Assembly rules of ground-foraging ant assemblages are contingent on disturbance, habitat and spatial scale

Aim A major endeavour of community ecology is documenting non‐random patterns in the composition and body size of coexisting species, and inferring the processes, or assembly rules, that may have given rise to the observed patterns. Such assembly rules include species sorting resulting from interspecific competition, aggregation at patchily distributed resources, and co‐evolutionary dynamics. However, for any given taxon, relatively little is known about how these patterns and processes change through time and vary with habitat type, disturbance history, and spatial scale. Here, we tested for non‐random patterns of species co‐occurrence and body size in assemblages of ground‐foraging ants and asked whether those patterns varied with habitat type, disturbance history, and spatial scale. Location Burned and unburned forests and fens in the Siskiyou Mountains of southern Oregon and northern California, USA. Methods We describe ground‐foraging ant assemblages sampled over two years in two discrete habitat types, namely Darlingtonia fens and upland forests. Half of these sites had been subject to a large‐scale, discrete disturbance – a major fire – in the year prior to our first sample. We used null model analyses to compare observed species co‐occurrence patterns and body‐size distributions in these assemblages with randomly generated assemblages unstructured by competition both within (i.e. at a local spatial scale) and among (i.e. at a regional scale) sites. Results At local spatial scales, species co‐occurrence patterns and body‐size ratios did not differ from randomness. At regional scales, co‐occurrence patterns were random or aggregated, and there was evidence for constant body‐size ratios of forest ants. Although these patterns varied between habitats and years, they did not differ between burned and unburned sites. Main conclusions Our results suggest that the operation of assembly rules depends on spatial scale and habitat type, but that it was not affected by disturbance history from fire.     

What drives the species richness patterns of non‐volant small mammals along a subtropical elevational gradient?

The biodiversity of non‐volant small mammals along an extensive subtropical elevational gradient was studied for the first time on Gongga Mountain, the highest mountain in Hengduan Mountain ranges in China, located in one of the 25 global biodiversity hotspots. Non‐volant small mammals were replicate sampled in two seasons at eight sampling sites between 1000 and 4200 m elevation on the eastern slope of Gongga Mountain. In all, 726 individual small mammals representing 25 species were documented in 28 800 trap nights. The species richness pattern for non‐volant small mammals along the elevational gradients was hump‐shaped with highest richness at mid‐elevations. However, different richness patterns emerged between endemic and non‐endemic species, between larger‐ranged and smaller‐ranged species and between rodents and insectivores. Temperature, precipitation, plant species richness and geometric constraints (mid‐ domain effect) were most significant in explaining species richness patterns. Based on the analysis of simple ordinary least squares (OLS) and stepwise multiple regressions, the overall richness pattern, as well as the pattern of insectivores, endemic species and larger‐ranged species showed strong correlation with geometric constraint predictions. However, non‐endemic species richness was more strongly correlated with temperature, while rodent richness was correlated with plant species richness. Our study shows that no single key factor can explain all richness patterns of non‐volant small mammals. We need to be cautious in summarizing a general richness pattern of large species groups (e.g. small mammals or mammals) from species in smaller groups having different ecological distributions and life histories. Elevational richness patterns and their driving factors for small mammals are more likely dependent on what kind of species we study.     

Ecological biogeography of Malagasy non‐volant mammals: community structure is correlated with habitat

