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Geography plays a paramount role in many aspects of speciation, including the amount of morphological and niche variation expected between sister species. Current species distributions, when coupled with phylogenies, offer valuable information on likely modes of geographic speciation. I briefly review past studies of the geography of speciation in neotropical plethodontid salamanders and analyze the spatial distributions and climatic overlap between sister species of this group. Using 66 pairs of sister species distributed from Mexico to Ecuador, I find that vicariant allopatric speciation probably played a dominant role in divergence of the bolitoglossines, but that peripatric and parapatric speciation were likely also important in generating the high diversity of the group. I find no evidence for latitudinal variation in speciation mechanisms within the tropics. Future studies incorporating physiology, spatial modeling, and population genetic estimates of demographic parameters will be critical in determining the importance of these nonvicariant speciation modes in the bolitoglossines, with implications for tropical biodiversity in general. [ABSTRACT FROM AUTHOR]

Polyploidy (whole-genome duplication, WGD) is an integral feature of eukaryotic evolution with two main forms typically recognized, autopolyploidy and allopolyploidy. In plants, a growing body of research contradicts historical assumptions that autopolyploidy is both infrequent and inconsequential in comparison to allopolyploidy. However, the legacy of these assumptions still persists through a lack of research on central facets of autopolyploid evolution. This review highlights recent research that has significantly increased scientific understanding of autopolyploidy. Key advances include: 1) unreduced female gametes contribute disproportionally to polyploidization through the formation of triploids, 2) niche divergence in autopolyploids can occur immediately or gradually after WGD through a diverse set of mechanisms, but broad niche overlap is also common between diploids and autopolyploids, and 3) the degree of genomic and transcriptomic changes following WGD is lower in autopolyploids than allopolyploids, but is highly variable both within and between species in both types of polyploids. We discuss the implications of these and other recent findings, present promising systems for future research, and advocate for expanded research in diverse areas of autopolyploid evolution. [ABSTRACT FROM AUTHOR]

Aim The Australian Coptotermes (Family: Rhinotermitidae) are a small monophyletic group of termites, some of which build mounds. In this study, we construct predicted distributions based on environmental data (niche models) for all Australian species of Coptotermes to test whether specific environmental factors have contributed to the evolution of mound-building behaviour and whether the degree of niche similarity and degree of phylogenetic similarity are correlated. Location The Australian mainland, including the known native ranges of all Australian species of Coptotermes. Methods We estimated the phylogenetic relationships between the species of Australian Coptotermes. We then generated and compared environmental niche models in a phylogenetic framework for all study species to test niche conservation. Our analyses were based on location data from our own sampling and from the Atlas of Living Australia, genetic data from a previous study of Australian Coptotermes, and environmental data from WorldClim and ASRIS. Results We found that no environmental variable differed consistently between mound-building and non-mound-building taxa and that the differences in niches between pairs of Australian species of Coptotermes are uncorrelated with time since divergence. The environmental tolerances of the Australian Coptotermes termites are more restricted by rainfall than they are by soil or temperature. Main conclusions Our results show that mound-building behaviour has not necessarily evolved in response to similar abiotic conditions. Our results are consistent with ecological speciation leading to niche divergence since Coptotermes first arrived in Australia ~12.5 million years ago. [ABSTRACT FROM AUTHOR]

We examined the hypothesis that ecological niche models ( ENMs) more accurately predict species distributions when they incorporate information on population genetic structure, and concomitantly, local adaptation. Local adaptation is common in species that span a range of environmental gradients (e.g., soils and climate). Moreover, common garden studies have demonstrated a covariance between neutral markers and functional traits associated with a species' ability to adapt to environmental change. We therefore predicted that genetically distinct populations would respond differently to climate change, resulting in predicted distributions with little overlap. To test whether genetic information improves our ability to predict a species' niche space, we created genetically informed ecological niche models ( gENMs) using Populus fremontii (Salicaceae), a widespread tree species in which prior common garden experiments demonstrate strong evidence for local adaptation. Four major findings emerged: (i) gENMs predicted population occurrences with up to 12-fold greater accuracy than models without genetic information; (ii) tests of niche similarity revealed that three ecotypes, identified on the basis of neutral genetic markers and locally adapted populations, are associated with differences in climate; (iii) our forecasts indicate that ongoing climate change will likely shift these ecotypes further apart in geographic space, resulting in greater niche divergence; (iv) ecotypes that currently exhibit the largest geographic distribution and niche breadth appear to be buffered the most from climate change. As diverse agents of selection shape genetic variability and structure within species, we argue that gENMs will lead to more accurate predictions of species distributions under climate change. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first complete genus-level phylogeny of Papaveraceae was built. • Papaveraceae began to diversify in Asian wet forests during the Early Cretaceous. • The four Cretaceous xeric clades appear to be relictual lineages. • Three dispersals from Asia to western North America coincide with the Cretaceous Terrestrial Revolution. • Geographic expansion and niche divergence shaped Cretaceous biogeographic patterns in Papaveraceae. Angiosperms, a trigger for the Cretaceous Terrestrial Revolution (KTR), underwent a rapid expansion and occupied all the environments during the Mid-Upper Cretaceous. Yet, Cretaceous biogeographic patterns and processes underlying the distribution of angiosperm diversity in the Northern Hemisphere are still poorly known. Here, we elucidated the biogeographic diversification of the angiosperm family Papaveraceae, an ancient Northern Hemisphere clade characterized by poor dispersal ability and high level of regional endemism. Based on both plastome and multi-locus datasets, we reconstructed a robust time-calibrated phylogeny that includes all currently recognized 45 genera of this family. Within the time-calibrated phylogenetic framework, we conducted 72 biogeographic analyses by testing the sensitivity of uncertainties of area delimitation, maxarea constraints, and the parameters of the model, i.e., j (describing jump-dispersal events) and w (modifying dispersal multiplier matrices), to ancestral range estimations. We also inferred ancestral habitat and ecological niches. Phylogenetic analyses strongly support Papaveraceae as monophyletic. Pteridophylloideae is strongly supported as sister to Hypecoideae-Fumarioideae. Our results indicate that the j parameter and number of predefined areas strongly affect ancestral range estimates, generating questionable ancestral ranges, whereas maxarea constraint and w parameter have no effect and improve model fit. After accounting for these uncertainties, our results indicate that Papaveraceae differentiated in Asian wet forests during the Lower Cretaceous and subsequently occupied the Asian and western North American arid and open areas. Three dispersals from Asia to western North America via the Bering land bridge occurred in the Mid-Upper Cretaceous, largely in agreement with the KTR. Habitat shift and ecological niche divergence resulted in the subsequent disjunctions between Asia and western North America. These findings suggest that the interplay of range expansion and niche divergence-driven vicariance might have shaped Cretaceous biogeographic patterns of angiosperms with Papaveraceae-like ecological requirements and dispersal abilities in the Northern Hemisphere, hence contributing to the knowledge on the geographic expansion of angiosperms during the KTR. [ABSTRACT FROM AUTHOR]

