Wiley: Journal of Biogeography: Table of Contents

Geographic and Genomic Signatures of a Dynamic Evolutionary History in Lake Tanganyika's Synodontis Catfish Radiation

Wed, 22 Apr 2026 07:46:30 -0700

ABSTRACT

Aim

Lacustrine systems generally exhibit greater habitat stability than riverine systems, yet some lakes have experienced substantial lake-level fluctuations throughout the Pleistocene. These environmental perturbations repeatedly altered habitat availability critical to the evolution of their diverse fish communities. In this context, we inferred phylogenetic relationships and divergence times of lacustrine Synodontis catfishes in Lake Tanganyika. We then focused on three closely related species with distinct ecomorphological specializations (Synodontis petricola, S. polli, S. irsacae) to further investigate their evolutionary dynamics and elucidate responses to a temporally dynamic lacustrine environment.

Location

Lake Tanganyika, East Africa.

Taxa

Synodontis spp. (Mochokidae).

Methods

We used mitochondrial genomes for phylogenetic reconstruction and divergence time estimation, mitochondrial COI sequences for haplotype network analysis, and genome-wide SNPs from ddRADseq to assess population structure, demographic history, and patterns of gene flow.

Results

Mitochondrial genomes indicate that diversification within lacustrine Synodontis of Lake Tanganyika occurred in two main phases during the Pleistocene (2.5–1.5 Ma and 1.0–0.5 Ma), coinciding with pronounced lake-level fluctuations and palaeoclimatic shifts. Across three closely related but ecologically distinct species, S. petricola and S. polli exhibited mitonuclear discordance—with distinct mtDNA lineages in the northern and southern lake basins—and also showed strong population structure based on nuclear genomic SNP data, whereas S. irsacae lacked geographically structured mtDNA lineages and displayed weaker nuclear differentiation. Demographic reconstructions revealed asynchronous, species-specific expansions across lake basins, and gene-flow modelling indicated introgression across all species following a period of isolation after divergence.

Main Conclusions

Our results show that—in Lake Tanganyika—complex phylogeographic patterns in lacustrine fishes can arise through combined effects of lake-level fluctuations, ecological specialization, and spatially variable gene flow. These findings highlight how dynamic environmental histories in lacustrine systems can profoundly shape diversification of their biodiversity.

Biogeographic History and Morphological Trait Influence in the Diversification of the Subtribe Calothecinae (Poaceae)

Mon, 20 Apr 2026 05:41:31 -0700

ABSTRACT

Aim

The biodiversity of the Neotropics has been shaped by complex interactions over time with several major geological and climatic events linked to the diversification of lineages. The subtribe Calothecinae (Poaceae) comprises 28 species adapted to open environments, ranging from lowlands to high-altitude grasslands in America. We aimed to investigate ancestral geographical range shifts, diversification rates and the influence of altitude and anthecia number on the diversification of Calothecinae.

Location

Neotropics.

Taxon

Subtribe Calothecinae (Poaceae).

Methods

We reconstructed a dated phylogeny using data from eight DNA regions for 27 Calothecinae taxa to analyse biogeographic processes, infer diversification rates and assess the influence of altitude and anthecia number per spikelet on the subtribe's diversification. We estimated changes in diversification rates using a Bayesian branch-specific diversification model implemented in the software RevBayes.

Results

Calothecinae likely originated during the Miocene, in the Southeastern Brazilian Highlands, after a vicariant event separating it from an Andean clade. Net diversification rates increased at the divergence of the most recent common ancestor of Calothecinae and its sister clade, subtribe Paramochloinae and at the emergence of Poidium within Calothecinae. Ancestral elevation reconstruction suggested that the subtribe originated after a movement from high to mid-elevations. The best-fitting model for trait-dependent diversification indicates that the number of anthecia per spikelet might have influenced the diversification patterns observed across the Calothecinae tree.

Main Conclusions

We found that Calothecinae originated in the Miocene in the Southeastern Brazilian Highlands, then expanded south-to-north across the Americas. Long-distance dispersal likely facilitated the colonisation of Central America and Mexico. This biogeographic history appears to have been shaped by geological and climatic events, such as the uplift of the Andes and marine transgressions. Additionally, morphological traits, particularly the number of anthecia per spikelet, seem to have played a key role in the group's diversification.

Elevational Range Changes of Tropical Forest Birds on the Small Caribbean Island of Montserrat

Fri, 17 Apr 2026 03:39:49 -0700

ABSTRACT

Aim

Globally, species are changing their ranges poleward and uphill due to climate warming. This poses a particular risk to biodiversity endemic to islands, where dispersal limitations may hinder latitudinal movement across the sea and elevational range changes can result in a smaller area of potentially suitable habitat. Few studies have examined whether bird species on small tropical islands exhibit changes in elevational ranges. Here we study elevational range changes in a forest bird community that hosts two globally threatened species, of which one is endemic to the small Caribbean Island of Montserrat.

Location

Montserrat, Lesser Antilles, West Indies.

Taxon

Forest birds.

Methods

We analysed point-count data collected between 2011 and 2024 with dynamic occupancy models which explain changes in occupancy over time by colonisation and extinction while accounting for imperfect detection. We assessed the influence of elevation on both colonisation and extinction to gather robust evidence of potential elevational range changes.

Results

We found evidence for range changes in five out of 12 species, with four species changing uphill, including the endemic Montserrat Oriole (Icterus oberi), and one species showing a range contraction towards lower elevations. However, model selection uncertainty limited our ability to infer the influence of elevation on occupancy dynamics in five species. We caution that the time span of our study may not have been long enough to detect range changes in all species.

Main Conclusions

Uphill range changes observed in this study may result from synergistic interactions of anthropogenic forest degradation at lower elevations, increasing temperatures due to global warming in the Caribbean, and other consequences of global change such as the impact of hurricanes on high elevation forest structure. Our study suggests that uphill range shifts may reduce the available habitat of a globally threatened bird species endemic to a small tropical island in the Caribbean.

Secrets of the Spring‐Keepers: Phylogeographic Analyses of a Freshwater Amphipod Uncover Dispersal Pathways in Eastern North America

Andrew G. Cannizzaro, Thomas R. Sawicki, David A. Lieb, David J. Berg — Fri, 17 Apr 2026 03:33:33 -0700

ABSTRACT

Aim

While the Nearctic freshwater amphipod Gammarus minus is known for its adaptation to groundwater environments, relatively little is known about other aspects of the evolutionary history of the species throughout its range, which spans much of the eastern United States. As a result, we investigated the phylogeography of the species.

