Researchers have long recognized the potential explanatory power of precise molecular clocks for placing dates on important evolutionary events. Unfortunately, it is now recognized that molecular evolution often does not proceed in a clock-like fashion and development of more complex relaxed-clock methods is ongoing. A major goal of this study will be to evaluate the assumptions and behavior of newly developed relaxed-clock divergence dating methodologies in the context of a 20-locus empirical data set for the scincid lizard genus Plestiodon. Plestiodon lizards are a common subject of biological research and inhabit most of the United States, yet little is known about their evolutionary history. Identifying and dating biological events in the past is a fundamental goal of evolutionary biology. Chronology is central to analyses of historical biogeography, as well as to efforts to elucidate the rate at which a morphological structures, behaviors, or physiologies have evolved. It is furthermore important to place dates on critical evolutionary events, whether they be extinction events, historical human migration events, or epidemiological events associated with disease outbreak. The results of this research investigating the performance of recently developed molecular dating methodologies will be applicable to the entire field of molecular divergence dating and will improve the ability of biologists to estimate the timing of important biological events.
