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Mountainous regions are biodiversity hotspots with a high rate of endemism. However, these areas are witnessing accelerated warming, that threaten biodiversity and potentially causes habitat shrinkage for many species. Our study focuses on one such species, Andesiops peruvianus, a native mayfly of the mountains regions of South America. Our objectives were to analyze the genetic diversity of the 16 S gene in several populations, to assess their climate niche and potential distribution under future climate change scenarios. For genetic analysis samples were collected and sequenced from different sites across the South America (Argentina, Bolivia, Ecuador, and Colombia) and combine with the GenBank database. We identified 17 unique haplotypes based on 16 S gene, grouping them into two mains lineages: northern (Colombia and Ecuador) and southern (Bolivia and Argentina). Niche analysis showed a significant divergence between the northern and the southern lineages, suggesting distinct ecological niches. As future climatic changes were examined, both groups were observed to potentially lose about half of their suitable habitats. Habitat loss is the greatest at lower altitudes, but with some gain at higher altitudes. Isothermality and Annual Mean Temperature played a crucial role in defining habitats suitable for A. peruvianus. These features, coupled with their low thermal tolerance, might render the species particularly vulnerable to the impacts of climate change. Implications for insect conservation: This study highlights the need for targeted conservation strategies that protect and restore habitats along the altitudinal gradient to facilitate gene flow and enhance the resilience of A. peruvianus and other species to climate change. [ABSTRACT FROM AUTHOR]

Ecological niche differentiation is a process that accompanies lineage diversification and community assembly. Traditionally, the degree of niche differentiation is estimated by contrasting niche hypervolumes of two taxa, reconstructed using ecologically relevant variables. These methods disregard the fact that niches can shift in different ways and directions. Without means of discriminating between different types of niche differentiation, important evolutionary and ecological patterns may go unrecognized. Herein, we introduce a new conceptual and methodological framework that allows quantification and classification of niche differentiation and divergence between taxa along single niche axis. This new method, the Niche Divergence Plane, is based on species' responses to an underlying environmental gradient, from which we derive a two‐dimensional plane defined by two indices, niche exclusivity and niche dissimilarity. These two indices identify the proportion of the environmental gradient that is unique to each species, that is, how much of the environmental gradient species do not share (niche breadth exclusivity) and how different the species' responses are along the environmental gradient (niche dissimilarity). Thus, the latter can also be seen as a measure of the differences in niche preference or importance, even when there is significant overlap in niche breadth (i.e., low niche exclusivity). Based on the position of the two indices on the divergence plane, we can distinguish niche conservatism from four other general types of niche divergence: hard, soft, weighted, and nested. We demonstrate that the Niche Divergence Plane complements traditional measures of niche similarity (e.g., Schoener's D or Hellinger's I). Additionally, we show an empirical comparison using the Niche Divergence Plane framework on two Ambystoma salamanders. Overall, we demonstrate that the Niche Divergence Plane is a versatile tool that can be used to complement and expand previous methods of ecological niche comparisons and the study of ecological niche divergence. [ABSTRACT FROM AUTHOR]

Abstract The Persian fallow deer or Mesopotamian fallow Deer (Dama mesopotamica, Brook 1875), a species of significant ecological importance, had faced the threat of extinction in Iran. One conservation strategy involved the translocation of Persian deer to enclosed areas across Iran, where they were afforded protection from external threats and provided with essential care by human caretakers. While human caretakers diligently attend to their needs and mitigate external threats, climate variables may now become critical factors affecting population dynamics in enclosed areas. This study aims to assess the similarity in climate niches between the original area (Dez and Karkheh) of the Persian deer species and 11 newly enclosed areas. To achieve this, we employed climate data and ecological niche modeling (ENM) techniques to assess the variations in climate among 12 areas. We utilized the environmental equivalency test to determine whether the environmental spaces of area pairs exhibit significant differences and whether these spaces are interchangeable. Extrapolation analyses were also constructed in the next steps to explore climatic conditions in original fallow deer habitats that are non-analogous to those in other parts of Iran. Our results reveal significant disparities in climate conditions between the original and all translocated areas. Based on observations of population growth in specific enclosed areas where translocated deer populations have thrived, we hypothesize that the species may demonstrate a non-equilibrium distribution in Iran. Consequently, these new areas could potentially be regarded as part of the species’ potential climate niche. Extrapolation analysis showed that for a significant portion of Iran, extrapolation predictions are highly uncertain and potentially unreliable for the translocation of Persian fallow deer. However, the primary objective of translocation efforts remains the establishment of self-sustaining populations of Persian deer capable of thriving in natural areas beyond enclosed areas, thus ensuring their long-term survival and contributing to preservation efforts. Evaluating the success of newly translocated species requires additional time, with varying levels of success observed. In cases where the growth rate of the species in certain enclosed areas falls below expectations, it is prudent to consider climate variables that may contribute to population declines. Furthermore, for future translocations, we recommend selecting areas with climate similarities to regions where the species has demonstrated growth rates.

The timing and order of species arrival have been shown to be a significant factor in the assembly of biotic communities. Therefore, understanding priority effects, which refer to the impact of an early‐arriving species on a later‐arriving one, can help us better predict community assembly processes. However, little is known about the role of phylogenetic distance (PD) in priority effects and how they are mediated by the biogeographic history (BH) and the life stages (LSs) of interacting species.To shed light on the role of PD in priority effects, we conducted a multispecies greenhouse experiment. We created 10 allopatric and 10 sympatric species pairs, representing a PD gradient between early‐ and late‐arriving species from 5 to 270 Myr in evolutionary history and tested the priority effect of early‐arriving species on the late‐arriving species at multiple LSs.We found evidence of stronger competition between closely related species, as late‐arriving plants produced less above‐ground biomass when the PD was low. However, priority effects varied across the development of late‐arriving plants, as there were no effects on seedling emergence and survival, independent of PD. Regardless of PD, the pairs of allopatric and sympatric species did not differ in their responses.Synthesis. While many studies have produced contradictory results regarding the effect of PD on plant–plant interactions, our study provides experimental evidence that priority effects can be stronger when PD is small. This effect was independent of BH but varied across different LSs of late‐arriving plants. The dependence of the effect of PD on the LS of late‐arriving species highlights the importance of the timing of interactions for the assembly of plant communities, which could also have significant implications for the fields of invasion and restoration ecology. [ABSTRACT FROM AUTHOR]

Mexico’s topographic and environmental heterogeneity, in combination with environmental fluctuations of the Neogene-Quaternary, has uniquely influenced the evolutionary history and distribution patterns of the region’s flora and fauna, sometimes causing closely related species to exhibit distinct climatic niches. Our study aimed to characterize the climatic niches of Thamnophis scalaris and Thamnophis scaliger, as well as evaluate the impact of the Pleistocene-Holocene transition on their paleodistributions. We generated 357 models per species, each with three sets of distinct combinations of climatic variables, based on 108 occurrence records for T. scalaris and 62 for T. scaliger. We evaluated the niche overlap, equivalency, and similarity between both species and transferred the present-day models to eight distinct historical periods, with the goal of encompassing the distinctive climatic variation of the Pleistocene-Holocene (P-H) transition. Both species showed significant differences in their respective climatic regimes and did not display climatic niche conservatism (the tendency of species to retain ancestral ecological characteristics), despite their previously reported ecological, morphological, and biogeographic similarities. Likewise, they seem to have responded similarly to the environmental changes in the P-H, with both paleodistributions experiencing expansion phases during glacial periods and contraction phases during interglacial periods. Possible areas of refugia that remained climatically stable and viable for both species throughout this period were identified. These refugia could potentially harbor a greater genetic diversity with respect to regions that recently acquired suitable conditions for the establishment of these populations. As such, this work offers a methodological procedure that may be used as an early inference for identifying specific regions of interest in phylogeographic studies and conservation planning.

