from most regions are smooth and male-like, whereas those from some populations have a strongly roughened dorsum, a trait that has attracted the name dispar. We demonstrate that rough and smooth females differ consistently in the development of dorsal surface microreticulation, and that these females are associated with males that differ in the development of their persistence traits. These findings extend the occurrence of pre-insemination sexual conflict and associated intrasexual dimorphism in Dytiscidae, and suggest that such mating systems are relatively widespread in these beetles.

Size changes in island plants: independent trait evolution in Alyxia ruscifolia (Apocynaceae) on Lord Howe Island

K. C. Burns — Fri, 18 Nov 2016 00:00:00 -0800

Species that are endemic to isolated islands often differ dramatically in size from their mainland relatives, for reasons that are poorly understood. While decades of research have sought to better understand insular size changes in animals, far fewer studies have investigated insular size changes in plants. Here, I test for changes in plant stature, seed size and leaf area in a woody shrub (Alyxia ruscifolia, Apocynaceae), which inhabits both the continent of Australia, and Lord Howe Island, a subtropical island located 600 km off Australia's east coast. Results showed that island plants became reproductively mature at earlier stages of ontogeny than mainland plants, and that mature plants were taller on the mainland, providing a rare example of dwarfism in plants. Conversely, island plants produced larger seeds, which might make them more competitive as seedlings. Seeds produced by island plants were also less circular and more oblong in shape than their mainland counterparts, perhaps to facilitate their dispersal by avian frugivores with limited gape sizes. Lastly, island and mainland plants had similar average leaf sizes. However, juvenile plants on the mainland produced smaller, more needle-shaped leaves with larger terminal spines relative to adult plants, which may help protect them against large, ground-dwelling herbivores. On the other hand, island plants showed weaker ontogenetic shifts in leaf morphology in the absence of large herbivores. When interpreted jointly, results indicate that stature, seed size and leaf area are on separate evolutionary trajectories in A. ruscifolia, which appear to be determined by a complex suite of disparate selection pressures between Lord Howe Island and the mainland.

Biparental care is predominant and beneficial to parents in the burying beetle Nicrophorus orbicollis (Coleoptera: Silphidae)

Kyle M. Benowitz, Allen J. Moore — Fri, 18 Nov 2016 00:00:00 -0800

Parenting strategies can be flexible within a species and may have varying fitness effects. Understanding this flexibility and its fitness consequences is important for understanding why parenting strategies evolve. In the present study, we investigate the fitness consequences of flexible parenting in the burying beetle Nicrophorus orbicollis, a species known for its advanced provisioning behaviour of regurgitated vertebrate carrion to offspring by both sexes. We show that, even when a parent is freely allowed to abandon the carcass at any point in time, biparental post-hatching care is the most common pattern of care adopted in N. orbicollis. Furthermore, two parents together raised more offspring than single parents of either sex, showing that the presence of the male can directly influence parental fitness even in the absence of competitors. This contrasts with studies in other species of burying beetle, where biparental families do not differ in offspring number. This may explain why biparental care is more common in N. orbicollis than in other burying beetles. We suggest how the fitness benefits of two parents may play a role in the evolution and maintenance of flexible biparental care in N. orbicollis.

Evolution of dentition in salamanders: relative roles of phylogeny and diet

Fri, 18 Nov 2016 00:00:00 -0800

Despite being widely regarded as generalist predators, amphibians exhibit a diversity of tooth shapes and dentition patterns, which may indicate the influence of dietary specialization on the evolution of tooth morphology. Very few studies have analysed the relationship between tooth morphology and diet (i.e., prey items) in amphibians, and those existing studies are highly speculative. We investigated the evolution of salamander teeth and the relationship between tooth morphology and diet in a phylogenetically independent fashion. We used a phylogeny of 23 species of salamander representing three families (Ambystomatidae, Plethodontidae, and Salamandridae) to, first, analyse the divergence of tooth morphology and its relationship to phylogeny and, second, to analyse the relationship between tooth morphology and diet diversity. We used electron scanning microscopy and a statistical comparative approach using Spatial Evolutionary and Ecological Analysis (SEEVA) and phylogenetic generalized least-squares regression in R. Our results indicated significant divergence in tooth morphology at major phylogenetic splits. Moreover, there was a significant, phylogenetically independent relationship between tooth morphology and diet diversity. The relationship between diet and tooth morphology indicates not only a reflection of phylogenetic history, but also a degree of dietary specialization, indicating that evolution in tooth morphology has had an adaptive aspect in relation to salamander diet.

Extrinsic and intrinsic factors influence fitness in an avian hybrid zone

Fri, 18 Nov 2016 00:00:00 -0800

The effects of hybridization on evolutionary processes are primarily determined by the differential between hybrid and parental species fitness. Assessing the impacts of hybridization can be challenging, however, as determining the relationship between individual fitness and the extent of introgression in wild populations is difficult. We evaluated the fitness consequences of hybridization for pure and hybrid females in a hybrid zone between two tidal marsh birds, the saltmarsh sparrow (Ammodramus caudacutus), a salt marsh obligate, and Nelson's sparrow (A. nelsoni), which has a broader ecological niche and a much younger evolutionary association with salt marshes. Biotic stressors associated with nesting in tidal environments suggest an important role for differential adaptation in shaping hybrid zone dynamics, with saltmarsh sparrows predicted to be better adapted to nesting in salt marshes. We collected DNA samples from adults (n = 394) and nestlings (n = 431) to determine the extent of introgression using 12 microsatellite loci and tested for the influence of extrinsic (nest placement) and intrinsic (genotype) factors on female reproductive success. We monitored nests (n = 228), collected data on reproductive output, and estimated daily nest survival rates using female genotype and nest characteristics as covariates. To test for reduced survival of hybrid females, we also used capture data to assess the distribution of admixed male and female individuals across age classes. Reproductive success of females varied by genotypic class, but hybrids did not have intermediate success as predicted. Instead, we found that pure Nelson's sparrows had, on average, 33% lower hatching success than any other genotype, whereas F1/F2 hybrids, backcrossed Nelson's sparrows, and backcrossed and pure saltmarsh sparrows all had similar hatching success. We found no effect of genotype or nest placement on daily nest survival probabilities. However, hybrid individuals with a higher proportion of saltmarsh sparrow alleles exhibit nesting behaviours better suited to nesting successfully in tidal marshes. Further, while the proportion of F1/F2 individuals was similar between nestling and adult males, we found that the proportion of F1/F2 individuals was 2.3 times greater in nestling females compared with adult females, indicating reduced survival of F1 females. We conclude that differences in reproductive success among pure and admixed individuals coupled with intrinsic mechanisms (reduced survival in F1 females) shape hybrid zone dynamics in this system.

Reproductive failure: a new paradigm for extinction

Delbert Wiens, Thomas Worsley — Fri, 18 Nov 2016 00:00:00 -0800

Extinction was recognized as a scientific fact 200 years ago, although no adequate paradigm has emerged to explain the process. Prevailing theory has focused on ‘cause(s)’ of extinction but has neglected ‘effect’ and ‘mechanism’. These omissions preclude the formulation of a functional paradigm necessary for remedial action in response to the impending anthropogenic mediated, worldwide extinction crisis. The new paradigm is defined as the multi-generational, attritional loss of reproductive fitness. Stabilizing selection continuously adapts species to specific ecosystems, which often results in highly evolved species prone to extinction when environments shift. Some species survive by tracking the declining palaeoclimates in which they presumably evolved, often becoming relicts prior to extinction. Compelling new evidence shows that even mass extinctions are largely a result of environmental change leading to widespread, attritional reproductive decline, rather than a result of instantaneous global catastrophes.

Sexual size dimorphism and Rensch's rule in Canidae

Claudio J. Bidau, Pablo A. Martinez — Fri, 18 Nov 2016 00:00:00 -0800

The size variation between males and females of a species is a phenomenon known as sexual size dimorphism (SSD). The observed patterns of variation in SSD among species has led to the formulation of Rensch's rule, which establishes that, in species showing a male size bias, SSD increases with an increase in the body size of the species. However, for species in which there is a female size bias, the SSD would decrease when the body size of the species increases. In the present study, we examined the variation in body size and SSD of 33 species of canids from estimates of body mass and body length. We studied its relationship with life-history characteristics and tested Rensch's rule using phylogenetic generalized least squares and phylogenetic reduced major axis regressions, respectively. We observed the existence of correlation between body mass and body length, although the SSDs from these estimators are uncorrelated. SSD did not show the pattern predicted by Rensch's rule. SSD also did not show any correlation with life-history traits. It is likely that the low SSD observed in canids is related to the monogamy observed in the family, which is a rare situation in mammals.

Black rat invasion of inland Sahel: insights from interviews and population genetics in south‐western Niger

Fri, 18 Nov 2016 00:00:00 -0800

Human population migrations, as well as long-distance trade activities, have been responsible for the spread of many invasive organisms. The black rat, Rattus rattus, has colonized most of the world following ship-mediated trade. Owing to its tight association with human infrastructures, this species has been able to survive in unfavourable environments, such as Sahelian Africa. In this work, we combined interview-based and population genetic surveys to investigate the processes underlying the ongoing invasion of south-western Niger by black rats, with special emphasis on the capital city, Niamey. Our trapping and interview data are quite congruent, and all together point towards a patchy, but rather widespread, current distribution of R. rattus. Genetic data strongly suggest that road network development for truck-based commercial flow from/to international harbours located in neighbouring countries (Benin, Togo, and Nigeria) facilitates the passive dispersal of black rats over a long distance through unfavourable landscapes. Another potentially, more ancient, invasion route may be associated with boat transport along the Niger River. Human-mediated dispersal thus probably allows the foundation of persisting populations within highly anthropized areas while population dynamics may be more unstable in remote areas and mostly depends on propagule pressure.

Repeated evolution of local adaptation in swimming performance: population‐level trade‐offs between burst and endurance swimming in Brachyrhaphis freshwater fish

Spencer J. Ingley, Henry Camarillo, Hannah Willis, Jerald B. Johnson — Fri, 18 Nov 2016 00:00:00 -0800

Specialization is fundamentally important in biology because specialized traits allow species to expand into new environments, in turn promoting population differentiation and speciation. Specialization often results in trade-offs between traits that maximize fitness in one environment but not others. Despite the ubiquity of trade-offs, we know relatively little about how consistently trade-offs evolve between populations when multiple sets of populations experience similarly divergent selective regimes. In the present study, we report a case study on Brachyrhaphis fishes from different predation environments. We evaluate apparent within/between population trade-offs in burst-speed and endurance at two levels of evolutionary diversification: high- and low-predation populations of Brachyrhaphis rhabdophora, and sister species Brachyrhaphis roseni and Brachyrhaphis terrabensis, which occur in high- and low-predation environments, respectively. Populations of Brachyrhaphis experiencing different predation regimes consistently evolved swimming specializations indicative of a trade-off between two swimming forms that are likely highly adaptive in the environment in which they occur. We show that populations have become similarly locally adapted at both levels of diversification, suggesting that swimming specialization has evolved rather rapidly and persisted post-speciation. Our findings provide valuable insight into how local adaptation evolves at different stages of evolutionary divergence.

Diving in head first: trade‐offs between phenotypic traits and sand‐diving predator escape strategy in Meroles desert lizards

Fri, 18 Nov 2016 00:00:00 -0800

Survival, in part, depends on an individual's ability to evade predators. In desert regions some lizard species have evolved head-first sand-diving strategies to escape predators. To facilitate this behaviour, a distinctive head morphology that facilitates sand-diving has evolved. This specialised head morphology may, however, come at a cost to other ecologically relevant functions, particularly bite force. Here, we investigated the relationship between morphology and function in a southern African lacertid lizard genus, Meroles, which consists of eight species that utilise different escape strategies, including sand-diving and running for cover. It was hypothesized that the specialised head morphology of diving species would negatively affect bite force capacity. We found that species from each escape strategy category differed significantly in head shape, but not bite force performance. A phylogenetic tree of the genus was constructed using two mitochondrial and two nuclear genes, and we conducted phylogenetic comparative analyses. One aspect of the head shape differed between the escape strategies once phylogeny was taken into account. We found that bite force may have co-evolved with head morphology, but that there was no trade-off between biting capacity and escape strategy in Meroles.

Ecogeographical patterns of morphological variation in pygmy shrews Sorex minutus (Soricomorpha: Soricinae) within a phylogeographical and continental‐and‐island framework

Rodrigo Vega, Allan D. Mcdevitt, Boris Kryštufek, Jeremy B. Searle — Fri, 18 Nov 2016 00:00:00 -0800

Ecogeographical patterns of morphological variation were studied in the Eurasian pygmy shrew Sorex minutus aiming to understand the species’ morphological diversity in a continental and island setting, and within the context of previous detailed phylogeographical studies. In total, 568 mandibles and 377 skulls of S. minutus from continental and island populations from Europe and Atlantic islands were examined using a geometric morphometrics approach, and the general relationships of mandible and skull size and shape with geographical and environmental variables were studied. Samples were then pooled into predefined geographical groups to evaluate the morphological differences among them using analyses of variance, aiming to contrast the morphological and genetic relationships based on morphological and genetic distances and ancestral state reconstructions, as well as assess the correlations of morphological, genetic, and geographical distances with Mantel tests. We found significant relationships of mandible size with geographical and environmental variables, fitting the converse Bergmann's rule; however, for skull size, this was less evident. Continental groups of S. minutus could not readily be differentiated from each other by shape. Most island groups of S. minutus were easily discriminated from the continental groups by being larger, indicative of an island effect. Moreover, morphological and genetic distances differed substantially and, again, island groups were distinctive morphologically. Morphological and geographical distances were significantly correlated, although this was not the case for morphological and genetic distances, indicating that morphological variation does not reflect genetic subdivision in S. minutus. Our analyses showed that environmental variables and insularity had important effects on the morphological differentiation of S. minutus.

