The Graduate School and University Center, The City University of New York, 365 Fifth Avenue, New York, NY 10016, USA.
Syst Biol. 2010 Mar;59(2):185-94. doi: 10.1093/sysbio/syp090. Epub 2009 Dec 17.
Estimating divergence times using molecular sequence data has become a common application of statistical phylogenetics. However, disparities between estimated ages for clades produced in different studies have become equally commonplace. Here, I propose a method for the objective assessment of the likelihood of inferred divergence times to evaluate the placement of fossil constraints using information from the broader fossil record. The inclusion of nodes from the Tree of Life for which credible age ranges are known, in addition to the fossil constraints used in the ingroup, will allow for the comparison of alternate fossil placements when the phylogenetic affinity of a fossil is ambiguous as well as provide a heuristic assessment of the global likelihood of estimated divergence times. The use of these "likelihood checkpoints" will allow for the comparison of inferred dates across data sets and across taxonomic groups to place divergence time estimates into a broader evolutionary timescale. The method is illustrated with an example using an expanded phylogenetic estimate of the Gnathostomata, inferred with relaxed-clock molecular dating methods.
利用分子序列数据估计分歧时间已经成为统计系统发育学的一个常见应用。然而，不同研究中产生的分支估计年龄之间的差异也变得同样普遍。在这里，我提出了一种方法来客观评估推断分歧时间的可能性，以使用更广泛的化石记录中的信息来评估化石约束的位置。除了在同组中使用的化石约束之外，还包括来自生命之树的具有可信年龄范围的节点，这将允许在化石的系统发育亲和力不明确时比较替代的化石位置，并且为估计分歧时间的全球可能性提供启发式评估。使用这些“可能性检查点”将允许跨数据集和分类群比较推断日期，将分歧时间估计纳入更广泛的进化时间尺度。该方法通过使用松弛时钟分子定年方法对颌类进行扩展的系统发育估计示例来说明。