The introduction of new species can have unpredictable effects on native communities. Understanding the potential for competitive interactions between widow spiders (Theridiidae: Latrodectus), and how they may have shaped species’ geographic distributions, is critical for predicting the impacts of biological invasions in this historically cryptic group. North America is home to three native widows (L. hesperus, L. mactans, L. variolus) and one invasive widow (L. geometricus) with distributions that are at least partly sympatric. Given the relative novelty of L. geometricus in native communities as they expand their range, it is unclear if and how they share resources with their congeners, and competition for climatic resources (space) could result in ecological impacts to native widows. Here we aim to model niche differentiation and niche dynamics between native widows, that have coevolved over time, and between native and brown widows to assess the potential for ecological impact. We investigated the potential for climatic niche partitioning to shape sympatric geographic distributions of native widows compared to each other and to L. geometricus. We aggregated photographed occurrences from social media communities and online repositories to quantify climatic niche overlap for all four species on a continental scale, to assess niche dynamics among native species and between invasive and nativespecies. We found that native species had distributions that were more strongly partitioned, showing weaker niche overlap, except for the two eastern widows, which showed strong overlap and niche equivalency. Conversely, we found greater niche overlap between L. geometricus and native widows, possibly because it is too soon to see the effect of competition on species’ geographic distributions, or because differences in diet or partitioning of urban versus nonurban microhabitats promote coexistence.

The Black-throated Gray Warbler (Setophaga nigrescens) is a migratory songbird with a widespread and continuous distribution in the North American West. Previously published morphological data support the designation of 2 putative subspecies based on subtle differences in plumage and song; however, whether these patterns are clinal or discrete has yet to be determined. Furthermore, given that patterns of morphological variation occur across multiple distinct habitats and geographical boundaries, underlying population genetic structure may be present. To investigate this question and explore the evolutionary history of S. nigrescens, we conducted the first range-wide phylogeographic analysis of this species using genetic (mitochondrial DNA [mtDNA], ND2 gene sequences), morphological (body measurements), and environmental (niche modeling) data. Overall, our results identified 2 major mtDNA clades. One clade occurs east of the Cascade-Sierra ranges throughout the southwestern, Great Basin, and Rocky Mountain regions in North America (Interior clade), while a second widespread clade is comprised of birds that span the Pacific Northwest, and also across the Great Basin and southwest into the Rocky Mountains (Coastal clade). Divergence time estimates suggest a Pleistocene epoch vicariance event. Environmental niche models predict habitat modification and fragmentation from glacial–interglacial cycles, which were frequent over the Pleistocene. Range expansion northwards following the Last Glacial Maximum was identified from neutrality tests and shifts in suitable habitat from the Mid-Holocene to present-day conditions, where both clades are likely experiencing secondary contact. We found support for nonequivalent environmental niches among both clades based on a spatial analysis of environmental variables, with the Coastal clade showing greater tolerance to both temperate and xeric climatic conditions across the North American West; however, the environmental space occupied by both clades was more similar to each other than expected by chance. High levels of geographic overlap and a lack of discrete patterns in morphology suggest few contemporary reproductive barriers to gene flow. [ABSTRACT FROM AUTHOR]

Polyploid organisms are common and can be found across the tree of life. A key question is to understand how and why these polyploid lineages become established and persist in populations, particularly since they are predicted to have a low probability of success. While the collection of papers in this special issue addresses broad questions on the evolutionary ecology of polyploids, ultimately, these studies also highlight the myriad ways that we are examining what drives the success of polyploid lineages. In this paper we consider where we've been and the challenges that we face, and then propose several directions that will allow us to continue to propel the field towards our ultimate goal of understanding the rules that govern the establishment and persistence of polyploid populations. We conclude that developing this rule set will require a combination of model systems for which we have detailed knowledge of the phylogenetic and population genetic history, expanding our perspective beyond plants to include greater taxonomic breadth, and conducting studies in ecologically relevant settings. Additionally, we argue that future research on the evolutionary ecology of polyploidy should focus on integrating theory and empirical research, providing mechanistic linkages between the effects of whole genome duplication and population demography, and build a predictive framework to understand how anthropogenic change will impact polyploid organisms. [ABSTRACT FROM AUTHOR]

Cold‐adapted species at high elevations may be especially impacted by global warming since they may be limited in their capacity to adapt to changing conditions or may be prevented from shifting their distributions upwards if no suitable habitats are available.The latter may be true for Erebia nivalis, a high‐elevation specialist that mainly occurs in the Austrian Alps and on few mountaintops in Switzerland, where its taxonomic and conservation status remains unclear.We aimed to clarify the relationships among geographically isolated populations of E. nivalis using whole‐genome resequencing data to reconstruct population connectivity and phylogenetic relationships. We inferred current and historical effective population sizes and combined these with tests for ecological differentiation based on available occurrence data to re‐evaluate the conservation status of E. nivalis.Our results confirm that Swiss and Austrian E. nivalis should be considered different evolutionarily significant units for conservation purposes, as they are marked by moderate genomic differentiation, distinct demographic histories and a difference in the abiotic conditions of their habitats.In both Austria and Switzerland, we found rapid uphill range shifts over the last decades, little population connectivity, low current effective population sizes and low genetic diversity. The above, combined with the low dispersal capacity of this 2‐year lifecycle species and its need to overwinter under snow, which is rapidly retreating from several regions of the Alps, leads us to suggest that the status of E. nivalis should be updated to 'Vulnerable' or 'Endangered' in the European, Swiss and Austrian Red Lists. [ABSTRACT FROM AUTHOR]

Aim: Species are largely thought to maintain broadly static niches over time, an assumption underpinning much theoretical ecology including the implementation of ecological models to project species' current and future distributions. Here, we assess niche conservatism in odonates in Great Britain over the past six decades by simultaneously quantifying changes in species geographic distribution and evaluating temporal trends in species realised climatic niche. Location: Great Britain. Methods: Distributional changes were assessed by calculating changes in species distribution centres and deriving occupancy trends. Changes in climatic niches were assessed using a principal component analysis to quantify niche overlap, using information on both climate averages and extremes. Results: We show that dragonflies and damselflies displayed distinct responses to changing climatic conditions. Dragonflies shifting to higher latitudes maintained, on average, greater consistency in their climatic niches, providing evidence for climate tracking. Greater climate niche flexibility and increased occupancy over time, on the other hand, were more common in damselflies. Main Conclusions: We unveil evidence for climatic niche divergence in damselflies on a national scale, casting doubt on the relevance of species distribution models for predicting the impacts of climate change on this, and potentially other, groups of species. More broadly, our results call for more multi‐species temporal comparisons of spatial distributions and climate niches during recent periods of changes in climatic conditions to improve our ability to contrast species' vulnerability risk to the ongoing climate crisis. [ABSTRACT FROM AUTHOR]

Simple Summary: Falcons are keystone species that maintain ecosystem structures, functions, and services. With the help of phylogenetic comparative methods, climatic data, and species distribution modeling, we investigated how European falcon climatic niches have changed over evolutionary time. Convergent evolution and niche divergence have played an important role in the evolutionary history of these species, with speciation being influenced by climatic niche differentiation, more prevalent in the last 4 million years, with the main climatic niche shifts occurring between closely related falcon species. By integrating species distribution modeling techniques, phylogenetic comparative methods, and climatic data, we analyzed how European falcon climatic niches have changed over evolutionary time in order to understand their tempo and mode of evolution and gain phylogenetic insights related to the ecological context of falcon evolution. For this purpose, we tested the relative contributions of niche conservatism, convergent evolution, and divergent evolution in the evolutionary history of this group of species in Europe. The occupation of climatic niche spaces by falcon species in Europe was not similar, considering that their climatic niche evolution was characterized by heterotachy, especially after ca. 4 Mya. Our results indicate that convergent evolution and niche divergence played an important role in the evolutionary history of these species, with no significant evidence of closely related species retaining their fundamental niche over time (phylogenetic niche conservatism). In most analyses, less closely related falcon species occupied similar climatic environments. We found that speciation in the European genus Falco was influenced by climatic niche differentiation, more prevalent in the last 4 million years, with the main climatic niche shifts occurring between closely related falcon species. [ABSTRACT FROM AUTHOR]

The evolution of reproductive barriers, that is, the speciation process, implies the limitation of gene flow between populations. Different patterns of genomic differentiation throughout the speciation continuum may provide insights into the causal evolutionary forces of species divergence. In this study, we analysed a cryptic species complex of the genus Hetaerina (Odonata). This complex includes H. americana and H. calverti; however, in H. americana two highly differentiated genetic groups have been previously detected, which, we hypothesize, may correspond to different species with low morphological variation. We obtained single nucleotide polymorphism (SNP) data for 90 individuals belonging to the different taxa in the complex and carried out differentiation tests to identify genetic isolation. The results from STRUCTURE and discriminant analysis of principal components (DAPC), based on almost 5000 SNPs, confirmed the presence of three highly differentiated taxa. Also, we found FST values above 0.5 in pairwise comparisons, which indicates a considerable degree of genetic isolation among the suggested species. We also found low climatic niche overlap among all taxa, suggesting that each group occurs at specific conditions of temperature, precipitation and elevation. We propose that H. americana comprises two cryptic species, which may be reproductively isolated by ecological barriers related to niche divergence, since the morphological variation is minimal and, therefore, mechanical barriers are probably less effective compared to other related species such as H. calverti. [ABSTRACT FROM AUTHOR]