Environment and space as drivers of variation in skull shape in two widely distributed South‐American Tayassuidae, Pecari tajacu and Tayassu pecari (Mammalia: Cetartiodactyla)

Carla D. Hendges, Jamile M. Bubadué, Nilton C. Cáceres — Fri, 18 Nov 2016 00:00:00 -0800

The influence of the environment on the geographical variation of morphological traits has been recognized in a number of taxa. Pecari tajacu and Tayassu pecari are ideal models to investigate intraspecific geographic variation in skull because of their wide and heterogeneous geographical distribution in South America. We used geometric morphometric procedures to examine the geographical variation in skull shape of 294 adult specimens of these species from 134 localities. We quantified to what extent skull shape variation was explained by environment, skull size and geographical space using variation partitioning analysis. We detected a strong pattern of geographic variation for P. tajacu skull shape, but not for T. pecari. The environment seems to be the major selective force that drives skull shape variation in both species. Nevertheless, other spatially structured processes (e.g. genetic drift, gene flow) might also have affected variation in the skull shape of the more widespread species P. tajacu. Allometric relationships might reflect the biomechanical constraints that are thought to be strong enough to limit size-related changes in T. pecari skull shape.

Dietary adaptations in the teeth of murine rodents (Muridae): a test of biomechanical predictions

Stephanie A. Martin, Bader H. Alhajeri, Scott J. Steppan — Fri, 18 Nov 2016 00:00:00 -0800

Functional dental theory predicts that tooth shape responds evolutionarily to the mechanical properties of food. Most studies of mammalian teeth have focused on qualitative measures of dental anatomy and have not formally tested how the functional components of teeth adapt in response to diet. Here we generated a series of predictions for tooth morphology based on biomechanical models of food processing. We used murine rodents (Old World rats and mice) to test these predictions for the relationship between diet and morphology and to identify a suite of functional dental characteristics that best predict diets. One hundred and five dental characteristics were extracted from images of the upper and lower tooth rows and incisors for 98 species. After accounting for phylogenetic relationships, we showed that species evolving plant-dominated diets evolved deeper incisors, longer third molars, longer molar crests, blunter posteriorly angled cusps, and more expanded laterally oriented occlusal cusps than species adapting to animal-dominated diets. Measures of incisor depth, crest length, cusp angle and sharpness, occlusal cusp orientation, and the lengths of third molars proved the best predictors of dietary adaptation. Accounting for evolutionary history in a phylogenetic discriminant function analysis notably improved the classification accuracy. Molar morphology is strongly correlated with diet and we suggest that these dental traits can be used to infer diet with good accuracy for both extinct and extant murine species.

Production and sex‐pheromonal activity of alkaloid‐derived androconial compounds in the danaine butterfly, Parantica sita (Lepidoptera: Nymphalidae: Danainae)

Fri, 18 Nov 2016 00:00:00 -0800

Close associations of certain lepidopteran taxa with pyrrolizidine alkaloids (PAs), a typical class of plant secondary metabolites, have been well documented from the perspective of evolutionary ecology. Male danaine butterflies are thought to utilize PAs as precursors for the production of dihydropyrrolizines [e.g. danaidone (DO) and hydroxydanaidal (HD)] in their two distinct androconial organs, viz. alar scent organs (sex brands) and abdominal hairpencils. However, little is known about the quantitative profiles of these compounds in danaines, the mechanism for their formation in the androconial organs, or their biological functions, particularly in mating behaviour. The present study addressed these unanswered questions posed for males of the danaine butterfly, Parantica sita. Chemical analyses of androconial extracts revealed considerable seasonal/regional and individual variations of the amounts of DO (the major dihydropyrrolizine produced) and 7R-HD (the 7R-enantiomer of HD detected in this study) found in the two organs. These variations seemed to depend primarily on the age of the male and the phenological traits of PA-containing plants available. Males were found to acquire an adequate capability to produce DO ~1 week after eclosion. DO was shown to be produced exclusively in the sex brand and subsequently physically transferred to the hairpencil through a contact behaviour between the two organs, here termed ‘perfuming behaviour’. The results of behavioural experiments with PA-fed and PA-unfed males that were allowed to compete for mates, combined with the positive electroantennographic (EAG) responses of the female, to both DO and 7R-HD, led to the conclusion that either or both of these compounds can act as the sex pheromone. Oral administration of PAs to males indicated that DO can be biosynthesized from various PA precursors, while 7R-HD, unlike in arctiid moths, is derived only from PAs with the 7R-configuration. The putative biosynthetic pathways of DO and 7R-HD, and the evolutionary provenance of the binate androconial system in the Danainae are also discussed.

Phylogeny, biogeography, and diversification of barn owls (Aves: Strigiformes)

Fri, 18 Nov 2016 00:00:00 -0800

The existence of substantial morphological variation has resulted in the description of numerous subspecies of the cosmopolitan barn owl, Tyto alba. However, preliminary studies have revealed a high degree of genetic variation between Old and New World barn owls, suggesting that the T. alba complex may consist of several species. We present a comprehensive study of its taxonomy and propose a spatiotemporal framework to explain the origin and patterns of dispersal and diversification within these cosmopolitan owls. We used a Bayesian relaxed molecular clock approach to assess the timing of diversification. To evaluate the biogeographical pattern, we considered dispersal in addition to temporal connectivity between areas. Finally, we used ecological niche modelling to evaluate their ecological niches. Our phylogenetic analyses suggest that barn owls of the Old and New World show a high degree of genetic divergence, and the barn owls of South and South-east Asia (Tyto alba stertens and Tyto alba javanica) cluster with the Australian barn owl Tyto delicatula. We propose to treat the T. alba complex as three species: T. alba (Africa, Europe), Tyto furcata (New World), and Tyto javanica (Australasia). The dating analyses indicate that the early divergence among the species of the T. alba complex took place in the Middle Miocene and we hypothesize that a common ancestor of the T. alba complex lived in Africa. A potential scenario suggests that T. alba dispersed to Europe and south-western Asia during the interglacial periods of the Miocene/Pliocene, and dispersed into the New World either via an eastern Asian route or a western north Atlantic one.

Athletic anurans: the impact of morphology, ecology and evolution on climbing ability in invasive cane toads

Cameron M. Hudson, Gregory P. Brown, Richard Shine — Fri, 18 Nov 2016 00:00:00 -0800

Although primarily terrestrial, cane toads (Rhinella marina) sometimes climb near-vertical surfaces (tree-trunks, cliffs, fences) during foraging or dispersal activities. We scored climbing ability (in laboratory trials) of 288 cane toads from four regions in Australia, plus two sites on the island of Hawai'i. We found strong divergence in climbing ability associated not only with sex and relative limb length, but also population of origin. Within each population, longer-limbed individuals (and hence, males rather than females) were better climbers, although the geographical divergence in climbing ability remained significant even when sex and limb length were included in multivariate regression models. The geographical difference in climbing ability (but not morphology) disappeared when the progeny were raised in captivity under identical conditions, without climbing opportunities. Although influenced by morphology, climbing ability in wild-caught cane toads appears to be driven primarily by local environmental conditions that facilitate and/or reward arboreal activity.

Genetic implications of phylogeographical patterns in the conservation of the boreal wetland butterfly Colias palaeno (Pieridae)

Fri, 18 Nov 2016 00:00:00 -0800

The boreo-montane wetland butterfly species Colias palaeno has a European distribution from the Alps to northern Fennoscandia. Within its European range, the species’ populations have shrunk dramatically in recent historical times. Therefore, detailed baseline knowledge of the genetic makeup of the species is pivotal in planning potential conservation strategies. We collected 523 individuals from 21 populations across the entire European range and analyzed nuclear (20 allozyme loci) and mitochondrial (600 bp of the cytochrome c oxidase subunit I gene) genetic markers. The markers revealed contrasting levels of genetic diversity and divergence: higher in allozymes and lower in mitochondrial sequences. Five main groups were identified by allozymes: Alps, two Czech groups, Baltic countries, Fennoscandia, and Poland. The haplotype mitochondrial network indicates a recent range expansion. The most parsimonious interpretation for our results is the existence of a continuous Würm glacial distribution in Central Europe, with secondary disjunction during the Last Glacial Maximum into a south-western and a north-eastern fragment and subsequent moderate differentiation. Both groups present signs of postglacial intermixing in the Czech Republic. However, even a complete extinction in this region would not considerably affect the species’ genetic basis, as long as the source populations in the Alps and in northern Europe, comprising the most relevant evolutionary units for conservation, are surviving.

Phylogeographic analysis reveals northerly refugia for the riverine amphibian Triturus dobrogicus (Caudata: Salamandridae)

Judit Vörös, Peter Mikulíček, Ágnes Major, Ernesto Recuero, Jan W. Arntzen — Fri, 18 Nov 2016 00:00:00 -0800

We investigated the recent evolutionary history of the Danube crested newt, Triturus dobrogicus through reconstructions of: (1) the number and position of refugia at the last glacial maximum, (2) the role of major central European rivers in pattern of post-glacial dispersal, and (3) the present-day distribution pattern. We analysed sequences of mitochondrial DNA (ND2, 1065 bp) and six microsatellite loci in 363 T. dobrogicus individuals from 58 populations covering the range of the species. Our analyses suggested that T. dobrogicus survived the last glacial maximum in two separate refugia positioned in northwestern Pannonia and in Southern Pannonia from where its range expanded along the Danube and Tisza Rivers. Our findings also confirmed that rivers played an important role in shaping the evolutionary history of amphibian species in Central Europe. We compared the T. dobrogicus range with another lowland amphibian, the fire-bellied toad Bombina bombina, using species distribution modelling. In line with these models, the isolated mountains inside Pannonia are occupied not by B. bombina, but by its mountain-dwelling sister-species B. variegata. However, in contrast to the model, crested newts (including T. dobrogicus) are absent from these mountains. We attribute this biogeographical discrepancy to the positioning of the species’ refugia at the last glacial maximum.

Phenological matching rather than genetic variation in host preference underlies geographical variation in host plants used by orange tip butterflies

Fri, 18 Nov 2016 00:00:00 -0800

An insect species that shows variation in host species association across its geographical range may do so either because of local adaptation in host plant preference of the insect or through environmentally or genetically induced differences in the plants, causing variation in host plant suitability between regions. In the present study, we experimentally investigate the host plant preference of Anthocharis cardamines (orange tip butterfly) in two populations from the UK and two from Sweden. Previous reports indicate that A. cardamines larvae are found on different host plant species in different regions of the UK, and some variation has been reported in Sweden. Host plant choice trials showed that females prefer to oviposit on plants in an earlier phenological stage, as well as on larger plants. When controlling for plant phenological stage and size, the host species had no statistically significant effect on the choice of the females. Moreover, there were no differences in host plant species preference among the four butterfly populations. Based on our experiment, the oviposition choice by A. cardamines mainly depends on the phenological stage and the size of the host plant. This finding supports the idea that the geographical patterns of host–plant association of A. cardamines in the UK and Sweden are consequences of the phenology and availability of the local hosts, rather than regional genetic differences in the host species preference of the butterfly.

Comparative anatomy of the bony labyrinth of extant and extinct porpoises (Cetacea: Phocoenidae)

Rachel A. Racicot, William Gearty, Naoki Kohno, John J. Flynn — Fri, 18 Nov 2016 00:00:00 -0800

The inner ear anatomy of cetaceans, now more readily accessible by means of nondestructive high-resolution X-ray computed tomographic (CT) scanning, provides a window into their acoustic abilities and ecological preferences. Inner ear labyrinths also may be a source for additional morphological characters for phylogenetic analyses. In this study, we explore digital endocasts of the inner ear labyrinths of representative species of extinct and extant porpoises (Mammalia: Cetacea: Phocoenidae), a clade of some of the smallest odontocete cetaceans, which produce some of the highest-frequency clicks for biosonar and communication. Metrics used to infer hearing ranges based on cochlear morphology indicate that all taxa considered could hear high-frequency sounds, thus the group had already acquired high-frequency hearing capabilities by the Miocene (9–11 Mya) at the latest. Vestibular morphology indicates that extant species with pelagic preferences have similarly low semicircular canal deviations from 90°, values indicating more sensitivity to head rotations. Species with near-shore preferences have higher canal deviation values, indicating less sensitivity to head rotations. Extending these analyses to the extinct species, we demonstrate a good match between those predicted to have coastal (such as Semirostrum cerutti) preferences and high canal deviation values. We establish new body length relationships based on correlations with inner ear labyrinth volume, which can be further explored among other aquatic mammals to infer body size of specimens consisting of fragmentary material.

