Longitudinal gradients in the phylogenetic community structure of European Tenebrionidae (Coleoptera) do not coincide with the major routes of postglacial colonization

Species specific colonization abilities and biotic and abiotic filters influence the local and regional faunal composition along colonization trajectories. Using a recent compilation of the occurrences of 1373 darkling beetle (Tenebrionidae) species and subspecies in 49 European countries and major islands, we reconstructed the tenebrionid postglacial colonization of middle and northern Europe from southern European glacial refuges and linked species composition to latitudinal and longitudinal gradients in phylogenetic relatedness across Europe. The majority of European islands and mainland countries appeared to be phylogenetically clustered. We did not find significant latitudinal trends in average phylogenetic relatedness of regional faunas along the supposed postglacial colonization routes but detected a strong positive correlation between mean relatedness and longitude of mainland faunas and an opposite negative correlation for island faunas. The strength of phylogenetic relatedness in the regional tenebrionid faunas decreased significantly with latitude and to a lesser degree with longitude. These findings are in accordance with two trajectories of postglacial colonization from centres in Spain and middle Asia that caused a strong longitudinal trend in the phylogenetic relatedness. Subsequent pair‐wise analyses of species co‐occurrences showed that species of similar distributional ranges tend to be phylogenetically clustered and species of different spatial distribution to be phylogenetically segregated. Both findings are in accordance with the concept of ‘range size heritability’. Our study demonstrates that taxonomic data are sufficiently powerful to infer continental wide patterns in phylogenetic relatedness that can be linked to colonization history and geographic information.     

Does the colonization of new biogeographic regions influence the diversification and accumulation of clade richness among the Corvides (Aves: Passeriformes)?

Regional variation in clade richness can be vast, reflecting differences in the dynamics of historical dispersal and diversification among lineages. Although it has been proposed that dispersal into new biogeographic regions may facilitate diversification, to date there has been limited assessment of the importance of this process in the generation, and maintenance, of broad‐scale biodiversity gradients. To address this issue, we analytically derive biogeographic regions for a global radiation of passerine birds (the Corvides, c. 790 species) that are highly variable in the geographic and taxonomic distribution of species. Subsequently, we determine rates of historical dispersal between regions, the dynamics of diversification following regional colonization, and spatial variation in the distribution of species that differ in their rates of lineage diversification. The results of these analyses reveal spatiotemporal differences in the build‐up of lineages across regions. The number of regions occupied and the rate of transition between regions both predict family richness well, indicating that the accumulation of high clade richness is associated with repeated expansion into new geographic areas. However, only the largest family (the Corvidae) had significantly heightened rates of both speciation and regional transition, implying that repeated regional colonization is not a general mechanism promoting lineage diversification among the Corvides.     

Morphological disparity opposes latitudinal diversity gradient in lacertid lizards

While global variation in taxonomic diversity is strongly linked to latitude, the extent to which morphological disparity follows geographical gradients is less well known. We estimated patterns of lineage diversification, morphological disparity and rates of phenotypic evolution in the Old World lizard family Lacertidae, which displays a nearly inverse latitudinal diversity gradient with decreasing species richness towards the tropics. We found that lacertids exhibit relatively constant rates of lineage accumulation over time, although the majority of morphological variation appears to have originated during recent divergence events, resulting in increased partitioning of disparity within subclades. Among subclades, tropical arboreal taxa exhibited the fastest rates of shape change while temperate European taxa were the slowest, resulting in an inverse relationship between latitudinal diversity and rates of phenotypic evolution. This pattern demonstrates a compelling counterexample to the ecological opportunity theory of diversification, suggesting an uncoupling of the processes generating species diversity and morphological differentiation across spatial scales.     