Aim To examine the relationship between ecoregions, as a proxy for regional climate and habitat type, and mammalian community structure, defined by species composition and richness (e.g. taxonomic structure) and ecological diversity (e.g. ecological structure) of non‐volant species. Location Madagascar. Methods Faunal lists of non‐volant mammal species occurring in 35 communities from five World Wildlife Fund ecoregions were collected from published and unpublished sources. Species were assigned to ecological groups defined by trophic status, locomotor habits, activity cycle and body mass. We used Mantel tests, cluster analysis and principal coordinates analysis to evaluate geographic patterning in taxonomic composition and species richness. We used stepwise multiple discriminant analysis to characterize patterns in the ecological diversity of the mammalian communities from each ecoregion. Communities from transitional habitats (e.g. representing more than one ecoregion) were used to test the predictive power of the analyses. Results Non‐volant mammal communities divided into clusters that correspond to ecoregions. There was a strong distance effect in the taxonomic structure of communities across the island and within both humid and dry forest communities, but this effect was weak within humid forest communities. Mammalian species richness was significantly lower in dry forest than in humid forest communities. The ecological structure of communities was also correlated with ecoregions. Changes in the relative percentages of omnivory, arboreal quadrupedalism, terrestrial/arboreal quadrupedalism and two body mass classes accounted for 98.1% of the variation in ecological structure. Transitional communities were projected in intermediate positions by the discriminant model. Main conclusions Our analysis demonstrates that the broad‐scale habitat and climate variables captured by the ecoregion model have shaped the assembly of non‐volant mammal communities in Madagascar over evolutionary time. The spatial pattern is consistent with ecological sorting of species ranges along environmental gradients. Historical processes, such as recent extinction and migration, may have also affected the structure of mammal communities, although these factors have played a secondary role.     

Species interactions weakly modify climate‐induced tree co‐occurrence patterns

Aims

Species distributions are hypothesized to be underlain by a complex association of processes that span multiple spatial scales including biotic interactions, dispersal limitation, fine‐scale resource gradients and climate. Species disequilibrium with climate may reflect the effects of non‐climatic processes on species distributions, yet distribution models have rarely directly considered non‐climatic processes. Here, we use a Joint Species Distribution Model (JSDM) to investigate the influence of non‐climatic factors on species co‐occurrence patterns and to directly quantify the relative influences of climate and alternative processes that may generate correlated responses in species distributions, such as species interactions, on tree co‐occurrence patterns.

Location

US Rocky Mountains.

Methods

We apply a Bayesian JSDM to simultaneously model the co‐occurrence patterns of ten dominant tree species across the Rocky Mountains, and evaluate climatic and residual correlations from the fitted model to determine the relative contribution of each component to observed co‐occurrence patterns. We also evaluate predictions generated from the fitted model relative to a single‐species modelling approach.

Results

For most species, correlation due to climate covariates exceeded residual correlation, indicating an overriding influence of broad‐scale climate on co‐occurrence patterns. Accounting for covariance among species did not significantly improve predictions relative to a single‐species approach, providing limited evidence for a strong independent influence of species interactions on distribution patterns.

Conclusions

Overall, our findings indicate that climate is an important driver of regional biodiversity patterns and that interactions between dominant tree species contribute little to explain species co‐occurrence patterns among Rocky Mountain trees.     

Resilient forest faunal communities in South Africa: a legacy of palaeoclimatic change and extinction filtering?

Aim To examine the influence of climatic extinction filtering during the last glacial maximum (LGM; c. 18,000 yr bp ) and of the subsequent recolonization of forest faunas on contemporary assemblage composition in southern African forests. Location South Africa, Mozambique, Swaziland, Zimbabwe. Methods Data comprised presence/absence by quarter‐degree grid cell for forest‐dependent and forest‐associated birds, non‐volant mammals and frogs. Twenty‐one forest subregions were assigned to one of three previously identified forest types: Afrotemperate, scarp, and Indian Ocean coastal belt. Differences among forest types were examined through patterns and gradients of species richness and endemism, assemblage similarity, species turnover, and coefficients of species dispersal direction. The influence of contemporary environment on assemblage composition was investigated using partial canonical correspondence analysis. Several alternative biogeographical hypotheses for the recolonization of forest faunas were tested. Results Afrotemperate faunas are relatively species‐poor, have low species turnover, and are unsaturated and infiltrated by generalist species. In northern and central regions, communities are supplemented by recolonization from scarp forest refugia, and among frogs by autochthanous speciation in localized refugia. Scarp faunas are relatively species‐rich, contain many forest‐dependent species, have high species turnover, and overlap with coastal and Afrotemperate faunas. Coastal forests are relatively species‐rich with high species turnover. Main conclusions Afrotemperate communities were affected most by climatic extinction filtering events. Scarp forests were Afrotemperate refugia during the LGM and are a contemporary overlap zone between Afrotemperate and coastal forest. Coastal faunas derive from post‐LGM colonization along the eastern seaboard from tropical East African refugia. The greatest diversity is achieved in scarp and coastal forest faunas in northern KwaZulu–Natal province. This historical centre of diversity has influenced the faunal diversity of nearly all other forests in South Africa. The response of vertebrate taxa to large‐scale, historical processes is dependent on their relative mobility: forest birds best illustrate patterns resulting from post‐glacial faunal dispersal, while among mammals and frogs the legacy of climatic extinction filtering remains stronger.     

