Amphibian Beta Diversity in the Brazilian Atlantic Forest: Contrasting the Roles of Historical Events and Contemporary Conditions at Different Spatial Scales

Abstract

Current patterns of biodiversity distribution result from a combination of historical and contemporary processes. Here, we compiled checklists of amphibian species to assess the roles of long-term climate stability (Quaternary oscillations), contemporary environmental gradients and geographical distance as determinants of change in amphibian taxonomic and phylogenetic composition in the Brazilian Atlantic Forest. We calculated beta diversity as both variation in species composition (CBD) and phylogenetic differentiation (PBD) among the assemblages. In both cases, overall beta diversity was partitioned into two basic components: species replacement and difference in species richness. Our results suggest that the CBD and PBD of amphibians are determined by spatial turnover. Geographical distance, current environmental gradients and long-term climatic conditions were complementary predictors of the variation in CBD and PBD of amphibian species. Furthermore, the turnover components between sites from different regions and between sites within the stable region were greater than between sites within the unstable region. On the other hand, the proportion of beta-diversity due to species richness difference for both CBD and PBD was higher between sites in the unstable region than between sites in the stable region. The high turnover components from CBD and PBD between sites in unstable vs stable regions suggest that these distinct regions have different biogeographic histories. Sites in the stable region shared distinct clades that might have led to greater diversity, whereas sites in the unstable region shared close relatives. Taken together, these results indicate that speciation, environmental filtering and limited dispersal are complementary drivers of beta-diversity of amphibian assemblages in the Brazilian Atlantic Forest.

Evaluating multiple spatial scales to understand the distribution of anuran beta diversity in the Brazilian Atlantic Forest

“…We observed that at the largest spatial extent (SS4), species replacement was lower among the sites within the same region than among sites among the regions. Increasing the spatial extent usually includes biogeographical regions that have undergone different processes of speciation, extinction, and colonization, resulting in different regional species pools among the regions (Barton et al., ; da Silva et al., ; Comte et al., ; Qian & Ricklefs, ). Recently, da Silva et al.…”

“…Because regions contain different regional species pools (Vasconcelos et al., ), we predict that the values of species replacement will be lower among sites within the same region than among those of different regions. Therefore, we expect that the values of species replacement will be associated with the region in which sites are located due to environmental filters and/or dispersal limitations (da Silva, Almeida‐Neto, & Arena, ; da Silva, Almeida‐Neto, et al., ).…”

Anurofauna de um remanescente alterado de floresta estacional semidecidual as margens do Rio Paranapanema

“…Entretanto, a distância geográfica não foi o principal fator, no qual as regiões mais próximas nem sempre foram as mais similares. Silva et al (2014) sugeriram que não somente os eventos atuais, como a distância geográfica, mas também os históricos, tais como condições topográficas, vegetação, limitação de dispersão, pontos de dispersão e isolamento geográfico, são possíveis formadores de comunidades. Além disso, as condições climáticas distintas entre regiões também podem restringir a dispersão de indivíduos que permanecem dentro da distribuição das espécies ancestrais (Wiens & Donoghue, 2004).…”

Functional traits explain amphibian distribution in the Brazilian Atlantic Forest

“…The distribution of organisms is the basis of ecological studies and can be determined by biotic and abiotic factors (Hutchinson, 1957;Soberón, 2007). For example, current patterns of species distributions are linked to historical and contemporary dispersals influenced by species characteristics and their specific functional traits (Baselga, Lobo, Svenning, Aragón, & Araújo, 2012;Carnaval, Hickerson, Haddad, Rodrigues, & Moritz, 2009;Carnaval & Moritz, 2008;Oberdorff, Hugueny, & Guegan, 1997;Ricklefs, 1987;Silva, Almeida-Neto, & Arena, 2014;Svenning & Skov, 2007).…”