Since Darwin, the influence of environmental factors on the evolutionary processes of species has been underlined, especially for areas with high species richness, such as the tropics. Mexican oaks offer an opportunity as a model group for evaluating the association between the degree of ecological specialization and evolutionary patterns in a context of high species richness. As an example, here we considered differences in niche affinities and breadth of three closely related section Quercus (White Oak) species (Quercus deserticola, Q. glaucoides, and Q. peduncularis) distributed in the central and southern parts of Mexico, to determine if niche differences are associated with values of population genetic diversity and structure, and with the distributional responses of the species throughout periods of historical climate changes. Differences in genetic diversity and structure were found between the three species, as were differences between potential distribution through time. Niche breadth was associated with genetic structure and heterozygosity, with the more ecologically generalist species having lower values of genetic structure and higher levels of heterozygosity, possibly due to higher gene flow and demographic stability over time. Meanwhile, species with narrower niches showed higher levels of genetic structure, reflecting his torical population isolation. Finally, ecological niche divergence was confirmed for these closely related species. This supports previous hypotheses that oak communities are composed of distantly related species whereas closely related species tend to have different climatic affinities. [ABSTRACT FROM AUTHOR]

Sex-specific phenotypic differences are widespread throughout the animal kingdom. Reproductive advantages provided by trait differences come at a cost. Here, we link sex-specific foraging strategies to trade-offs between foraging reward and mortality risk in sexually dimorphic northern elephant seals (Mirounga angustirostris). We analyse a decadal dataset on movement patterns, dive behaviour, foraging success and mortality rates. Females are deep-diving predators in open ocean habitats. Males are shallow-diving benthic predators in continental shelf habitats. Males gain six times more mass and acquire energy 4.1 times faster than females. High foraging success comes with a high mortality rate. Males are six times more likely to die than females. These foraging strategies and trade-offs are related to different energy demands and life-history strategies. Males use a foraging strategy with a high mortality risk to attain large body sizes necessary to compete for females, as only a fraction of the largest males ever mate. Females use a foraging strategy with a lower mortality risk, maximizing reproductive success by pupping annually over a long lifespan. Our results highlight how sex-specific traits can drive disparity in mortality rates and expand species' niche space. Further, trade-offs between foraging rewards and mortality risk can differentially affect each sex's ability to maximize fitness.

PremiseEcogeographic isolation, or geographic isolation caused by ecological divergence, is thought to be of primary importance in speciation, yet is difficult to demonstrate and quantify. To determine whether distributions are limited by divergent adaptation or historical contingency, the gold standard is to reciprocally transplant species between their geographic ranges. Alternatively, ecogeographic isolation is inferred from species distribution models and niche divergence tests using widely available environmental and occurrence data.MethodsWe tested for ecogeographic isolation between two sister species of California annual wildflowers, Clarkia concinna and C. breweri, with a hybrid approach. We used niche models to predict water availability as the major axis of ecological divergence and then tested that with a greenhouse experiment. Specifically, we manipulated water availability in field soils for two populations of each species and predicted higher fitness in conditions representing home habitats to those representing the environment of each's sister species.ResultsWater availability and soil representing C. concinna generally increased both species' fitness. Thus, water and soil may indeed limit C. concinna from colonizing the range of C. breweri, but not vice versa. We suggest that the competitive environment and pollinator availability, which are not directly captured with either approach, may be key biotic factors correlated with climate that contribute to unexplained ecogeographic isolation for C. breweri.ConclusionsOurs is a valuable approach to assessing ecogeographic isolation, in that it balances feasibility with model validation, and our results have implications for species distribution modeling efforts geared toward predicting climate change responses.

Functional traits are morphological and physiological characteristics that determine growth, reproduction, and survival strategies. The leaf economics spectrum proposes two opposing life history strategies: species with an "acquisitive" strategy grow fast and exploit high-resource environments, while species with a "conservative" strategy emphasize survival and slow growth under low resource conditions. We analyzed intra and interspecific variation in nine functional traits related to biomass allocation and tissue quality in seven Neotropical palm species from understory and canopy strata. We expected that the level of resources of a stratum that a species typically exploits would determine the dominance of either the exploitative or conservative strategy, as well as degree of divergence in functional traits between species. If this is correct, then canopy species will show an acquisitive strategy emphasizing traits targeting a larger size, whereas understory species will show a conservative strategy with traits promoting efficient biomass allocation and survival in the shade. Two principal components (57.22% of the variation) separated palm species into: (a) canopy species whose traits were congruent with the acquisitive strategy and emphasized large size (i.e., diameter, height, carbon content, and leaf area), and (b) understory species whose traits were associated with efficient biomass allocation (i.e., dry mass fraction -DMF- and tissue density). As we unravel the variation in functional traits in palms, which make up a substantial proportion of the tropical flora, we gain a deeper understanding of how plants adapt to environmental gradients. [ABSTRACT FROM AUTHOR]

Aim: Species richness varies widely across space and is determined by underlying factors that drive species coexistence. Such factors include the speciation process (sympatric vs. allopatric), time since divergence, geographic context and intrinsic properties of the organisms. We model for the first time the coexistence dynamics of lizards and snakes across broad temporal and spatial scales, investigating whether an increase in niche divergence, dispersal abilities and inhabiting islands or continents affect their probability of coexistence. Location: Global. Time period: Cenozoic. Major taxa studied: Squamata. Methods: We used 447 sister species pairs, their age since divergence, their level of spatial (sympatric or allopatric) and niche overlap and geographical setting (islands or continents) to fit probabilistic models of species coexistence. We measured morphological traits to quantify niche divergence and used range and body size as proxies for dispersal ability. We applied a model‐comparison framework in lizards and snakes separately to evaluate which factors best explained their coexistence dynamics. Results: Allopatric speciation is the main speciation mode in snakes but we did not find evidence to favour one speciation mode in lizards. In snakes, sympatric pairs tend to occur on islands and to be more different in body size. On the contrary, dispersal ability shaped the coexistence of lizards, where species were more likely to coexist when they have higher dispersal abilities. Main conclusions: Distinct patterns and mechanisms underlie species coexistence within the order Squamata. Snake coexistence is preferentially produced by secondary sympatry favoured by niche divergence and is more likely to occur in more restricted geographical settings (islands vs. continents). Coexistence in lizards is strongly influenced only by dispersal abilities, but the high heterogeneity of processes simultaneously shaping the distribution of different lizard lineages might have masked specific coexistence signals, and future work should compare coexistence dynamics between clades (e.g. families). [ABSTRACT FROM AUTHOR]

Background and Research Aims: Historical geological events and climatic changes have played important roles in shaping population differentiation and distribution within species. Amazilia rutila (Trochilidae) is a widespread hummingbird species in the tropical dry forest along the Pacific slope and the Yucatán Peninsula in Mexico. Methods: We used mitochondrial DNA sequence, ecological niche modelling and niche divergence tests to determine the effects of major geographic barriers and environmental variability on genetic and niche divergence of A. rutila continental populations. Results: Our results revealed three genetic groups without haplotype sharing corresponding to the distribution of individuals/populations from the Pacific slope W of the Isthmus of Tehuantepec (PAC), in Oaxaca and Chiapas E of the Isthmus of Tehuantepec (CHIS_OAX) and those from the Yucatán Peninsula and Guatemala (YUC). Values of neutrality tests suggest past demographic expansion without effective population size changes over time, and the time since the demographic expansion ranged between 39.4 and 84.45 ka BP. Each genetic group differed in their position in environmental space, with low-to-very limited overlap in the fundamental climatic niche dimensions of all groups analyzed, particularly between YUC and PAC. Analysis of climate differentiation and ecological niche comparisons showed that the environmental space occupied by these mtDNA groups is similar but not identical. Conclusion: We conclude that the genetic differentiation of A. rutila is consistent with a model of population isolation by geographical barriers and environmental differences. Inferences about the consequences of past demographic expansion and isolation underlying intraspecific evolutionary relationships await further study. Implications for Conservation: Our findings highlight the importance of preserving evolutionary significant units of this widespread hummingbird species. Conservation actions must consider intrinsic requirements of evolutionarily distinct populations and the environmental drivers that shape their distributions, maximizing preservation of intraspecific genetic variability and monitoring changes in genetic diversity. [ABSTRACT FROM AUTHOR]