Location

Eastern United States.

Taxon

Gammarus minus.

Methods

Sequence data for two nuclear and two mitochondrial loci were generated for 13 populations of G. minus. These data were combined with sequences from 15 populations obtained from GenBank. From this partitioned dataset, phylogenetic trees were reconstructed using both maximum-likelihood (IQTREE) and Bayesian Inference (MrBayes/BEAST), and haplotype networks were generated using POPART. BEAST trees were time-calibrated based on a set of four mixed calibration points. RASP software was used to investigate ancestral areas. Ecological niche models were generated in R using the dismo/ENMeval packages.

Results

We identified the presence of three clades within G. minus: (I) a “Susquehanna-Potomac” clade containing populations from central Pennsylvania and northern West Virginia; (II) an “Ozark” clade containing populations from Missouri/Illinois; and (III) a widely distributed “Circum-Appalachian” clade containing populations from the Appalachians, Interior Plateau, and Piedmont. Time-calibrated phylogenies place the origin of the G. minus lineage during the Miocene, with clades diverging in the late Miocene to early Pliocene. Phylogenetic reconstructions recovered populations from the Susquehanna-Potomac clade as basally derived, with other clades likely dispersing southward and westward to reach the Ozarks and Appalachians.

Main Conclusions

Diversification within G. minus likely was promoted by climatic changes and uplift of the Appalachians during the Miocene. These results suggest a novel model for how drainage reorganizations, climate shifts, and geological processes in eastern North America shaped lineage diversification in freshwater taxa. More broadly, this study demonstrates the value of phylogeographic analyses in revealing hidden patterns of biotic assembly and dispersal across complex landscapes.

Rare Sex and a Long Life Sustain Seaweed Populations at the Warm Edge of Their Range

Fri, 17 Apr 2026 00:00:00 -0700

ABSTRACT

Aim

The life cycle of many organisms is all but fixed across their distribution range. Most commonly, populations respond to environmental variation by shifting the timing of reproductive events (phenology). More profoundly, populations may (partly) shift their mode of reproduction from sexual to asexual. Life cycle variation can impact reproductive success, gene flow, genetic diversity and, ultimately, the evolutionary trajectory of populations. Understanding the factors that influence life cycle variation is essential for grasping the biology and ecological roles of species. This study investigates the variation in life cycles and its effects on the genetic diversity of a brown seaweed, Dictyota, across its European range.

Location

North-East Atlantic Ocean and the Mediterranean Sea.

Taxon

Dictyota dichotoma (Hudson) J.V. Lamouroux (Phaeophyceae, Dictyotales).

Methods

We monitored phenology, fertility and lifespan in Atlantic and Mediterranean populations at its northern and southern boundaries and used microsatellite markers to assess how these factors influence genetic and genotypic diversity.

Results

We observed significant differences in phenology, reproductive strategies and genetic diversity among northern and southern European populations. In Mediterranean populations, D. dichotoma exhibited sporophytic dominance with gametophytes being extremely rare, suggesting a shift towards asexual reproduction. In contrast, North-East Atlantic populations displayed more pronounced seasonal reproductive patterns with higher frequencies of gametophytes, indicating predominant sexual reproduction. However, genetic analysis showed lower allelic richness and unique alleles in northern populations, whereas southern populations were genetically more diverse, reflecting historical biogeographic processes. Clonal reproduction was more pronounced in the Mediterranean populations, influencing the spatial genetic substructure and contributing to locally lower genotypic diversity compared to Atlantic populations.

Main Conclusions

Our findings demonstrate that life cycle variation and phenology in D. dichotoma are closely tied to regional environmental conditions and have significant implications for population structure and genetic diversity. Results highlight how shifts in reproductive strategies contribute to the evolutionary and ecological dynamics of marine macroalgae across biogeographical gradients.

Heterogeneous Evolutionary History Defines the Rear Edge of the North American Herb Campanula americana

Antoine Perrier, Keric S. Lamb, Laura F. Galloway — Thu, 16 Apr 2026 00:00:00 -0700

ABSTRACT

Aim

Warmer range limits of species distributions offer a window into the ecological and evolutionary processes associated with long-term warming, as they often harbour relicts of refugial populations from the last glaciation. However, warm-edge populations vary in their refugial, evolutionary, and climatic histories, complicating their use as models. Here, we characterise this variation at the warmer range limit of the North American herb Campanula americana.

Location

Eastern North America.

Taxon

Campanula americana.

Methods

We evaluated the warmer range limit using species distribution model hindcasting, range-wide analyses of population structure, effective migration, and phylogenetic relationships.

Results

Warm-edge populations vary in their refugial history; most are relicts of historic refugial populations (i.e., rear edge), but some result from southward postglacial colonisation. Within the rear edge, populations exhibit pronounced genetic structure, forming highly isolated clusters despite contiguous geography and only modest landscape barriers. Distinct rear-edge clusters varied in climate history and gene flow among populations, with more southern populations experiencing greater habitat decline, fragmentation and isolation. Finally, only rear-edge populations from northern refugial areas contributed to postglacial range expansion.

Main Conclusions

Our study highlights the challenges of using warm-edge populations as ecological and evolutionary models of response to climate change. Even in a geographically simple setting, warm-edge populations exhibit refugial, genetic, and climatic heterogeneity. Characterising this variation is essential for accurately identifying rear-edge populations and inferring their evolutionary history. Knowledge of the contribution of warm-edge populations to range-wide genetic variation is key when considering how these populations may inform studies of adaptation to future climate change.

Urban Heat and Colour Morphs: Urban Thermal Environments Shape Screech‐Owl Polymorphism

Christopher W. Briggs, Ella G. Milani, Elizabeth A. Wommack — Tue, 14 Apr 2026 22:01:03 -0700

ABSTRACT

Aim

Urban environments provide unique challenges and opportunities for wildlife, including altered thermal regimes caused by the urban heat island (UHI) effect. Gloger's rule predicts that animals in warmer environments will exhibit more pheomelanin-based (reddish-brown) plumage. For species with colour polymorphisms, local warming may shift morph frequencies towards those with more pheomelanin. Eastern screech-owls (Megascops asio) have rufous, brown, and grey morphs, with a strong latitudinal cline where grey morphs increase in the northern areas of the species range, likely due to lower metabolic demands. We predicted that the proportion of rufous morphs will increase in warmer UHIs compared to the cooler surrounding rural areas.

