A TIME-CALIBRATED SPECIES TREE OF CROCODYLIA REVEALS A RECENT RADIATION OF THE TRUE CROCODILES
Version of Record online: 6 JUL 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 11, pages 3285–3297, November 2011
How to Cite
Oaks, J. R. (2011), A TIME-CALIBRATED SPECIES TREE OF CROCODYLIA REVEALS A RECENT RADIATION OF THE TRUE CROCODILES. Evolution, 65: 3285–3297. doi: 10.1111/j.1558-5646.2011.01373.x
- Issue online: 24 OCT 2011
- Version of Record online: 6 JUL 2011
- Accepted manuscript online: 3 JUN 2011 02:03AM EST
- Received March 12, 2011, Accepted May 20, 2011, Data Archived: Dryad doi:10.5061/dryad.5k9s0
- Dirichlet process;
- multispecies coalescent;
- relaxed clock
True crocodiles (Crocodylus) are the most broadly distributed, ecologically diverse, and species-rich crocodylian genus, comprising about half of extant crocodylian diversity and exhibiting a circumtropical distribution. Crocodylus traditionally has been viewed as an ancient group of morphologically conserved species that originated in Africa prior to continental breakup. In this study, these long-held notions about the temporal and geographic origin of Crocodylus are tested using DNA sequence data of 10 loci from 76 individuals representing all 23 crocodylian species. I infer a time-calibrated species tree of all Crocodylia and estimate the spatial pattern of diversification within Crocodylus. For the first time, a fully resolved phylogenetic estimate of all Crocodylia is well-supported. The results overturn traditional views of the evolution of Crocodylus by demonstrating that the true crocodiles are not “living-fossils” that originated in Africa. Rather, Crocodylus originated from an ancestor in the tropics of the Late Miocene Indo-Pacific, and rapidly radiated and dispersed around the globe during a period marked by mass extinctions of fellow crocodylians. The findings also reveal more diversity within the genus than is recognized by current taxonomy.