The opposing effects of environmental filtering and competitive interactions may influence community assembly and coexistence of related species. Competition, both in the domain of ecological resources, and in the sensory domain (for example, acoustic interference) may also result in sympatric species evolving divergent traits and niches. Delineating these scenarios within communities requires understanding trait distributions and phylogenetic structure within the community, as well as patterns of trait evolution. We report that sympatric assemblages of Asian barbets (frugivorous canopy birds) consist of a random phylogenetic sample of species, but are divergent in both morphological and acoustic traits. Additionally, we find that morphology is more divergent than expected under Brownian evolution, whereas vocal frequency evolution is close to the pattern expected under Brownian motion (i.e. a random walk). Together, these patterns are consistent with a role for competition or competitive exclusion in driving community assembly. Phylogenetic patterns of morphological divergence between related species suggest that these traits are key in species coexistence. Because vocal frequency and size are correlated in barbets, we therefore hypothesize that frequency differences between sympatric barbets are a by-product of their divergent morphologies.

A population of small-sized Arctic charr living their entire life cycle in deep water was recently found in Lake Skogsfjordvatn, Northern Norway. Their phenotype and life history closely resembles the profundal charr morph in another subarctic Norwegian lake, Fjellfrøsvatn. Fjellfrøsvatn has one littoral omnivorous and one small profundal benthivorous (PB) charr morph coexisting with brown trout, whereas Skogsfjordvatn has migratory salmon, trout, charr and eel populations in addition to threespined sticklebacks, resident trout and three resident charr morphs of which one is a large piscivorous profundal morph. We predicted that the small profundal charr morph in Skogsfjordvatn would have a similar trophic niche to the PB-morph in Fjellfrøsvatn and tested this by using stomach content and stable isotope (δC and δN) analyses. Profundal benthic invertebrates, mainly chironomid larvae, Pisidium sp. mussels and small crustaceans, dominated the diets, and the δC and δN values indicated almost identical long-term trophic niches of the PB-morphs in both lakes. The prediction was therefore supported. This seems to indicate that the small profundal Arctic charr morphs in these lakes have evolved in parallel, in nearly identical and stable habitat and dietary niches in spite of likely different ecological interactions within the contrasting fish communities. [ABSTRACT FROM AUTHOR]

Aim: Despite the incredible diversity of lowland tropical rain forests, we still have limited understanding of the drivers of speciation in these ecoregions. Here, we investigated the relative contribution of geographical and environmental factors to the diversification of a Neotropical genus of poison frogs (Oophaga). Location: Central and South America, including regions from southern Nicaragua to northern Ecuador. Methods: We generated gene genealogies (12S, 16S, COI, CytB and tRNA-val, SIAH1, H3 and Rag1) and used species phylogenetic methods (MDC and *beast) to generate a robust phylogeny of Oophaga frogs. Then, we combined the resulting phylogenetic hypothesis with detailed geographical data and environmental niche modelling (ENM) to test the role of geographical isolation, climatic niche divergence and altitudinal gradients. Results: Gene genealogies were discordant and did not show exclusive genealogical patterns; however, species tree resolved the phylogenetic relationship among Oophaga species with strong node support (> 0.9 ML/BPP). Geographical ranges showed little overlap between distantly related species. However, within the South American and Central American clades, sister taxa showed substantially overlapping ranges. Analyses of ecological disparity (DTT) indicated a departure from a neutral (Brownian) model of evolution, and agerange correlations, predicted niche occupancy profiles, and Seeva analyses showed that different species tend to evolve under different potential climatic niches. Main conclusions: Oophaga frogs originated in Central America and reached South America after the closure of the Panama Isthmus. The South- and Central-American clades of this genus have convergently evolved to similar patterns of geographical distribution and niche occupancy. Within clades, sister taxa showed parapatric distributions replacing each other along elevational gradients as predicted by the models of divergence along continuous ecological gradients. Accordingly, we found strong shifts in climatic niches throughout the history of these two clades. However, the largest niche shifts seem to post-date the final elevation of the Talamanca and northern Andes. Overall, our data suggest that speciation along climatic gradients on a structured landscape has been a major evolutionary force behind the diversification of Oophaga poison frogs. [ABSTRACT FROM AUTHOR]

Sexual dimorphism attributed to niche divergence is often linked to differentiation between the sexes in both dietary resources and characters related to feeding and resource procurement. Although recent studies have indicated that southern sea otters (Enhydra lutris nereis) exhibit differences in dietary preferences as well as sexual dimorphism in skull size and shape, whether these intersexual differences translate to differentiation in feeding performances between the sexes remains to be investigated. To test the hypothesis that scaling patterns of bite force, a metric of feeding performance, differ between the sexes, we calculated theoretical bite forces for 55 naturally deceased male and female southern sea otters spanning the size ranges encountered over ontogeny. We then used standardized major axis regressions to simultaneously determine the scaling patterns of theoretical bite forces and skull components across ontogeny and assess whether these scaling patterns differed between the sexes. We found that positive allometric increases in theoretical bite force resulted from positive allometric increases in physiological cross-sectional area for the major jaw adductor muscle and mechanical advantage. Closer examination revealed that allometric increases in temporalis muscle mass and relative allometric decreases in out-lever lengths are driving these patterns. In our analysis of sexual dimorphism, we found that scaling patterns of theoretical bite force and morphological traits do not differ between the sexes. However, adult sea otters differed in their absolute bite forces, revealing that adult males exhibited greater bite forces as a result of their larger sizes. We found intersexual differences in biting ability that provide some support for the niche divergence hypothesis. Continued work in this field may link intersexual differences in feeding functional morphology with foraging ecology to show how niche divergence has the potential to reinforce sexual dimorphism in southern sea otters. [ABSTRACT FROM AUTHOR]