Phylogeny and biogeography of Caribbean mammals

Vicariance and dispersal hypotheses have been proposed over the last two hundred years to explain the distribution, diversity, and faunal composition of the Caribbean biota. Despite great advances in understanding the geological history of the region, recent biogeographical reviews have not used historical biogeographical methods. In this paper I review the taxonomy, distribution and phylogeny of all Cenozoic Caribbean non‐volant mammals and four bat lineages, and present reconciled trees for available phylogenies. Dates available from the fossil record and hypotheses of divergence based on molecular phylogenetic studies are also included in general assessments of fit between proposed geological models and Caribbean mammal diversification. The evidence posited in mammalian phylogenies does not add to the argument of dispersal vs. vicariance. One previously unidentified temporal pattern, the colonization of the Caribbean by South American mammals between the Palaeocene and the Middle Miocene, accounts for the distribution and phylogeny of the majority of lineages studied. Choloepodine and megalocnine sloths, hystricognath rodents, and primates all arrived during this window of colonization. Of these, megalocnine sloths, hystricognath rodents, Brachyphylla and allied bats, Stenodermatina bats, and primates fit the pattern of divergence from the mainland implied by the Gaarlandia hypothesis. Sloths, rodents and primates also roughly fit the timing of arrival to the Caribbean implied by Gaarlandia. The remaining taxa show contradictory dates of divergence according to molecular clock estimates, and no taxa fit the predicted timing and pattern of divergence among Antillean landmasses under the Gaarlandia model. Choloepodine sloths, murid rodents, insectivorans, mormoopids, and natalids show patterns of divergence from the mainland that are inconsistent with the Gaarlandia hypothesis and seem to require taxon‐specific biogeographical explanations. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81 , 373–394.     

The Indochinese–Sundaic zoogeographic transition: a description and analysis of terrestrial mammal species distributions

Aim We describe the distributions of mammal species between the Indochinese and Sundaic subregions and examine the traditional view that the two faunas show a transition near the Isthmus of Kra on the Thai–Malay peninsula. Location Species distributions are described along a 2000‐km transect from 20° N (northernmost Thailand) to 1° N (Singapore). Methods For the 325 species of native non‐marine mammals occurring along the transect we used published records to provide a database of their distributional records by degree of latitude. Results Along the transect we found 128 Indochinese species with southern range limits, 121 Sundaic species with northern range limits, four un‐assignable endemics and 72 widespread species. In total, 152 southern and 147 northern range limits were identified, and their distribution provides no evidence for a narrow faunal transition near the Isthmus of Kra (10°30′ N) or elsewhere. Range limits of both bats and non‐volant mammals cluster in northernmost peninsular Malaysia (5° N) and 800 km further north, where the peninsula joins the continent proper (14° N). The clusters of northern and southern range limits are not concordant but overlap by 100–200 km. Similarly, the range limits of bats and non‐volant mammals cluster at slightly different latitudes. There are 30% fewer species and range limits in the central and northern peninsula (between 6 and 13° N), and 35 more widely distributed species have range gaps in this region. In addition, we found 70 fewer species at the southern tip of the peninsula (1° N) than at 3–4° N. Main conclusions The deficiencies of both species and species range limits in the central and northern peninsula are attributed to an area effect caused by repeated sea‐level changes. Using a new global glacioeustatic curve developed by Miller and associates we show that there were > 58 rapid sea‐level rises of > 40 m in the last 5 Myr that would have resulted in significant faunal compression and local population extirpation in the narrow central and northern parts of the peninsula. This new global sea‐level curve appears to account for the observed patterns of the latitudinal diversity of mammal species, the concentration of species range limits north and south of this area, the nature and position of the transition between biogeographical subregions, and possibly the divergence of the faunas themselves during the Neogene. The decline of species diversity at the southern end of the transect is attributed to a peninsula effect similar to that described elsewhere.     