Dynamics in the evolution of sexual traits: losses and gains,radiation and convergence in yellow wagtails (Motacilla flava)

We analyse patterns of genetic diversity and song complexity in the Palaearctic yellow wagtail (Motacilla flava), a highly polytypic species complex. Mitochondrial and nuclear DNA show that the complex is polyphyletic, despite parallel plumage variation in western and eastern clades. In the western clade there is genetic structure among southern subspecies, haplotype diversity decreases with latitude, and northern subspecies show evidence of bottlenecking and rapid expansions, as expected from isolation in glacial refugia followed by postglacial colonization. However, northern subspecies, which have more divergent male plumages, lack genetic structure and sing simpler songs. Loss of song complexity and evolution of plumage in founder populations are consistent with the Kaneshiro model, which posits that variation among species is a consequence of founder-induced shifts in female preference leading to loss of ancestral male sexual traits. Our results suggest possible postglacial founder-effect mechanisms for the morhological diversification of the yellow wagtail complex.     

An inverse latitudinal gradient of diversity of peracarid crustaceans along the Pacific Coast of South America: out of the deep south

Aim To understand the ecological and historical/evolutionary processes underlying an inverse latitudinal gradient of richness (LGR) using crustacean peracarid species as a model group. Location The Pacific coast of South America, along the Chilean coast between 18° S and 56° S. Methods The LGR was evaluated using a dataset including 320 marine peracarid species reported for the coasts of Chile. Five ecological hypotheses invoking a relationship between species richness and present‐day conditions were tested: species–energy, species–area, Rapoport rescue effect, mid‐domain geometric constraint and niche breadth. Historical/evolutionary hypotheses (i.e. biogeographic conservatism, and diversification rates) were indirectly tested by analysing the latitudinal variation in the taxonomic distinctness, the taxonomic conservatism of the midpoint of the latitudinal range and the degree of nestedness at different taxonomic levels. Results Richness increased poleward, varying approximately eightfold, following an inverse LGR coupled with an increase in bathymetric distribution. Overall this inverse LGR seems robust to uncertainties in the completeness of the species inventory. We found support for only two of the five ecological hypotheses tested: species–area and Rapoport rescue effect. Historical/evolutionary hypotheses seemed important in structuring the richness pattern, as indicated by the higher taxonomic distinctness in the southern region, the strong taxonomic inertia in the mean range size and the high degree of nestedness of assemblages at different taxonomic levels. Conclusions When combined, these results underscore the importance of long‐term processes and historical/evolutionary explanations for the inverse LGR, conceptualized in what we term the ‘out of the deep south’ hypothesis that involves the effects of both biogeographic niche conservatism and evolutionary rates. We propose that the southern region may be a source of evolutionary novelties and/or exhibit higher diversification rates (i.e. higher speciation/lower extinction rates). Furthermore, phylogenetic conservatism of latitudinal range may limit the geographic expansion of these new taxa towards the depauperated northern region.     

Global patterns of amphibian phylogenetic diversity

Aim Phylogenetic diversity can provide insight into how evolutionary processes may have shaped contemporary patterns of species richness. Here, we aim to test for the influence of phylogenetic history on global patterns of amphibian species richness, and to identify areas where macroevolutionary processes such as diversification and dispersal have left strong signatures on contemporary species richness. Location Global; equal‐area grid cells of approximately 10,000 km². Methods We generated an amphibian global supertree (6111 species) and repeated analyses with the largest available molecular phylogeny (2792 species). We combined each tree with global species distributions to map four indices of phylogenetic diversity. To investigate congruence between global spatial patterns of amphibian species richness and phylogenetic diversity, we selected Faith’s phylogenetic diversity (PD) index and the total taxonomic distinctness (TTD) index, because we found that the variance of the other two indices we examined (average taxonomic distinctness and mean root distance) strongly depended on species richness. We then identified regions with unusually high or low phylogenetic diversity given the underlying level of species richness by using the residuals from the global relationship of species richness and phylogenetic diversity. Results Phylogenetic diversity as measured by either Faith’s PD or TTD was strongly correlated with species richness globally, while the other two indices showed very different patterns. When either Faith’s PD or TTD was tested against species richness, residuals were strongly spatially structured. Areas with unusually low phylogenetic diversity for their associated species richness were mostly on islands, indicating large radiations of few lineages that have successfully colonized these archipelagos. Areas with unusually high phylogenetic diversity were located around biogeographic contact zones in Central America and southern China, and seem to have experienced high immigration or in situ diversification rates, combined with local persistence of old lineages. Main conclusions We show spatial structure in the residuals of the relationship between species richness and phylogenetic diversity, which together with the positive relationship itself indicates strong signatures of evolutionary history on contemporary global patterns of amphibian species richness. Areas with unusually low and high phylogenetic diversity for their associated richness demonstrate the importance of biogeographic barriers to dispersal, colonization and diversification processes.     