Eremias strauchi strauchiandEremias strauchi kopetdaghicaare genetically and morphologically distinct and are distributed allopatrically in northeastern and northwestern Iran.E. s. strauchiis distinguishable by having green spots on lateral parts of the body, whileE. s. kopetdaghicais characterized by white spots and irregular black dots on lateral parts of the body. Recent molecular studies have suggested that these are two distinct species, but other types of analyses leave their classification unclear. In this study, we evaluated their taxonomic status using additional data (including ecological niches) to confirm the hypothesis that they are two species. All known records of their occurrence were employed to predict and evaluate the suitable areas where they may be expected to be found in Iran. We then performed niche similarity tests (niche identity and background tests) and point-based analyses to compare their ecological niches and explain ecological differentiation. Niche models ofE. s. strauchiandE. s. kopetdaghicahad good results and powerful performance based on high area under the curve (AUC) values [E. s. strauchi = 0.992, standard deviation (SD) = ± 0.008;E. s. kopetdaghica = 0.978, SD = ± 0.032]. Ecological differentiation has been found across the entire range, indicating that ecological differentiation had an important role in species differentiation. Environmental conditions for the species diverged along environmental variables, as precipitation of coldest quarter for the “Strauch” subspecies and precipitation of warmest quarter for the “Kopet dagh” subspecies were most important in determining habitat suitability, respectively. These two factors are important in niche differentiation between the two species and influenced their genetic divergence. Finally, our results confirmed the niche differentiation betweenE. s. strauchiandE. s. kopetdaghicaand added new insights into the taxonomic distinction betweenE. s. strauchiandE. s. kopetdaghica. [ABSTRACT FROM PUBLISHER]

PREMISE OF STUDY: Polyploidy is common in eukaryotes and is of major evolutionary importance over both short and long time-scales. Compared to allopolyploids, autopolyploids remain understudied; they are often morphologically cryptic and frequently remain taxonomically unrecognized, although there is increasing recognition of the high frequency of autopolyploidy in angiosperms. While autopolyploidy can serve as an instant speciation mechanism, little is known about the ecological consequences of this process. We describe the ecological divergence of a diploid-autotetraploid species pair in Tolmiea. METHODS: We investigated whether abiotic niche divergence has shaped the current allopatric distribution of diploid T. diplomenziesii and its autotetraploid derivative, T. menziesii, in the Pacific Northwest of North America. We employed field measures of light availability, as well as niche modeling and a principal component analysis of environmental space. Within a common garden, we also investigated physiological responses to changes in soil moisture. KEY RESULTS: Diploid and autotetraploid Tolmiea inhabit significantly different climatic niche spaces. The climatic niche divergence between these two species is best explained by a shift in precipitation availability, and we found evidence of differing physiological response to water availability between these species. CONCLUSIONS: We found that spatial segregation of T. diplomenziesii and T. menziesii was accompanied by adaptation to changes in climatic regime. Tolmiea menziesii is not a nascent autotetraploid, having persisted long enough to be established throughout the Pacific Northwest, and therefore both polyploidization and subsequent evolution have contributed to the observed differences between T. menziesii and T. diplomenziesii. [ABSTRACT FROM AUTHOR]

Context: Multispecies and multiscale habitat suitability models (HSM) are important to identify the environmental variables and scales influencing habitat selection and facilitate the comparison of closely related species with different ecological requirements. Objectives: This study explores the multiscale relationships of habitat suitability for the pine ( Martes martes) and stone marten ( M. foina) in northern Spain to evaluate differences in habitat selection and scaling, and to determine if there is habitat niche displacement when both species coexist. Methods: We combined bivariate scaling and maximum entropy modeling to compare the multiscale habitat selection of the two martens. To optimize the HSM, the performance of three sampling bias correction methods at four spatial scales was explored. HSMs were compared to explore niche differentiation between species through a niche identity test. Results: The comparison among HSMs resulted in the detection of a significant niche divergence between species. The pine marten was positively associated with cooler mountainous areas, low levels of human disturbance, high proportion of natural forests and well-connected forestry plantations, and medium-extent agroforestry mosaics. The stone marten was positively related to the density of urban areas, the proportion and extensiveness of croplands, the existence of some scrub cover and semi-continuous grasslands. Conclusions: This study outlines the influence of the spatial scale and the importance of the sampling bias corrections in HSM, and to our knowledge, it is the first comparing multiscale habitat selection and niche divergence of two related marten species. This study provides a useful methodological framework for multispecies and multiscale comparatives. [ABSTRACT FROM AUTHOR]

The environmental variables that define a species ecological niche should be associated with the evolutionary patterns present in the adaptations that resulted from living in these conditions. Thus, when comparing across species, we can expect to find an association between phylogenetically independent phenotypic characters and ecological niche evolution. Few studies have evaluated how organismal phenotypes might mirror patterns of niche evolution if these phenotypes reflect adaptations. Doing so could contribute on the understanding of the origin and maintenance of phenotypic diversity observed in nature. Here, we show the pattern of niche evolution of the pinyon pine lineage ( Pinus subsection Cembroides); then, we suggest morphological adaptations possibly related to niche divergence, and finally, we test for correlation between ecological niche and morphology. We demonstrate that niche divergence is the general pattern within the clade and that it is positively correlated with adaptation. [ABSTRACT FROM AUTHOR]