Two closely related bracken (Pteridium) species, P. caudatum and P. aquilinum ssp. pseudocaudatum, have mostly separate ranges that overlap in Peninsular Florida. Congeneric species that occupy similar niches in distinct geographic ranges but whose native ranges narrowly overlap present an eco-evolutionary conundrum: How can species evolved to occupy similar niches in distinct ranges coexist? Research suggests that for a stable coexistence the species should differ at least subtly in their ecological niches, otherwise their coexistence would be unstable. We investigated whether these bracken species share a habitat and co-occur locally, and whether their coexistence is predicted to be stable. We surveyed bracken populations from seven sites at Archbold Biological Station (Venus, Florida, USA) and characterized their biotic and abiotic microhabitat. Both bracken species co-occur at three sites. The two species showed significantly different trends in canopy cover and in response to fire frequency, and they grew at different densities and biomass. These results suggest these two bracken species coexist stably by occupying distinct ecological niches. [ABSTRACT FROM AUTHOR]

The relict genus Paradactylodon is narrowly distributed in temperate forests throughout the Middle East region, including P. mustersi in Afghanistan, P. persicus , and P. gorganensis in northwestern and northeastern Iran. Recent phylogenetic analyses suggest that the Iranian Paradactylodon populations may belong to a single species, P. persicus. In this study, we addressed how climatic niche conservatism and/or niche divergence may have affected the evolution of all Paradactylodon species using ecological niche models and multivariate niche analyses to identify niche overlap and assess equivalency and similarity tests. We also used an ensemble of ten algorithms to predict Paradactylodon species distributions for recent (1970-2000) and future (2081-2100) climate conditions. The results show that future climate change may cause the loss of 80 to 97% of these species' suitable habitat, especially at lower elevations. The niche divergence hypothesis was supported by the results of niche equivalency tests on P. persicus vs. P. gorganensis (and vice versa) with moderate overlap (D = 0.23, I = 0.41) and P. persicus vs. P. mustersi (and vice versa) with little overlap (D = 0.05, I = 0.06). Meanwhile, the niche similarity test for the niche conservatism hypothesis revealed significant results for P. persicus vs. P. gorganensis , P. mustersi vs. P. persicus , and P. persicus + P. gorganensis (as a single species) vs. P. mustersi. Due to these complex evolutionary ecological patterns and allopatric distributions, we recommend that P. gorganensis be considered a valid subspecies. [ABSTRACT FROM AUTHOR]

We evaluated the genetic structure and ecological niche segregation of Apis florea Fabricius 1787 (Apidae: Apini) across its native range using genetic and ecological niche data. The bee samples were from 62 colonies representing 40 localities across Iran, Iraq, Pakistan, Oman, and Egypt. Ecological niche divergence was estimated based on a principal component analysis of climatic/ecological variables. We confirmed the presence of two distinct lineages (eastern and western) for the species using mtDNA. There was no significant climatic heterogeneity between the lineages and their ecological niches are likely to be somewhat conserved. They were probably separated from each other during the Pleistocene and evolved in isolation. The two lineages of A. florea can be considered separate conservation units and used to develop strategies for effectively conserving this keystone pollinator species in Asia. [ABSTRACT FROM AUTHOR]

The Military Macaw (Ara militaris) is an endangered bird species with disjunct geographic distribution across the Neotropics, consisting of three recognized subspecies: One in Mexico (A. m. mexicanus) and two in South America (A. m. militaris and A. m. bolivianus). However, due to the limited phenotypic differentiation between these allopatric taxa, their taxonomic status has been the subject of debate. In this study, we explored mitochondrial DNA (mtDNA) variability to determine the phylogeographical pattern through phylogenetic and ecological modelling analyses. We also aimed to describe the evolutionary relationships of twelve A. militaris populations. We identified 41 haplotypes in the 300 bp region of the Cytochrome b (Cyt-b) gene of the mtDNA and low nucleotide diversity. The observed phylogeographic structure suggests the existence of two clades: One composed of A. m. militaris and A. m. bolivianus and another consisting solely of A. m. mexicanus. The A. m. mexicanus clade further divides into two recognized subclades: Sierra Madre Oriental and northeastern portion of the Sierra Madre Occidental. Ecological analyses revealed that the niche similarity between these lineages was lower than expected by chance. Additionally, results from low cross-prediction tests indicated that the two lineages have inhabited different environmental spaces since the Late Pleistocene. This divergence may be associated with a steep ecological gradient and contemporary geographical barrier. Based on our results, we suggest that at least the A. m. mexicanus has a divergent evolutionary history; therefore, it should be considered as a different evolutionarily significant and management unit. We recommend that future conservation strategies in Mexico incorporate effective protection measures, including habitat preservation and the reduction of illegal trade, to ensure the preservation of viable populations. [ABSTRACT FROM AUTHOR]

Background. Sexual dimorphism in size and shape is widespread among squamate reptiles. Sex differences in snake skull size and shape are often accompanied by intersexual feeding niche separation. However, allometric trajectories underlying these differences remain largely unstudied in several lineages. The sea krait Laticauda colubrina (Serpentes: Elapidae) exhibits very clear sexual dimorphism in body size, with previous studies having reported females to be larger and to have a relatively longer and wider head. The two sexes also differ in feeding habits: males tend to prey in shallow water on muraenid eels, whereas females prey in deeper water on congerid eels. Methods. I investigated sexual dimorphism in skull shape and size as well as the pattern of skull growth, to determine whether males and females follow the same ontogenetic trajectories. I studied skull characteristics and body length in 61 male and female sea kraits. Results. The sexes differ in skull shape. Males and females follow distinct allometric trajectories. Structures associated with feeding performance are female-biased, whereas rostral and orbital regions are male-biased. The two sexes differ in allometric trajectories of feeding-related structures (female biased) that correspond to dietary divergence between the sexes. Conclusions. Sea kraits exhibit clear sexual dimorphism in the skull form that may be explained by intersexual differences in the feeding habits as well as reproductive roles. The overall skull growth pattern resembles the typical pattern observed in other tetrapods. [ABSTRACT FROM AUTHOR]

As environmental conditions change over time, some species can follow the spatial footprint of their ecological niches or can adapt physiologically to the new conditions; modifying behavior can offer an alternative means of adapting to novel environments. The burrowing habit allows organisms to avoid adverse climatic conditions during part of the year by remaining inside burrows. Smilisca fodiens and S. dentata are two burrowing hylid frogs that inhabit areas beyond the northernmost distributional limits of the other six arboreal species of their genus, and indeed beyond of most American hylids. In this study, we tested whether burrowing habit allows these species to adapt to drier conditions while conserving the climatic niche of the arboreal species. We compared the annual niches of the arboreal species to those of the burrowing species under two assumptions: true seasonal niches and full annual niches. Through ecological niche similarity tests, we performed 24 comparisons in both geographic and environmental spaces. In geographic space, when considering burrowing annual niches, only five of 24 tests indicated similarity, yet as regards seasonal niche, 18 of 24 tests indicated similarity. In environmental space, all tests failed to reject null hypotheses. The analyses showed clearly that burrowing and arboreal species were closer in environmental space when seasonal niches of the burrowing species were used, rather than annual niches. That is, climatic conditions in seasonal niches of burrowing species resemble the annual niches of arboreal species, supporting the proposition that reduction of activity to certain periods of the year is a strategy in burrowing species to conserve their tropical niches while living in dry regions.

