Short-term Visitor

Integrating molecular sequence data and morphological character evolution to date species divergences

PI(s): Mario dos Reis (University College London (UNITED KINGDOM))
Start Date: 1-Jul-2013
End Date: 28-Sep-2013
Keywords: phylogenetics, computational modeling, evolutionary genetics, molecular biology, paleontology

Molecular sequence data provide information about the relative distances of species in a phylogeny, but not on the absolute geological times of divergence or the molecular evolutionary rate. The Bayesian method offers a way to use fossil information to construct a prior on divergence times, which can be integrated with the molecular data to generate estimates of species divergences in a phylogeny. Modelling clade ages with statistical distributions based on fossil information is subjective and fraught with difficulties. Fossils provide good estimates of minimum clade ages, but maximum ages are hard to justify when based on the absence of fossil evidence. A way to overcome this limitation is to model morphological character evolution of species, and then use this to estimate the morphological distance among all extant and fossil species. Since fossil ages are known, fossils can then be used as 'dated-tips' in the Bayesian analysis. When combined with molecular data from extant species, this technique is expected to provide a powerful way to estimate divergence times of all species in the phylogeny. In this project I explore the use of models of morphological evolution and integrate them with molecular data in Bayesian estimation of divergence times. Particularly, I explore the application of the method to date species-level phylogenies using large genome sequence alignments. A nearly complete primate phylogeny will be analysed as a test case.