Bayesian Estimation of Species Divergence Times Integrating Fossil and Molecular Information

如果我们的基因随时间以恒定的速率积累变化，那么两个物种之间的遗传距离，以积累的变化数量来衡量，将与物种分化的时间成正比。因此，分子可以作为一个时钟，通过累积的变化来记录物种分化的时间。如果化石记录或地质事件可以用来为系统发育树上的物种分化事件指定一个绝对的地质时间，人们可以将所有计算的遗传距离转换为绝对的地质时间。这种分子时钟定年的基本原理最近被扩展到处理进化速率的局部变异。分子定年的关键是使用化石信息来校准时钟。在本项目中，我们将开发统计模型和计算机程序来分析化石和分子数据，以便在分子测年分析中准确地表示和整合化石记录中的信息。新方法将用于分析数据集，以估计哺乳动物之间的分化时间，并确定病毒传播事件的日期。

If our genes accumulate changes over time at a constant rate, the genetic distance between two species, measured by the number of changes accumulated, will be proportional to the time of species divergence. Thus molecules can serve as a clock, keeping time of species divergence by the accumulated changes. If fossil records or geological events can be used to assign an absolute geological time to a species divergence event on the phylogenetic tree, one can convert all calculated genetic distances into absolute geological times. This rationale for molecular clock dating has recently been extended to deal with local variation in evolutionary rate. Critical to molecular dating is the use of fossil information to calibrate the clock. In this project, we will develop statistical models and computer programs to analyze fossil and molecular data to accurately represent and incorporate the information in the fossil record in molecular dating analysis. The new methods will be applied to analyze datasets to estimate divergence times among mammals and to date viral transmission events.