Background Sexual dimorphism in size and shape is widespread among squamate reptiles. Sex differences in snake skull size and shape are often accompanied by intersexual feeding niche separation. However, allometric trajectories underlying these differences remain largely unstudied in several lineages. The sea krait Laticauda colubrina (Serpentes: Elapidae) exhibits very clear sexual dimorphism in body size, with previous studies having reported females to be larger and to have a relatively longer and wider head. The two sexes also differ in feeding habits: males tend to prey in shallow water on muraenid eels, whereas females prey in deeper water on congerid eels. Methods I investigated sexual dimorphism in skull shape and size as well as the pattern of skull growth, to determine whether males and females follow the same ontogenetic trajectories. I studied skull characteristics and body length in 61 male and female sea kraits. Results The sexes differ in skull shape. Males and females follow distinct allometric trajectories. Structures associated with feeding performance are female-biased, whereas rostral and orbital regions are male-biased. The two sexes differ in allometric trajectories of feeding-related structures (female biased) that correspond to dietary divergence between the sexes. Conclusions Sea kraits exhibit clear sexual dimorphism in the skull form that may be explained by intersexual differences in the feeding habits as well as reproductive roles. The overall skull growth pattern resembles the typical pattern observed in other tetrapods.

The relict, endemic taxa Allopaa and Chrysopaa are key elements of the Hindu Kush–Himalayan amphibian fauna and potentially share a similar biogeographic evolution, making them important proxies for the reconstruction of the palaeoenvironmental and palaeotopographic history of the Himalaya–Tibet–Orogen. However, little is known about the taxonomy, phylogeography, genetic diversity and distribution of these taxa. We here provide new molecular data on Himalayan spiny frogs and species distribution models (SDMs) for A. hazarensis and C. sternosignata. The results reveal a better resolved phylogeny of these frogs compared to previous trees and strongly support the placement of A. hazarensis in the genus Nanorana. We further identify a so far unknown clade from the western Himalayas in Nanorana , apart from the subgroups Chaparana , Paa and the nominal Nanorana. In A. hazarensis , genetic diversity is relatively low. The results strengthen support for the recently proposed out-of-Tibet-into-the-Himalayan-exile hypothesis and a trans-Tibet dispersal of ancestral spiny frogs during the Palaeogene. Moreover, SDMs provide the first detailed distribution maps of A. hazarensis and C. sternosignata and strong evidence for distinct niche divergence among the two taxa. Our findings contribute to the knowledge about the distribution of these species and provide basic information for guiding future conservation management of them. [ABSTRACT FROM AUTHOR]

Historical geological events and Pleistocene climatic fluctuations have played important roles in shaping distribution and population differentiation across taxa. The buff-bellied hummingbird (Amazilia yucatanensis) is widely distributed along the Gulf of Mexico slope and the Yucatan Peninsula. Here, we obtained measurements and sequenced two mitochondrial DNA fragments from currently recognized subspecies: Amazilia yucatanensis yucatanensis (YUC), Amazilia yucatanensis cerviniventris (CER) and Amazilia yucatanensis chalconota (CHA). Additionally, we tested for their genetic and morphological differentiation, demographic expansion, palaeoclimatic distribution and niche overlap. Our results reveal genetic differentiation between two groups of populations: (1) from the Yucatan Peninsula to Veracruz (YUC+CER); and (2) from Veracruz to Tamaulipas (CHA). Neutrality tests and Bayesian skyline plots suggest past demographic expansion without changes in the effective population size over time. The potential distribution was fragmented at the Trans-Mexican Volcanic Belt and expanded northwards during the Last Glacial Maximum and Mid-Holocene to current conditions. Niche overlap was higher between YUC and CER. The environmental space occupied by subspecies was more similar to each other than expected by chance but significantly non-equivalent. Our results provide new insight on the distribution of this widespread hummingbird species and suggest that fragmentation during glaciations and differences in habitat have played a role in the recent diversification. [ABSTRACT FROM AUTHOR]

Given the high degrees of adaptation to specific microhabitats and restricted-range endemism, Goniurosaurus (Tiger geckos) serves as a unique model to study the complex evolution in lizards. Using phylogenetic analyses, we estimated the first divergence date of Goniurosaurus to the Eocene (~ 45.3 mya). The diversification within four monophyletic species groups began in the mid-Miocene between ~ 13.4 and 7.7 mya and continued to at least the early Pleistocene (~ 2 mya). Their ancestor was predicted to originate somewhere in contiguous continental Eastern Asia, whereas the current regions in which each monophyletic Goniurosaurus species group radiated are respectively their own ancestral regions. Together with factors of altitudinal gradient and climate conditions, we reconstructed relevant niche models of Goniurosaurus including ancestral reconstructions. Consequently, low elevations were predicted to be the most probable ancestral state for Goniurosaurus and all its groups as well. Both climatic niche conservatism and divergence have shaped the extraordinary species richness of allopatric Chinese and Vietnamese tiger geckos. In terms of endangerment, Goniurosaurus has been considered one of the most susceptible lizard groups under severe human impacts, especially climate change. The assessments of their niche evolution can provide a science-based pre-signal of vulnerability, thereby improving the efficacy of conservation measures to safeguard species of Goniurosaurus in the future. Accordingly, almost all closely related species of Goniurosaurus in China and Vietnam were identified with a high rate of niche conservatism, which should be included in conservation priorities under potential impacts of climate change. [ABSTRACT FROM AUTHOR]

By integrating species distribution modeling techniques, phylogenetic comparative methods, and climatic data, we analyzed how European falcon climatic niches have changed over evolutionary time in order to understand their tempo and mode of evolution and gain phylogenetic insights related to the ecological context of falcon evolution. For this purpose, we tested the relative contributions of niche conservatism, convergent evolution, and divergent evolution in the evolutionary history of this group of species in Europe. The occupation of climatic niche spaces by falcon species in Europe was not similar, considering that their climatic niche evolution was characterized by heterotachy, especially after ca. 4 Mya. Our results indicate that convergent evolution and niche divergence played an important role in the evolutionary history of these species, with no significant evidence of closely related species retaining their fundamental niche over time (phylogenetic niche conservatism). In most analyses, less closely related falcon species occupied similar climatic environments. We found that speciation in the European genus Falco was influenced by climatic niche differentiation, more prevalent in the last 4 million years, with the main climatic niche shifts occurring between closely related falcon species.

Being snapshots in time, species ranges may fall short of representing all of the geographic or environmental space that they are able to occupy. This has important implications for niche studies yet most comparative studies overlook the transient nature of species distributions and assume that they are at equilibrium. We review the methods most widely used for niche comparisons today and suggest a modified framework to describe and compare niches based on snapshot species range data. First, we introduce a new environmental space-based Niche Equivalence Statistic to test niche similarity between two species, which explicitly incorporates the spatial distribution of environments and their availability into statistical tests. We also introduce a new Background Statistic to measure the ability of this Niche Equivalence Statistic to detect differences based on the available environmental-space. These metrics enable fair comparisons between different geographies when the ranges of species are out of equilibrium. Based on distinct parameterizations of the new Equivalence and Background statistics, we then propose a Niche Divergence Test and a Niche Overlap Test, which allow assessment of whether differences between species emerge from true niche divergences. These methods are implemented in a new R package, ‘humboldt’ and applied to simulated species with pre-defined niches. The new methods improve accuracy of niche similarity and associated tests – consistently outperforming other tests. We show that the quantification of niche similarity should be performed only in environmental space, which is less sensitive than geographic space to the spatial abundance of key environmental variables. Further, our methods characterize the relationships between non-analogous and analogous climates in the species’ distributions, something not available previously. These improvements allow assessment of whether the different environmental spaces occupied by two taxa emerge from true niche evolution, as opposed to differences in life history and biological interactors, or differences in the variety and configuration of environments accessible to them.