Break the pattern: breakpoints in beta diversity of vertebrates are general across clades and suggest common historical causes

The use of correlative analyses might be insufficient to understand the processes that control biodiversity, because the variables accounting for different hypotheses (e.g. current climate, past climate change, post‐glacial dispersal limitation) are mutually correlated. We suggest here that, in order to gain insight, it could be useful to search for latitudinal thresholds that could provide information about qualitative changes in the way biodiversity varies in space. Such tipping points could inform about higher‐level processes that are not reflected in correlative analyses. We test whether similar breakpoints in latitudinal beta‐diversity patterns exist for different vertebrate groups with diverse life histories and dispersal abilities. In birds, bats and non‐volant mammals we find breakpoints similar to those of amphibians. Differences in species composition are mainly due to species replacement from the equator to the breakpoint, but are dominated by nested species losses from the breakpoint to higher latitudes. Thus, marked thresholds discriminate two world regions where different processes appear to drive biodiversity.     

Body size evolution in insular vertebrates: generality of the island rule

Aim My goals here are to (1) assess the generality of the island rule – the graded trend from gigantism in small species to dwarfism in larger species – for mammals and other terrestrial vertebrates on islands and island‐like ecosystems; (2) explore some related patterns of body size variation in insular vertebrates, in particular variation in body size as a function of island area and isolation; (3) offer causal explanations for these patterns; and (4) identify promising areas for future studies on body size evolution in insular vertebrates. Location Oceanic and near‐shore archipelagos, and island‐like ecosystems world‐wide. Methods Body size measurements of insular vertebrates (non‐volant mammals, bats, birds, snakes and turtles) were obtained from the literature, and then regression analyses were conducted to test whether body size of insular populations varies as a function of body size of the species on the mainland (the island rule) and with characteristics of the islands (i.e. island isolation and area). Results The island rule appears to be a general phenomenon both with mammalian orders (and to some degree within families and particular subfamilies) as well as across the species groups studied, including non‐volant mammals, bats, passerine birds, snakes and turtles. In addition, body size of numerous species in these classes of vertebrates varies significantly with island isolation and island area. Main conclusions The patterns observed here – the island rule and the tendency for body size among populations of particular species to vary with characteristics of the islands – are actually distinct and scale‐dependent phenomena. Patterns within archipelagos reflect the influence of island isolation and area on selective pressures (immigration filters, resource limitation, and intra‐ and interspecific interactions) within particular species. These patterns contribute to variation about the general trend referred to as the island rule, not the signal for that more general, large‐scale pattern. The island rule itself is an emergent pattern resulting from a combination of selective forces whose importance and influence on insular populations vary in a predictable manner along a gradient from relatively small to large species. As a result, body size of insular species tends to converge on a size that is optimal, or fundamental, for a particular bau plan and ecological strategy.     

