Phylogenetics has provided evolutionary biology with the potential to reconstruct genealogical relationships; however, the ability to estimate the timing of divergence between lineages is just as important. Since the early 1960s investigators have attempted to correlate genetic divergence with the absolute timing of divergence. The initial promise of a “molecular clock” has not been realized, but molecular approaches to estimate divergence times have proven useful in just about every area of evolutionary biology.
I am interested in methods that use external absolute age estimates to calibrate molecular phylogenies. In particular, my collaborators Brad Shaffer and Peter Meylan and I have developed a novel fossil-cross validation method that offers a strategy to assess the relative and absolute agreement in molecular age estimates among a set of fossil or paleogeographic calibrations. Collaboration with Mike Sanderson has resulted in the development of a new method that uses the agreement of fossil calibrations to estimate an optimal model of molecular evolution in Mike’s penalized likelihood method.