Allopatric speciation followed by the evolution of range overlap (sympatry) allows the build‐up of regional diversity. However, local species richness requires that species co‐occur locally (syntopy). Importantly, correct estimates of syntopy must be available to identify ecological traits facilitating it. We thus provide a method to correctly estimate local co‐occurrence and demonstrate it on the evolution of secondary syntopy. First, we performed probabilistic co‐occurrence analyses on simulated data across a sympatry gradient from 0 to 100%. Second, we extracted 116 species pairs younger than 10 My from a dated phylogeny of Meliphagoidea songbirds. We constructed a presence–absence matrix of 58 species across 470 sites based on 37 250 censuses in Australia and Tasmania from 1989 to 1995. We also constructed a spatial mask based on species ranges, identifying sites within versus outside the area of sympatry. We ran both unconstrained and range mask‐constrained co‐occurrence analyses. We compared the resulting syntopy and predicted it by species ecology. Simulations and exact analyses showed that co‐occurrence analyses must be limited to sites in the area of sympatry between species. Without this spatial limit, syntopy was negatively biased, especially in common species. Accordingly, syntopy was negatively biased in Meliphagoidea when data from all sites were used, but this bias decreased with increasing sympatry, in agreement with numerical and exact analyses. When using correct estimates, syntopy increased with increasing divergence in the use of foraging stratum (ground, shrub, subcanopy and canopy) and with decreasing divergence in diet. In conclusion, we introduced a general method for calculating local species co‐occurrence and confirmed its validity by simulations. We illustrated its use by analyzing the evolution of secondary syntopy in a phylogenetic framework. We found support for both niche divergence (foraging stratum) and niche conservatism (diet) in facilitating evolutionary transitions to secondary syntopy, allowing the build‐up of local species richness. [ABSTRACT FROM AUTHOR]

Artibeus aztecus is a Mesoamerican montane bat with three currently recognized, allopatric subspecies. No study has evaluated the phylogenetic status of the subspecies. However, through an analysis of its ecological niche and its geographic distribution, here we analyze whether there is differentiation of the climatic requirements for each subspecies, assessing whether niche evolution is a potential factor in subspecies differentiation. We assayed ecological niche models for each subspecies, analyzed the response curves for the most important climatic variables of each model, and generated the potential distribution model for each subspecies. We assayed a background similarity test between the subspecies to determine how similar their niches were. We found differences in climatic requirements for the three allopatric subspecies and the most important variables and their response curves. Potential distribution models concur with Mesoamerican highlands and highlight the lowlands of the isthmus of Tehuantepec and the Nicaraguan depression as possible geographic barriers. Differences found between ecological niches for each subspecies contrast with previous findings for the species and other phyllostomid bats. Niche conservatism may have caused geographic isolation in the past, and differences in environmental requirements may have appeared later. Molecular and morphological analyses are necessary to clarify the taxonomic status of these populations and the evolutionary processes involved in their diversification. Artibeus aztecus es un murciélago montano mesoamericano, cuyas tres poblaciones alopátricas son reconocidas como subespecies. Sin embargo, no hay estudios filogenéticos que permitan aclarar su situación taxonómica, por lo que, a través del análisis de su nicho ecológico y distribución geográfica, se analizó si existe diferenciación en los requerimientos climáticos para cada subespecie, evaluando si la evolución del nicho es un factor potencial en la diferenciación de las subespecies. Se llevaron a cabo modelos de nicho ecológico para cada subespecie, se analizaron las curvas de respuesta de las variables más importantes y, se generó el modelo de distribución potencial para cada subespecie. Adicionalmente se realizaron pruebas de similitud de background entre las tres subespecies para determinar qué tan similares son sus nichos. Se encontraron diferencias en los requerimientos climáticos entre las tres subespecies, así como en las variables más importantes y sus curvas de respuesta. Los modelos de distribución potencial coinciden con las tierras altas de Mesoamérica y destacan las zonas bajas del istmo de Tehuantepec y la depresión de Nicaragua como posibles barreras geográficas. Las diferencias encontradas en los nichos ecológicos de las subespecies contrastan con los hallazgos previos para la especie y otros murciélagos filostómidos. Conservadurismo de nicho ecológico pudo provocar aislamiento geográfico en el pasado y las diferencias en los requerimientos climáticos pudieron aparecer después. Son necesarios análisis moleculares y morfológicos que permitan conocer de manera más amplia los patrones evolutivos involucrados en la diversificación de la especie. [ABSTRACT FROM AUTHOR]

• The sympatric zone of the pied and collared flycatchers shows clear habitat partitioning. • Habitat preferences of both flycatcher species change significantly in the presence of a competitor. • Pied flycatchers exhibit consistent habitat preferences in allopatric and allotopic sites. • Niche divergence and competition are critical in shaping habitat preferences of hybridising species. Describing mechanisms that ensure stable co-occurrence of sympatric species is fundamental to understanding the complexity of ecological community dynamics. In this study, the Pied flycatcher and the Collared flycatcher were used as model species for the analysis of co-occurrence patterns of closely related hybridising species that inhabit overlapping forest habitats. I hypothesise that spatial niche partitioning between species emerges as a vital adaptive response to interspecific competition and manifests itself in significant shifts in habitat preferences in syntopic areas but not in the allotopic ones. The study leverages a comprehensive dataset that includes species density in 372 randomly selected 1 km² grid cells across the territory of Poland. The analysis of habitat preferences was performed with linear mixed-effect modeling, whereas a contrast analysis was used to investigate changes in habitat preferences resulting from the presence of a competitor. The findings indicate that both species modify their habitat preferences when transitioning between syntopic and allotopic sites. Remarkably, in regions without competitors, such shifts are significantly less pronounced, as demonstrated by the Pied flycatcher that prefers the same habitats both in allopatric regions and allotopic sites. When these results are compared with other studies on closely related hybridising and non-hybridising species, it turns out that what influences the degree and number of niches subjected to competition is the time that passes from species divergence. This study highlights the imperative need to incorporate co-occurrence parameters of closely related species into niche and species distribution models to enhance their ecological realism. [ABSTRACT FROM AUTHOR]

Here, we explored how variations in the allopatric speciation scenario, specifically ecological vs. vicariant allopatry, relate to climatic niche change in sister species. We selected two sister species pairs of North American hummingbirds (Calypte anna, C. costae , Basilinna leucotis, B. xantusii) that diverged 2.5 and 3.6 million years ago, under ecological (arid climate tendency during Pliocene) and vicariant (Baja California peninsula separation) allopatric processes, respectively. We constructed the climatic niche of each species using occurrence records and estimated the distance, similarity, and unique fraction of climatic niche between sister species. Calypte species showed moderate niche divergence (Euclidean distance between centroids = 1.94, Sørensen index of similarity = 0.080, unique fraction of hypervolume in C. costae = 0.57, and C. anna = 0.95). However, contrary to expectations, Basilinna species, which diverged under a vicariant scenario, displayed clear niche divergence (Euclidean distance between centroids = 3.78, Sørensen index of similarity = 0.0001, and unique fraction of hypervolume in B. xantusii = 0.98, and B. leucotis = 0.99). We explained dissimilarity in climatic niches between Basilinna species by the ecological divergence between habitats of disjunct populations, which would have also been associated with increased aridity during the Pliocene. [Display omitted] • Type of allopatry affects the degree of niche conservatism in the speciation process. • We tested it in hummingbirds speciation under geographical and ecological allopatry. • Soft ecological allopatry in Calypte species led to expected niche divergence. • Hard geographical allopatry in Basilinna species led to unexpected niche divergence. • Environmental changes in the Pliocene and niche truncation may explain these patterns. [ABSTRACT FROM AUTHOR]

Abstract Background The evolutionary history of biodiversity in South America has been poorly studied in the seasonal dry tropical forest (SDTF). Species diversification in this ecosystem may have a twofold explanation. First, intermittent connections in the middle and late Pleistocene promoted species dispersal and/or genetic connectivity between lineages isolated in disjunct patches of forest. Second, allopatric speciation proceeded immediately after the formation and colonization of the SDTF in the Neogene. Here we studied the diversification of Psammolestes, a genus endemic of the SDTF and naturally infected with Trypanosoma cruzi (agent of Chagas disease), using a combination of phylogenetic, population genetics and niche model methods, and evaluated the reliability of the three morphospecies currently recognized. Results Our multilocus analyses recovered P. coreodes and P. tertius in a monophyletic clade sister to P. arthuri. Species delimitation tests recovered these lineages as different species despite the shared genetic variation observed between P. coreodes and P. tertius in five genes. Also, genetic variation of the genus clustered in three groups that were consistent with the three morphospecies. Our demographic model predicted a scenario of divergence in absence of gene flow, suggesting that mixed haplotypes may be the result of shared ancestral variation since the divergence of the subtropical-temperate species P. coreodes and P. tertius. In contrast, the tropical species P. arthuri was highly differentiated from the other two in all tests of genetic structure, and consistently, the Monmonier’s algorithm identified a clear geographical barrier that separates this species from P. coreodes and P. tertius. Conclusions We found three genetically structured lineages within Psammolestes that diverged in absence of gene flow in the late Miocene. This result supports a scenario of species formation driven by geographical isolation rather than by divergence in the face of gene flow associated with climatic oscillations in the Pleistocene. Also, we identified the Amazon basin as a climatic barrier that separates tropical from subtropical-temperate species, thus promoting allopatric speciation after long range dispersion. Finally, each species of Psammolestes occupies different climatic niches suggesting that niche conservatism is not crucial for species differentiation. These findings influence the current vector surveillance programs of Chagas disease in the region.