Beta‐diversity in temperate and tropical forests reflects dissimilar mechanisms of community assembly

Site‐to‐site variation in species composition (β‐diversity) generally increases from low‐ to high‐diversity regions. Although biogeographical differences in community assembly mechanisms may explain this pattern, random sampling effects can create this pattern through differences in regional species pools. Here, we compared assembly mechanisms between spatially extensive networks of temperate and tropical forest plots with highly divergent species pools (46 vs. 607 species). After controlling for sampling effects, β‐diversity of woody plants was similar and higher than expected by chance in both forests, reflecting strong intraspecific aggregation. However, different mechanisms appeared to explain aggregation in the two forests. In the temperate forest, aggregation reflected stronger environmental correlations, suggesting an important role for species‐sorting (e.g. environmental filtering) processes, whereas in the tropics, aggregation reflected stronger spatial correlations, more likely reflecting dispersal limitation. We suggest that biogeographical differences in the relative importance of different community assembly mechanisms contribute to these striking gradients in global biodiversity.     

Using functional diversity patterns to explore metacommunity dynamics: a framework for understanding local and regional influences on community structure

The metacommunity concept, describing how local and regional scale processes interact to structure communities, has been successfully applied to patterns of taxonomic diversity. Functional diversity has proved useful for understanding local scale processes, but has less often been applied to understanding regional scale processes. Here, we explore functional diversity patterns within a metacommunity context to help elucidate how local and regional scale processes influence community assembly. We detail how each of the four metacommunity perspectives (species sorting, mass effects, patch dynamics, neutral) predict different patterns of functional beta‐ and alpha‐diversity and spatial structure along two key gradients: dispersal limitation and environmental conditions. We then apply this conceptual model to a case study from alpine tundra plant communities. We sampled species composition in 17 ‘sky islands’ of alpine tundra in the Colorado Rocky Mountains, USA that differed in geographic isolation and area (key factors related to dispersal limitation) and temperature and elevation (key environmental factors). We quantified functional diversity in each site based on specific leaf area, leaf area, stomatal conductance, plant height and chlorophyll content. We found that colder high elevation sites were functionally more similar to each other (decreased functional beta‐diversity) and had lower functional alpha‐diversity. Geographic isolation and area did not influence functional beta‐ or alpha‐diversity. These results suggest a strong role for environmental conditions structuring alpine plant communities, patterns consistent with the species sorting metacommunity perspective. Incorporating functional diversity into metacommunity theory can help elucidate how local and regional factors structure communities and provide a framework for observationally examining the role of metacommunity dynamics in systems where experimental approaches are less tractable.     

Effects of rain forest logging on species richness and assemblage composition of small mammals in Southeast Asia

Aim The effects of logging and habitat degradation on the richness and abundance of small mammals in Asian rain forests are largely unknown. This work compares the species richness, dominance and evenness of small non‐volant mammals between logged and unlogged forests, and assesses whether assemblage variability (β‐diversity) is similar between forest types. Location Southeast Asia, northern Borneo (Sabah, Malaysia), Sunda‐shelf. Methods We surveyed species‐rich assemblages of small non‐volant mammals in three unlogged and three logged forests for 2 years. At each forest site, we sampled a permanently marked transect and two additional sites in three trapping sessions. All analyses were performed at both levels to include the effects of local abundances and point estimates, separately from the relative abundances of species on a more regional scale. Results We trapped a total of 1218 individuals of 28 species. Eleven common species accounted for 95% of all captures. Species richness and diversity were significantly higher in unlogged forest (27 species) than in logged forest (17 species). This was mainly attributable to the smaller number of rarely recorded species in logged forest (five compared with 16 in unlogged forest, with a total of fewer than 10 captures). However, all common species were present in both logged and unlogged forests, and our analyses revealed similar patterns of dominance, evenness and fluctuations in abundance. Hence overall assemblage composition in multivariate space did not differ greatly between forest types. Assemblages of Muridae and Tupaiidae showed similar population fluctuations in space and time, indicating that the ecology of these taxa may be partially driven by the same environmental factors. Main conclusions Although species were distributed patchily within sites, analyses at local and regional scales revealed similar patterns in diversity and assemblage variability, suggesting that effects of forest modification did not differ extensively locally and regionally, but had a profound effect on rare species. Our results emphasize the importance and conservation value of logged forest stands that are able to hold a large proportion of the small mammals also found in unlogged forests. Rare and more specialized species are more vulnerable to forest degradation than commonly caught species, resulting in the complete loss, or a decrease in numbers, of certain groups, such as arboreal small mammals and Viverridae.     

