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

<div><p>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 <i>vs</i> 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.</p></div

Partition of the variance of Compositional Beta Diversity (CBD, β_jac, β_jtu and β_jne) and Phylogenetic Beta Diversity (PBD, UniFrac_Total, UniFrac_Turn and UniFrac_PD) components explained by geographical distance (Space), current environmental gradients (Environ) and long-term climatic conditions (refugia) for 44 sites in the southern range of Brazilian Atlantic Forest.

<p>Res  =  unexplained variance. “-”  =  variation explained <0.</p

Standardized effect size (SES) values for phylogenetic beta diversity (PBD, A = UniFrac_Total, B = UniFrac_Turn and C = UniFrac_PD) components among 44 sites in Brazilian Atlantic Forest.

<p>Values between dashed lines indicate that PBD components have no difference with respect to null expectation. Symbol colors indicate the region where the sites occur in the southern range of Brazilian Atlantic Forest. Black circles indicate SES between sites within stable region (Quaternary Climatic Stability). Gray circles indicates SES between sites within unstable region (Quaternary Climatic Oscillations). White circles indicate SES between unstable and stable sites (different regions).</p

Distribution of the10% highest values of annual precipitation for the current time, the two last glacial maximum period (LGM), and the intersection of the three maps.

<p>Symbols (in the intersection map) indicate the 44 sites in the southern range of Brazilian Atlantic Forest. Dark shading indicates stable regions. White circles represent sites in an unstable region (Quaternary Climatic Oscillations). White triangles represent sites in a stable region (Quaternary Climatic Stability). Abbreviations of each site as in Appendix S1 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109642#pone.0109642.s002" target="_blank">File S1</a>.</p

all data used in the paper

Data available: i) presence and absence of tadpoles in the ponds; ii) tadpole traits; iii) characteristics of the ponds; and iv) geographic coordenates