Despite the assessment of long-term niche dynamics could provide crucial information for investigating species responses to environmental changes, it is a poorly investigated topic in ecology. Here, we present a case study of multi-species niche analysis for 71 common breeding birds in Northern Italy, exploring long-term niche changes from 1992 to 2017 and their relationship with both population trends and species traits. We (i) quantified the realized Grinnellian niche in the environmental space, (ii) compared variations in niche breadth and centroid, (iii) tested niche divergence and conservatism through equivalency and similarity tests, (iv) calculated niche temporal overlap, expansion and unfilling indices, and (v) investigated their association with both population changes and species traits. Results supported niche divergence (equivalency test) for 32% of species, although two-thirds were not supported by the similarity test. We detected a general tendency to adjust the niche centroids towards warmer thermal conditions. Increasing populations were positively correlated with niche expansion, while negatively correlated with niche overlap, albeit at the limit of the significance threshold. We found moderate evidence for a non-random association between niche changes and species traits, especially for body size, clutch size, number of broods per year, inhabited landscape type, and migration strategy. We encourage studies correlating long-term population trends and niche changes with species traits’ information and a specific focus on cause-effect relationship at both the single and multiple-species level.

Ecological niche modelling is useful in estimating the environmental requirements of species and, by extension, can also estimate their distributional areas. For most cacti, ecological niche modelling and comparisons between species have only been performed for a set of variables mainly associated with temperature and precipitation. To expand environmental predictors in addition to climate variables, we use topographic and edaphic variables. The aims of this study were to determine which environmental factors influence the geographical distribution of the P. leucocephalus species group s.s. from Mexico and Central America, to build species distribution models, and to assess whether species have different climatic preferences. Based on ecological niche modelling, the main environmental variables that contribute to the distribution of species and the similarities or differences in ecological niches between species were inferred using Maxent and ENMTools. The results revealed that the studied species had different responses to environmental variables, resulting in a unique combination of conditions for each species, showing only six environmental variables in common. In general, variables with the greatest contributions to the models were climatic, followed by edaphic and topographic variables. The results of the quantification of niches between species showed that there was less than 0.5 overlap in Schoener's D values, suggesting niche divergence for the group species but in environments more similar than would be expected by random chance. Although species shared affinities for seasonally dry tropical forests, the importance of preferences for different sets of environmental variables by each species was clear. In addition, niche divergence between closely related species of the P. leucocephalus group s.s. is concordant with the previous delimitation at the species level. [ABSTRACT FROM AUTHOR]

The Atlantic and Amazon rainforests have a shared but unclear past, with intermittent connections resulting from historical climate change. We investigate these connections by studying the phylogeography and climatic niche of the disjunct distributed frog Lithobates palmipes. We sequenced two fragments of mitochondrial DNA from Atlantic Forest (AtF) and Amazonia (AmF) individuals and evaluated how genetic diversity is distributed in space and whether past demographic changes occurred. Also, we evaluated the existence of past suitable connections between biomes for L. palmipes through ecological niche models (ENM) and tested for niche divergence. The AtF group is nested within the AmF group and closely related to individuals from eastern Amazonia, a pattern recovered in many species that used northeast connection routes. We found evidence of recurrent use of connections in different directions and time during the Pleistocene, resulting in genetic structure between biomes, with no signal of demographic change and evidence of niche divergence across both genetic groups. ENMs indicated suitable areas connecting forests throughout northeastern Brazil during the Pleistocene. Mitochondrial lineages do not match biomes exactly. One lineage is composed of AtF populations and eastern Amazonia individuals. The other is composed of western Amazonia individuals, suggesting an effect of past climatic heterogeneity within the Amazonia forest. This is the first evidence that this route drove genetic and ecological diversity for amphibians recently, a group with habits and ecological requirements different from other vertebrates that have been shown to use this putative corridor. [ABSTRACT FROM AUTHOR]

The Andean region is one of the most biodiverse areas, displaying high levels of endemism and spatial turnover of species. Tribe Eudemeae includes nine genera and 40 species distributed from the northern Andes in Colombia to the southernmost portion of the Andes in Argentina and Chile. Here, we generated a species-level phylogenetic tree to study their climatic niche evolution. We first analysed phylogenetic structure and evolutionary shifts among the main climatic spaces using model-based estimates. Second, we estimated climatic niches for each species and compared them in a phylogenetic context. In Eudemeae, three main groups of climatic spaces were found, mainly related to the northern and central Andes, the north-central portion of the southern Andes and the central-southern portion of the southern Andes. Results suggest that initial colonization of new climatic spaces in the evolution of the tribe appears to be promoted through shifts in adaptive regimes, whereas subsequent diversification of genera occurred predominantly under the same climatic regimes. This trade-off between niche conservatism and divergence appears to have modulated their diversification across the Andes and contributed to their current geographical distribution. [ABSTRACT FROM AUTHOR]

The Himalayas and the Hengduan Mountains of southwest China are hotspots of both climatic and species diversity. Yet, the distribution patterns of semi‐arid plant communities that have arisen throughout the region's complex uplift history remain insufficiently understood. In particular, the striking disjunctions of plants associated with dry river valleys that solely occur on the eastern and western ends of the Himalayan arc, but are absent in between, lack a sound explanation. Here we aim to disentangle the more recent environmental drivers behind the disjunction of the semi‐woody shrub Rumex hastatus found in dry river valleys of the western Himalayas and the Hengduan Mountains. We used ecological niche modeling and enhanced random forest parameterizations (down‐sampling) to infer suitable and unsuitable habitats within the study area during the last glacial maximum, under present climate conditions, and under four future climate scenarios. Annual and seasonal precipitation contributed the strongest to the discrimination between occurrences and the distribution gap, with the latter showing much higher rainfall amounts. The gap was also characterized by low overall habitat suitability, whereas occurrence probabilities in dry river valleys inhabited by R. hastatus were very high. However, some suitable but isolated habitats within the gap were detected in Bhutan and the southeastern Tibetan Plateau. The identified distribution gap was consistent in all simulated scenarios from the last glacial maximum to the near future. Our results suggest that the South Asian summer monsoon system acts as a persistent ecological barrier maintaining the disjunct distribution of dry river valley‐dwelling plants in the western Himalayas and the Hengduan Mountains. [ABSTRACT FROM AUTHOR]

Abstract Combining genetic data with ecological niche models is an effective approach for exploring climatic and nonclimatic environmental variables affecting spatial patterns of intraspecific genetic variation. Here, we adopted this combined approach to evaluate genetic structure and ecological niche of the Indian gray mongoose (Urva edwardsii) in Iran, as the most western part of the species range. Using mtDNA, we confirmed the presence of two highly differentiated clades. Then, we incorporated ensemble of small models (ESMs) using climatic and nonclimatic variables with genetic data to assess whether genetic differentiation among clades was coupled with their ecological niche. Climate niche divergence was also examined based on a principal component analysis on climatic factors only. The relative habitat suitability values predicted by the ESMs for both clades revealed their niche separation. Between‐clade climate only niche comparison revealed that climate space occupied by clades is similar to some extent, but the niches that they utilize differ between the distribution ranges of clades. We found that in the absence of evidence for recent genetic exchanges, distribution models suggest the species occurs in different niches and that there are apparent areas of disconnection across the species range. The estimated divergence time between the two Iranian clades (4.9 Mya) coincides with the uplifting of the Zagros Mountains during the Early Pliocene. The Zagros mountain‐building event seems to have prevented the distribution of U. edwardsii populations between the western and eastern parts of the mountains as a result of vicariance events. Our findings indicated that the two U. edwardsii genetic clades in Iran can be considered as two conservation units and can be utilized to develop habitat‐specific and climate change‐integrated management strategies.