Aim To analyse the underpinnings of historical drivers of diversity and their contributions to current distributions and future roles in a changing climate, we studied the relationship between ecological niche divergence and phylogenetic signal in tropical carnivorous pitcher plants. Location Southeast Asia. Methods Estimates of realized ecological niches were reconstructed and plotted along a newly created multilocus molecular phylogeny. Phylogenetic signal was analysed by comparisons of calculated phylogenetic relatedness with ecological niche divergence. Current and projected future potentially suitable habitats were mapped for several species of plants with variable evolutionary histories and distributions. Results Highland and lowland species had distinct phylogenetic signals. Higher altitude species had significantly lower molecular divergence as compared with the lowland species, yet ecological niches with less overlap. When projected onto a future climate scenario, highland species lose a greater amount of potentially suitable habitat compared to lower altitude species, and the majority of studied higher altitude species will face an overall loss of future suitable habitat. Main conclusion We conclude that distinct phylogenetic signals not only unravel differing evolutionary histories but also show that the implications of species' tolerances to future changing climate vary. Over the past million years, historical climate change shaped the differing evolution and ecological niches of highland and lowland tropical pitcher plant species. Rapid, recent radiations of the higher altitude species are reflected in limited molecular divergence, which is in sharp contrast with the more gradually evolved and genetically distinct lower altitude species in our study. Our projections for future potentially suitable habitats show that on-going climate shifts will have detrimental effects on especially the higher altitude species due to a narrower niche tolerance and dramatic loss of potentially suitable habitat. [ABSTRACT FROM AUTHOR]

Understanding the factors promoting species formation is a major task in evolutionary research. Here, we employ an integrative approach to study the evolutionary history of the Californian scrub white oak species complex (genus Quercus). To infer the relative importance of geographical isolation and ecological divergence in driving the speciation process, we (i) analysed inter- and intraspecific patterns of genetic differentiation and employed an approximate Bayesian computation (ABC) framework to evaluate different plausible scenarios of species divergence. In a second step, we (ii) linked the inferred divergence pathways with current and past species distribution models (SDMs) and (iii) tested for niche differentiation and phylogenetic niche conservatism across taxa. ABC analyses showed that the most plausible scenario is the one considering the divergence of two main lineages followed by a more recent pulse of speciation. Genotypic data in conjunction with SDMs and niche differentiation analyses support that different factors (geography vs. environment) and modes of speciation (parapatry, allopatry and maybe sympatry) have played a role in the divergence process within this complex. We found no significant relationship between genetic differentiation and niche overlap, which probably reflects niche lability and/or that multiple factors, have contributed to speciation. Our study shows that different mechanisms can drive divergence even among closely related taxa representing early stages of species formation and exemplifies the importance of adopting integrative approaches to get a better understanding of the speciation process. [ABSTRACT FROM AUTHOR]

ABSTRACT Phylogenetic niche conservatism ( PNC) typically refers to the tendency of closely related species to be more similar to each other in terms of niche than they are to more distant relatives. This has been implicated as a potential driving force in speciation and other species-richness patterns, such as latitudinal gradients. However, PNC has not been very well defined in most previous studies. Is it a pattern or a process? What are the underlying endogenous (e.g. genetic) and exogenous (e.g. ecological) factors that cause niches to be conserved? What degree of similarity is necessary to qualify as PNC? Is it possible for the evolutionary processes causing niches to be conserved to also result in niche divergence in different habitats? Here, we revisit these questions, codifying a theoretical and operational definition of PNC as a mechanistic evolutionary process resulting from several factors. We frame this both from a macroevolutionary and population-genetic perspective. We discuss how different axes of physical (e.g. geographic) and environmental (e.g. climatic) heterogeneity interact with the fundamental process of PNC to produce different outcomes of ecological speciation. We also review tests for PNC, and suggest ways that these could be improved or better utilized in future studies. Ultimately, PNC as a process has a well-defined mechanistic basis in organisms, and future studies investigating ecological speciation would be well served to consider this, and frame hypothesis testing in terms of the processes and expected patterns described herein. The process of PNC may lead to patterns where niches are conserved (more similar than expected), constrained (divergent within a limited subset of available niches), or divergent (less similar than expected), based on degree of phylogenetic relatedness between species. [ABSTRACT FROM AUTHOR]

Aims This study explores the patterns of niche differentiation in a group of seven closely related columbines (genus Aquilegia, Ranunculaceae) from the Iberian Peninsula. Populations of these columbines are subject to complex patterns of divergent selection across environments, which partly explain the taxonomic structure of the group. This suggests the hypothesis that niche divergence must have occurred along the process of diversification of the group. Methods We used MaxEnt to build environmental niche models of seven subspecies belonging to the three species of Aquilegia present in the Iberian Peninsula. From these models, we compared the environmental niches through two different approaches: ENMtools and multivariate methods. Important Findings MaxEnt distributions conformed closely to the actual distribution of the study taxa. ENMtools methods failed to uncover any clear patterns of niche differentiation or conservatism in Iberian columbines. Multivariate analyses indicate the existence of differentiation along altitudinal gradients and along a gradient of climatic conditions determined by the summer precipitation and temperatures. However, climatic conditions related to winter temperature and precipitation, as well as soil properties, were equally likely to show conservatism or divergence. The complex patterns of niche evolution we found suggest that Iberian Columbines have not been significantly constrained by forces of niche conservatism, so they could respond adaptively to the fast and profound climate changes in the Iberian Peninsula through the glacial cycles of the Pleistocene. [ABSTRACT FROM AUTHOR]

Aim Diversification rates are critically important for understanding patterns of species richness, both among clades and among regions. However, the ecological correlates of variation in diversification rates remain poorly explored. Here, we test several hypotheses relating diversification rate and niche width across amphibian families (frogs and salamanders). Location Global. Methods We characterized climatic niches for 5784 amphibian species using databases for species distributions and climate. We estimated the niche width of each family using the range of values for climatic variables across all sampled species, and using the mean of species niche widths. We estimated diversification rates for families given their total number of described species and a time-calibrated phylogeny. We estimated relationships between variables using phylogenetic comparative methods. Results We found a significant positive relationship between family niche width and diversification rate, but a weak relationship between mean species niche width and diversification rate, despite both niche width variables being correlated. In fact, the deviation from this relationship (i.e. residuals of family niche width versus mean species niche width) was the best predictor of diversification rate. The observed relationship between niche width and diversification was independent of clade range size and niche position (e.g. whether clades occurred in tropical or temperate climates) and significantly different from null patterns derived from random sampling effects. Main conclusions Our results identify climatic niche width, and especially the relationship between family and species-level niche widths, as a major correlate of diversification rates among amphibian families. These results suggest that climatic niche divergence among species within clades can be important in explaining large-scale diversity patterns, possibly even more so than a clade's geographic area or whether it is primarily temperate or tropical. [ABSTRACT FROM AUTHOR]