Current biogeographical roles of the Kunlun Mountains

Large‐scale patterns of biodiversity and formation have garnered increasing attention in biogeography and macroecology. The Qinghai‐Tibet Plateau (QTP) is an ideal area for exploring these issues. However, the QTP consists of multiple geographic subunits, which are understudied. The Kunlun Mountains is a geographical subunit situated in the northern edge of the QTP, in northwest China. The diversity pattern, community phylogenetic structures, and biogeographical roles of the current flora of the Kunlun Mountains were analyzed by collecting and integrating plant distribution, regional geological evolution, and phylogeography. A total of 1911 species, 397 genera, and 75 families present on the Kunlun Mountains, of which 29.8% of the seed plants were endemic to China. The mean divergence time (MDT) of the Kunlun Mountains flora was in the early Miocene (19.40 Ma). Analysis of plant diversity and MDT indicated that the eastern regions of the Kunlun Mountains were the center of species richness, endemic taxa, and ancient taxa. Geographical origins analysis showed that the Kunlun Mountains flora was diverse and that numerous clades were from East Asia and Tethyan. Analysis of geographical origins and geological history together highlighted that the extant biodiversity on the Kunlun Mountains appeared through species recolonization after climatic fluctuations and glaciations during the Quaternary. The nearest taxon index speculated that habitat filtering was the most important driving force for biodiversity patterns. These results suggest that the biogeographical roles of the Kunlun Mountains are corridor and sink, and the corresponding key processes are species extinction and immigration. The Kunlun Mountains also form a barrier, representing a boundary among multiple floras, and convert the Qinghai‐Tibet Plateau into a relatively closed geographical unit.     

Island biogeography of Caribbean coral reef fish

Aim The goal of our study was to test fundamental predictions of biogeographical theories in tropical reef fish assemblages, in particular relationships between fish species richness and island area, isolation and oceanographic variables (temperature and productivity) in the insular Caribbean. These analyses complement an analogous and more voluminous body of work from the tropical Indo‐Pacific. The Caribbean is more limited in area with smaller inter‐island distances than the Indo‐Pacific, providing a unique context to consider fundamental processes likely to affect richness patterns of reef fish. Location Caribbean Sea. Methods We compiled a set of data describing reef‐associated fish assemblages from 24 island nations across the Caribbean Sea, representing a wide range of isolation and varying in land area from 53 to 110,860 km². Regression‐based analyses compared the univariate and combined effects of island‐specific physical predictors on fish species richness. Results We found that diversity of reef‐associated fishes increases strongly with increasing island area and with decreasing isolation. Richness also increases with increasing nearshore productivity. Analyses of various subsets of the entire data set reveal the robustness of the richness data and biogeographical patterns. Main conclusions Within the relatively small and densely packed Caribbean basin, fish species richness fits the classical species–area relationship. Richness also was related negatively to isolation, suggesting direct effects of dispersal limitation in community assembly. Because oceanic productivity was correlated with isolation, however, the related effects of system‐wide productivity on richness cannot be disentangled. These results highlight fundamental mechanisms that underlie spatial patterns of biodiversity among Caribbean coral reefs, and which are probably also are functioning in the more widespread and heterogeneous reefs of the Indo‐Pacific.     

