What Shapes the Phylogenetic Structure of Anuran Communities in a Seasonal Environment? The Influence of Determinism at Regional Scale to Stochasticity or Antagonistic Forces at Local Scale

<div><p>Ecological communities are structured by both deterministic and stochastic processes. We investigated phylogenetic patterns at regional and local scales to understand the influences of seasonal processes in shaping the structure of anuran communities in the southern Pantanal wetland, Brazil. We assessed the phylogenetic structure at different scales, using the Net Relatedness Index (NRI), the Nearest Taxon Index (NTI), and phylobetadiversity indexes, as well as a permutation test, to evaluate the effect of seasonality. The anuran community was represented by a non-random set of species with a high degree of phylogenetic relatedness at the regional scale. However, at the local scale the phylogenetic structure of the community was weakly related with the seasonality of the system, indicating that oriented stochastic processes (e.g. colonization, extinction and ecological drift) and/or antagonist forces drive the structure of such communities in the southern Pantanal.</p></div

Location Nhumirim Ranch.

<p>Location in South America of the study area, Nhumirim Ranch (square), in Pantanal floodplain of Brazil.</p

Values of standardized phylobetadiversity (betaNRI and betaNTI) in Dry-Dry, Rainy-Rainy, and Dry-Rainy periods.

<p>Symbols indicate statistical significance of a t-test comparing observed values versus expected value of zero for random data (*p<0.05).</p><p>Values of standardized phylobetadiversity (betaNRI and betaNTI) in Dry-Dry, Rainy-Rainy, and Dry-Rainy periods.</p

Meteorological data from the Nhumirim Ranch.

<p>Precipitation (left axis) and maximum and minimum average temperatures between February 2005 and December 2012 (right axis). The arrows indicate the peak periods of drought and rain that we selected for the analysis.</p

NRI and NTI index values for the anuran communities in rainy and dry periods at Nhumirim Ranch, Pantanal wetland, Brazil, using presence/absence and abundance metrics.

<p>*Significant values.</p><p>NRI and NTI index values for the anuran communities in rainy and dry periods at Nhumirim Ranch, Pantanal wetland, Brazil, using presence/absence and abundance metrics.</p

NRI and NTI values between seasons.

<p>Permutation test using mean difference in indices of phylogenetic structure of anuran communities, NRI and NTI, in rainy and dry seasons in the Nhecolândia region, Pantanal wetland, Brazil. The dashed lines indicate the actual mean difference between the periods (nri p/a p = 0.102, nti p/a p = 0.384, nri abd p = 0.076, nti abd p = 0.006).</p