Long‐distance dispersal and inter‐island colonization across the western Malagasy Region explain diversification in brush‐warblers (Passeriformes: Nesillas)

Fri, 18 Nov 2016 00:00:00 -0800

The present study examines the colonization history and phylogeography of the brush-warblers (Nesillas), a genus of passerines endemic to islands of the western Indian Ocean (Madagascar, Comoros, and Aldabra Atoll). The phylogeny of all recognized Nesillas taxa was reconstructed employing Bayesian phylogenetic methods and divergence times were estimated using a range of substitution rates and clock assumptions. Spatiotemporal patterns of population expansion were inferred and niches of different lineages were compared using ecological niche modelling. Our results indicate that taxa endemic to the Comoros are paraphyletic and that the two endemic species on Madagascar (Nesillas typica and Nesillas lantzii) are not sister taxa. The brush-warblers started to diversify approximately 1.6 Mya, commencing with the separation of the clade formed by two species endemic to the Comoros (Nesillas brevicaudata and Nesillas mariae) from the rest of the genus. The lineages leading to the two Malagasy species diverged approximately 0.9 Mya; each with significantly different modern ecological niches and the subject of separate demographic processes. Patterns of diversification and endemism in Nesillas were shaped by multiple long distance dispersal events and inter-island colonization, a recurring pattern for different lineages on western Indian Ocean islands. The diversification dynamics observed for Nesillas are also consistent with the taxon cycle hypothesis.

Effects of Pleistocene climate changes on species ranges and evolutionary processes in the Neotropical Atlantic Forest

Fri, 18 Nov 2016 00:00:00 -0800

The effects of global glaciations on the distribution of organisms is an essential element of many diversification models. However, the empirical evidence supporting this idea is mixed, in particular with respect to explaining tropical forest evolution. In the present study, we evaluated the impacts of range shifts associated with Pleistocene global glacial cycles on the evolution of tropical forests. In particular, we tested the predictions: (1) that population genetic structure increases with fragmentation variation between the present and the Last Glacial Maximum (LGM) and also (2) with geographical range instability; and (3) that genetic diversity increases with range stability and (4) decreases with fragmentation variation between periods. To address our predictions, we studied population genetic structures and modelled present and past distributions of 15 Atlantic Forest (AF) endemic birds. Afterwards, we evaluated the relationship of population genetic parameters with metrics of species range shifts between the present and the LGM. We found that geographical ranges of AF birds changed in concert with Pleistocene glacial cycles but, unexpectedly, our findings suggest the novel idea that ranges during glacial maxima were slightly larger on average, as well as equally fragmented and displaced from the interglacial ranges. Our findings suggest that range shifts over the late Pleistocene impacted on the diversification of forest organisms, although they did not show that those range shifts had a strong effect. We found that a combination of fragmentation variation across time, small current range size, and range stability increased population genetic structure. However, neither fragmentation, nor range stability affected genetic diversity. Our study showed that evolutionary responses to range shifts across AF birds have a high variance, which could explain the mixed support given by single-species studies to the action of Pleistocene range shifts on population evolution.

Pleistocene diversification in Morocco and recent demographic expansion in the Mediterranean pond turtle Mauremys leprosa

Fri, 18 Nov 2016 00:00:00 -0800

Quaternary climatic oscillations and geographic barriers have strongly influenced the distribution and diversification of thermophilic species occurring in the Mediterranean Basin. The Western Mediterranean pond turtle, Mauremys leprosa, is widely distributed throughout the Iberian Peninsula, southern France and most of the Maghreb region, with two subspecies currently recognized. In this work, we used 566 samples, including 259 new individuals, across the species range, and sequenced two mitochondrial markers (cytochrome b gene and control region; 163 samples in a concatenated mtDNA dataset) and one nuclear intron (R35; 23 samples representing all identified sublineages) to study the evolutionary history of M. leprosa. We combined phylogenetic methods and phylogeographic continuous diffusion models with spatial analysis. Our results (1) show a high level of genetic structure in Morocco originated during the Pleistocene; (2) reveal two independent population expansion waves from Morocco to Tunisia and to southern Europe, which later expanded throughout the Iberian Peninsula, and (3) identify several secondary contact zones in Morocco. Our study also sheds new light on the role of geographical features (Moroccan mountains ranges and the Strait of Gibraltar) and Pleistocene climatic oscillations in shaping genetic diversity and structure of M. leprosa, and underlines the importance of the Maghreb as a differentiation centre harbouring distinct glacial refugia.

Comment on Altaba (2015): a case of species misidentification?

Michal Horsák, Robert A. D. Cameron — Fri, 18 Nov 2016 00:00:00 -0800

Previously in this journal, Altaba (2015) presented an original hypothesis on the dispersal of small wetland snails in Central Europe after the Last Glacial Maximum, based on the discovery of rare species of the genus Vallonia at the foot of the Devín Hill (Slovakia). On the basis of the evidence available to us, it is our opinion that the existence of Vallonia declivis, Vallonia suevica, Vallonia enniensis, and Vallonia tenuilabris at Devín Gate has not been established, and that the hypothesis advanced in Altaba (2015) is therefore unsubstantiated by hard evidence.

Issue Information

Fri, 18 Nov 2016 00:00:00 -0800

Biological Journal of the Linnean Society, Volume 119, Issue 4, Page 745-747, December 2016.

Convergent evolution in the colour polymorphism of Selkirkiella spiders (Theridiidae) from the South American temperate rainforest

Thu, 17 Nov 2016 00:00:00 -0800

Convergent evolution tends to lead to similar phenotypic responses to the same selective pressures. However, when the phenotypic response is polymorphic, it is less clear how evolutionary convergence can lead to parallel diversity across species and populations. The present study focuses on South American spiders in the genus Selkirkiella (Theridiidae), which are shown to be polymorphic for colour. We (1) examine the number of morphs and their correspondence across taxa and (2) place the phenomenon in a phylogenetic context to determine whether the colour polymorphism in Selkirkiella albogutatta from the Juan Fernández archipelago represents a case of independent evolution and convergence, or whether there is common ancestry with other colour-polymorphic theridiids. Regarding the latter question, we also examine colour morphs in a related species (Selkirkiella luisi) from continental areas. We show that S. alboguttata and S. luisi have six and two morphs, respectively. The rank-order of morph frequencies in both species is approximately similar to that reported in other polymorphic theridiids. A molecular phylogeny supports previous work and shows that the colour polymorphism in Selkirkiella species appears to be a case of convergent evolution of a diverse colour polymorphism at the family level.

Challenge to the model of lake charr evolution: shallow‐ and deep‐water morphs exist within a small postglacial lake

Wed, 16 Nov 2016 00:00:00 -0800

All examples of lake charr (Salvelinus namaycush) diversity occur within the largest, deepest lakes of North America (i.e. > 2000 km²). We report here Rush Lake (1.3 km²) as the first example of a small lake with two lake charr morphs (lean and huronicus). Morphology, diet, life history, and genetics were examined to demonstrate the existence of morphs and determine the potential influence of evolutionary processes that led to their formation or maintenance. Results showed that the huronicus morph, caught in deep-water, had a deeper body, smaller head and jaws, higher eye position, greater buoyancy, and deeper peduncle than the shallow-water lean morph. Huronicus grew slower to a smaller adult size, and had an older mean age than the lean morph. Genetic comparisons showed low genetic divergence between morphs, indicating incomplete reproductive isolation. Phenotypic plasticity and differences in habitat use between deep and shallow waters associated with variation in foraging opportunities seems to have been sufficient to maintain the two morphs, demonstrating their important roles in resource polymorphism. Rush Lake expands previous explanations for lake charr intraspecific diversity, from large to small lakes and from reproductive isolation to the presence of gene flow associated with strong ecological drivers.

Large‐scale phylogenetic structure of European springtails (Collembola) depends on species range size and postglacial colonization history

Cristina Fiera, Jan Christian Habel, Mieczysław Kunz, Werner Ulrich — Fri, 11 Nov 2016 00:00:00 -0800

The postglacial European colonization history has come into the focus of biogeographical interest and the study of phylogenetic relatedness within and between regional faunas and floras has proven to be an effective tool for the reconstruction of postglacial colonization trajectories. In the present study, we used a faunal compilation of 2078 European springtail species and data on taxonomic relatedness to investigate whether phylogenetic diversity increases along the gradients from southern glacial refugia towards northern Europe and also whether glacial refugia are phylogenetically segregated, as predicted by models of glacial evolutionary processes and postglacial colonization. In addition, we investigated whether species of restricted range sizes differ in phylogenetic diversity from widespread species as expected by niche models. Proportions of species with restricted range size were highest in glacial refugia, particularly in Spain, as well as on Northern European islands. We found contrasting latitudinal gradients of phylogenetic diversity decreasing in widespread species and increasing in restricted species. Endemic relatedness was negatively correlated with island size. Peaks of phylogenetic diversity in the Pannonian regions and on islands far north indicate a faunal contribution from several glacial refugia and additional refugia north of the Alps, respectively. High phylogenetic clustering in the Iberian Peninsula corroborates models of glacial speciation pulses within major refugia.

Temporal frames of 45S rDNA site‐number variation in diploid plant lineages: lessons from the rock rose genus Cistus (Cistaceae)

Thu, 10 Nov 2016 00:00:00 -0800

The perception that the turnover of 45S rDNA site number in plants is highly dynamic pervades the literature on rDNA evolution. However, most reported evidences come from the study of polyploid systems and from crop species subjected to intense agronomic selection. In sharp contrast with polyploids, the evolutionary patterns of rDNA loci number in predominantly diploid lineages have received less attention. Most studies on rDNA loci changes lack explicit temporal frames, and hence their dynamics could not be assessed. Here, we assess the temporal patterns of rDNA site evolution in Cistus, an entirely diploid lineage. We assessed the number and chromosomal position of 45S rDNA loci in Cistus species using fluorescence in situ hybridization (FISH) and Ag-nucleolus organizing regions (Ag-NOR) staining. Maximum likelihood and maximum parsimony reconstructions of the ancestral state of the 45S rDNA locus number were inferred onto a dated phylogeny. 45S rDNA locus number in Cistus ranged from one to four. Maximum likelihood and maximum parsimony reconstructions suggested that the two-loci state was the ancestral condition in Cistaceae, including the sister genera Tuberaria and Cistus. The most likely basal number of rDNA loci (two) has been maintained from the hypothesized ancient splitting events between Fumana and the remaining Cistaceae lineages in the Oligocene to most of the recent clades of Cistus diversified in the Middle Pleistocene. Our results support the view that evolutionary stasis regarding the number of 45S rDNA loci have been prevalent in several Cistus lineages and close relatives along their evolutionary history. It is suggested that conservation in rDNA site number likely occurred along more than 25 Mya of plant evolution, leading support to hypothesize that rDNA stasis in site number may have been neglected and underestimated in plant evolution at the diploid level.

Giant cannibals drive selection for inducible defence in heterospecific prey

Kunio Takatsu, Volker H. W. Rudolf, Osamu Kishida — Wed, 09 Nov 2016 00:00:00 -0800

Predation can strongly influence the evolution of prey species by selecting for defensive phenotypes that reduce the risk of predation. Although cannibalism is frequent in predators and is known to strongly influence predator–prey dynamics, it is largely neglected when studying the evolution of phenotypic defences in prey. Changes in cannibalism can alter the abundance, size-structure, and even phenotypes within predator populations, and thereby change the numerical and per-capita effects driving the selection pressure on defensive phenotypes in prey. In the present study, we experimentally manipulated the presence and absence of cannibalism in predatory salamander larvae Hynobius retardatus (Dunn) and examined how this affects the expression of and selection pressure on inducible defensive phenotype (bulgy phenotype) in its prey, Rana pirica (Matsui) tadpoles. In the absence of cannibalism, salamanders were generally not sufficiently large to consume tadpoles, tadpoles did not express the defensive phenotype, and all phenotypes had equally high survival. By contrast, cannibalism of salamanders accelerated growth rates, leading to the development of ‘giant’ cannibalistic morphs that were able to consume tadpoles. Importantly, only in the presence of these giant cannibals did tadpoles express a defensive ‘bulgy’ phenotype that had significantly higher survival rates than phenotypes without this defence, indicating that cannibalism altered the selective regime for defensive traits in prey. The results of the present study demonstrate that cannibalism can drive trait evolution in predator–prey systems and suggest that we cannot predict how changes in numerical effects in predator populations affect selection regimes on prey traits without accounting for concurrent changes in predator per-capita effects.

Receiver‐error in deception, including mimicry: making the leap from inter‐ to intraspecific domains

Paul J. Weldon — Wed, 09 Nov 2016 00:00:00 -0800

The present study examines the constructs of ‘deception’ and ‘mimicry’ and describes how they are related as errors committed by signal receivers, citing parallels in inter- and intraspecific interactions. Previous authors have suggested that deception embraces two types of receiver-error that can be likened to type I and type II errors encountered in statistical tests of the null hypothesis: responses to misinterpreted cues (type I error: embracing a non-existent effect) and failed responses to concealed traits of interest or undetected opportunities (type II error: failing to detect a real effect). The present study builds upon these suggestions, co-opting the terms ‘type I and type II receiver-errors’ to denote the aforementioned kinds of deception. Type I receiver-errors occur in many cases of Batesian mimicry, bluffing, and intersexual mimicry, where members of one sex mimic members of the opposite sex. Type II receiver-errors are illustrated by prey and predator crypsis and some covert (‘sneaky’) mating strategies. A third kind of receiver-error, designated type II–I, occurs when organisms are misidentified contingent upon the concealment of tell-tale features, such as with cephalopods that hide select arms in visual mimetic displays. The occurrence of advantages and disadvantages for signallers and signal receivers in inter- and intraspecific deception, and in their evolutionary repercussions, is discussed. Advergence, where deceptive signallers evolve increased resemblance to honest signallers, and divergence, where honest signallers become distinct from deceptive signallers, may arise from the dynamical interactions between signallers and signal receivers. Signal senders, by definition, benefit from deception. Deceived signal receivers also may benefit from some, perhaps many, interactions. Deception and evolutionary responses to deception are abundantly represented in both inter- and intraspecific domains.

