Global patterns of amphibian phylogenetic diversity
Article first published online: 22 JUN 2012
© 2012 Blackwell Publishing Ltd
Journal of Biogeography
Volume 39, Issue 8, pages 1373–1382, August 2012
How to Cite
Fritz, S. A. and Rahbek, C. (2012), Global patterns of amphibian phylogenetic diversity. Journal of Biogeography, 39: 1373–1382. doi: 10.1111/j.1365-2699.2012.02757.x
- Issue published online: 18 JUL 2012
- Article first published online: 22 JUN 2012
- global species richness;
- mean root distance;
- phylogenetic diversity;
- taxonomic distinctness
Aim Phylogenetic diversity can provide insight into how evolutionary processes may have shaped contemporary patterns of species richness. Here, we aim to test for the influence of phylogenetic history on global patterns of amphibian species richness, and to identify areas where macroevolutionary processes such as diversification and dispersal have left strong signatures on contemporary species richness.
Location Global; equal-area grid cells of approximately 10,000 km2.
Methods We generated an amphibian global supertree (6111 species) and repeated analyses with the largest available molecular phylogeny (2792 species). We combined each tree with global species distributions to map four indices of phylogenetic diversity. To investigate congruence between global spatial patterns of amphibian species richness and phylogenetic diversity, we selected Faith’s phylogenetic diversity (PD) index and the total taxonomic distinctness (TTD) index, because we found that the variance of the other two indices we examined (average taxonomic distinctness and mean root distance) strongly depended on species richness. We then identified regions with unusually high or low phylogenetic diversity given the underlying level of species richness by using the residuals from the global relationship of species richness and phylogenetic diversity.
Results Phylogenetic diversity as measured by either Faith’s PD or TTD was strongly correlated with species richness globally, while the other two indices showed very different patterns. When either Faith’s PD or TTD was tested against species richness, residuals were strongly spatially structured. Areas with unusually low phylogenetic diversity for their associated species richness were mostly on islands, indicating large radiations of few lineages that have successfully colonized these archipelagos. Areas with unusually high phylogenetic diversity were located around biogeographic contact zones in Central America and southern China, and seem to have experienced high immigration or in situ diversification rates, combined with local persistence of old lineages.
Main conclusions We show spatial structure in the residuals of the relationship between species richness and phylogenetic diversity, which together with the positive relationship itself indicates strong signatures of evolutionary history on contemporary global patterns of amphibian species richness. Areas with unusually low and high phylogenetic diversity for their associated richness demonstrate the importance of biogeographic barriers to dispersal, colonization and diversification processes.