Combining phylogenetic and ecological niche modeling approaches to determine distribution and historical biogeography of Black Hills mountain snails (Oreohelicidae)

We aim to show how a combination of molecular systematics and ecological niche modelling approaches can be used to test historical biogeographical hypotheses for species of conservation concern. We focus on the land snail genus Oreohelix (Oreohelicidae), a group found throughout the Rocky Mountains. In addition to its larger distribution, a group of Oreohelix is also found in the Black Hills of Wyoming and South Dakota, an isolated, easternmost extension of the Rocky Mountains. We determine the number, distribution, and relationships of Black Hills Oreohelicids, which are a current conservation concern due to their fragmented distribution. We compared Black Hills groups to those in the main part of the Rockies to test historical biogeographical patterns that explain current diversity. We collected mtDNA data (COI and 12S sequences) from multiple populations of Oreohelix throughout the Black Hills and in adjacent populations in the Rocky Mountains to construct phylogenetic hypotheses. To determine whether favourable environmental conditions currently exist between the Black Hills and the north-eastern Rocky Mountains, we used DesktopGARP to generate an ecological niche model for distinct lineages discovered in the molecular phylogenetic analysis. Results show that all Black Hills populations are likely Oreohelix cooperi and that little genetic differentiation exists within this clade. In addition, Black Hills groups are genetically similar or identical to populations found in the Judith Mountains and Bighorn Mountains (north-eastern Rockies). Ecological niche models show that suitable environmental conditions may exist between eastern Rockies and Black Hills O. cooperi samples. Taken together, the phylogenetic and niche model data, along with the low vagility of the snails, support passive long-distance dispersal as a likely explanation for current arrangement of biodiversity.     

Phylogeography and biogeography of the lower Central American Neotropics: diversification between two continents and between two seas

Lower Central America (LCA) provides a geologically complex and dynamic, richly biodiverse model for studying the recent assembly and diversification of a Neotropical biota. Here, we review the growing literature of LCA phylogeography studies and their contribution to understanding the origins, assembly, and diversification of the LCA biota against the backdrop of regional geologic and climatic history, and previous biogeographical inquiry. Studies to date reveal that phylogeographical signal within taxa of differing distributions reflects a diversity of patterns and processes rivalling the complexities of LCA landscapes themselves. Even so, phylogeography is providing novel insights into regional diversification (e.g. cryptic lineage divergences), and general evolutionary patterns are emerging. Congruent multi‐taxon phylogeographic breaks are found across the Nicaraguan depression, Chorotega volcanic front, western and central Panama, and the Darién isthmus, indicating that a potentially shared history of responses to regional‐scale (e.g. geological) processes has shaped the genetic diversity of LCA communities. By contrast, other species show unique demographic histories in response to overriding historical events, including no phylogeographic structure at all. These low‐structure or incongruent patterns provide some evidence for a role of local, ecological factors (e.g. long‐distance dispersal and gene flow in plants and bats) in shaping LCA communities. Temporally, comparative phylogeographical structuring reflects Pliocene–Pleistocene dispersal and vicariance events consistent with the timeline of emergence of the LCA isthmus and its major physiographic features, e.g. cordilleras. We emphasise the need to improve biogeographic inferences in LCA through in‐depth comparative phylogeography projects capitalising on the latest statistical phylogeographical methods. While meeting the challenges of reconstructing the biogeographical history of this complex region, phylogeographers should also take up the critical service to society of applying their work to the conservation of its fascinating biodiversity.     

Seasonal Change of Species Diversity Patterns of Non‐volant Small Mammals along Three Subtropical Elevational Gradients