Location

Eastern North America.

Taxon

Eastern screech-owl (Megascops asio).

Methods

We used community science images from Cornell's Macaulay Library and iNaturalist from throughout M. asio asio's range to quantify proportions of rufous versus non-rufous morphs across 26 UHIs and their adjacent rural area.

Results

Populations of eastern screech-owls within UHIs had significantly more rufous individuals compared to the surrounding rural areas, and there was a strong latitudinal cline in morph frequency. However, site-specific climatic variables did not predict differences in morphs between UHI and their surrounding rural sites.

Main Conclusions

Warmer urban microclimates within UHIs may favour pheomelanic morphs with higher metabolic demands, consistent with Gloger's rule. These results suggest that even relatively small-scale environmental differences can shape selection pressures among populations. These findings underscore the potential for urban environments to influence phenotypic variation and offer insight into how climate-driven selection may operate at fine spatial scales.

Diversity, Distribution and Postglacial History of Native Pinus sylvestris Forests in the Iberian Peninsula

Tue, 14 Apr 2026 21:44:56 -0700

ABSTRACT

Aim

Pinus sylvestris is the most widely distributed Pinus species in the world, highlighting its ecological, economic and socio-cultural importance. The Iberian Peninsula marks its south-western distribution limit, whose extent has been significantly reduced since the Mid-Holocene. In this study, we investigated the current diversity of native Pinus sylvestris forests in the Iberian Peninsula and their postglacial distribution and history.

Location

Iberian Peninsula, south-western Europe.

Taxon

Pinus sylvestris L.

Methods

We compiled 1299 vegetation plots from native Pinus sylvestris forests and performed a numerical classification, modified TWINSPAN, to identify major forest types. We characterized their floristic composition, diversity and environmental drivers. Ecosystem Distribution Models were fitted using climatic and edaphic variables to estimate their potential distributions during the Last Glacial Maximum (21 ka BP), Mid-Holocene (6 ka BP) and present. Model outputs were validated with palaeobotanical records.

Results

We identified four different forest types: acidophilous oromediterranean, acidophilous temperate, basophilous, and thermophilous mixed forests. These forests host unique assemblages of endemic, relict and broadly distributed plant species. Ecosystem Distribution Models revealed that, among the three studied periods, present climatic conditions are the most suitable for the development of Pinus sylvestris forests. Yet, their present-day distribution is considerably more restricted than predicted, a mismatch that agrees with palaeobotanical records.

Main Conclusions

Native Pinus sylvestris forests in the Iberian Peninsula display a wide ecological range. Their current distribution is more restricted than expected by suitable climatic conditions, suggesting the key role of anthropogenic historical pressures. Conservation strategies should not only consider future climate scenarios but also integrate historical land-use legacies.

Environmental Drivers of Temperate Bat Species Richness and Abundance: The Role of Hibernacula

Tomáš Bartonička, Rafael da Rocha Fortes, Jan Zukal — Tue, 14 Apr 2026 00:00:00 -0700

ABSTRACT

Aim

Explaining the phenomenon of high biodiversity of biota remains one of the most significant challenges in the natural sciences, especially when it concerns long-lived, highly mobile and cryptic taxa. Underground hibernation sites, where temperate bats congregate in winter, are key biodiversity hotspots that are systematically monitored in many countries and represent important population data. We investigated bat species richness and abundance in relation to hibernacula, considering multiple scale features—climate, ecoregion, topography, landscape use and site characteristics.

Location

Central Europe, Czech Republic.

Taxon

Bats (Chiroptera).

Methods

We used unpublished data from a long-term monitoring programme of bat censuses at hibernation sites (caves, mines, cellars and bunkers) in the Czech Republic. To test the possible effects of four features (environmental, climatic, entrance position and inner roost parameters) on bat species richness and abundance, we ran Generalized Linear Models for each dependent variable. Further, an additional step was performed to eliminate multicollinear variables using variance inflation factors.

Results

Species richness was most strongly influenced by temperature seasonality, with additional effects from hibernaculum entrance height and length. In the total abundance models, the most influential predictors were hibernaculum accessibility and complexity of the hibernaculum, determined by the profile of the corridors and denivelation. Climate and internal spatial features of hibernacula were stronger predictors of bat occupancy and species richness than broad-scale environmental variables.

Main Conclusions

Our study jointly analysed how climate, land use, entrance position and the internal structure of a hibernaculum influence the species richness and abundance of bats. Our results show that, in addition to relationships documented in previous studies, the internal structure of hibernacula is of fundamental importance in structuring bat assemblages in hibernation sites and in the distribution of certain species populations.

Assembling the Neotropical Tree Flora: Andean Uplift and the Historical Biogeography of the Brazil Nut Family (Lecythidaceae)

Tue, 14 Apr 2026 00:00:00 -0700

ABSTRACT

Aim

The assembly of tropical tree floras is complex, involving many lineage-specific histories; however, focusing on the biogeographic history of diverse clades can reveal general patterns. We investigated the historical biogeography of the ecologically important Brazil nut clade (Lecythidoideae) to: (1) expand prior phylogenies with greater sampling of the early branching Andean-centered subclades; (2) infer the ages and dispersal histories of the major subclades; and (3) document instances of niche evolution within Lecythidoideae, with an emphasis on elevational range shifts.

Location

Tropical America.

Taxon

The Neotropical subfamily Lecythidoideae (Lecythidaceae).

Methods

We expanded phylogenetic taxon sampling to 371 samples representing 197 species across bioregions, emphasizing the Andean-centered genera Grias and Gustavia. A maximum likelihood phylogeny was inferred using 665 nuclear loci, and divergence times were estimated with four fossil constraints. Ancestral ranges were reconstructed across bioregions and ecoregions using three biogeographic models.

Results

The crown age of Lecythidaceae is placed in the mid-Cretaceous (~94 Ma) and the Neotropical clade Lecythidoideae in the Eocene (~51.5 Ma). Grias likely originated in Central America or the Pacific coastal forests of South America (~35.5 Ma), Gustavia in the Amazonian moist forests (~36 Ma) and the Bertholletia clade in Western-Central Amazonia (~20 Ma). Following geographic dispersal from eastern and western sources, Grias, Gustavia and Lecythis diversified along the Andean slopes; Scottmoria in Central America, and Imbiriba in the Atlantic Forest.