Homoploid hybridization has increasingly been recognized as an important source of genetic variation to support adaptation to changing environmental conditions, the invasion of novel ecological niches and, ultimately, speciation. Although ecological selection pressures have been theorized to play a key role in the stabilization of homoploid hybrid lineages, surprisingly few detailed quantitative studies compare the realized ecological niches of hybrids and their progenitors. In this study, we compare twenty bioclimatic variables (Worldclim) at representative occurrence sites of Abies grandis, Abies concolor, and two classes of their natural hybrids, which are variably intergradient between their progenitors, to assess the potential role of ecological selection in the evolution of the observed morphological patterns of introgression. We find that both hybrid classes occupy distinct habitats that are variably intermediate between those associated with A. grandis and A. concolor for a majority of environmental variables, but with lower precipitation in the summertime in the southern Cascade, Siskiyou, and Sierra Nevada Mountains than associated with either progenitor. We hypothesize that moisture stress and high levels of solar insolation in the summertime associated with hybrid populations have played an important role in the observed patterns of introgression of key traits: leaf angle, specific leaf area, and abundance of adaxial stomates. Phenotypic plasticity in two of these traits may allow hybrids to adapt to an environment with a higher degree of variability in moisture stress. Moreover, in the context of moisture stress associated with predicted climate change, hybrids may have an adaptive advantage over A. grandis. [ABSTRACT FROM AUTHOR]

Genetic diversity analyses, coupled with ecological niche modelling ( ENM) of species with a restricted distribution, may provide valuable information for understanding diversification patterns in endangered areas. We analyzed the genetic diversity of Recordia reitzii, a tree restricted to the threatened and highly fragmented Brazilian Atlantic forest, using three intergenic cpDNA spacers and ten microsatellite ( SSR) loci. To assess the historical processes that may have influenced the distribution of extant R. reitzii populations, the current potential distributions of R. reitzii and Recordia boliviana, a closely related species, were modelled and projected onto the Last Glacial Maximum ( LGM) and Last Interglacial ( LIG) periods. Niche divergence was quantified between these two. The cpDNA and SSR data showed a north-south pattern of the diversity distribution and structured populations, suggesting that gene flow is probably limited. According to our data, R. reitzii exhibits low genetic diversity, which may be a result of a founder or distribution-reduction effect, narrow distribution or small population size. The ecological niche models showed a wider palaeodistribution during the LIG and a retraction during the LGM for both species. Tests of niche divergence and conservatism indicated that bioclimatic factors might have influenced the diversification of these Recordia species. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176, 332-348. [ABSTRACT FROM AUTHOR]

The black-spotted tokay and the red-spotted tokay are morphologically distinct and have largely allopatric distributions. The black-spotted tokay is characterized by a small body size and dark skin with sundry spots, while the red-spotted tokay has a relatively large body size and red spots. Based on morphological, karyotypic, genetic, and distribution differences, recent studies suggested their species status; however, their classifications remain controversial, and additional data such as ecological niches are necessary to establish firm hypotheses regarding their taxonomic status. We reconstructed their ecological niches models using climatic and geographic data. We then performed niche similarity tests (niche identity and background tests) and point-based analyses to explore whether ecological differentiation has occurred, and whether such differences are sufficient to explain the maintenance of their separate segments of environmental ranges. We found that both niche models of the black- and the red-spotted tokay had a good fit and a robust performance, as indicated by the high area under the curve ( AUC) values ('black' = 0.982, SD = ± 0.002, 'red' = 0.966 ± 0.02). Significant ecological differentiation across the entire geographic range was found, indicating that the involvement of ecological differentiation is important for species differentiation. Divergence along the environmental axes is highly associated with climatic conditions, with isothermality being important for the 'black' form, while temperature seasonality, precipitation of warmest quarter, and annual temperature range together being important for the 'red' form. These factors are likely important factors in niche differentiation between the two forms, which result in morphological replacement. Overall, beside morphological and genetic differentiation information, our results contribute to additional insights into taxonomic distinction and niche differentiation between the black- and the red-spotted tokay. [ABSTRACT FROM AUTHOR]

Classic niche theory predicts that competing species will evolve to use different resources and interact less, whereas recent niche-converge ideas predict that species evolve to use similar resources and interact more. Most data supporting niche evolution are based on observations of contemporary niche use, whereas experimental support is quite sparse. We followed the evolution of four species of Protozoa during succession in the water-filled leaves of the pitcher plant, Sarracenia purpurea, and found that evolution in multispecies systems follows a surprising pattern. Over several hundred generations, weak competitors evolved to be stronger, while strong competitors evolved to become weaker, which does not conform to expectations of either niche divergence or convergence. Evolution in this system appears to occur in response to characteristics of a suite of several competitors in the community, rather than pairwise interactions. Ecologists may need to rethink the roles of competition and evolution in structuring communities. [ABSTRACT FROM AUTHOR]