Our understanding of geographic patterns of species diversity and the underlying mechanisms is increasing rapidly, whereas the temporal variation in these patterns remains poorly understood. We examined the seasonal species richness and species turnover patterns of non‐volant small mammals along three subtropical elevational gradients in southwest China. Small mammal diversity was surveyed in two seasons (early wet season and late wet season) using a standardized sampling protocol. The comparison of species richness patterns between two seasons indicated a temporal component in magnitude and shape, with species richness at high elevations clearly increased during the late wet season. Species richness demonstrated weak correlations with modelled temperature and precipitation. The elevational pattern of species turnover measured by Chao‐Sørenson similarity index also changed seasonally, even though the temporal pattern varied with scale. Species turnover between neighboring elevations at high elevations was slower in the late wet season. Meanwhile, there was an acceleration of species turnover along the whole range of the gradient. The seasonal change in species diversity patterns may be due to population‐level increases in abundance and elevational migration, whereas seasonal variation in factors other than temperature and precipitation may play a greater role in driving seasonal diversity patterns. Our study strongly supports the seasonality in elevational patterns of small mammal diversity in subtropical montane forests. Thus it is recommended that subsequent field surveys consider temporal sampling replicate for elevational diversity studies.     

Dispersal limitation and geographical distributions of mammal species

Aim To relate the dispersal limitation of endemic terrestrial mammals in Mexico to species life‐history traits and latitude. Location Mexico. Methods We modelled species ecological niches projected as potential distributions (P) using point occurrence data and 19 environmental variables for 89 endemic mammal species, and compared the areas covered by these ecological niche models with maps of species actual distributions (R) based on minimum convex polygons connecting marginal records based on museum specimens. We correlated body mass, food habits (herbivore, omnivore, insectivore, frugivore/granivore), volant and non‐volant (fossorial, arboreal, terrestrial) habits and mean latitude to the proportion of occupancy of species potential distributional areas (R/P). Results R and P were significantly positively correlated, with an overall average R/P ratio of 0.49. Less than half of the endemics (41 species) had a high occupancy (R/P values ranging from 0.50 to 0.90); a few (four species) showed full occupancy (> 0.90). Body mass and food habits were not correlated with R/P, but latitude showed significant correlations with R/P; volant mammals tended to show higher R/P values than non‐volant mammals. Main conclusions Few species filled most of the spatial extent of their ecological niches. Life‐history traits were generally poor predictors of proportional occupancy of species potential distributions. Endemics occurring at higher latitudes showed higher occupancy, suggesting that abiotic factors are likely to limit their distributions. Conversely, species at lower latitudes showed lower occupancy, suggesting that their distributions are limited by biotic factors and/or by geographical or historical barriers that prevent dispersal. The dispersal abilities of volant compared with non‐volant endemics can explain the higher occupancy in species potential distributions in the former group. These trends provide a baseline for exploring the importance of life‐history traits and abiotic versus biotic factors in limiting species distributions.     

The mammals of northern Melanesia: speciation,ecology, and biogeography

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The functional biogeography of species: biogeographical species roles of birds in Wallacea and the West Indies

Biogeographical systems can be analyzed as networks of species and geographical units. Within such a biogeographical network, individual species may differ fundamentally in their linkage pattern, and therefore hold different topological roles. To advance our understanding of the relationship between species traits and large‐scale species distribution patterns in archipelagos, we use a network approach to classify birds as one of four biogeographical species roles: peripherals, connectors, module hubs, and network hubs. These roles are based upon the position of species within the modular network of islands and species in Wallacea and the West Indies. We test whether species traits – including habitat requirements, altitudinal range‐span, feeding guild, trophic level, and body length – correlate with species roles. In both archipelagos, habitat requirements, altitudinal range‐span and body length show strong relations to species roles. In particular, species that occupy coastal‐ and open habitats, as well as habitat generalists, show higher proportions of connectors and network hubs and thus tend to span several biogeographical modules (i.e. subregions). Likewise, large body size and a wide altitudinal range‐span are related to a wide distribution on many islands and across several biogeographical modules. On the other hand, species restricted to interior forest are mainly characterized as peripherals and, thus, have narrow and localized distributions within biogeographical modules rather than across the archipelago‐wide network. These results suggest that the ecological amplitude of a species is highly related to its geographical distribution within and across bio geographical subregions and furthermore supports the idea that large‐scale species distributions relate to distributions at the local community level. We finally discuss how our biogeographical species roles may correspond to the stages of the taxon cycle and other prominent theories of species assembly.