Dados do Trabalho

TÍTULO

SPATIALLY-STRUCTURED ENVIRONMENTAL VARIATION DRIVES METACOMMUNITY ORGANIZATION OF PHYLLOSTOMID BATS IN ATLANTIC FOREST

Resumo

The metacommunity framework enhances understanding the dynamical balance between local (biotic interactions, environmental tolerance) and regional processes (dispersal, habitat fragmentation) in organizing communities along environmental gradients. Both environmental and spatial processes combine to determine the distributional ranges of species with metacommunity structures arising as an emergent property. We used incidence data for 54 phyllostomid bat species from 30 sites in the Atlantic Forest of Brazil to (1) determine species distributions, (2) characterize metacommunity structure, and (3) identify environmental and spatial characteristics that are associated with the emergent structure. Phyllostomid bats were analyzed from two perspective: entire metacommunity (all species) and separately for each of two functional groups (carnivores and herbivores). For 280 Atlantic Forest sites, we initially compiled from phyllostomid presence based on literature and the Adriano Lucio Peracchi Mammal Collection at the Federal Rural University of Rio de Janeiro, Brazil. More than 65% of these sites were sampled insufficiently (≤ 10 species). To enhance accuracy of estimates of species composition at sites, a systematic optimization was performed, resulting in 30 well-sampled locations (> 19 species). We extracted 19 climate variables from WorldClim database. Latitude and longitude were used to create Moran’s Eigenvectors Maps (MEMs) from which attributes were chosen to represent variation at broad to fine spatial scales. A forward selection with a double stopping criterion was used to reduce co-linearity among climate and spatial variables, and to select factors most likely to be important to bat distributions. Analyses of the Elements of Metacommunity Structure (coherence, turnover and boundary clumping) and Canonical Correspondence Analysis were used to determine the best-fit metacommunity structure and the characteristics associated with the latent environmental gradient, respectively. We used Variation Partitioning to determine the relative contribution of temperature, precipitation, and space to metacommunity composition. The metacommunity comprising all phyllostomids, as well as that comprising only carnivorous or herbivorous phyllostomids, exhibited positive coherence, indicating that the preponderance of species responded to the same latent environmental gradient in each case. The phyllostomid metacommunity showed non-significant positive species turnover, and significant positive boundary clumping, consistent with quasi-Clementsian structure. In contrast, carnivorous phyllostomids exhibited non-significant and negative species turnover, and non-significant boundary clumping, consistent with quasi-nested structure with stochastic species loss. Herbivorous phyllostomids showed significant and positive species turnover and boundary clumping, consistent with Clementsian structure. The environmental gradient reflected shared variation in temperature, precipitation, and space, and was consistent for each groups. Together, these three factors explained ~80% of variation in metacommunity composition. The quasi-Clementsian (all phyllostomids) and Clementsian (herbivores) structures indicate that compartments (i.e., groups of sites with similar species composition that differ from other such groups of sites) exist along the gradient. Conversely, the quasi-nested structure of carnivores indicates that (1) distributions of restricted range species are contained within the distributions of more wide-ranging species, and (2) range boundaries of species were related to species-specific environmental tolerances. In general, phyllostomid bats of the Atlantic Forest, regardless of group, exhibit non-random distributional patterns that are related to spatially structured environmental variation.

Palavras-chave

Brazil, Chiroptera, functional groups, precipitation, spatial structure, species distribution, temperature

Financiamento

CAPES, PSDE CAPES