Connectivity and vagility determine spatial richness gradients and diversification of freshwater fish in North America and Europe

The latitudinal species richness gradient (LRG) has been the subject of intense interest and many hypotheses but much less consideration has been given to longitudinal richness differences. The effect of postglacial dispersal, determined by connectivity and vagility, on richness was evaluated for the species‐poor European and North American Pacific and species‐rich Atlantic regional freshwater fish faunas. The numbers of species, by habitat, migration and distributional range categories, were determined from regional species lists for these three realms. The current orientation and past connections of drainage channels indicate that connectivity is greatest in the Atlantic and least in the Pacific. With increasing connectivity across realms, endemism decreased and postglacial recolonization increased, as did the LRG slope, with the greatest richness difference occurring between southern Atlantic and Pacific regions. Recolonizing species tended to be migratory, habitat generalists and from families of marine origin. Diversification, as indicated by species/genus ratios, probability of diversification, taxonomic distinctness and endemicity, declined with increasing latitude in all realms and was least in Europe. Richness patterns are consistent with an LRG driven by the time available for postglacial recolonization and by differences in dispersal ability, with richness differences across realms reflecting differences in dispersal and diversification.     

What determines species richness of parasitic organisms? A meta‐analysis across animal,plant and fungal hosts

Although a small set of external factors account for much of the spatial variation in plant and animal diversity, the search continues for general drivers of variation in parasite species richness among host species. Qualitative reviews of existing evidence suggest idiosyncrasies and inconsistent predictive power for all proposed determinants of parasite richness. Here, we provide the first quantitative synthesis of the evidence using a meta‐analysis of 62 original studies testing the relationship between parasite richness across animal, plant and fungal hosts, and each of its four most widely used presumed predictors: host body size, host geographical range size, host population density, and latitude. We uncover three universal predictors of parasite richness across host species, namely host body size, geographical range size and population density, applicable regardless of the taxa considered and independently of most aspects of study design. A proper match in the primary studies between the focal predictor and both the spatial scale of study and the level at which parasite species richness was quantified (i.e. within host populations or tallied across a host species' entire range) also affected the magnitude of effect sizes. By contrast, except for a couple of indicative trends in subsets of the full dataset, there was no strong evidence for an effect of latitude on parasite species richness; where found, this effect ran counter to the general latitude gradient in diversity, with parasite species richness tending to be higher further from the equator. Finally, the meta‐analysis also revealed a negative relationship between the magnitude of effect sizes and the year of publication of original studies (i.e. a time‐lag bias). This temporal bias may be due to the increasing use of phylogenetic correction in comparative analyses of parasite richness over time, as this correction yields more conservative effect sizes. Overall, these findings point to common underlying processes of parasite diversification fundamentally different from those controlling the diversity of free‐living organisms.     

Testing historical explanations for gradients in species richness in heliconiine butterflies of tropical America

We compiled a large database of 58 059 point locality records for 70 species and 434 subspecies of heliconiine butterflies and used these data to test evolutionary hypotheses for their diversification. To study geographical patterns of diversity and contact zones, we mapped: (1) species richness; (2) mean molecular phylogenetic terminal branch length; (3) subspecies richness and the proportion of specimens that were subspecific hybrids, and (4) museum sampling effort. Heliconiine species richness is high throughout the Amazon region and peaks near the equator in the foothills and middle elevations of the eastern Andes. Mean phylogenetic terminal branch length is lowest in the eastern Andes and tends to be low in species‐rich areas. By contrast, areas of high subspecies richness, where subspecies overlap in range and/or hybridize, are concentrated along the course of the Amazon River, with the eastern Andes slopes and foothills relatively depauperate in terms of local intraspecific phenotypic diversity. Spatial gradients in heliconiine species richness in the Neotropics are consistent with the hypothesis that species richness gradients are driven at least in part by variation in speciation and/or extinction rates, resulting in observed gradients in mean phylogenetic branch length, rather than via evolutionary age or niche conservatism alone. The data obtained in the present study, coupled with individual case studies of recently evolved Heliconius species, suggest that the radiation of heliconiine butterflies occurred predominantly on the eastern slopes of the Andes in Colombia, Ecuador, and Peru, as well as in the upper/middle Amazon basin. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 479–497.     

