This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2008. The fellowship supports a research and training plan entitled "Complex models of substitution rate variation and a comparison of Bayesian methods for estimating species divergence times" for Tracy A. Heath. The host institution for this research is University of California-Berkeley and University of Kansas, and the sponsoring scientists are Dr. John Huelsenbeck and Dr. Mark Holder, respectively.
Among the questions explored in evolutionary biology, understanding the timing and rates of evolutionary processes has been central. Phylogenetic tree (branching diagrams depicting species relationships) are essential tools for understanding broad evolutionary patterns and are frequently used to estimate the timing of speciation events. Accurate estimates of these species divergence times are vital to understanding historical biogeography, estimating rates of speciation and extinction, and identifying the causes of variation in rates of molecular evolution. This research is focusing on the development of new molecular models for phylogenetic analysis and divergence time estimation. The research provides a general and flexible framework for incorporating more biologically realistic patterns of variation in the rates of molecular evolution into statistical phylogenetic methods by using a model called the "Dirichlet process prior". New models will be implemented in freely available, open source software programs using Bayesian inference methods (powerful methods for estimating the parameters of a statistical model). Simulated data sets generated under complex molecular models will be used to conduct a thorough comparison of Bayesian methods for dating species divergences.
Training objectives include strengthening computational skills and programming ability. Moreover, because this project integrates molecular evolution, statistics, and computer science, it will lead to the cultivation of interdisciplinary collaborations with researchers at all levels.