Main Conclusions

Most Lecythidoideae subclades diversified during the Miocene, a period of major landscape change associated with the tectonic activities that generated the Northern Andes, the formation of the Amazon drainage system and the closure of the Isthmus of Panama. While most species retained lowland rainforest niches, several lineages shifted into Andean montane forests, highlighting how geological change and ecological transitions shaped the assembly of Neotropical tree floras.

Diversification and Colonisation in the Indo‐Australian Archipelago: Genomic Insights From Colubrid Snakes

Mon, 13 Apr 2026 07:20:51 -0700

ABSTRACT

Aim

The Indo-Australian Archipelago (IAA) is one of the most geologically complex and species-rich regions on Earth. However, our knowledge of the geological processes and dispersal mechanisms that generate archipelago-wide distributions across the IAA is limited to a few vertebrate groups and often solely attributed to Plio-Pleistocene sea-level fluctuations. In this study, we use phylogenomics-based analyses to investigate two speciose and closely related genera of snakes, Lycodon and Stegonotus (Serpentes: Colubridae), which are widely distributed across the IAA to identify which biogeographic and environmental processes have shaped snake diversity in this region.

Location

South Asia and the Indo-Australian Archipelago (Indochina, Sundaland, Philippines, Wallacea, Australasia).

Taxon

Snakes (Colubridae: Lycodon, Stegonotus).

Methods

We inferred a phylogeny using a genomic dataset consisting of ultraconserved elements, anchored hybrid enrichment loci, and protein-coding genes (~5400 nuclear loci) from 38 species (154 samples) of Lycodon and Stegonotus. We used ancestral range estimation analysis to identify dispersal patterns across the IAA. Additionally, we implemented ensemble species distribution models to identify potential hotspots of Lycodon and Stegonotus species richness and determined the environmental influence on geographic distributions and species diversity.

Results

We find that these snakes comprise six deeply divergent lineages (genera) that initially originated in Mainland Southeast Asia during the Oligocene. Diversification of these lineages is influenced not by Plio-Pleistocene sea-level fluctuations but by multiple historical processes, including in situ diversification, island hopping, long-distance rafting, possible microcontinental block drifting, Cenozoic land bridge migrations and founder events. The species distribution models do not consistently estimate lower or higher species richness in any particular region within the IAA, but precipitation overall is considered an important factor in estimated species richness.

Main Conclusion

Although Plio-Pleistocene sea-level fluctuations are notorious species pump diversification paradigms in the IAA, multiple and more ancient geological processes and environmental factors contributed to current diversity levels and distributions. Our approach expands future investigations of alternative hypotheses of biodiversity sources in the IAA and greatly expands the diversity of causal mechanisms for discussions of terrestrial Southeast Asian biodiversity beyond dispersal versus vicariance hypotheses.

Leaf Size Variation in Response to Climate Drivers Depends on Plant Life Form

Mon, 13 Apr 2026 07:14:26 -0700

ABSTRACT

Aim

Plant leaf size and shape vary across major climatic gradients, reflecting the mechanisms for how plants regulate the balance of carbon, water, and heat. However, the influence of climate on leaf traits can be confounded by multiple factors, and the complex variation among different plant groups remains insufficiently understood. Here, we investigated how climate influences leaf size traits and whether this effect is moderated by plant life form.

Location

China.

Taxon

Angiosperms.

Methods

Based on leaf length, width, and aspect ratio data from 26,726 angiosperm species distributed across major climate gradients in China, we analysed the effects of temperature and precipitation on leaf size traits, and compared differences among plant life forms (woody vs. herbaceous and evergreen vs. deciduous). Additionally, spatial heterogeneity was assessed across eight vegetation zones.

Results

Leaves are generally larger and rounder in warm and humid areas, and smaller and narrower in cooler and more arid areas. All leaf size traits respond more strongly to precipitation than temperature, with leaf length showing the strongest responses to both climate variables. Herbaceous and deciduous species exhibit stronger climate responses nationwide, whereas woody and evergreen species are more sensitive within vegetation zones. Key responsive traits show clear geographic shifts.

Main Conclusions

Overall, we find that leaf size and shape vary strongly across China, as a result of climate variation, but these patterns are modified by dominant regional ecological processes and the ecological strategies of plant life forms. These findings not only help clarify variation in plant traits along climatic gradients, but also provide a theoretical framework for predicting how different plant morphologies will respond to ongoing climate change.

Distribution Patterns of Scarabaeoidea: A Biogeographical Regionalization Proposal for El Salvador

Mon, 13 Apr 2026 01:41:32 -0700

ABSTRACT

Aim

To conduct a biogeographical regionalization of El Salvador, based on the potential distribution patterns of the superfamily Scarabaeoidea and using Parsimony Analysis of Endemicity.

Location

El Salvador, Central America.

Taxon

Superfamily Scarabaeoidea (Insecta: Coleoptera).

Methods

Potential distribution models were developed for 160 species using Maxent. Based on the resulting potential richness patterns, a Parsimony Analysis of Endemicity was performed using hexagonal grids of 50 km² across El Salvador. Clades of cells sharing species compositions (geographical synapomorphies) were identified, and the regions corresponding to each clade were delineated.

Results

Five clades were identified, corresponding to the following biogeographic regions: (1) Pacific Lowlands; (2) Eastern Interior Valley; (3) Chortis Volcanic Front (Central American Volcanic Arc); (4) Western Interior Valley; (5) Northern Mountains.

Main Conclusions

Species distribution models, combined with parsimony analyses, strengthen the versatility of both methods for identifying biogeographical patterns at finer spatial scales, facilitate the first species-based biogeographic regionalization of El Salvador, and demonstrate that micro-scale analyses can reveal internal structure within broadly defined Central American provinces.

From Mountain Birth to Mammalian Marvels: A Review of the Himalayas' Role in Mammalian Biogeography

Basant Sharma, Andrew Hope — Sat, 11 Apr 2026 01:05:14 -0700

ABSTRACT

Background

The Himalayas emerged from a semi-aquatic landscape into the tallest mountain system on Earth, driving major environmental changes. Yet, how mammalian communities responded to this transition remains poorly understood. Addressing this gap is critical for understanding the resilience of mammalian assemblages under ongoing environmental changes.