Historical contingency and ecological determinism interact to prime speciation in sticklebacks, Gasterosteus

Historical contingency and determinism are often cast as opposing paradigms under which evolutionary diversification operates. It may be, however, that both factors act together to promote evolutionary divergence, although there are few examples of such interaction in nature. We tested phylogenetic predictions of an explicit historical model of divergence (double invasions of freshwater by marine ancestors) in sympatric species of three-spined sticklebacks (Gasterosteus aculeatus) where determinism has been implicated as an important factor driving evolutionary novelty. Microsatellite DNA variation at six loci revealed relatively low genetic variation in freshwater populations, supporting the hypothesis that they were derived by colonization of freshwater by more diverse marine ancestors. Phylogenetic and genetic distance analyses suggested that pairs of sympatric species have evolved multiple times, further implicating determinism as a factor in speciation. Our data also supported predictions based on the hypothesis that the evolution of sympatric species was contingent upon 'double invasions' of postglacial lakes by ancestral marine sticklebacks. Sympatric sticklebacks, therefore, provide an example of adaptive radiation by determinism contingent upon historical conditions promoting unique ecological interactions, and illustrate how contingency and determinism may interact to generate geographical variation in species diversity     

Rates of morphological evolution are correlated with species richness in salamanders

The tempo and mode of species diversification and phenotypic evolution vary widely across the tree of life, yet the relationship between these processes is poorly known. Previous tests of the relationship between rates of phenotypic evolution and rates of species diversification have assumed that species richness increases continuously through time. If this assumption is violated, simple phylogenetic estimates of net diversification rate may bear no relationship to processes that influence the distribution of species richness among clades. Here, we demonstrate that the variation in species richness among plethodontid salamander clades is unlikely to have resulted from simple time-dependent processes, leading to fundamentally different conclusions about the relationship between rates of phenotypic evolution and species diversification. Morphological evolutionary rates of both size and shape evolution are correlated with clade species richness, but are uncorrelated with simple estimators of net diversification that assume constancy of rates through time. This coupling between species diversification and phenotypic evolution is consistent with the hypothesis that clades with high rates of morphological trait evolution may diversify more than clades with low rates. Our results indicate that assumptions about underlying processes of diversity regulation have important consequences for interpreting macroevolutionary patterns.     

Latitudinal variation in the shape of the species body size distribution: an analysis using freshwater fishes

Many taxonomic and ecological assemblages of species exhibit a right-skewed body size-frequency distribution when characterized at a regional scale. Although this distribution has been frequently described, factors influencing geographic variation in the distribution are not well understood, nor are mechanisms responsible for distribution shape. In this study, variation in the species body size-frequency distributions of 344 regional communities of North American freshwater fishes is examined in relation to latitude, species richness, and taxonomic composition. Although the distribution of all species of North American fishes is right-skewed, a negative correlation exists between latitude and regional community size distribution skewness, with size distributions becoming left-skewed at high latitudes. This relationship is not an artifact of the confounding relationship between latitude and species richness in North American fishes. The negative correlation between latitude and regional community size distribution skewness is partially due to the geographic distribution of families of fishes and apparently enhanced by a nonrandom geographic distribution of species within families. These results are discussed in the context of previous explanations of factors responsible for the generation of species size-frequency distributions related to the fractal nature of the environment, energetics, and evolutionary patterns of body size in North American fishes.     

