Correlates of species richness in the largest Neotropical amphibian radiation.
Bottom Line: Clade-age and species richness were nonsignificantly, negatively correlated, suggesting that clade age alone does not explain among-clade variation in species richness.A more vascularized ventral skin, the ability to colonize high-altitude ranges, encompassing a large variety of vegetation types, correlated significantly with species richness, whereas larger body size was marginally correlated with species richness.Hence, whereas high-altitude ranges play a role in shaping clade diversity in the Neotropics, intrinsic factors, such as skin structures and possibly body size, might ultimately determine which clades are more speciose than others.
Affiliation: Department of Integrative Ecology, Estación Biológica de Doñana-CSIC, Av. Américo Vespucio s/n, Seville, Spain. email@example.comShow MeSH
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Mentions: We found a nonsignificant negative correlation between log-transformed species richness and the age of the clade (PGLS: β = −0.03 ± 0.04, t24 = −0.88, P = 0.39; Fig. 2), even when incorporating phylogenetic information. The negative correlation between species richness and clade-age suggests that contrary to what would be predicted under unbounded diversification within clades, older clades are not more species-rich than younger clades. The two estimates of rate of diversification (diversification rate and method-of-moments estimator) were significantly correlated with species richness, even when correcting for phylogenetic effects (β = 28.03 ± 1.73, t24 = 16.21, P < 0.0001 and β = 32.04 ± 2.01, t24 = 15.92, P < 0.0001, respectively). These results suggest that diversification rate is a relevant metric, even if the suggested assumption is violated. High diversification rates in young clades may decouple diversification rates from patterns of species richness, in any case the highly significant correlation between species richness and rate of diversification suggests that, even if diversification rates change over time, variation in rates of species accumulation nonetheless capture differences in species richness among the clades studied (Kozak & Wiens, 2010).
Affiliation: Department of Integrative Ecology, Estación Biológica de Doñana-CSIC, Av. Américo Vespucio s/n, Seville, Spain. firstname.lastname@example.org