Aim

We summarize the history of the Himalayas, highlighting key landscape and environmental transformations, and use mammals to exemplify the Himalayas' role in community assembly.

Findings

Our review highlights that initial uplift due to the northward movement of the Indian Plate towards the Eurasian Plate resulted in a shallow sea and surrounding semi-aquatic environments, supporting earliest ancestors of modern cetaceans. As uplift progressed, it served as a biological corridor between two plates, facilitating mammalian dispersal in both directions, with subsequent radiations. Continued uplift gave rise to differential climate zones, establishing diverse mammalian communities across elevational gradients. With further increase, it transitioned into a significant biogeographic barrier, driving desertification to the north, intensifying monsoon systems in the south, and shaping river systems and valleys, all impacting the biogeographic complexity of the region. During Quaternary glaciations, river valleys acted as climatic refugia, enabling the persistence of many mammalian lineages. Throughout, precipitation remained higher in the Eastern Himalayas than in the west, leading to additional longitudinal variation in mammalian assemblages. Today, Himalayan mammals span multiple biogeographic realms, with strongest mammalian community similarities to Southeast Asia.

Future Direction

Much of the material presented reflects evidence from the fossil record, spatial mapping, and recent but sparse genomic work on megafauna, which alone cannot fully explain mammalian responses to changes in the Himalayas. Modern genomic studies and broader sampling, mainly of highly diverse but underrepresented small taxa (rodents, bats, and shrews) are needed to update species origins, diversification, and community assembly to advance knowledge on Himalayan biodiversity dynamics.

Geographical Variation in Body Size and Sexual Size Dimorphism (SSD) in the Epaulette Shark (Hemiscyllium ocellatum)

Fri, 10 Apr 2026 02:45:31 -0700

ABSTRACT

Aim

Body size is of paramount importance to the survival of all organisms because of the intimate associations between size, physiological processes and ecology. Sexual size dimorphism (SSD: differences in size between the sexes) is a direct consequence of these ecomorphological relationships, arising due to sex-based differences in selection on body size. Latitudinal variation in SSD—equivalent to sex-specific manifestations of Bergmann's, Rensch's and other temperature-size rules—has been recorded in many terrestrial species. Yet, the underlying proximate and ultimate causes of this geographical variation remain poorly understood and have been quantified in just a handful of marine taxa. Here, we assessed latitudinal variation in SSD among three distinct epaulette shark (Hemiscyllium ocellatum) populations across the Great Barrier Reef to better understand factors influencing geographical body size variation in a marine context.

Location

The Great Barrier Reef, Queensland, Australia.

Taxon

The epaulette shark (Hemiscyllium ocellatum) (Bonnaterre, 1788).

Methods

We measured the length and mass of 183 adult and subadult H. ocellatum individuals from three populations along the Great Barrier Reef (GBR), Australia. Using these data, we also calculated Fulton's K, a measure of overall condition. We then fit ANOVA and GLM models comparing the latitudinal distribution of each body size metric between the sexes.

Results and Main Conclusion

Both length and mass decrease with increasing latitude, directly contradicting the temperature–size rule. The slope of this cline varies significantly among the sexes, with males responding more strongly to latitudinal changes. This results in male-biased SSD in lower-latitude populations becoming statistically non-significant at higher latitudes. We suggest that these results are indicative of a latitudinal gradient in resource availability and sex-specific resource allocation.

Comparative Biogeography of Benthic and Mid‐Water Coastal Fish Communities of the Galapagos: Stereo‐BRUVs Surveys Support the Use of Bioregions for Management

Fri, 10 Apr 2026 02:36:39 -0700

ABSTRACT

Aim

Biogeographical frameworks inform effective marine spatial planning, assessing ecological patterns across taxa and environments. In the Galapagos Archipelago, benthic bioregions guided marine reserve zoning, yet their representation of the mid-water environment remains unassessed. Our study aimed to strengthen the understanding of patterns in marine biogeography in Galapagos by assessing whether the currently accepted benthic bioregions also represent mid-water reef fish communities.

Location

Galapagos Archipelago.

Taxon

Marine fish species.

Methods

We used baited remote underwater stereo-video systems to conduct archipelago-wide surveys of benthic and mid-water fish communities. Locations were sampled during the cold and warm seasons, yielding 598 deployments which were analysed to compare multivariate patterns between bioregions and environments.

Results

Bioregion partitioning based on benthic fish community data was more distinct than in previous studies with the Far-North, North, Centre-Southeast and West bioregions displaying significantly different community compositions. The main Galapagos bioregions displayed less distinct coastal mid-water fish communities suggesting three subdivisions may be more representative, namely the Far-North, West and the Centre-Southeast plus North combined. When compared with benthic communities, mid-water communities displayed higher heterogeneity, lower species richness and were dominated by species with extensive distribution ranges.

Main Conclusions

Our study builds upon previous biogeographic studies in the Galapagos Islands by considering previous limitations and assessing both benthic and mid-water environments. Our results support the currently accepted bioregion scheme but suggest that the coastal mid-water environment could be divided into three, not four bioregions. Mid-water stereo-BRUVs represent a useful tool to study mid-water biogeographical patterns, and we recommend their application in other regions of the world to improve our understanding of biogeography in this understudied environment.

Genetic Legacy of the Last Ice Age Shapes Shallow Phylogeographic Structure in a Widespread Mediterranean Snake

Fri, 10 Apr 2026 00:00:00 -0700

ABSTRACT

Aim

Mediterranean peninsulas typically harbour high intraspecific genetic diversity associated with long-term persistence in multiple glacial refugia. However, some widespread taxa show unexpectedly shallow phylogeographic structure. Here, we investigate which historical processes can generate a pattern of strong genetic depletion within a classic southern European refugial region.

Location

Iberian Peninsula and southern France.

Taxon

A widespread Mediterranean colubrid snake (Zamenis scalaris).

Methods

We combined range-wide multilocus genetic data (mitochondrial and nuclear markers) with coalescent-based demographic inference, species distribution modelling under present and Last Glacial Maximum climatic conditions, and Pliocene–Pleistocene fossil evidence. This integrative framework was used to reconstruct refugial history, post-glacial expansion dynamics, and spatial patterns of genetic diversity.