Integrating ecological roles and trophic diversification on coral reefs: multiple lines of evidence identify parrotfishes as microphages

Wed, 09 Nov 2016 00:00:00 -0800

Coral reef ecosystems are remarkable for their high productivity in nutrient-poor waters. A high proportion of primary production is consumed by the dominant herbivore assemblage, teleost fishes, many of which are the product of recent and rapid diversification. Our review and synthesis of the trophodynamics of herbivorous reef fishes suggests that current models underestimate the level of resource partitioning, and thus trophic innovation, in this diverse assemblage. We examine several lines of evidence including feeding observations, trophic anatomy, and biochemical analyses of diet, tissue composition and digestive processes to show that the prevailing view (including explicit models) of parrotfishes as primary consumers of macroscopic algae is incompatible with available data. Instead, the data are consistent with the hypothesis that most parrotfishes are microphages that target cyanobacteria and other protein-rich autotrophic microorganisms that live on (epilithic) or within (endolithic) calcareous substrata, are epiphytic on algae or seagrasses, or endosymbiotic within sessile invertebrates. This novel view of parrotfish feeding biology provides a unified explanation for the apparently disparate range of feeding substrata used by parrotfishes, and integrates parrotfish nutrition with their ecological roles in reef bioerosion and sediment transport. Accelerated evolution in parrotfishes can now be explained as the result of (1) the ability to utilize a novel food resource for reef fishes, i.e. microscopic autotrophs; and (2) the partitioning of this resource by habitat and successional stage.

Isolation barriers and genetic divergence in non‐territorial Argia damselflies

Sat, 05 Nov 2016 00:00:00 -0700

Isolation barriers work at different instances during the mating process in odonate insects. In territorial damselflies, heterospecific interactions are mainly precluded by sexual (visual) isolation, while in non-territorial damselflies, heterospecific interactions are mostly precluded by mechanical isolation and sexual (tactile) isolation. In this study we investigated the strength of three premating barriers (visual, mechanical and tactile), genetic divergence and degree of sympatry (on their entire distribution) between four non-territorial Argia damselflies (A. anceps, A. extranea, A. oenea and A. tezpi). Our results are explained in the light of learned mating preferences and Kaneshiro's hypothesis. We detected a strong reproductive isolation between all pairs of species by the joint action of the three studied barriers [visual (90.6%), mechanical (8.7%) and tactile (0.7%)]. Sexual (visual) isolation was the most important barrier, perhaps driven by learning mating preferences. One of the studied species, A. extranea, which is the most derived of the studied species, showed a highly asymmetric isolation in reciprocal crosses, which is consistent with Kaneshiro's hypothesis. Moreover, we detected a negligible ecological niche differentiation between the studied species (70% of shared distribution). Our results suggest that sexual (visual) selection may be an important force driving speciation in non-territorial species.

Food partitioning and the evolution of non‐randomly structured communities in tailed amphibians: a worldwide systematic review

Leonardo Vignoli, Alessandra Maria Bissattini, Luca Luiselli — Fri, 04 Nov 2016 00:00:00 -0700

The evolutionary response to interspecific competition is the partitioning of the resources used by the competing species. At the community level, the ultimate outcome of resource partitioning determines how communities evolve in terms of their species composition, explaining the distribution and abundance of organisms within natural assemblages. Despite amphibians having attracted considerable attention from population biologists, niche partitioning patterns have never been explored with a systematic approach in tailed amphibians (order Urodela). To fill this gap we tested whether Urodela communities are assembled in a non-random fashion along the trophic niche and which determinants (environmental factors and interspecific interactions) explained the observed patterns. We used a suite of statistical tools, including Generalized Linear Models and Null Models with Monte Carlo simulations, in order: (1) to explore the occurrence of non-random assemblage structure among the Urodela communities, and (2) to test environmental features (habitat) and interspecific interactions (exemplified by the overlap in species’ body size) as predictors of non-random assemblage composition. Our systematic review pointed out that: (1) the evolution of non-random structure in Urodela assemblages was determined by both biotic and abiotic factors, and (2) the food niche plays a key role in the coexistence of Urodela syntopic species. The considered assemblages showed a non-random structure influenced by diet, habitat and morphological features acting in an interactive fashion. Lawlor's RA2 algorithm was more effective than any other randomization algorithms to reveal community structure based on interspecific competition. The assemblage structure was influenced by the niche breadth of the species in the generalist–specialist nature of the resource utilization: the much higher the niche breadth similarity among species, the most likely was a non-random structure in the assemblage. In an aquatic habitat, where species can partition the space in three dimensions, assemblages composed by species overlapping in body size and generalist in feeding behaviour show non-random structure. Conversely, in terrestrial habitats, probably due to the lack of vertical stratification, differently sized species composed assemblages in a non-random fashion.

Genetic evidence for promiscuity in the Ornate Tinamou Nothoprocta ornata (Aves: Tinamiformes)

Lina M. Giraldo‐Deck, Jan C. Habel, Harald Meimberg, Álvaro Garitano‐Zavala — Mon, 31 Oct 2016 00:00:00 -0700

Tinamous have male-only parental care. For their mating system, simultaneous polygyny and sequential polyandry is proposed as an optimal model and is confirmed in all species according to the existing literature, except in the Ornate Tinamou. For the Ornate Tinamou a monogamous mating system is reported. However, this knowledge is based only on few direct observations in the field. Social monogamy in association with promiscuity would probably expose males to cuckoldry and, at the same time, constrain additional mating opportunities for them. To understand the evolutionary context for monogamy in the Ornate Tinamou, the present study aimed to determine whether this species is genetically monogamous or not and whether males are subjected to cuckoldry. We used polymorphic microsatellite markers to perform a sib-ship and paternity analysis based on samples from eggs and feathers of incubating males from four clutches. Promiscuity was found in all nests and the observed rate of cuckoldry ranged from 0% to 33.3%. These results rebut the consideration of monogamy for the Ornate Tinamou. Thus, the optimal model with polygynous males and polyandrous females prevails as an evolutionary stable strategy among tinamous, even in different social mating systems and despite high levels of cuckoldry.

One tunic but more than one barcode: evolutionary insights from dynamic mitochondrial DNA in Salpa thompsoni (Tunicata: Salpida)

William P. Goodall‐Copestake — Wed, 26 Oct 2016 00:00:00 -0700

The DNA barcode within the mitochondrial cox1 gene is typically used to assess the identity and diversity of animals under the assumption that individuals contain a single form of this genetic marker. This study reports on a novel exception from the pelagic tunicate Salpa thompsoni Foxton. Oozoids caught off South Georgia and the Antarctic Peninsula generated barcodes consisting of a single prominent DNA sequence with some additional, subtler signals of intra-individual variation. Further investigation revealed this was due to duplicated and/or minicircular DNAs. These could not simply be explained as artefacts or nuclear copies of mitochondrial DNA, but provided evidence for heteroplasmy arising from a dynamic mitochondrial genome. Genetic variation of this sort may allow S. thompsoni to ecologically benefit from asexually driven population blooms without incurring the genetic cost of an excessive mutational load. Analysis of the prominent barcode sequence data yielded low haplotype (h < 0.61) and nucleotide (π < 0.0014) diversities, and no evidence for genetic structure between sampling locations as assessed using analysis of molecular variance. These results are consistent with the impact of population blooms and the mixing effect of Southern Ocean currents on S. thompsoni genetic diversity.

Spatial genetic structure of forest and xerophytic plant species in arid Eastern Central Asia: insights from comparative phylogeography and ecological niche modelling

Hong‐Xiang Zhang, Ming‐Li Zhang, Stewart C. Sanderson — Wed, 26 Oct 2016 00:00:00 -0700

Central Asia is one of the major arid regions of the world, and the spatial genetic structure of plant species in this area displays broad significance with respect to the understanding of plant evolution and biogeographical patterns of temperate arid lands. Although the genetic structure of some plants has been examined in previous studies, it remains mostly unconfirmed whether different plants in the same habitat have similar genetic structure, and the factors that have influenced structure in plants of the region are also unknown. Accordingly, we employed the approaches of molecular phylogeography and species distribution modelling to compare spatial genetic structure and ecological niches for three montane forest and four lowland xerophytic plants in East Central Asia. The results obtained suggest that the three forest species retreat westward during the Last Glacial Maximum as indicated by higher genetic differentiation in western populations. By contrast, multiple peaks of genetic differentiation were detected from chloroplast DNA datasets among populations in each of the four xerophytic species. Based on nuclear ribosomal internal transcribed spacer datasets, anemophilous pollination had shaped the high dispersal ability for pollen-mediated gene flow and outcrossing pollination had triggered extensive heterozygosity among populations. In conclusion, palaeoclimatic changes and species traits have mainly influenced the spatial genetic structure of forest and xerophytic plants in arid Eastern Central Asia.

Population genetic structure and demographic history of Streptococcus mutans (Bacteria: Streptococcaceae)

Wed, 26 Oct 2016 00:00:00 -0700

Population genetic studies can contribute to current knowledge about the epidemiology of pathogens such as Streptococcus mutans, which is one of the most widely distributed bacteria in the world to be associated with human dental caries. In the present study, we investigated whether the population genetic structure of the species is clonal or recombinant, and we also evaluated the current levels of gene flow, admixed ancestry, and the hypothesis of an expansion of the bacteria within the last 10 000 years. Strains of S. mutans from Córdoba (Argentina) were obtained, with sequences of the genes aroE, gltA, gyrA, and lepC genes being aligned with those of strains from Japan, Thailand, and Finland. Most of our statistical analyses performed on the DNA matrix of 193 strains supported the existence of recombination at the intergene level. We also estimated the number of genetic clusters via Bayesian analyses, with three genetic clusters being detected in the four countries at different frequencies, as well as the number of strains with pure or admixed ancestry varying among countries. Argentina revealed 50% admixed strains, whereas these types of strains were present in only 8–19% of the other three countries analyzed. This result could be associated with the important human migration waves that Argentina has experienced, which may have mixed strains of S. mutans of different geographical origins. The demographic history was obtained using Extended Bayesian Skyline Plot anslysis, which showed important growth in the effective population size approximately 5000 years ago, coincident with the beginning of the dispersion of agriculture and a change to a diet rich in carbohydrates.

Speciation history and species‐delimitation within the Seychelles Bronze geckos, Ailuronyx spp.: molecular and morphological evidence

Mon, 03 Oct 2016 00:00:00 -0700

Research on the genetic variability across various organisms from the Seychelles granitic islands has revealed considerable differentiation within many taxa, often with deep evolutionary lineages, likely corresponding to cryptic species. Although an accurate description of insular diversity is important for biogeographical and conservation reasons, there is frequently a lack of information even for presumably better known groups, such as vertebrates. One example is the endemic genus Ailuronyx, which includes the emblematic Seychelles giant bronze gecko Ailuronyx trachygaster. In the present study, we investigate, for the first time, based on morphological and molecular information, the intraspecific diversity of the three currently recognized Ailuronyx species, and reassess their distribution and history of diversification. Our data clearly indicate an old (Miocenic) divergence between these species, as well as the existence of cryptic diversity within Ailuronyx seychellensis, and, to a lesser extent, within Ailuronyx tachyscopaeus, that should be further explored and described. Preliminary data suggest concordant patterns of morphological and molecular differentiation. The results also show that, although morphological discrimination between the currently described species is possible, some previous distribution records based on observations may be wrong, which is important for conservation management. The observed genetic structure patterns are congruent with those of other endemic taxa from the Seychelles, again highlighting the evolutionary importance of historical fragmentation across this ancient archipelago, the existence of overlooked diversity, and the need for detailed morphological and genetic assessments to accurately identify and address conservation priorities.

Combining geometric morphometric analyses of multiple 2D observation views improves interpretation of evolutionary allometry and shape diversification in monitor lizard (Varanus) crania

Gabrielle H. Openshaw, Domenic C. D'Amore, Marta Vidal‐García, J. Scott Keogh — Thu, 29 Sep 2016 00:00:00 -0700

Geometric morphometrics is a powerful tool for the quantification, visualization and analysis of morphological variation and change. This approach is being applied more frequently in a phylogenetic comparative context to assess the relative influence of size, ecology, function, and developmental constraints on morphological evolution. Geometric morphometric methods rely on homologous landmarks as the source of shape data, and the level of detail and accuracy increases with the amount of information contained in a landmark configuration. It may be possible, however, to capture particular elements of shape variation by concentrating on different observation angles of a complex structure like the vertebrate cranium. Our study examines how observation view (dorsal, ventral and lateral) influences 2D geometric morphometric analysis of interspecific cranial shape variation in monitor lizards. We recover a strong phylogenetic signal in all three views and general concordance in patterns of size-corrected shape diversification within the genus. We also find subtle, but important differences, however, among views in analyses of evolutionary allometry and shape variation, which may reflect both landmark configuration design and adaptive functional trends of the study system. Our study shows that studies restricted to a 2D geometric morphometric analysis of a complex 3D biological structure can combine carefully designed 2D landmark configurations describing alternative planes to maximize shape coverage.