• For Whinchat and Stonecheat the secondary contact zone is a mosaic of allotopic and syntopic sites. • For both congeneric species, shift in habitat preferences in the sympatric zone is observed. • There are no differences between species in habitat preferences in allotopic sites. Co-occurence of related congeners is one of the most complicated ecological phenomena. Although such species are characterised by niche conservatism, which should exclude their stable co-existence, a communities often consist of sister species. Thus, there must be some ecological mechanism that separates them spatially or temporally. This study advocates that the answer is niche divergence that results from interspecific competition. Despite numerous studies documenting this biotic interaction as an important ecological process that segregates species spatially, only few deal with niche divergence between allotopy and syntopy in a mosaic of a large sympatric zone. That is why I decided to analyse the co-existence of two sister species, the Whinchat Saxicola rubetra and the Stonechat Saxicola rubicola in a sympatric zone, where both species occur alongside in syntopic sites, and separately in allotopic sites. Besides, I analyse the Whinchat's potential niche divergence between sympatric and allopatric zones which can be designated on the territory of Poland. It is assumed that niche divergence resulting from interspecific competition can be observed on the basis of differences in habitat preferences of one or both species between syntopy and allotopy, and also for the Whinchat between the sympatric and the allopatric zone. The assumptions were tested in generalised mixed-effect modelling and contrast analyses based on a large dataset of bird density in Poland. Both species demonstrated shifted environmental preferences between syntopy and allotopy, while in allopatry both species had similar niche preferences. The Whinchat also indicated no differences between allopatry and allotopy. Thus, the adopted analytical system clearly proves that the co-existence of congeneric species is possible due to niche divergence, which most likely results from interspecific competition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Species in the Leptodactylus latrans complex showed old origin during late Miocene. • Species limits and genetic breaks coincides with ecologically transitional areas rather than barriers. • Intraspecific lineages exhibited synchronous divergence within late Pleistocene and population expansion since Last Interglacial. • Pleistocene climatic oscillations prompted ecologically adapted lineages along eastern South America. • Rivers might not be important in the diversification of Leptodactylus latrans complex. Phylogeographic studies primarily focus on the major role of landscape topography in driving lineage diversification. However, populational phylogeographic breaks may also occur as a result of either niche conservatism or divergence, in the absence of geographic barriers to gene flow. Furthermore, these two factors are not mutually exclusive and can act in concert, making it challenging to evaluate their relative importances on explaining genetic variation in nature. Herein, we use sequences of two mitochondrial and four nuclear genes to investigate the timing and diversification patterns of species pertaining to the Leptodactylus latrans complex, which harbors four morphologically cryptic species with broad distributions across environmental gradients in eastern South America. The origin of this species complex dates back to the late Miocene (ca. 5.5 Mya), but most diversification events occurred synchronically during the late Pleistocene likely as the result of ecological divergence driven by Quaternary climatic oscillations. Further, significant patterns of environmental niche divergences among species in the L. latrans complex imply that ecological isolation is the primary mode of genetic diversification, mostly because phylogenetic breaks are associated with environmental transitions rather than topographic barriers at both species and populational scales. We provided new insights about diversification patterns and processes within a species complex of broadly and continuously distributed group of frogs along South America. [ABSTRACT FROM AUTHOR]

The Woodland Salamander genus Plethodon Tschudi, 1838, consists of terrestrial lungless salamanders, has been cited as an exemplar of a lineage characterized by niche conservatism. This conclusion has contributed to broader hypotheses dealing with the role of niche conservatism in speciation and the maintenance of species diversity. We re-evaluated these salamanders using newly published techniques designed to detect niche conservatism versus niche divergence using computer-based niche modeling and spatial analysis within a phylogenetic framework. We specifically studied parapatric neighbors in the species complex of Plethodon glutinosus (Green, 1818) to determine if there is evidence of a role for niche divergence at speciation or if niche conservatism characterizes the complex as has been reported for the larger genus. We found that new statistical approaches yield different results from earlier work, suggesting that niche divergence has been a much more important player in the speciation process than has heretofore been understood. Although different parts of the overall Plethodon phylogeny may be characterized by different rates of niche evolution, the rapidly burgeoning area of research centered on niche conservatism appears to be in a state of flux with regards to methods that give consistently repeatable results. [ABSTRACT FROM AUTHOR]

Aim Diversification and rapid radiation are well documented in lacertid lizards. Niche conservation is frequently observed among related taxa, whereby niches will not change much during speciation events. Here, we investigate the relationship between environmental niche divergence and phylogenetic relatedness in a widespread group of green lizards, the Lacerta trilineata group. Location Eastern Mediterranean, Anatolia and adjacent regions. Methods A dated phylogeny based on three mitochondrial genes was contextualized using species distribution models of all genetically identified lineages in the Lacerta trilineata group. Based on this analysis, ancestral climatic niche occupancy was reconstructed using niche occupancy profiles. Niche divergence among lineages was quantified by computing multivariate niche overlaps. Results All taxa are associated with humid areas, but there is extensive variation in their climatic niche breadths and positions, which accord with the main phylogenetic split in the group. Our results suggest divergent niche evolution within subclades and convergent evolution among clades, which implies only a limited degree of niche conservatism regarding annual variations in temperature and precipitation. In contrast, niche axes - mainly reflecting precipitation patterns of the coldest quarter - show a greater difference among clades than within clades, and therefore a higher degree of niche conservatism. Main conclusions Based on estimated divergence times between taxa and geological events in Anatolia, our results can be explained by fragmentation of the range of a hypothetical ancestral species, resulting in different adaptations of subclades either to humid continental climates or to more Mediterranean climates. Our study highlights deviations from classical niche conservatism theory due to significant niche shifts among sister taxa. [ABSTRACT FROM AUTHOR]

Aim We test whether populations of the Mesoamerican azure-crowned hummingbird, Amazilia cyanocephala (Trochilidae), located east and west of the Isthmus of Tehuantepec are genetically, morphologically and environmentally differentiated and examine the relative role of drift and selection in driving diversification. Location Mexico. Methods We sequenced the mitochondrial ATPase-6 and ATPase-8 genes and the control region of 130 individuals collected throughout the range of the species in Mexico. Population genetic methods and coalescent tests were used to reconstruct the phylogeography of the species. Morphological and niche variation between genetic groups of A. cyanocephala were assessed. Results The data revealed two genetic groups separated by the Isthmus of Tehuantepec in the late Pleistocene (49,300-75,800 years ago), with the split occurring in the presence of gene flow. Deviations from demographic equilibrium were detected for the two genetic groups, indicating more recent population expansions. Amazilia cyanocephala individuals from populations on either side of the Isthmus of Tehuantepec differed in morphology and were distributed in unique environmental space. A coalescent-based test indicated that selection is driving the observed morphological differentiation. Main conclusions Our findings implicate the Isthmus of Tehuantepec as a permeable barrier driving recent diversification of A. cyanocephala in the presence of gene flow. The two A. cyanocephala mitochondrial DNA (mt DNA) groups corresponding with morphological and environmental niche differences, in concert with the results of a coalescent-based test, suggest that selection has been strong enough to counteract the effects of gene flow. [ABSTRACT FROM AUTHOR]