Results

Both mitochondrial and nuclear markers indicate very low genetic variation across most of the species' range, with rare, derived haplotypes geographically clustered in southeastern and eastern Iberia. This pattern, combined with demographic reconstructions, indicates persistence through the Late Pleistocene in a single, spatially restricted refugium with reduced effective population size, followed by rapid post-glacial expansion around ~20 ka. Climatic suitability models and fossil records independently support this scenario, showing persistent suitable conditions confined to eastern–southeastern Iberia during glacial phases and a broad east-to-west temporal gradient of fossil occurrences consistent with long-term eastern persistence and subsequent westward expansion.

Main Conclusions

Despite its long-term presence in Iberia, Zamenis scalaris lacks the multilayered phylogeographic structure typical of many Mediterranean vertebrates. Its genetic legacy is consistent with strong Late Pleistocene contraction that overrode deeper evolutionary history. This study highlights how glacial dynamics can erode genetic complexity even in widespread taxa within classical refugial regions, with broader implications for comparative phylogeography and the interpretation of genetic diversity patterns in southern Europe.

Ecological Niche Conservatism and Evolutionary Dynamics in Octopodidae: A Phylogenetic Comparative Approach

Thu, 09 Apr 2026 04:08:35 -0700

ABSTRACT

Aim

Understanding how ecological niches evolve is crucial for predicting species' responses to environmental change. Cephalopods, particularly those in the Octopodidae family, offer a compelling model system due to their short life spans, phenotypic plasticity and divergent developmental modes. We examined the evolutionary dynamics of the fundamental niche (FN) in Octopodidae by assessing niche overlap among closely related species pairs, quantifying phylogenetic niche conservatism (PNC) for temperature and dissolved oxygen, and evaluating phylogenetic signal and best-fitting evolutionary models across the family.

Location

Temperate, tropical and subtropical oceanic waters.

Time Period

Occurrence records span from 1858 to 2024, with more than 80% of the records from 2000 to 2024. Environmental variables were obtained from monthly data available for 2000–2020, with the subset from 2010 to 2020 used in the analyses.

Major Taxa Studies

Octopodidae (d'Orbigny, 1839).

Methods

We conducted pairwise niche overlap analyses, incorporating both occurrence data and multiple definitions of the accessible area. Phylogenetic signal was estimated using Pagel's λ and Blomberg's K, and evolutionary models (Brownian Motion, BM; Ornstein-Uhlenbeck, OU; and Early Burst, EB) were fitted for each niche trait.

Results

Sister-species comparisons revealed no statistically significant niche overlap (p > 0.05), suggesting niche lability at shallow phylogenetic levels, while evolutionary model selection supported the Ornstein–Uhlenbeck model for all traits (α: 0.018–12.399), which is also consistent with the influence of stabilizing selection. Our analyses indicated stronger environmental constraints on temperature-related traits, suggesting greater limitations under thermal stress, whereas oxygen-related traits exhibited more variable patterns of phylogenetic constraints across niche dimensions.

Main Conclusions

Collectively, these findings support a mosaic pattern of niche evolution, challenging traditional assumptions of strong PNC in marine organisms. Taken together, stronger constraints under thermal stress suggest that cephalopods may have a limited capacity for rapid evolutionary adaptation to ongoing climate warming. This study provides the first comprehensive assessment of FN evolution in cephalopods, highlighting ecological constraints that may influence their adaptive capacity under future climate change scenarios.

The Biogeography of ENSO‐Induced Climate Variability, Deforestation Trends and Fire‐Induced Forest Loss in the Neotropics

Thu, 09 Apr 2026 02:51:11 -0700

ABSTRACT

Aim

To identify Neotropical ecoregions experiencing compound environmental exposure to El Niño/La Niña-driven climate variability, deforestation trends and fire-induced forest loss.

Location

Neotropical realm.

Methods

We quantified historical exposure to ENSO-related climate variability by correlating the Oceanic Niño Index with four terrestrial climate variables (minimum and maximum temperatures, precipitation and Palmer drought severity index) for the period 1961–2021. Pixel-level correlations were aggregated into El Niño and La Niña exposure indices using entropy-weighting. Forest disturbance was characterized using cumulative forest loss, mean annual loss rate and fire-induced canopy loss derived from global remote-sensing datasets (2001–2023). Principal component analysis and K-means were used to classify ecoregions based on multi-variate exposure profiles.

Results

Four clusters were identified across 150 forested ecoregions. ENSO-related climate exposure dominated regions from Central America to northern South America (27.3% of ecoregions), while deforestation (10.7%) and fire-induced forest loss (8.0%) characterized ecoregions primarily in the Amazon Basin and the Caribbean. Seven ecoregions, mainly in Colombia and Venezuela, exhibited consistently high exposure across climate variability, deforestation and fire-related disturbance: lowland moist forests (Catatumbo and Magdalena-Urabá), montane forests (Cordillera Oriental and Magdalena Valley) and dry forests (Apure-Villavicencio, Maracaibo and Patía).

Main Conclusion

Our results highlighted clear patterns of compound exposure, identifying ecoregions where climatic variability may interact with ongoing land-use pressures. While exposure does not equate to ecological vulnerability, these findings provide a biogeographical foundation for prioritizing regions where sensitivity and adaptive capacity assessments are most urgently needed.

Functional Traits as Predictors of Global Dominance and Prevalence in Herbaceous Plants

Sat, 04 Apr 2026 01:23:56 -0700

ABSTRACT

Aim

Understanding why some plant species are abundant or widely distributed is a long-standing aim of plant ecology. This research investigated whether the position of herbaceous plant species within the plant economics spectrum (aboveground and belowground) and along the mycorrhizal collaboration gradient could explain their local abundance, geographic occupancy, and global abundance.

Location

Global.

Methods

We used two published sources of global plant community data (sPlotOpen and the global biodiversity initiative facility; GBIF) to determine whether the local abundance, geographic occupancy, and global abundance of herbaceous plant species can be explained by their above- and belowground traits and estimates of mycorrhizal dependence and flexibility.

Results

Both above- and belowground traits were only weakly associated with local abundance, while geographic occupancy was associated with small plant size and traits indicating fast return on investment in aboveground tissues. Geographic occupancy was also related to belowground traits, being positively associated with specific root length and negatively associated with root diameter, and weakly positively associated with mycorrhizal flexibility. The traits associated with global abundance largely mirrored those associated with occupancy.