On the origin of frictional adhesion in geckos: small morphological changes lead to a major biomechanical transition in the genus Gonatodes

Timothy E. Higham, Tony Gamble, Anthony P. Russell — Thu, 29 Sep 2016 00:00:00 -0700

The evolutionary history of vertebrate locomotion is punctuated by innovations that have permitted expansion into novel ecological niches. Frictional adhesion of geckos is an innovation renowned for enabling locomotion on vertical and inverted smooth surfaces. Much is known about the microstructure and function of the fully-expressed gekkotan adhesive apparatus, although how it originated is poorly understood. Therefore, identifying species that exhibit the earliest stages of expression of frictional adhesion will provide significant insights into the evolution of this trait. Our previous investigation of digital proportions, shape, scalation, skeletal form, and subdigital epidermal micro-ornamentation in the genus Gonatodes led us to hypothesize that Gonatodes humeralis expresses incipient frictional adhesion. To test this, we first conducted a phylogenetic analysis of Gonatodes and related sphaerodactyl genera to clarify the historical context of the evolution of frictional adhesive capability in the genus. We then measured the ability of G. humeralis and its close relatives to generate frictional adhesive force, examined their locomotor capabilities on low-friction surfaces, and observed animals in their natural habitat. After accounting for body mass and phylogenetic relationships, we found that G. humeralis generates frictional adhesive force essentially equivalent to that of Anolis, and can scale vertical smooth surfaces. Gonatodes vittatus, a species that lacks elaborated epidermal setae, generates negligible frictional adhesive force and can only ascend smooth inclined surfaces with a pitch of ≤ 40°. We conclude that the ostensibly padless G. humeralis, with feet lacking the musculoskeletal, tendinous, and vascular modifications typical of pad-bearing geckos, nevertheless can employ frictional adhesive contact to assist locomotion. As in Anolis, the release of frictional adhesive contact occurs when the foot is plantar flexed after the heel has lifted from the surface. Our findings indicate that the origin of frictional adhesion was likely gradual but that, ultimately, this led to major shifts in ecology and function.

Skeletal variation and taxonomic boundaries among mainland and island populations of the common treeshrew (Mammalia: Scandentia: Tupaiidae)

Mon, 26 Sep 2016 00:00:00 -0700

Treeshrews (order Scandentia) include 23 currently recognized species of small-bodied mammals from South and Southeast Asia. The taxonomy of the common treeshrew, Tupaia glis, which inhabits the Malay Peninsula south of the Isthmus of Kra, as well as a variety of offshore islands, has an extremely complicated history resulting from its wide distribution and subtly variable pelage. In our ongoing investigation of species boundaries in Tupaia, we compared island and mainland populations of T. glis using multivariate analyses. Specifically, we compared the skull and hand morphology of 13 island populations, most of which have been recognized as separate species or subspecies, to that of the mainland population. Island populations generally average smaller body size than those on the mainland, but none of the island populations are sufficiently distinct from the mainland population to warrant species recognition. This has important conservation implications for this widespread and morphologically variable species. It also highlights the potential role that ecogeographic explanations can play in understanding intraspecific variation, a role that should be considered in taxonomic studies and investigated further in T. glis and other treeshrews.

Different roads lead to Rome: Integrative taxonomic approaches lead to the discovery of two new lizard lineages in the Liolaemus montanus group (Squamata: Liolaemidae)

Cesar Aguilar, Perry L. Wood, Mark C. Belk, Mike H. Duff, Jack W. Sites — Mon, 26 Sep 2016 00:00:00 -0700

Integrative taxonomy (IT) is becoming a preferred approach to delimiting species boundaries by including different empirical criteria. IT methods can be divided into two types of procedures both of which use multiple kinds of evidence: step-by-step approaches test hypotheses by sequential evaluation in a hypothetic-deductive framework, while model-based procedures delimit groups based on statistical information criteria. In this study we used a step-by-step approach and a Gaussian clustering (GC) method to test species boundaries in the northernmost species of the Liolaemus montanus group. We used different methods based on mitochondrial and nuclear DNA sequence data, morphological measures and niche envelope variables. In contrast with GC, our step-by- step approach shows that one Andean population (Abra Apacheta) previously considered part of L. melanogaster, is actually nested within another clade; another Andean species, L. thomasi, is equivocally shown to be either a distinct species or conspecific with L. ortizi; and an additional Andean population (Abra Toccto) is delimited by concordance among most lines of evidence and different methods as a distinct lineage. However, one of the oldest and low-elevation populations (Nazca) is strongly delimited by all data sets and IT procedures as a new lineage distinct from any currently recognized species.

Archipelago‐wide survey of Philippine forest dragons (Agamidae: Gonocephalus): multilocus phylogeny uncovers unprecedented levels of genetic diversity in a biodiversity hotspot

Fri, 23 Sep 2016 00:00:00 -0700

We utilize robust geographical genetic sampling, and phylogenetic analysis of a new multilocus dataset to provide the first inference of relationships among Philippine Gonocephalus, combined with estimates of putative species diversity, in this almost unknown island radiation. Our results reveal startling levels of undocumented diversity, genetically partitioned at a number of geographical levels across the archipelago. We present the first survey of genetic lineage diversity, coupled with an archipelago-wide clarification of geographical structure in a unique archipelago-endemic radiation. Philippine Gonocephalus have previously escaped the attention of biogeographers as a result of the taxonomic confusion associated with low numbers of preserved specimens in museum collections. With new vouchered material and genetic sampling from a comprehensive, archipelago-wide vertebrate biodiversity inventory, our findings join many recent studies in highlighting the unprecedented faunal diversity in one of the world's most unique biodiversity conservation hotspots.

Discovery of mass migration and breeding of the painted lady butterfly Vanessa cardui in the Sub‐Sahara: the Europe–Africa migration revisited

Gerard Talavera, Roger Vila — Wed, 21 Sep 2016 00:00:00 -0700

Migratory behaviour has repeatedly evolved across taxa as an adaptation to heterogeneity in space and time. However, insect migration is still poorly understood, partly because of the lack of field data. The painted lady butterfly Vanessa cardui undertakes a long-distance annual migration between Europe and Africa. While spring flights from the Maghreb to Europe are well characterized, it is not known how far the European autumn migrants travel into Africa and whether they massively cross the Sahara Desert. We conducted fieldwork in four African countries (Chad, Benin, Senegal, and Ethiopia) in autumn and documented southward migrants in central Chad and abundant breeding sites across the tropical savannah as far south as the Niger River in the west and the Ethiopian highlands in the east. Given directionality and timing, these migrants probably originated in Europe and crossed the Mediterranean, the Sahara and the Sahel, a hypothesis that implies the longest (>4000 km) migratory flight recorded for a butterfly in a single generation. In the light of the new evidence, we revise the prevailing spatiotemporal model for the annual migration of V. cardui to incorporate tropical Africa, which could potentially be regarded as the missing geographic link between autumn (southwards) and spring (northwards) movements.

Are diurnal iguanian lizards the evolutionary drivers of New World female velvet ant (Hymenoptera: Mutillidae) Müllerian mimicry rings?

Aaron D. Pan, Kevin A. Williams, Joseph S. Wilson — Wed, 21 Sep 2016 00:00:00 -0700

Although several recent studies have described a vast mimicry complex among New World mutillid wasps (velvet ants), little is known about the potential predators that could be driving the colour convergence in these wasps. Identifying potential predators can be a necessary part of understanding the evolution of large mimicry complexes because predation pressures likely are a key evolutionary driver of aposematism in these systems. However, pinpointing potential predators is difficult given the rarity of observing predation events in the wild. Furthermore, laboratory-based feeding trials are difficult to design without a priori information about which potential predators should be investigated. In the present study, we explore the potential predator communities that may have driven the evolution of the large North American velvet ant mimicry complex. We hypothesize that potential predators can be identified by examining: (1) distributional similarities between predators and prey; (2) similarities of predator assemblages in areas where convergently coloured prey occur; (3) known dietary preferences of potential predators; and (4) evolutionary concordance (both spatially and temporally) of predator and prey clades. We find that iguanians are likely predators of two of the described mutillid mimicry rings. We hypothesize that the warning coloration of the Black-headed Timulla and Tropical mimicry rings is particularly directed towards dactyloids (anoles).

Biogeographical and co‐evolutionary origins of scarabaeine dung beetles: Mesozoic vicariance versus Cenozoic dispersal and dinosaur versus mammal dung

Adrian L. V. Davis, Clarke H. Scholtz, Catherine L. Sole — Wed, 21 Sep 2016 00:00:00 -0700

The subfamily Scarabaeinae (Coleoptera: Scarabaeidae) may have originated in Gondwanaland, through Mesozoic vicariance or dispersal in association with dinosaur dung, or through Cenozoic dispersal in association with mammal dung. We review evidence from age-calibrated phylogenies, fossil records, biogeographical patterns, and ecological associations. Fossil calibrated phylogenies for Scarabaeoidea predict a Cretaceous origin for Scarabaeinae, although age estimates would rely on other scarabaeoid groups given the doubtful validity of Mesozoic ‘scarabaeine’ fossils. Molecular clock calibrated phylogenies for Scarabaeinae predict an early Cenozoic origin coeval with modern mammal diversification. Trace fossil evidence suggests the exploitation of dinosaur dung by fossorial insects, although scarabaeine fossils are only validated for the Cenozoic. Although we discuss fossil evidence for dinosaur dung as a faunal resource, the origin of modern scarabaeines from an earlier Mesozoic vicariant or dispersal fauna remains unsupported. Although clock-constrained, phylogram topography is consistent with early Cenozoic palaeoclimatic and palaeoecological events, Eocene marine barriers would demand dispersal to explain the distributional origins of Scarabaeinae. Inconsistencies between classification and phylogeny complicate biogeographical analysis, although earlier southern radiation of basally-derived tribes has probably been followed by later diversification and the global dispersal of both basally and terminally-derived taxa, primarily via restored land links.

Mating patterns of the European grapevine moth, Lobesia botrana (Lepidoptera: Tortricidae) in sympatric and allopatric populations

Karen Muller, Denis Thiéry, Lionel Delbac, Jérôme Moreau — Mon, 19 Sep 2016 00:00:00 -0700

Phytophagous insects have been at the heart of investigations of ecological speciation, and it is clear that adaptation to different host plant species can promote host race formation and insect speciation. However, the evolution of host races has typically been studied at the plant species scale, using sympatric populations of insects that are specialized on particular plant species. Because many crop pest species are adapted to various plant varieties selected from a single plant species, it is of interest to establish whether reproductive barriers could evolve at this much smaller geographical scale, between individuals exploiting different plant varieties. To assess this we evaluated premating and postmating prezygotic barriers among sympatric populations of the European grapevine moth Lobesia botrana originated from different cultivars of the same plant species (Vitis vinifera), and between allopatric populations originated from different geographical sites. We found weak reproductive isolation for sympatric populations of L. botrana, but marked reproductive isolation among allopatric populations. In sympatric populations, the only effect was on the latency period prior to mating, which was longer for heterotypic partners that originated from different cultivars than for homotypic partners originated from the same cultivar. In allopatric populations, reproductive isolation was evident in both premating barriers and postmating prezygotic barriers. In summary, we did not find any trend for sympatric host race formation in L. botrana, but the occurrence of non-random mating patterns between different allopatric populations suggests the beginning of reproductive isolation, which could lead to the evolution of cryptic species of L. botrana.

Righting ability in hatchling turtles does not predict survival during dispersal in the field

Timothy S. Mitchell, Erin M. Myers, John K. Tucker, Suzanne E. McGaugh — Mon, 19 Sep 2016 00:00:00 -0700

While many studies use laboratory-based whole-organism performance measures as proxies for fitness, the implicit assumption that better laboratory performance translates into higher fitness in the wild is rarely tested. Righting response in turtles is frequently quantified in the laboratory and interpreted as either a measure of coordination or a direct proxy for survival. Here, we quantify two aspects of the righting response (latency time and active righting time) of hatchling red-eared sliders (Trachemys scripta elegans) in the laboratory and perform a release experiment to measure survival at a critical, terrestrial life-history stage. We found no relationship with active righting time or latency with the number of days hatchlings took to reach the drift fence. We also found no directional selection during dispersal from nest to water on either active righting time (the most commonly reported righting metric) or latency to right. We detected disruptive selection acting on latency time, although latency time also was shown to be highly sensitive to experimental perturbations. Our results, however, do not shed light on the relationship of these performance measures with survival at other life stages, and further studies clarifying the relationship between righting and survival in the field are warranted.

Niche conservatism for ecological preference in the Louisiana iris species complex

Jennafer A. P. Hamlin, Tyler J. Simmonds, Michael L. Arnold — Mon, 19 Sep 2016 00:00:00 -0700

Spatial and temporal environmental variation influences evolutionary processes such as divergence among populations and species. In the present study, we investigated the patterns of niche evolution for the Louisiana irises, as well as the phylogenetic relationship between these species. Using BEAST, a species phylogeny was generated for the Louisiana irises aiming to test the hypothesis of whether niche conservatism has played an important role for this species complex. Species distribution models were constructed for present day distributions to determine the environmental factors that contribute to species ranges. Tests of niche similarity were performed to evaluate whether niche conservatism is apparent within this species complex. We demonstrate that the Louisiana iris species complex is a monophyletic clade with Iris brevicaulis and Iris fulva as being sister to each other. The differences observed among the iris species with respect to the associated environmental factors suggest that these components have an effect on the distributions and habitats occupied. Furthermore, tests of niche similarity indicate niche conservatism for all species comparisons. Working at the species level and assessing the various factors that can influence differentiation, the present study obtained a more complete picture of the ecological and evolutionary history of this species complex across the geographical and ecological range.