The Military Macaw (Ara militaris) is an endangered bird species with disjunct geographic distribution across the Neotropics, consisting of three recognized subspecies: One in Mexico (A. m. mexicanus) and two in South America (A. m. militaris and A. m. bolivianus). However, due to the limited phenotypic differentiation between these allopatric taxa, their taxonomic status has been the subject of debate. In this study, we explored mitochondrial DNA (mtDNA) variability to determine the phylogeographical pattern through phylogenetic and ecological modelling analyses. We also aimed to describe the evolutionary relationships of twelve A. militaris populations. We identified 41 haplotypes in the 300 bp region of the Cytochrome b (Cyt-b) gene of the mtDNA and low nucleotide diversity. The observed phylogeographic structure suggests the existence of two clades: One composed of A. m. militaris and A. m. bolivianus and another consisting solely of A. m. mexicanus. The A. m. mexicanus clade further divides into two recognized subclades: Sierra Madre Oriental and northeastern portion of the Sierra Madre Occidental. Ecological analyses revealed that the niche similarity between these lineages was lower than expected by chance. Additionally, results from low cross-prediction tests indicated that the two lineages have inhabited different environmental spaces since the Late Pleistocene. This divergence may be associated with a steep ecological gradient and contemporary geographical barrier. Based on our results, we suggest that at least the A. m. mexicanus has a divergent evolutionary history; therefore, it should be considered as a different evolutionarily significant and management unit. We recommend that future conservation strategies in Mexico incorporate effective protection measures, including habitat preservation and the reduction of illegal trade, to ensure the preservation of viable populations.

Defining appropriate null expectations for species distribution hypotheses is important because sampling bias and spatial autocorrelation can produce realistic, but ecologically meaningless, geographic patterns. Generating null species occurrences with similar spatial structure to observed data can help overcome these problems, but existing methods focus on single or pairs of species and do not incorporate between‐species spatial structure that may occlude comparative biogeographic analyses. Here, we describe an algorithm for generating randomised species occurrence points that mimic the within‐ and between‐species spatial structure of real datasets and implement it in a new R package – fauxcurrence. The algorithm can be implemented on any geographic domain for any number of species, limited only by computing power. To demonstrate its utility, we apply the algorithm to two common analysis‐types: testing the fit of species distribution models (SDMs) and evaluating niche‐overlap. The method works well on all tested datasets within reasonable timescales. We found that many SDMs, despite a good fit to the data, were not significantly better than null expectations and identified only two cases (out of a possible 32) of significantly higher niche divergence than expected by chance. The package is user‐friendly, flexible and has many potential applications beyond those tested here, such as joint SDM evaluation and species co‐occurrence analysis, spanning the areas of ecology, evolutionary biology and biogeography. [ABSTRACT FROM AUTHOR]

Premise: A switch in pollinator can occur when a plant lineage enters a new habitat where the ancestral pollinator is less common, and a novel pollinator is more common. Because pollinator communities vary according to environmental tolerances and availability of resources, there may be consistent associations between pollination mode and specific regions and habitats. Such associations can be studied in lineages that have experienced multiple pollinator transitions, representing evolutionary replicates. Methods: Our study focused on a large clade of Penstemon wildflower species in western North America, which has repeatedly evolved hummingbird‐adapted flowers from ancestral bee‐adapted flowers. For each species, we estimated geographic ranges from occurrence data and inferred environmental niches from climate, topographical, and soil data. Using a phylogenetic comparative approach, we investigated whether hummingbird‐adapted species occupy distinct geographic regions or habitats relative to bee‐adapted species. Results: Hummingbird‐adapted species occur at lower latitudes and lower elevations than bee‐adapted species, resulting in a difference in their environmental niche. Bee‐adapted species sister to hummingbird‐adapted species are also found in relatively low elevations and latitudes, similar to their hummingbird‐adapted sister species, suggesting ecogeographic shifts precede pollinator divergence. Sister species pairs—regardless of whether they differ in pollinator—show relatively little geographic range overlap. Conclusions: Adaptation to a novel pollinator may often occur in geographic and ecological isolation from ancestral populations. The ability of a given lineage to adapt to novel pollinators may critically depend on its ability to colonize regions and habitats associated with novel pollinator communities. [ABSTRACT FROM AUTHOR]

Species of the Heteropogon‐Themeda clade are ecologically important grasses distributed across the tropics, including widespread species, such as the pantropical Heteropogon contortus and Themeda triandra, and range‐restricted species such as Heteropogon ritchiei and Themeda anathera. Here, we examine habitat preferences of the grassland/savanna and wetland species by describing bioclimatic niche characteristics, characterizing functional traits, and investigating the evolution of functional traits of 31 species in the Heteropogon‐Themeda clade in relation to precipitation and temperature. The climatic limits of the clade are linked to mean annual precipitation and seasonality that also distinguish seven wetland species from 24 grassland/savanna species. Tests of niche equivalency highlighted the unique bioclimatic niche of the wetland species. However, climatic factors do not fully explain species geographic range, and other factors are likely to contribute to their distribution ranges. Trait analyses demonstrated that the wetland and grassland/savanna species were separated by culm height, leaf length, leaf area, awn length, and awn types. Phylogenetic analyses showed that the wetland species had tall stature with long and large leaves and lack of hygroscopic awns, which suggest selective pressures in the shift between savanna/grassland and wetland. The two most widespread species, H. contortus and T. triandra, have significantly different bioclimatic niches, but we also found that climatic niche alone does not explain the current geographic distributions of H. contortus and T. triandra. Our study provides a new understanding of the biogeography and evolutionary history of an ecologically important clade of C4 tropical grasses. [ABSTRACT FROM AUTHOR]

Simple Summary: Temporal changes of ecological niches in relation to both population trends and species traits (life-history and ecological characteristics) are a poorly investigated topic in animal ecology even though they can provide crucial information for investigating how species respond to ongoing environmental changes. To fill this gap, we assessed niche changes from 1992 to 2017 for 71 common breeding birds in Northern Italy, using several niche metrics and relating them with both population trends and species traits. Our results showed that 32% of the species tended to change their niche in relation to the accessible environmental conditions. We found a tendency to adjust the niche towards warmer thermal conditions. This process may depend on several drivers, which act differently across species. Species undergoing a niche expansion showed increasing populations, while species tending to retain their niche showed a tendency to be associated with decreasing populations. We also found evidence for a non-random association between niche temporal changes and species traits. Investigating these relationships is a pivotal point to implement effective conservation strategies for wildlife. Despite the assessment of long-term niche dynamics could provide crucial information for investigating species responses to environmental changes, it is a poorly investigated topic in ecology. Here, we present a case study of multi-species niche analysis for 71 common breeding birds in Northern Italy, exploring long-term niche changes from 1992 to 2017 and their relationship with both population trends and species traits. We (i) quantified the realized Grinnellian niche in the environmental space, (ii) compared variations in niche breadth and centroid, (iii) tested niche divergence and conservatism through equivalency and similarity tests, (iv) calculated niche temporal overlap, expansion and unfilling indices, and (v) investigated their association with both population changes and species traits. Results supported niche divergence (equivalency test) for 32% of species, although two-thirds were not supported by the similarity test. We detected a general tendency to adjust the niche centroids towards warmer thermal conditions. Increasing populations were positively correlated with niche expansion, while negatively correlated with niche overlap, albeit at the limit of the significance threshold. We found moderate evidence for a non-random association between niche changes and species traits, especially for body size, clutch size, number of broods per year, inhabited landscape type, and migration strategy. We encourage studies correlating long-term population trends and niche changes with species traits' information and a specific focus on cause-effect relationship at both the single and multiple-species level. [ABSTRACT FROM AUTHOR]

Different groups of taxa exhibit varying degree of climatic niche conservatism or divergence due to evolutionary constraints imposed on taxa and distributional relationships among them. Herein, we explore to what extent regional environmental conditions that taxa occupy affect climatic niche overlap between pairs of congeneric species of Peromyscus mice exhibiting allopatric, parapatric, or sympatric distributions. We used Bayesian generalized linear mixed models to identify environmental variables that best explain differences in climatic niche overlap between species. Our results suggest that regional environmental conditions explain 13–44% of variation in climatic niche overlap. Specifically, allopatric and parapatric species pairs are more likely to occupy similar climatic niches in areas that are topographically less complex but with more complex habitats. Sympatric species are more likely to occupy similar climatic niches in areas that promote local niche partitioning (topographically less complex, warmer winter temperatures, higher precipitation, and higher habitat complexity on a local scale). By understanding the relationship between regional environmental conditions and niche overlap, we highlight how differences in geography can contribute to shaping niches of congeneric species. [ABSTRACT FROM AUTHOR]