Main Conclusions

Our analysis suggests that the local success of herbaceous plants is context-specific and there are no universal traits globally underlying high local abundance. By contrast, geographic occupancy aligns strongly with belowground traits, including specific root length and root diameter. The wide success of fine-rooted species may be related to nutrient enrichment during biogeographic history and in recent increasingly anthropogenic conditions.

Oyster Size Distributions Vary Across Time and Space in the Tampa Bay Estuary, 250–2024 ce

Sat, 04 Apr 2026 01:21:35 -0700

ABSTRACT

Aim

Restoration benchmarks often assume an undisturbed historic range of variability, if they include historic information at all. However, recent research highlights the need for a more nuanced understanding of shifting baselines and how to best incorporate past variabilities in modern management. We investigate trends in oyster size through time (ca. 250–2024 ce) and space (ca. 1000 km²) in the Tampa Bay Estuary to understand when and where ecologically significant changes to oyster populations occurred. By implementing a multiscalar approach, this study contributes historical ecological data relevant to contemporary restoration and management efforts and provides insights into understanding long-term socioecological dynamics in Florida's largest open-water estuary.

Location

Tampa Bay Estuary, Florida, USA.

Time Period

ca. 250–2024 ce.

Taxon

Mollusca; Crassostrea virginica.

Methods

We measured sizes of over 15,000 oyster shells from archaeological sites and contemporary reefs across four estuarine sub-basins over approximately 2000 years to assess how mean and maximum shell sizes responded to shifts in climate and human harvesting and settlement patterns.

Results

We demonstrate a non-linear decline in oyster sizes through time, including a steep decline in oyster size prior to European colonization and commercial harvest. Changes in oyster size varied across sub-regions, and there was no consistent response to climatic variability. A moderate rebound in oyster size during the 19th century is evident and coincides with several social factors that alleviated harvest pressures for a relatively short period. However, most of the largest contemporary oysters remain significantly smaller than those in the deeper past.

Main Conclusions

Archaeological datasets provide relevant historical ecological information for understanding modern era declines in molluscs. Our data reveal that no single baseline exists for oyster size in Tampa Bay. Instead, oyster populations responded in complex ways to climatic variability, ecological stressors and human interactions. Oyster size is a valuable functional trait linked to reproduction and reef resilience, and management targets that reference past demographic states should be framed as dynamic ranges and evaluated at sub-regional scales.

Connecting the Dots: Does COI Variability in Paramecium caudatum (Ciliates, Protista) Support the Moderate Endemicity Model of Microeukaryote Distribution?

Sat, 04 Apr 2026 01:10:14 -0700

ABSTRACT

Aim

Understanding the biodiversity and distribution patterns of microbial eukaryotes is fundamental to biosphere research. The biogeography of free-living protists remains contentious, with the ‘everything is everywhere’ and ‘moderate endemicity’ hypotheses representing competing paradigms. Here, we investigate whether and how global genetic variability within the cosmopolitan species Paramecium caudatum conforms to these models. We further examine whether genetic diversity within the COI gene can indicate the presence of cryptic species.

Location

Global study encompassing samples from nearly all major biogeographic realms, including the Palearctic, Nearctic, Neotropical, Indomalayan, and Australasian regions.

Time Period

Synthetic analysis combining historical data from public databases (GenBank) with newly collected data from strains isolated between 2015 and 2020.

Major Taxa Studied

The ciliate Paramecium caudatum.

Methods

We analysed the mitochondrial cytochrome c oxidase subunit I (COI) gene fragment from over 300 strains of P. caudatum, combining 231 newly sequenced samples with 103 sequences retrieved from the GenBank database. Phylogenetic relationships were reconstructed using maximum likelihood (ML), maximum parsimony (MP), neighbour-joining (NJ), and Bayesian inference (BI) methods. Haplotype networks were constructed using the median-joining method to assess genetic relationships and biogeographical patterns.

Results

Analysis revealed five distinct COI haplogroups (A, B, C, D and E) within a P. caudatum clade, each exhibiting distinct biogeographical signatures. Two haplogroups (A and B) displayed broad intercontinental distributions. In contrast, three others (C, D and E) showed restricted or endemic ranges, being confined to the Nearctic, northern Western Palearctic, and Indomalayan realms, respectively. The study revealed substantial intraspecific variability (Hd = 0.9252). Neutrality tests (Fu's F _s and Tajima's D) and congruence with previously published nuclear genomic data indicate that the major identified haplogroups are not random clusters but represent expanding evolutionary lineages.

Main Conclusions

Our findings demonstrate that while P. caudatum exhibits cosmopolitan distribution as a morphospecies, its intraspecific genetic structure displays pronounced heterogeneity at the global scale. The co-occurrence of haplogroups with contrasting distribution patterns, both widespread and endemic, provides compelling support for the moderate endemicity model in microbial eukaryote biogeography. These results underscore the existence of cryptic biodiversity and emphasise the need for high-resolution genetic analyses to gain a comprehensive understanding of microbial ecology and evolutionary processes.

General Biogeographic Rules and Lineage‐Specific History Shape the Assembly of Asian Tropical Megadiversity

Sat, 04 Apr 2026 01:08:57 -0700

ABSTRACT

Aim

Tropical Asia's extraordinary plant diversity is thought to be intrinsically linked to its dynamic geological history. However, quantifying the precise evolutionary processes that assembled this diversity across the archipelago remains challenging. A recently proposed biogeographic framework classifies the functional roles of different regions as “radiators,” “incubators,” “corridors” or “accumulators,” offering a useful framework to analyse this complexity. Here, we aim to provide a critical, independent test of this framework using the megadiverse tree genus Syzygium as a model system. Syzygium originated on the Sahul Shelf, contrasting with the Indochinese origin of rattan palms used in the original framework validation.

Location

Tropical Asia, Pacific Islands and Africa.

Methods

We analysed the complete chloroplast genome of 200 species of the genus Syzygium and performed phylogenetic analysis to estimate divergence times, ancestral region reconstruction, and estimated diversification and extinction rates. We then analysed the relationship between regional area and the dispersal of species and examined speciation and dispersal patterns in relation to the geographical environment.