Comparative phylogeography of the endemic Japanese weasel (Mustela itatsi) and the continental Siberian weasel (Mustela sibirica) revealed by complete mitochondrial genome sequences

Mon, 19 Sep 2016 00:00:00 -0700

We analyzed the complete mitochondrial genome for 26 individuals of the endemic Japanese weasel (Mustela itatsi) and 20 individuals of its continental sister species, the Siberian weasel (Mustela sibirica). These species diverged an estimated 1.19 Mya, in the Early Pleistocene. Mustela itatsi comprised two haplotype clades that diverged an estimated 0.93 Mya, in the Middle Pleistocene: a northern (Honshu) clade comprising geographically distinct basal, northern, and eastern subclades, and a western paraphyletic group, as well as a southern clade comprising geographically distinct subclades on Kyushu, Shikoku, and adjacent small islands. Our results indicate a single migration of an ancestral population from the Korean Peninsula to southern Japan across an Early Pleistocene land bridge, followed by allopatric speciation of M. itatsi in Japan. The southern lineage appears to have remained in place, whereas the range of the northern lineage expanded stepwise from south-western to northern Honshu between 0.31 and 0.11 Mya. Mustela sibirica also comprised two main clades that diverged an estimated 0.67 Mya; one containing haplotypes from continental Russia and Tsushima Island (Japan), and the other containing haplotypes from Korea, China, and Taiwan. The M. sibirica population on Tsushima Island is likely a relict from the continental Russian population.

A natural regionalization of the world based on primary biogeographic homology of terrestrial mammals

Tania Escalante — Mon, 19 Sep 2016 00:00:00 -0700

Primary biogeographic homology implies that different taxa are spatiotemporally integrated in a biota with a common biogeographic history, namely naturalness. Primary spatial homology includes the identification of areas of endemism. Therefore, the first step to approach a natural regionalization is to identify the patterns of endemism. In order to achieve this, I obtained the areas of endemism of terrestrial mammals of the world at two different spatial scales of analysis using a Parsimony Analysis of Endemicity (PAE): 8° latitude-longitude (families and genera) and 4° latitude-longitude (species). Fourteen general patterns, summarized from 54 areas of endemism, were recovered for the 8° scale, whereas 44 general patterns, from 176 areas of endemism, were recovered for the 4° scale. At both scales, there were patterns of successively nested endemism. In general, I found evidence for maintaining the regionalization proposed by Wallace in 1876 (Australian, Ethiopian, Neotropical, and Oriental regions), and I also found evidence supporting the addition of new regions, such as the Andean region. Other Wallace's regions were not recovered completely, such as the Nearctic and Palearctic regions, probably due to several biotic interchanges between them. Some transition zones were recovered (South American Transition Zone and Mediterranean). I also identified endemic species for small areas of endemism that may represent provinces. The results of this work can be used to propose hypotheses of secondary spatial homology and for making better inferences about the history of the biotas.

The essential role for graphs in allometric analysis

Gary C. Packard — Mon, 19 Sep 2016 00:00:00 -0700

The allometric method, which is widely (but somewhat inaccurately) attributed to Julian Huxley, is at the heart of some of the most important theoretical models in the field of evolutionary biology (e.g. the Metabolic Theory of Ecology). The procedure entails fitting a straight line to logarithmic transformations of the original bivariate data and then back-transforming the resulting equation to form a two-parameter power function on the arithmetic scale. Although the distribution for logarithms in graphical display may satisfy the requirement for linearity (as well as assumptions of the fitted model for normality and homoscedasticity), this does not guarantee that the power function estimated by back-transformation will actually describe the distribution for the original data. Situations of this kind arise with some regularity when untransformed observations lack a unitary pattern, thereby rendering them unsuitable for use in allometric research. Quality of the data and sufficiency of the power function can be judged only by examining a graph of observations on the arithmetic scale. Graphical display of untransformed observations needs to be incorporated into the allometric method to ensure that future studies on the influence of body size on the evolution of form and function are not compromised by bad data.

Why so many polyphagous fruit flies (Diptera: Tephritidae)? A further contribution to the ‘generalism’ debate

Anthony R Clarke — Mon, 19 Sep 2016 00:00:00 -0700

It has been suggested that generalist herbivorous insects are an evolutionary ‘improbability’. However, many species of tephritid fruit flies are generalists utilising larval hosts across two or more plant families. Focusing on the genus Bactrocera, it is argued that this high frequency of generalism is due to four evolutionary drivers which both decrease the need for specialism and promote generalism. Decreasing the need for specialism, there is firstly no co-evolutionary arms race between host plant and herbivore as Bactrocera do not negatively impact on plant fitness; this removes the need for specialism to counter plant defences. Secondly, the endemic hosts of most Bactrocera are plants with vertebrate-dispersed fleshy fruits. Fruit morphology and their display are highly constrained to attract those seed dispersers; Bactrocera thus do not need to specialize to increase host location capacity as many hosts produce a common signal. Thirdly, in native rainforest ecosystems Bactrocera are rare and so specialization to avoid competition seems unlikely. Promoting generalism are braconid parasitoids, which utilise plant cues to find their hosts. If a fly can use a novel host plant then it moves into enemy-free space, so promoting generalism. From this multi-part hypothesis, a group of testable predictions emerge. If shown to be correct then for the generalism/specialism debate frugivorous tephritids would provide an example where generalism may be a ‘probable’ evolutionary outcome.

Out of Borneo, again and again: biogeography of the Stream Toad genus Ansonia Stoliczka (Anura: Bufonidae) and the discovery of the first limestone cave‐dwelling species

Thu, 15 Sep 2016 00:00:00 -0700

Subsequent to the Miocene (approximately 35 Mya), Borneo has served as an insular refuge and a source of colonization for a broad range of species emigrating to others parts of Sundaland. A phylogeny-based historical biogeographical hypothesis for the Stream Toad genus Ansonia supports multiple instances of an out-of-Borneo scenario. An ancestral range estimation indicates that in situ speciation of Ansonia on the island of Borneo during the Late Miocene and Pliocene (approximately 2–13 Mya) eventually resulted in an invasion of the Philippines, Sumatra, and two independent invasions of the Thai-Malay Peninsula. When collecting material for the biogeographical analysis, a new species of Ansonia, Ansonia khaochangensis sp. nov. was discovered in a limestone cave from the Khao Chang karst tower in Phangnga Province, in southern Thailand. Ansonia khaochangensis sp. nov. can be differentiated from all other species of Ansonia by having a unique combination of morphological and colour pattern characteristics. Phylogenetic evidence based on the mitochondrial genes 12S and 16S indicates that it is nested within a clade of other species distributed north of the Isthmus of Kra. The cave lifestyle of this new species is a unique and a significant departure from lotic environments common to most other species of Ansonia. The reproductive biology of this species is unknown.

Crinoid phylogeny: new interpretation of the main Permo‐Triassic divergence, comparisons with echinoids and brachiopods, and EvoDevo interpretations of major morphological variations

Bernard L. Cohen, Andrzej Pisera — Thu, 15 Sep 2016 00:00:00 -0700

An alignment of nuclear and mitochondrial gene sequences (1529 data columns from three genes: nuclear-encoded 28S ribosomal DNA, mitochondrial 16S rDNA, and cytochrome oxidase subunit 1) from 120 specimens representing a wide selection of extant crinoids is used in Bayesian relaxed-clock analyses to construct the maximum clade credibility tree and to locate the root. This tree, and its root position, largely agree with those previously published on the basis of mid-point and outgroup rooting, and, using a likelihood ratio test, we find that our independently aligned data do not depart significantly from a strict molecular clock. Our tree, similar to those published previously, shows a basal split into two main clades but, unlike previous reports, we identify a phenotypic basis for the split and name the clades accordingly, ‘Stalked and quasi-stalked’ (SqS) and ‘Stalked but facultatively unstalked’ (SfU), with the latter corresponding to the ‘comatulids’. There is some correspondence between clades and morphologically-defined Linnean categories in the SqS clade (e.g. the family Hyocrinidae corresponds to a clade). However, there is almost no correspondence between them in the SfU clade, within which we abandon Linnean names and instead use the letters A to E, suggesting, as previously noted, that considerable morphology-based taxonomic oversplitting has occurred, such that critical revision that takes account of molecular results is overdue. The distinctive, living crinoid Caledonicrinus is placed as sister to all other members of the SqS clade (i.e. its detailed relationships remain obscure). The results of the present study do not exclude the Articulata hypothesis under which all extant crinoids belong to a single radiation but, using the first appearance of fossil cyrtocrinid ossicles as a calibration datum, the root node of our time-tree dates to before 258 Mya [i.e. in the Permian (Kungurian), rather than in the Triassic]. Simple comparisons are made between crinoids, echinoids, and selected articulate brachiopods using p-distance networks and maximum likelihood pairwise patristic distances as proxies for molecular evolution, and the numbers of extant families as (the only available but potentially unreliable) proxy for morphological evolution. These analyses suggest that, over approximately the same period (Triassic to present), echinoids show approximately five-fold lower rates of molecular evolution than crinoids or brachiopods, whereas both crinoids and echinoids show higher rates of morphological (taxonomic, family-level) evolution than brachiopods. These differences are discussed briefly in terms of developmental constraint and character plasticity. The evolutionary history of extant crinoids is given a speculative interpretation in terms of evolutionary developmental gene expression (EvoDevo) on the basis of four hypothetical gene regulatory networks or cassettes (Stalk, Cirrus, Abscission, and Multiply-or-Divide) whose presence/absence and activity/inactivity could combine to account for the phenotypes of the main crinoid clades. The conventional division of living crinoids into ‘stalked’ and ‘unstalked’ categories is strongly deprecated.

Evolution of gigantism and size‐based female mate choice in ice goby (Leucopsarion petersii) populations in a semi‐enclosed sea basin

Tomoyuki Kokita, Sayaka Takahashi, Masaki Kinoshita — Fri, 09 Sep 2016 00:00:00 -0700

Geographical isolation associated with Pleistocene glacial cycles has often caused allopatric genetic divergence, even in the marine realm. Therefore, an historically enclosed sea basin could harbour high endemism of both phenotypes and species. Divergent allopatric lineages have appeared inside and outside of a unique sea basin, the Sea of Japan, providing a valuable opportunity to explore marine phenotypic evolution and speciation in relation to Pleistocene glacial isolation. We examined divergence in body size-related and behavioural traits, which may be important drivers of reproductive isolation, between the allopatric Japan Sea (JS) and Pacific Ocean (PO) lineages of the ice goby Leucopsarion petersii. Our common garden experiments revealed that the JS lineage had rapid growth rates, and consequently evolved towards a larger size. Divergence in female mate choice patterns was also detected by within- and between-lineage mate choice experiments. The JS females demonstrated preferences for larger and same-lineage males, whereas the PO females did not. However, our genetic analysis of a contact zone population showed that such phenotypic divergence did not appear to contribute to reproductive isolation. Thus, the present study clarified the evolution of endemic phenotypes in this unique sea basin, together with the position of the diverging pair on the speciation continuum.

Evolution of dorsal pattern variation in Greater Antillean Anolis lizards

Iliana Medina, Jonathan B. Losos, D. Luke Mahler — Fri, 09 Sep 2016 00:00:00 -0700

Dorsal patterning in animals can serve as an antipredator defence and may be involved in sexual selection, and is thus likely to be the target of multiple selective forces. Intraspecific variation in dorsal patterning is not rare, but the reasons behind it are poorly understood. Anolis lizards offer an ideal system to test for a role of ecological factors in driving variation in dorsal pattern. Anoles show a high degree of variation in dorsal pattern not only among species, but also between and within sexes. We use a comparative framework to explore whether ecological variables such as habitat use and perch height can explain the evolution of sexual dimorphism in dorsal pattern and the presence of female pattern polymorphism (FPP) in 36 Greater Antillean Anolis species. We provide evidence that anoles that perch closer to the ground are more likely to exhibit sexual dimorphism in dorsal pattern, and we suggest that habitat-use differences between sexes in ground-affiliated ecomorphs may drive the evolution of dorsal pattern dimorphism. In contrast, the ecological variables we investigated cannot explain the presence of FPP. Our results demonstrate that niche-associated diversification can generate phenotypic diversity within as well as among species, but the factors responsible for intrasexual polymorphism in some anole species remain cryptic.

Post‐glacial colonization of Europe by the wood mouse, Apodemus sylvaticus: evidence of a northern refugium and dispersal with humans

Fri, 09 Sep 2016 00:00:00 -0700

The wood mouse Apodemus sylvaticus is an opportunistic rodent that is found throughout most of the European mainland. It is present on many islands around the margins of the continent and in northern Africa. The species has been the subject of previous phylogeographical studies, although these have focussed on the more southerly part of its range. A substantial number of new samples, many of them from the periphery of the species' range, contribute to an exceptional dataset comprising 981 mitochondrial cytochrome b sequences. These new data provide sufficient resolution to transform our understanding of the survival of the species through the last glaciation and its subsequent re-colonization of the continent. The deepest genetic split that we found is in agreement with previous studies and runs from the Alps to central Ukraine, although we further distinguish two separate lineages in wood mice to the north and west of this line. It is likely that this part of Europe was colonized from two refugia, putatively located in the Iberian peninsula and the Dordogne or Carpathian region. The wood mouse therefore joins the growing number of species with extant populations that appear to have survived the Last Glacial Maximum in northern refugia, rather than solely in traditionally recognized refugial locations in the southern European peninsulas. Furthermore, the existence of a northern refugium for the species was predicted in a study of mitochondrial variation in a specific parasite of the wood mouse, demonstrating the potential value of data from parasites to phylogeographical studies. Lastly, the presence of related haplotypes in widely disparate locations, often on islands or separated by substantial bodies of water, demonstrates the propensity of the wood mouse for accidental human-mediated transport.