Determinants of tapeworm species richness in elasmobranch fishes: untangling environmental and phylogenetic influences

Parasite species richness is a fundamental characteristic of host species and varies substantially among host communities. Hypotheses aiming to explain observed patterns of richness are numerous, and none is universal. In this study, we use tapeworm parasites of elasmobranch fishes to examine the phylogenetic and environmental influences on the variation in species richness for this specific system. Tapeworms are the most diverse group of helminths to infect elasmobranchs. Elasmobranchs are cosmopolitan in distribution and their tapeworm parasites are remarkably host specific; therefore, making this an ideal system in which to examine global patterns in species diversity. Here, we 1) quantify the tapeworm richness in elasmobranch fishes, 2) identify the host features correlated with tapeworm richness, and 3) determine whether tapeworm richness follows a latitudinal gradient. The individual and combined effects of host size, factors associated with water temperatures (influenced by latitude and depth), host habitat, and type of elasmobranch (shark or batoid) on measures of species diversity were assessed using general linear models. These analyses included tapeworm host records for 317 different elasmobranch species (124 species were included in our analyses) and were conducted with and without taking into account phylogenetic relationships between host species. Since sharks and batoids differ substantially in body form, analyses were repeated for each host subset. On average, batoids harboured significantly more tapeworm species than shark hosts. Tapeworm richness in sharks was influenced by median depth, whereas no predictor variable included in our models could adequately account for interspecific variation in tapeworm richness in batoid hosts. The taxonomic diversity of tapeworm assemblages of sharks and batoids was influenced by median depth and median latitude, respectively. When the influence of host phylogeny is accounted for, larger hosts harbour a greater tapeworm richness, whereas hosts exploiting wider latitudinal ranges harbour more taxonomically distinct tapeworm assemblages. Species richness and taxonomic diversity of tapeworm assemblages in elasmobranch fishes are influenced by different evolutionary pressures, including host phylogenetic relationships, space constraints and geographical area. Our results suggest that ca 3600 tapeworm species have yet to be described from elasmobranch fishes.     

Parasite species richness in carnivores: effects of host body mass, latitude, geographical range and population density

Aim  Comparative studies have revealed strong links between ecological factors and the number of parasite species harboured by different hosts, but studies of different taxonomic host groups have produced inconsistent results. As a step towards understanding the general patterns of parasite species richness, we present results from a new comprehensive data base of over 7000 host–parasite combinations representing 146 species of carnivores (Mammalia: Carnivora) and 980 species of parasites.
Methods  We used both phylogenetic and non-phylogenetic comparative methods while controlling for unequal sampling effort within a multivariate framework to ascertain the main determinants of parasite species richness in carnivores.
Results  We found that body mass, population density, geographical range size and distance from the equator are correlated with overall parasite species richness in fissiped carnivores. When parasites are classified by transmission mode, body mass and home range area are the main determinants of the richness of parasites spread by close contact between hosts, and population density, geographical range size and distance from the equator account for the diversity of parasites that are not dependent on close contact. For generalist parasites, population density, geographical range size and latitude are the primary predictors of parasite species richness. We found no significant ecological correlates for the richness of specialist or vector-borne parasites.
Main conclusions  Although we found that parasite species richness increases instead of decreases with distance from the equator, other comparative patterns in carnivores support previous findings in primates, suggesting that similar ecological factors operate in both these independent evolutionary lineages.     

Biogeography and ecological niche evolution in Diapensiaceae inferred from phylogenetic analysis

Diapensiaceae (Ericales) are a small family of about 15 species. Within this clade, two species are broadly distributed throughout the Northern Hemisphere, whereas the remaining species have a disjunct distribution between eastern North America and eastern Asia. To address patterns and processes of diversification in Diapensiaceae, we conducted biogeographic analyses and inferred shifts in the ecological niche across the phylogeny of the clade. Although Diapensiaceae have been the focus of multiple phylogenetic and biogeographic studies, previous studies have been taxonomically limited. This study has greatly improved the phylogenetic underpinning for Diapensiaceae with the most inclusive taxonomic sampling thus far, employing both nuclear and plastid gene sequence data for at least one sample per species in the family. Our estimates indicate that genera of Diapensiaceae variously diverged in the Eocene, Oligocene, and early to mid‐Miocene. The biogeographic analysis suggests that the probable ancestor of the Diapensiaceae crown clade originated in the Nearctic, with vicariance events contributing to the current distribution of the disjunct taxa. Ecological niche, when considered in a phylogenetic context, was observed to be clustered on the basis of biogeographic realm. In general, a greater ecological overlap was found at younger nodes and a greater niche divergence was found among distantly related species. Diversification in Diapensiaceae appears to have been shaped by both large‐scale biogeographic factors, such as vicariance, and divergence in an ecological niche among closely related species.     