Results

Our comprehensive chloroplast phylogenomic analysis indicates rapid diversification of Syzygium commencing ~12 million years ago, coinciding with shelf collision. Biogeographic reconstructions indicate that while the framework's general principles hold – continental shelf act as “radiators” and isolated islands as “incubators”–the specific geographic roles vary depend on lineage history.

Main Conclusions

Our study validates the radiator-incubator model as a general feature of tropical Asian evolution but refines it by demonstrating that historical contingency is key to understanding the assembly of Earth's richest biota. Tropical Asian plant diversity reflects a unique geological history of continental shelf collision and dynamic island geography, offering insights into biodiversity evolution in other geologically active regions worldwide, highlighting the importance of maintaining large, connected natural areas and dispersal corridors for preserving the evolutionary processes that generate Earth's botanical richness.

Spatial Mismatches of Plant‐Pollinator Interactions Under Future Climate Conditions

Samantha Day Briggs, Jill T. Anderson — Fri, 03 Apr 2026 22:26:03 -0700

ABSTRACT

Aim

Global change could disrupt critical ecological interactions, especially if interacting species shift their geographic ranges at different rates or in different directions. Functional redundancy within generalized networks could make them more resilient to climate change than networks with highly specialized interactions.

Location and Taxon

In the Elk Mountains of Colorado, we examined plant-pollinator interactions in the Rocky Mountain Iris (Iris missouriensis), a charismatic generalist wildflower distributed across broad climatic gradients over elevation and visited by a diversity of pollinators.

Methods

In 2021 and 2022, we recorded 90 h of video footage documenting potential pollinators that visited I. missouriensis flowers in seven populations arrayed across an elevational gradient. We recorded floral visitors twice per season in each population to capture spatial and temporal variation in pollinator species composition and abundance. We modelled plant-pollinator networks across I. missouriensis populations to evaluate species turnover and test the extent to which the diversity and abundance of pollinators vary across elevation. We examined range shifts in I. missouriensis and 11 of its key pollinators to test if climate change could generate spatial mismatches owing to species-specific changes in geographic distributions, disrupting plant-pollinator interactions.

Results

Our ecological network analysis revealed that pollinator species richness and diversity are highest at mid-elevation sites. Our species distribution models revealed that future climate scenarios could reduce the probability of I. missouriensis co-occurrence with current pollinators.

Main Conclusion

Thus, species-specific geographic responses to climate change could reshape the pollinator community even of generalist plants with diverse pollinator assemblages.

The Dynamic Nature of Nearshore Shark Nurseries in the Northern Gulf of Mexico

Fri, 03 Apr 2026 22:25:13 -0700

ABSTRACT

Aim

Some habitats serve particularly important functions for wildlife. Identifying and appropriately managing these ‘essential habitats’ is critical, especially for wildlife that have faced severe population declines like sharks. Nursery habitats aid in the survival and development of juvenile sharks, which until recently were not formally identified or managed throughout most regions. Managing shark nurseries was in part challenging because there was no standardized quantitative method to delineate these essential habitats prior to the seminal paper written by Michelle Heupel and colleagues in 2007. Management in some regions now includes the protection of shark nurseries; however, changes in nursery dynamics in response to environmental change and human impacts are unclear. Here, we used long-term monitoring data to identify bull shark (Carcharhinus leucas) and blacktip shark (C. limbatus) nurseries and assess how they have changed over time.

Location

Alabama coast and Texas coast, USA.

Time Period

1982–2023.

Taxa

Bull shark, blacktip shark.

Methods

Shark catch records (catch per unit effort) from long-term gillnet monitoring were assessed with general linear models and generalized linear models to determine (1) if shark nurseries exist in the Northern Gulf of Mexico, and (2) if and how they have changed over the study period using the shark nursery criteria established in 2007.

Results

Northern Gulf of Mexico nurseries first (re)emerged in the early 2000s on the Texas coast for bull sharks, followed by a relatively rapid expansion along the Texas and Alabama coast. Fewer nurseries were identified for blacktip sharks, which (re)emerged more recently starting in the 2010s.

Main Conclusions

Improved management has led to the re-establishment of shark nurseries. We expect that changes in these essential habitats will continue as environmental conditions and human impacts shape coastal ecosystems and the dynamics of nurseries within their waters. The delineation, management and reassessment of nurseries will therefore be imperative moving forward as shark populations continue to recover from historic and persistent overfishing and habitat degradation. Predicting where nurseries will (re)emerge in response to improved management and habitat suitability will also be essential to achieve conservation goals.

Diversity and Horizontal Turnover Depend on the Vertical Position in Neotropical Butterfly Communities

Fri, 03 Apr 2026 22:19:33 -0700

ABSTRACT

Aim

It is well-documented that the tropical forest biota is vertically stratified, and ecological theories from studies of the latitudinal gradient have been applied to predict and understand how communities vary across vertical strata. In butterflies, differences in abiotic conditions between the canopy and the understorey promote the evolution of distinct flight morphologies and physiologies. However, how these distinct morphologies relate to differences in dispersal ability is poorly explored and we lack a general understanding of how and why vertical stratification influences community turnover in tropical forests. Here, we explored how vertical stratification influences diversity, horizontal spatial similarity of assemblages and distance-decay patterns in understory and canopy butterflies across multiple ecosystems.

Location

Seven forest ecosystems in Ecuador, South America.

Taxon

Butterflies (Lepidoptera: Papilionoidea).

Methods

We assessed patterns of diversity by employing data from standardized butterfly monitoring programmes during the years 2011–2019 across seven sites in Ecuador (37,370 records from 1099 species), and a framework based on metacommunity theory and Jost's diversity estimates.

Results

Our results suggest three vertical patterns for neotropical butterfly communities: (a) a strong partitioning of canopy and understorey subcommunities, with distinct resulting diversity profiles; (b) greater spatial similarity for the canopy assemblages compared to the understorey (both locally and regionally); and (c) steeper distance-decay patterns for understorey assemblages compared to the canopy.

Main Conclusions

Our study shows the generality of vertical stratification diversity patterns across multiple Neotropical ecosystems, including previously unstudied montane cloud forests. It also shows that horizontal variation in community composition depends on the vertical position of taxa within Neotropical forests and is in general consistent with predictions based on species ecology and morphology.

Issue Information

Fri, 03 Apr 2026 06:42:25 -0700

Journal of Biogeography, Volume 53, Issue 4, April 2026.