2012 sees the 50th birthday of the molecular clock, but has it reached maturity? (Visiting Scholar)
The molecular clock represents the most powerful means of establishing an evolutionary timescale, through the integration of molecular and palaeontological data. The past fifty years have witnessed significant methodological advances to improve its efficacy. Knowledge and assumptions about the underlying evolutionary processes can be modeled with increasing realism. Approaches to implementing calibrations and modeling rate variation differ in their use of molecular and geological evidence, vary in complexity, and yield different divergence estimates. In the absence of the known evolutionary timescale, which – if any – of the available methods are able to estimate divergence times with accuracy or precision? Robust testing of the molecular clock can only be achieved using simulated data, where the relationship between fossil evidence, rate variation and genetic divergence is known. This project proposes to develop a simulation-based framework for quantitatively exploring the impact of fossil data on the calibration of the molecular clock. Methods for generating both data types are readily available, but have never been integrated. Simulated datasets that mimic the information available in empirical studies would provide a composite source for testing the impact of fossil evidence on estimates of evolutionary rates and times. I will apply the first test of the molecular clock using both simulated molecular and fossil data.