Aim Niche modelling is increasingly used to predict species' geographical distributions or to infer the evolutionary or ecological processes that constrain them, but relatively few studies have examined the ecological processes governing the distributions of parasites. Among such processes, niche divergence is frequently invoked to explain species range variation. Here, we test whether the geographical distributions of two lineages of Leucocytozoon (Haemosporida) avian parasites are linked to climatic conditions and whether niche divergence can explain their geographical separation. Location Réunion, Mascarene archipelago, south-western Indian Ocean. Methods Leucocytozoon prevalence data were obtained by PCR screening of avian blood samples. Prevalence data and 20 environmental layers were used to build species distribution models ( SDMs). SDMs were built by averaging the predictions of five different models: random forests ( RF), generalized linear models ( GLM), generalized additive models ( GAM), multivariate adaptive regression splines ( MARS) and support vector machines ( SVM). Niche identity and background tests were used to test for a role of niche divergence in explaining parasite distributions. Results The geographical ranges of the two lineages of Leucocytozoon under study showed little overlap. Species distribution modelling suggested that niche divergence may explain the spatial variation observed in Leucocytozoon distribution, implying that the geographical separation of parasites is linked to environmental conditions. The variables that best explained parasite distribution were all related to precipitation patterns. Main conclusions As precipitation cannot directly affect endosymbiotic Leucocytozoon parasites, we suggest that the geographical separation of Leucocytozoon lineages is the result of an underlying geographical structure in the dipteran vectors that transmit these parasites. This illustrates the need to consider the ecology of vectors when predicting the distribution of vector-borne parasites. Our study also shows that different parasite lineages, contained within broadly defined parasitic taxa, may have very different ecologies, and that these differences should be taken into account when attempting to understand the ecological determinants of parasite distribution and disease emergence. [ABSTRACT FROM AUTHOR]

Aim Geographical and climatic barriers to organismal dispersal and distribution play a major role in speciation. We use a sister-pair of widespread savanna trees ( Melaleuca argentea and M. fluviatilis) to test the influence of putative barriers on divergence within and between species across an otherwise continuous landscape. Location The Australian monsoon tropics ( AMT). Methods Chloroplast and nuclear DNA sequences were used to estimate variation between and within species. Hypotheses invoking vicariance and ecological speciation as the mechanisms of divergence between species were explicitly tested using ecological niche modelling. Results We found little evidence for divergence across the Carpentaria Basin, although some chloroplast DNA haplotypes were restricted to regions to the east or west. Pilbara populations were distinct from those to the east across the Great Sandy Desert, including those from the Kimberley. There was a complex pattern of genetic divergence and niche differentiation among M. argentea and M. fluviatilis within a region of secondary range overlap coincident with currently recognized species boundaries across the Great Dividing Range. Main conclusions The two morphospecies are ecologically and genetically distinct, and maintain those differences in sympatry. Speciation might have occurred in allopatry in separate drainage basins that later came into contact. The Pilbara population appears to be distinct but requires further investigation. [ABSTRACT FROM AUTHOR]

Abstract: A previously published phylogeographic analysis of mtDNA sequences from the widespread Palearctic common rosefinch (Carpodacus erythrinus) suggested the existence of three recently diverged groups, corresponding to the Caucasus, central-western Eurasia, and northeastern Eurasia. We re-evaluated the mtDNA data using coalescence methods and added sequence data from a sex-linked gene. The mtDNA gene tree and SAMOVA supported the distinctiveness of the Caucasian group but not the other two groups. However, UPGMA clustering of mtDNA Φ ST-values among populations recovered the three groups. The sex-linked gene tree recovered no phylogeographic signal, which was attributed to recent divergence and insufficient time for sorting of alleles. Overall, coalescence methods indicated a lack of gene flow among the three groups, and population expansion in the central-western and northeastern Eurasia groups. These three groups corresponded to named subspecies, further supporting their validity. A species distribution model revealed potential refugia at the Last Glacial Maximum. These three groups, which we hypothesized are in the early stages of speciation, provided an opportunity for testing tenets of ecological speciation. We showed that the early stages of speciation were not accompanied by ecological niche divergence, consistent with other avian studies. [Copyright &y& Elsevier]

Using a species distribution model, we reconstructed the environmental niches of Antirrhinum majus pseudomajus and Antirrhinum majus striatum, two closely related species with parapatric distributions. We tested whether retention of ancestral environmental niche (i.e. niche conservatism) or adaptation to different ecological conditions (i.e. niche divergence) could explain the maintenance of their non-overlapping geographic ranges. We found that the environmental niche of A. m. pseudomajus is almost twice as large as that of A. m. striatum, with substantial overlap indicating that A. m. pseudomajus and A. m. striatum should co-occur frequently within the geographic range of A. m. striatum. By analysing contact zones where both subspecies are geographically close, we found that the presence of one subspecies instead of the other was significantly influenced by particular combinations of climatic factors. Since independent genetic evidence indicates that the two subspecies have experienced phases of range overlap at or near contact zones over the course of their evolutionary history, we propose that ecological niche displacement might be an important factor in explaining the absence of current range overlap between A. majus subspecies. [ABSTRACT FROM AUTHOR]

The article discusses the depth of diversification in the long tailed antbirds of the Andes Region. It examines the taxonomy of birds representing leneage by evaluating divergence in mitochondrial DNA (mtDNA). The results revealed diversification for recognition of the species and provides valuable inputs to mapping of the avian evolution.

The factors that determine species' range limits are of central interest to biologists. One particularly interesting group comprises odonates (dragonflies and damsel-flies), which show large differences in secondary sexual traits and respond quickly to climatic factors, but often have minor interspecific niche differences, challenging models of niche-based species coexistence. We quantified the environmental niches at two geographic scales to understand the ecological causes of northern range limits and the coexistence of two congeneric damselfiies (Calopteryx splendens and C. virgo). Using environmental niche modeling, we quantified niche divergence first across the whole geographic range in Fennoscandia, and second only in the sympatric part of this range. We found evidence for interspecific divergence along the environmental axes of temperature and precipitation across the northern range in Fennoscandia, suggesting that adaptation to colder and wetter climate might have allowed C. virgo to expand farther north than C. splendens. However, in the sympatric zone in southern Fennoscandia we found only negligible and nonsignificant niche differences. Minor niche differences in sympatry lead to frequent encounters and intense interspecific sexual interactions at the local scale of populations. Nevertheless, niche differences across Fennoscandia suggest that species differences in physiological tolerances limit range expansions northward, and that current and future climate could have large effects on the distributional ranges of these and ecologically similar insects. [ABSTRACT FROM AUTHOR]