Evolutionary and ecological causes of species richness patterns in North American angiosperm trees

Climate and evolutionary factors (e.g. diversification, time‐for‐speciation, niche conservatism) are both thought to be major drivers of species richness in regional assemblages. However, few studies have simultaneously investigated the relative effects of climate and evolutionary factors on species richness across a broad geographical extent. Here, we assess their relative effects on species richness of angiosperm trees across North America. Species richness of angiosperm trees in 1175 regional assemblages were related to climate and phylogenetic structure using a structural equation modeling (SEM) approach. Climate was quantified based on the mean temperature of the coldest month and mean annual precipitation. Evolutionary factors (time‐for‐speciation vs diversification) were inferred from phylogeny‐based measures of mean root distance, phylogenetic species variability, and net relatedness index. We found that at the continental scale, species richness is correlated with temperature and precipitation with approximately similar strength. In the SEM with net relatedness index and phylogenetic species variability and with all the 1175 quadrats, the total direct effect size of phylogenetic structure on species richness is greater than the total direct effect size of climate on species richness by a factor of 3.7. The specific patterns of phylogenetic structure (i.e. greater phylogenetic distances in more species rich regions) are consistent with the idea that time and niche conservatism drive richness patterns in North American angiosperm trees. We conclude that angiosperm tree species richness in regional assemblages in North America is more strongly related to patterns of phylogenetic relatedness than to climatic variation. The results of the present study support the idea that climatic and evolutionary explanations for richness patterns are not in conflict, and that evolutionary processes explain both the relationship between climate and richness and substantial variation in richness that is independent of climate.     

Environmental harshness is positively correlated with intraspecific divergence in mammals and birds

Life on Earth is conspicuously more diverse in the tropics. Although this intriguing geographical pattern has been linked to many biotic and abiotic factors, their relative importance and potential interactions are still poorly understood. The way in which latitudinal changes in ecological conditions influence evolutionary processes is particularly controversial, as there is evidence for both a positive and a negative latitudinal gradient in speciation rates. Here, we identify and address some methodological issues (how patterns are analysed and how latitude is quantified) that could lead to such conflicting results. To address these issues, we assemble a comprehensive data set of the environmental correlates of latitude (including climate, net primary productivity and habitat heterogeneity) and combine it with biological, historical and molecular data to explore global patterns in recent divergence events (subspeciation). Surprisingly, we find that the harsher conditions that typify temperate habitats (lower primary productivity, decreased rainfall and more variable and unpredictable temperatures) are positively correlated with greater subspecies richness in terrestrial mammals and birds. Thus, our findings indicate that intraspecific divergence is greater in regions with lower biodiversity, a pattern that is robust to both sampling variation and latitudinal biases in taxonomic knowledge. We discuss possible causal mechanisms for the link between environmental harshness and subspecies richness (faster rates of evolution, greater likelihood of range discontinuities and more opportunities for divergence) and conclude that this pattern supports recent indications that latitudinal gradients of diversity are maintained by simultaneously higher potentials for both speciation and extinction in temperate than tropical regions.     