Large‐scale phylogeographic study of the cosmopolitan aphid pest Brachycaudus helichrysi reveals host plant associated lineages that evolved in allopatry

Wed, 07 Sep 2016 00:00:00 -0700

Many cosmopolitan plant-eating insect species comprise reproductively isolated population clusters that exhibit contrasting biological (e.g. life cycle) and ecological (e.g. host plant association) characteristics. Phylogeographical studies can untangle such complexities and shed light on the evolutionary forces that drove the divergence between population clusters. In the present study, we investigated the phylogeography of the leaf curl plum aphid (Brachycaudus helichrysi), a cosmopolitan pest of Prunus orchards. Using a combination of DNA markers on a set of specimens sampled worldwide, we confirmed the existence of two main lineages (H1 and H2), with differing life cycles. H1 is a sexually reproducing lineage found across the Holarctic on plum trees, whereas H2 consists of globally distributed asexual lineages and few sexual populations that are restricted to West Asia and use peach trees as primary hosts. We further characterized a third lineage (H3), restricted to East Asia, which is associated with apricot trees and Prunus species that are endemic to this region. The divergence of the lineages postdates the speciation of associated Prunus species but precedes their domestication. Our results suggest that, in B. helichrysi, the differentiation between host-specific lineages initially started in geographically isolated populations, which subsequently each adapted to local Prunus species.

Phylogeography and species delimitation in convict cichlids (Cichlidae: Amatitlania): implications for taxonomy and Plio–Pleistocene evolutionary history in Central America

Wed, 07 Sep 2016 00:00:00 -0700

We investigate phylogeographic patterns and delimit species boundaries within Amatitlania, a genus of Central American cichlid fishes. Phylogenetic analyses of mitochondrial DNA sequences from 318 individuals spanning the geographical ranges of all three currently recognized Amatitlania species strongly supported one major clade, with a relatively diverged subclade corresponding to A. kanna samples from eastern Costa Rica and Panama. Gene trees and networks revealed marked incongruences between phylogeographic structure and morpho-species taxonomy as a result of species-level polyphyly. Bayes factor comparisons of species delimitation models accounting for incomplete lineage sorting under the multispecies coalescent decisively supported the recognition of two distinct species within Amatitlania corresponding to Amatitlania nigrofasciata and A. kanna lineages. The only clearly genetically and morphologically diagnosable species was A. kanna. These results strongly suggest that incomplete lineage sorting provides the best explanation for the polyphyly of A. kanna, whereas the polyphyly of A. siquia is likely a result of an imperfect taxonomy. Additional insights from coalescent-dating, network, and historical demographic analyses suggested that the two species of Amatitlania diversified only since the early Pleistocene, and that A. nigrofasciata experienced population expansions from approximately 200 000 years ago in the mid-late Pleistocene onward. We discuss implications of our results for the taxonomy and evolutionary history of Amatitlania and, more broadly, of Central American freshwater fishes.

Environmental drivers of body size variation in the lesser treefrog (Dendropsophus minutus) across the Amazon‐Cerrado gradient

Hilton M. Oyamaguchi, Edvagner Oliveira, Thomas B. Smith — Wed, 07 Sep 2016 00:00:00 -0700

Environmental variation between habitats may impose divergent selection pressures resulting in phenotypic divergence that can lead to reproductive isolation, especially if these same traits are favoured by sexual selection. Anuran body size is an important trait in male mating success and can affect the spectral traits of calls that female frogs use in mate choice. Environmental differences in water availability and temperature influence anuran body size and may result in reproductive incompatibility between populations. We investigated the importance of environmental differences between the Amazon and the Cerrado in driving phenotypic variation in the lesser tree frog (Dendropsophus minutus). In the present study, we tested the relationship between body size and environmental variables (precipitation and temperature). The results obtained show that body size increases in a more seasonal climate. Precipitation seasonality is the most important variable in explaining body size variation. If environmental variables can be used as a proxy for phenotypic variation, our results suggest that environmental differences between habitats may be an important driver of intraspecific divergence. Thus, this divergence across the Amazon and the Cerrado suggests the early stages of the ecological speciation continuum.

No universal differences between female and male eukaryotes: anisogamy and asymmetrical female meiosis

Root Gorelick, Jessica Carpinone, Lindsay Jackson Derraugh — Wed, 07 Sep 2016 00:00:00 -0700

We previously showed that, across eukaryotes, universal differences do not exist between diploid females and males; hence, in the present study, we examine haploid stages. Unlike animal sperm, flowering plant sperm have nuclear pores, and so cannot be used to distinguish haploid females from males. Female and male gametes are not complementary: eggs and can fertilize eggs, whereas sperm can fertilize sperm, in some taxa. One sex of gametes is not universally parasitic on the other. Commonly held differences between eggs and sperm (e.g. only eggs, and not sperm, are large, long-lived, and immobile) do not apply to many eukaryotes. Many or all angiosperms have small eggs, sperm without flagella, and long-lived pollen. In many plants, we supposedly can distinguish females from males, although they have similar sized gametes. Theories of anisogamy are based on less energy being required to produce small sperm than large eggs. However any selective advantage of smaller sperm is nullified by sequestering most cytoplasmic biomass as residual bodies following meiosis in metazoa. Moreover, zoidogamous gymnosperms have numerous huge sperm. In both animals and plants, sperm are not the immediate products of meiosis but, instead, develop afterwards via haploid cell divisions. Consequently, we examined whether the most promising universal sexual difference in animals applies to plants and stramenopiles, namely asymmetrical female meiosis vs. symmetrical male meiosis. A few angiosperms (and some animals) have asymmetrical male meiosis, whereas many plants have symmetrical female meiosis. All bryophytes and stramenopiles with UV chromosomes do not have asymmetrical female meiosis insofar as meiosis produces two female and two male gametophytes. Homosporous monilophytes, lycophytes, and anthocerotophytes lack female vs. male meiosis, although they have distinct eggs and sperm. Therefore, currently, there are no universal criteria for distinguishing females from males across all animals, across all plants or across all stramenopiles, let alone across all eukaryotes.

Speciation through the looking‐glass

Felix Vaux, Steven A. Trewick, Mary Morgan‐Richards — Sun, 04 Sep 2016 00:00:00 -0700

We respond to a comment by Allmon WD (2016), who attempted to demonstrate that species are biologically ‘real’ as justification for retaining the terms ‘anagenesis’ and ‘cladogenesis’, which we argue are not necessary for the study of evolutionary biology (Vaux F, Trewick SA & Morgan-Richards M, 2016). Here, we summarize a wealth of literature demonstrating that supposedly separate species introgress frequently, and we clarify that evolutionary lineage-splitting with genotypic and phenotypic divergence (speciation) is not the same as taxonomic classification. The usefulness of the terms anagenesis and cladogenesis requires agreement on their meaning, and this debate reflects a wider dilemma in academic communication: whether to use imprecisely defined jargon or longer sentences with simple words. We favour the latter, because biological evolution operates under straightforward and generalizable principles that should not require complicated descriptions, especially when its study requires collaboration among many disciplines.

Species, lineages, splitting, and divergence: why we still need ‘anagenesis’ and ‘cladogenesis’

Warren D. Allmon — Thu, 01 Sep 2016 00:00:00 -0700

In a recent review, Vaux, Trewick & Morgan-Richards (2016) argued that species are ‘arbitrary’, speciation virtually unstudyable (especially in the fossil record), and that the terms ‘anagenesis’ and ‘cladogenesis’ are confusing, unnecessary, and perhaps even misleading as descriptors of evolution. Their paper, however, contains numerous debatable statements, and does not in the end accomplish what they say is their primary aim: to clarify terminology and facilitate communication. Species seldom appear instantaneously, and therefore their exact time of origin is difficult or impossible to identify precisely. Yet this does not mean that species do not exist, do not originate or cannot be studied objectively. Species are real biological phenomena in being separate evolutionary lineages and, as such, can frequently be recognized, at least to some level of resolution, in the fossil record. The concepts and terms of anagenesis and cladogenesis are still needed and very useful as descriptors of evolution.

Temperature‐dependent colour change is a function of sex and directionality of temperature shift in the eastern fence lizard (Sceloporus undulatus)

Tue, 30 Aug 2016 00:00:00 -0700

Sexually dimorphic colour traits are widespread across taxa, but relatively little is known about how and why these features change with body temperature. To examine whether sex and directionality (warming vs. cooling) influence temperature-dependent colour change, we used spectrophotometry to characterize ventral and dorsal coloration in eastern fence lizards (Sceloporus undulatus), a species with temperature-dependent conspecific signals (ventral patches). In general, we found that skin colour (hue) in both sexes changed with temperature. Only ventral patch colour in males changed visibly to human observers; ventral patch hue decreased (green to blue shift) with an increase in body temperature. Male dorsal colour also changed with temperature, with cooler males exhibiting a longer-wavelength hue (red shift) than that exhibited by warmer males. Female dorsal hue changed in a manner paralleling that of males, and female ventral hue trended in the same direction: overall, warmer females tended to exhibit shorter-wavelength hues. However, the magnitude of male ventral patch colour change was highly dependent upon temperature sequence; the colourful badges of males that were progressively warmed changed from green to blue, whereas those of males that were cooled over the same time period did not change hue. Notably, only the coloration of male ventral patches was dependent on the directionality of temperature change; no other measured skin surfaces in either sex exhibited similar temperature-directionality dependence. These results are considered in the context of models for badge colour production in Sceloporus, as well as in hypotheses for the functional significance of ventral patch coloration.

Sex‐specific catch‐up growth in the Texas field cricket, Gryllus texensis

Brittany R. Tawes, Clint D. Kelly — Wed, 24 Aug 2016 00:00:00 -0700

Periods of poor nutrition during an organism's development can negatively impact its adult fitness. If conditions improve, an organism may increase its growth rate (compensatory growth) or delay maturity to increase body size (catch-up growth). Heightened resource allocation to growth, however, could impair resource availability for other fitness-related traits. Because each sex maximizes fitness differently, there might be sex-specific responses to improving conditions. In this study, we investigated compensatory/catch-up growth and its sex-specific costs in a field cricket. After a 4-week period of poor-quality food, treatment crickets were switched to a good-quality diet until maturity. We predicted that males and females would respond to this diet change differently, as the importance of large body size differs between sexes. Contrary to our prediction, we found that neither male nor female crickets increased their growth rates after realimentation compared with controls. Despite a lack of compensatory growth, both sexes attained the same average body size, mass, and condition at adulthood as control individuals. Females achieved the same size as controls by delaying their maturation age (i.e. via catch-up growth) while males did not. Although the strategy used to catch-up differed between the sexes, its net effect on a suite of fitness-related traits was negligible in both sexes.

The effect of distastefulness and conspicuous coloration on the post‐attack rejection behaviour of predators and survival of prey

Christina G. Halpin, Candy Rowe — Tue, 23 Aug 2016 00:00:00 -0700

Aposematic insects use bright colours and/or distinct markings to advertise their toxins to potential predators. When toxins are bitter-tasting and detectable upon attack, birds are able to use taste when making decisions about whether or not to eat defended prey. Taste-rejection behaviour, when birds taste but do not ingest a prey item, is often assumed to increase the survival of defended prey, yet few empirical studies have investigated the post-attack survival rates of live defended insects. We used naïve domestic chicks (Gallus gallus domesticus) foraging on live waxmoth larvae (Galleria mellonella) in a laboratory setting, where conspicuousness and distastefulness could be controlled and manipulated to investigate the effects of taste-rejection behaviour, as well as the associated handling behaviour, on post-attack survival of prey. We found that being distasteful increased the probability of being rejected by naïve chicks, and taste-rejection behaviour tended to be more frequent when distasteful prey were conspicuous compared with when they were cryptic. Conspicuous coloration also appeared to affect predators’ assessment of prey distastefulness, with past experience strongly influencing the probability that conspicuous (but not cryptic) prey were rejected. However, in contrast to previous findings, there was no evidence that either distastefulness or conspicuousness altered how predators handled the prey before making a decision about whether or not to eat it, in any way that enhanced prey survival post-attack. Therefore, taste-rejection behaviour appears to be a useful measure of prey survival. Our results provide novel insights into the potential importance of signal conspicuousness for prey populations with variable defences, and highlight the need to consider the role of taste-rejection behaviour in mimicry dynamics.

Comparative analysis reveals migratory swallows (Hirundinidae) have less pointed wings than residents

Gernot H. Huber, Sheela P. Turbek, Kimberly S. Bostwick, Rebecca J. Safran — Tue, 23 Aug 2016 00:00:00 -0700

The correlation between migration and wing pointedness, a pattern generally attributed to the need to reduce drag during powered straight-line flight, is well established in avian ecomorphology. However, most studies investigating this pattern have focused on relatively rounded-wing taxa, which employ different flight modes during foraging and migration. The basic assumption that migrants have comparatively pointed wings has not been questioned by analysing taxa with similar migratory and foraging flight. This study examines the correlation between migration and wing shape in swallows (Hirundinidae), a family with relatively pointed wings in which foraging flight resembles migratory flight. Using a phylogeny-based analysis, we compare the wing shape of species pairs with varying migratory habits in eight swallow genera. Surprisingly, migratory swallows have less pointed wings than sedentary species, and wing pointedness declines linearly with increasing migratory distance. This study represents the first published result documenting a reversal of the correlation between migration and wing pointedness found in other avian taxa. Interpreting this reversal requires a more nuanced understanding of wing ecomorphology; we hypothesize that inclement weather conditions on the breeding grounds and/or the roosting habits of migratory swallows create conflicting selective pressures that increase the cost of wing pointedness in migratory swallows.