Speciation often has a strong geographical and environmental component, but the ecological factors that potentially underlie allopatric and parapatric speciation remain understudied. Two ecological mechanisms by which speciation may occur on geographic scales are allopatric speciation through niche conservatism and parapatric or allopatric speciation through niche divergence. A previous study on salamanders found a strong latitudinal pattern in the prevalence of these mechanisms, with niche conservatism dominating in temperate regions and niche divergence dominating in the tropics, and related this pattern to Janzen's hypothesis of greater climatic zonation between different elevations in the tropics. Here, we test for latitudinal patterns in speciation in a related but more diverse group of amphibians, the anurans. Using data from up to 79 sister-species pairs, we test for latitudinal variation in elevational and climatic overlap between sister species, and evaluate the frequency of speciation via niche conservatism versus niche divergence in relation to latitude. In contrast to salamanders, we find no tendency for greater niche divergence in the tropics or for greater niche conservatism in temperate regions. Although our results support the idea of greater climatic zonation in tropical regions, they show that this climatic pattern does not lead to straightforward relationships between speciation, latitude, and niche evolution. [ABSTRACT FROM AUTHOR]

Abstract: Species delimitation is a task that has engaged taxonomists for more than two centuries. Recently, it has been demonstrated that molecular data and ecological niche modeling are useful in species delimitation. In this paper multiple data sets (molecular, morphological, ecological) were utilized to set limits for the species belonging to the Neotropical bamboo Otatea, because there is disagreement about species circumscriptions and also because the genus has an interesting distribution, with most of its populations in Mexico and a single disjunct population in Colombia. Molecular and morphological phylogenetic analyses recovered trees with conflicting topologies. Tree-based morphological and character-based analyses recognized the same entities. Ecological niche models and PCA/MANOVAS agreed with the recognition of the same entities that resulted from the morphological analyses. Morphological analyses retrieved clades supported by diagnostic characters and coherent geographical distributions. Based on these results seven entities should be recognized in Otatea, instead of the three previously described species. [Copyright &y& Elsevier]

• The hump-shaped pattern of species richness and the allochronic divergence of adult scorpionflies emergence were found. • Spatial-temporal niche divergence was found in closely-related species. • Most scorpionflies preferred cool habitats covered with dense woods at intermediate elevations in mountain regions. • The habitat shrinking caused by global warming may be the biggest threat to cool-adapted relict species of scorpionflies in mountain regions. Scorpionflies (Mecoptera, Panorpidae) as a relict group of holometabolous insects normally inhabit dense vegetations of mountain regions in the northern hemisphere. They are vulnerable to temperature changes and deforestation and thus play a significant role in insect conservation as ecological indicators. However, their elevational distribution and seasonal emergence patterns remain largely unknown. We documented the elevational richness gradient of scorpionflies in the Qinling Mountains, central China. The result revealed a distinct pattern of mid-elevational peak (hump-shaped) in species richness. The linear relationship between elevational locations of the whole community and emergence dates showed a gradual movement from lower to higher elevations over time. Niche divergence is an important ecological mechanism for closely related species to co-exist in the same region. Our investigation showed that allochronic divergences of adult emergence occurred mainly in intermediate elevations to reduce interspecific competition for resources. Spatio-temporal niche divergence was also detected in closely related species, especially in Cerapanorpa scorpionflies. Our results showed a clearer pattern of elevational diversity of scorpionflies and indicated that niche conservatism and divergence could explain the richness pattern at the same time. The area of intermediate elevations with the greatest species richness should receive a priority consideration for insect conservation for such a cool-adapted group of insects. [ABSTRACT FROM AUTHOR]

• The South American Tern is a poorly known seabird. • The species ecological niche is maintained throughout the year. • Environmental space differentiation is present between fall breeding areas. • Marine coastal provinces have limited utility in the modelling procedure. • The species seems to be resident in Peru coastal area. Defining a species' ecological niche is not a trivial task particularly for marine taxa, since physical and biological constraints are not easily perceived in these environments. Yet, coastal habitats are divided into provinces, influenced by different environmental conditions, such as superficial marine currents, causing seasonality in marine productivity and biomass. The South American Tern Sterna hirundinacea is a poorly known, migratory seabird distributed along the Pacific and Atlantic coasts of South America, including the Malvinas/Falkland Islands, and occurring in most of the South American coastal provinces. Limited knowledge on the migratory behaviour of the species points to differential habits between southern and northern populations. The species' breeding season also varies with latitude and season, occurring during spring in the south and in the fall in northern areas of the species occurrence. These observations point to putatively ecologically distinct populations along the species range that seem to be coincident with coastal provinces. To test our hypotheses, we estimated full-range ecological niche models per season, and we used coastal provinces to model ecological niches for each of the known breeding areas/seasons. We also tested for environmental space differentiation between seasons and breeding and non-breeding areas. Overall, the species does not seem to occupy significantly different ecological niches throughout the year, except during the breeding season, particularly between the Warm Temperate Southeastern Pacific and Warm Temperate Southwestern Atlantic provinces in fall. This suggests that the South American Tern migratory behaviour, the selection of different microhabitats and reproductive areas or distinct biological interactors might be influencing the species environmental space. Nonetheless, our models reinforce the gradual migration of this tern species towards the south, spending the summer mostly in the Malvinas/Falkland Islands. Interestingly, the species seems to be resident in Peru coastal area. Thus, despite the absence of ecological divergence, population structure should be tested and demographic trends assessed along the species range. [ABSTRACT FROM AUTHOR]

Many species of platyrrhine primates are characterised by sex-linked color vision polymorphism. This presents an opportunity to study the biology and ecology of individuals with different phenotypes living in the same group. Several evolutionary processes could maintain polymorphic genes in populations. In this study, we evaluate the hypothesis that foraging niche divergence among monkeys explains the presence of multiple color vision phenotypes. Specifically, we test whether dichromats and trichromats differ in foraging time devoted to cryptic vs brightly colored resources. We did not find any differences in foraging time spent on different food types by dichromatic and trichromatic monkeys in two groups of white-faced capuchins ( Cebus capucinus) living in a tropical dry forest. We conclude that in so far as these variables are concerned, niche divergence does not likely explain color vision polymorphism in our study population. [ABSTRACT FROM AUTHOR]