Evolutionary processes,dispersal limitation and climatic history shape current diversity patterns of European dragonflies

We investigated the effects of contemporary and historical factors on the spatial variation of European dragonfly diversity. Specifically, we tested to what extent patterns of endemism and phylogenetic diversity of European dragonfly assemblages are structured by 1) phylogenetic conservatism of thermal adaptations and 2) differences in the ability of post‐glacial recolonization by species adapted to running waters (lotic) and still waters (lentic). We investigated patterns of dragonfly diversity using digital distribution maps and a phylogeny of 122 European dragonfly species, which we constructed by combining taxonomic and molecular data. We calculated total taxonomic distinctiveness and mean pairwise distances across 4192 50 × 50 km equal‐area grid cells as measures of phylogenetic diversity. We compared species richness with corrected weighted endemism and standardized effect sizes of mean pairwise distances or residuals of total taxonomic distinctiveness to identify areas with higher or lower phylogenetic diversity than expected by chance. Broken‐line regression was used to detect breakpoints in diversity–latitude relationships. Dragonfly species richness peaked in central Europe, whereas endemism and phylogenetic diversity decreased from warm areas in the south‐west to cold areas in the north‐east and with an increasing proportion of lentic species. Except for species richness, all measures of diversity were consistently higher in formerly unglaciated areas south of the 0°C isotherm during the Last Glacial Maximum than in formerly glaciated areas. These results indicate that the distributions of dragonfly species in Europe were shaped by both phylogenetic conservatism of thermal adaptations and differences between lentic and lotic species in the ability of post‐glacial recolonization/dispersal in concert with the climatic history of the continent. The complex diversity patterns of European dragonflies provide an example of how integrating climatic and evolutionary history with contemporary ecological data can improve our understanding of the processes driving the geographical variation of biological diversity.     

Environmental correlates of mammal species richness in South America: effects of spatial structure, taxonomy and geographic range

Although some consensus exists regarding the positive synergism between energy and heterogeneity in increasing species diversity, the role of environmental variability remains controversial. We examine how these factors interact to explain spatial variation in mammal species richness in South America. After taking into account the effects of spatial autocorrelation and area, elevation variability and energy mainly drive spatial variation in mammal species richness. The effect of environmental variability is less important. When different taxonomic groups of mammals are analyzed separately, three ways emerge whereby energy and heterogeneity interact to promote species richness. Heterogeneity may have no effect on species richness, habitat heterogeneity and energy availability contribute independently to species richness, or heterogeneity increases in importance with an increase in energy availability. The partition of species into range size quartiles shows that habitat heterogeneity and temporal instability in the resource supply account for the species richness pattern in the narrowest- ranging species. Habitat heterogeneity is significant also for intermediate ranging species but not for the widest-ranging species. Energy alone drives the species richness pattern in the latter species. The interplay between ecology and biogeographic history may ultimately explain these differences given that narrow- and wide-ranging species show distinct biogeographic patterns, and different taxonomic groups also unequally represent them.     

The role of frugivory in the diversification of bats in the Neotropics

Aim Ecological interactions are among the most important biotic factors influencing the processes of speciation and extinction. Our aim was to test whether diversification rates of New World Noctilionoidea bats are associated with specialization for frugivory, and how this pattern differs between the mainland and the West Indies. Location The New World. Methods We reconstructed a time‐calibrated molecular phylogenetic hypothesis for the New World genera of the superfamily Noctilionoidea. We compiled data on diet, morphology, geographical distribution and number of ecoregions in which each genus occurs. Then, using the phylogenetic tree constructed, we tested whether diversification was driven by diet (animalivorous and sanguinivorous versus nectarivorous and frugivorous) and specialization for frugivory. Afterwards, we conducted phylogenetic comparative analyses to identify correlates of species richness and net diversification rates. Results The diversification rate was higher in mutualistic than in antagonistic clades in mainland and Antillean biogeographical scenarios, but only strictly frugivorous clades showed a markedly higher diversification rate than the rest of the genera. Geographical range and number of ecoregions were positively associated with species richness and diversification rate in continental and insular lineages. Lower body mass, lower forearm length and specialization for frugivory were significantly positively correlated with higher diversification rates in continental lineages, whereas these parameters were negatively correlated in Antillean lineages. Main conclusions The direction of the relationship of intrinsic factors (specialization for frugivory and body size) with diversification of noctilionoid bats depends on the biogeographical context, whereas the direction of the relationship of extrinsic factors (geographical range and number of ecoregions) with diversification is consistent in both mainland and the West Indian lineages.