Three‐dimensional cranial ontogeny in pantherines (Panthera leo, P. onca, P. pardus, P. tigris; Carnivora:, Felidae)

Valentina Segura, Guillermo H. Cassini, Francisco J. Prevosti — Tue, 23 Aug 2016 00:00:00 -0700

The Panthera lineage is a monophyletic clade of felids, supported by both morphological and molecular evidence. The lineage includes large species with cranial similarity such as Panthera leo and P. tigris, and other with very different cranium such as P. pardus. The aim of our work was to study the cranial ontogeny of Pantherines, elucidating whether their cranial shape is a product of size or phylogeny, and to compare these findings with available information about other carnivores. We studied 370 specimens using geometric morphometrics technique in three dimensions. Panthera leo and P. tigris show similar ontogenetic trajectories, sharing adult crania with wider rostrum, shorter basicranium and vertical occipital plate. The cranial configuration of P. leo is a scaling version of P. tigris. P. pardus shows the most different cranial pattern, with adults having a rounded braincase and zygomatic arches less expanded than the rest, whereas P. onca occupies an intermediate place between these patterns. P. pardus is the species with the smallest birth weight and the lowest growth rate, reaching a final size and shape later than the remaining species. Adult shape morphology reflects no relation to phylogenetic placement of the species and it is probably related to Pantherine body size.

The limpet form in gastropods: evolution, distribution, and implications for the comparative study of history

Geerat J. Vermeij — Mon, 22 Aug 2016 00:00:00 -0700

The limpet form – a cap-shaped or slipper-shaped univalved shell – convergently evolved in many gastropod lineages, but questions remain about when, how often, and under which circumstances it originated. Except for some predation-resistant limpets in shallow-water marine environments, limpets are not well adapted to intense competition and predation, leading to the prediction that they originated in refugial habitats where exposure to predators and competitors is low. A survey of fossil and living limpets indicates that the limpet form evolved independently in at least 54 lineages, with particularly frequent origins in early-diverging gastropod clades, as well as in Neritimorpha and Heterobranchia. There are at least 14 origins in freshwater and 10 in the deep sea, with known times ranging from the Cambrian to the Neogene. Shallow-water limpets are most diverse at mid-latitudes; predation-resistant taxa are rare in cold water and absent in freshwater. These patterns contrast with the mainly Late Cretaceous and Caenozoic warm-water origins of features such as the labral tooth, enveloped shell, varices, and burrowing-enhancing sculpture that confer defensive and competitive benefits on molluscs.

Phylogeography and population structure of two Brachistosternus species (Scorpiones: Bothriuridae) from the Chilean coastal desert – the perils of coastal living

F. Sara Ceccarelli, Jaime Pizarro‐Araya, Andrés A. Ojanguren‐Affilastro — Mon, 22 Aug 2016 00:00:00 -0700

Coastal deserts are geologically dynamic areas of the Earth, affected by historical changes in sea levels and in some cases also by fault-line tectonic activity. An example of such a dynamic area is the Chilean coastal desert of the Antofagasta and Atacama regions, which harbours many endemic species, such as the bothriurid scorpion species Brachistosternus paposo and Brachistosternus roigalsinai. In this work, we carry out phylogeographic and population genetic analyses on these scorpions, using two mitochondrial (COI and cyt b) and two nuclear (Actin 5C and wingless) markers to identify species and population structuring, and link these findings to the geological history of the area. The geographical feature separating the two species is identified as the Huasco River, and distinguishing morphological features for these scorpions are presented. Population genetic and phylogeographic outcomes reflect an unstable history across this region for B. paposo and B. roigalsinai, related to sea-level changes affecting coastal habitats, including nearby islands.

Scale asymmetries and lateral rib duplication in snakes: correlates and effects on locomotor performance

Kristin Löwenborg, Mattias Hagman — Fri, 19 Aug 2016 00:00:00 -0700

Thermally-induced scale asymmetries in reptiles are often considered to be indicative of underlying osteological deformities that incur fitness costs. However, this typically rests on subjective plausibility arguments and anecdotal reports about links between deformities and fitness, as well as between superficial asymmetries and deeper deformities rather than on empirical data. To shed light on these issues, we used a combination of X-rays of museum specimens and locomotor performance trials of hatchlings grass snakes (Natrix natrix) incubated in the laboratory at either 25 °C or 31 °C. We found that 30% of the museum specimens with asymmetrical ventral scales also had a rib duplication on one side of the underlying vertebrae associated with a scale asymmetry. In some cases, there was also a second extra rib on the opposite side of the vertebrae. However, although there was a statistically significant association between asymmetric ventral scales and rib duplication, a relatively weak correlation coefficient (r _s = 0.35) indicated that scale asymmetries are not a very strong predictor of rib duplication. In the performance trials, scale asymmetries had a significant effect on terrestrial but not aquatic locomotor ability of the hatchlings, and the magnitude of this effect depended on the temperature regimes that they experienced as embryos during incubation. Although both asymmetrical and normal snakes incubated at the higher temperature had more stamina than their respective counterparts incubated at the lower temperature, asymmetrical hatchlings overall became exhausted much sooner than normal snakes across the two treatments.

Mediterranean scrubland and elevation drive gene flow of a Mediterranean carnivore, the Egyptian mongoose Herpestes ichneumon (Herpestidae)

Tânia Barros, Samuel A. Cushman, João Carvalho, Carlos Fonseca — Fri, 19 Aug 2016 00:00:00 -0700

Identifying the environmental features affecting gene flow across a species range is of extreme importance for conservation planning. We investigated the genetic structure of the Egyptian mongoose (Herpestes ichneumon) in Western Iberian Peninsula by analyzing the correlations between genetic distances and landscape resistance models. We evaluated several functional relationships between elevation, vegetation cover, temperature, and genetic differentiation under the original and reciprocal causal modelling approaches. Additionally, we assessed evidence of isolation-by-distance (IBD) in the mongoose population. Original causal modelling identified IBD as the best model explaining genetic patterns in the mongoose population. By contrast, reciprocal causal modelling supported high shrub cover at middle elevations as the best model explaining species gene flow. The results from reciprocal causal modelling demonstrate that the Egyptian mongoose is dependent of ecosystems dominated by Mediterranean shrub cover. Recent land-use changes related to rural abandonment promoted the growth of shrub areas, especially at middle elevations, facilitating genetic connectivity in the mongoose population in those areas, where anthropogenic activities are less intense. The present study should be considered as a model for landscape genetics studies of Mediterranean carnivores in the Iberian range with the aim of better understanding how recent land-use changes affect a broad guild of species.

Ontogenetic changes in the external anatomy of the parasitic castrator crab Calyptraeotheres garthi: implications for the timing of host colonization and sexual behaviour

Emiliano H. Ocampo, Eduardo D. Spivak, J. Antonio Baeza, Tomás A. Luppi — Wed, 27 Jul 2016 00:00:00 -0700

Pea-crabs are symbiotic crustaceans that live in association with a diverse array of macro-invertebrate hosts. Some pea-crabs exhibit an unusual and incompletely known post-larval cycle characterized by the alternation of free-life and symbiotic forms. We analyzed post-larval morphology, the allometry of various body parts, and sexual dimorphism in Calyptraeotheres garthi, an endosymbiotic pea-crab infesting the brooding chamber of limpets in the southwestern Atlantic. In C. garthi, the smallest invasive crab moults into a male or female pre-hard stage, which is immediately followed by a hard stage. Then, hard-stage females, but not hard-stage males, pass through four post-hard stages before attaining a fifth terminal stage. The invasive and hard stages exhibit morphological traits (plumose natatory setae on the legs, compressed body shape, and moderate or strong carapace hardness) that likely permit them to swim efficiency while outside of hosts and entering and/or leaving host individuals. In contrast, pre- and post-hard crabs are well endowed for an endosymbiotic lifestyle featuring a soft and rounded carapace, and slender appendages. The allometry of selected traits suggests that males attain sexual maturity during the hard stage and likely roam among host individuals in search of mating opportunities. It remains unclear at which moment females become sexually active and whether hard females abandon host individuals in search of sexual partners.

The scent of a hatchling: intra‐species variation in the use of chemosensory cues by neonate freshwater turtles

Wed, 20 Jul 2016 00:00:00 -0700

Chemosensory cues transmit information about the sender's species, sex, reproductive status, health, and genetic relatedness, moderating social behaviour. Adaptations for chemosensory communication and social interactions are well studied in some vertebrate taxa but have been historically discounted in others. For example, chemosensory communication in Testudines was only recently documented, and these studies are largely limited to adults. In the present study, we test the hypothesis that hatchling freshwater turtles can identify conspecific hatchlings and close kin through chemosensory cues and we also investigate potential variation in the use of chemosensory cues among species with different habitat preferences. Hatchling of semi-aquatic species (Emydoidea blandingii and Graptemys geographica) showed no significant preference for conspecific-scented water over unscented water. However, hatchlings of a strictly aquatic species (Apalone spinifera) preferred water scented by conspecific hatchlings to unscented water, and preferred water scented by distantly-related conspecifics to water scented by close kin. Hatchlings of aquatic species may rely more on water-borne chemosensory cues than hatchlings of semi-aquatic species. This is the first evidence of kin recognition in Testudines, and provides an intriguing example of the avoidance of close kin. Increasing the chemical pollution of wetland habitats may impact the ‘chemoscape’ of turtles and other aquatic species, and this potential threat merits further investigation.

Multiple lines of anti‐predator defence in the spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae)

Wed, 20 Jul 2016 00:00:00 -0700

Many species have evolved a suite of anti-predator defences, rather than a single defence. These multiple defences may operate in synchrony or separately at different stages of predation sequence to protect the prey. However, empirical documentation on how multiple defences, as a whole, combine to protect prey, as well as quantitative evaluations of how and when they are deployed, are scarce. In the present study, we investigated the univoltine spotted lanternfly, Lycorma delicatula, which has cryptic forewings, defensive chemicals, and multiple behavioural defences, including rapid jumping away, sudden display of its conspicuous hindwings and abdomen (a startle/deimatic display), and death feigning. The aims of the present study were to: (1) characterize the modality of sensory stimuli that trigger the behavioural defences; (2) identify the stage(s) of the predation sequence in which L. delicatula employs each behavioural defence; and (3) investigate a range of intrinsic/extrinsic factors that might affect the execution of anti-predator responses. First, a preliminary test that simulated a range of sensory stimuli on L. delicatula suggested that they rarely responded to nontactile stimuli. This suggests that the species relies on crypsis as a primary defence unless it is physically contacted. Next, we simulated predatory attacks on the species at two different times of year (early and late season as adults). When physically contacted, the primary response of individuals was jumping away. However, when jumping was initially hindered (by grabbing), they then tended to employ deimatic display. Intriguingly, we found clear seasonal differences in these post-attack defences: after performing deimatic display, individuals were more likely to jump away in the early season, whereas death feigning was more frequent in the late season. We present adaptive explanations for this seasonal switch in anti-predator responses.

Fitness implications of simulated climate change in three species of copper butterflies (Lepidoptera: Lycaenidae)

Sat, 16 Jul 2016 00:00:00 -0700

Ongoing climate change and especially the associated heat waves may pose a major challenge to biodiversity conservation. Although many ectotherms in temperate zones may benefit from current climate change, others will suffer. However, the specific biological features determining the response of a given species to climate change have remained largely unknown. In the present study, conducted in three copper butterfly species that likely differ in their vulnerability to climate change, we tested the responses to simulated heat waves using ecologically realistic diurnal temperature cycles. Surprisingly, we found little support for our hypothesis that the most vulnerable species will suffer most from simulated climate change. Although species differed significantly in their responses to treatments, such variation appears to be largely ruled by selection pressures associated with the specific developmental pathway. In general, simulated heat waves had little effect on fitness components including fat content and immune function. Consequently, all three species appear to be capable of dealing with projected changes during their larval and pupal development. Whether this also applies to other developmental stages, more extreme stress or indirect effects climate change remains to be seen. Identifying the critical factors determining the vulnerability of a species to climate change will remain an important task for future research.

Local not vocal: assortative female choice in divergent populations of red‐eyed treefrogs, Agalychnis callidryas (Hylidae: Phyllomedusinae)

Sat, 16 Jul 2016 00:00:00 -0700

Premating behavioural isolation can facilitate divergence among natural populations. The red-eyed treefrog (Agalychnis callidryas) exhibits a strong population genetic structure that coincides with geographical differentiation in colour pattern and body size. We examined assortative mating for local males in two geographically isolated populations that exhibit high levels of phenotypic and genetic differentiation in Costa Rica. At each site, we placed a gravid female in an enclosure that contained one local and one nonlocal male (N = 79 trials total). We used log-linear modelling to analyze the parameters that best predicted female choice. We found that females in each population preferred local mates. Furthermore, 73% of females chose a male in the absence of any male advertisement call, highlighting the importance of non-acoustic cues in mate choice. Our mate-choice trials provide evidence that population divergence in phenotype could be partly mediated by behavioural interactions. We found no significant effect of male body size on female choice; however, because body size, colour pattern, and behaviour are all important sexual signals for anuran species, we discuss the potential roles of these divergent phenotypes in mate recognition and female choice in the red-eyed treefrog.