The evolution of methods for establishing evolutionary timescales.
The evolution of methods for establishing evolutionary timescales.
复制标题
DOI：
10.1098/rstb.2016.0020
复制
发表时间：
2016-07-19
期刊：
影响因子：
--
通讯作者：
Yang Z
中科院分区：
文献类型：
--
作者：
Donoghue PC;Yang Z
众所周知，化石记录是不完整的。从字面上看，它提供了一种扭曲的物种分化和灭绝的历史观点，因为不同的物种有不同的石化倾向，岩石的数量在地质时间尺度上波动，就像它所保护的环境的性质一样。即便如此，化石证据中的模式使我们能够评估化石记录的不完整性。虽然分子钟可以用于将化石物种的时间估计扩展到化石记录中没有代表的谱系，但化石是分子测年分析中有关绝对（地质）时间的唯一信息来源。我们回顾了在现代时钟测年分析中结合化石证据的不同方法，包括节点校准，其中谱系分化时间使用概率密度限制，以及尖端校准，其中树的尖端化石物种被指定日期来自已确定的岩石地层。虽然节点校准通常是通过对化石证据的粗略评估来构建的，因此具有随意性，但尖端校准可能对先前的分化时间或分支过程过于敏感，并且受到众所周知的形态特征进化问题的过度影响，例如环境对形态表型的影响，性状之间的相关性，以及不同物种的趋同进化。我们讨论了化石时间信息在系统发育估计和化石记录中寻找祖先方面的应用。这篇文章是“用岩石和时钟测定物种差异”主题的一部分。
The fossil record is well known to be incomplete. Read literally, it provides a distorted view of the history of species divergence and extinction, because different species have different propensities to fossilize, the amount of rock fluctuates over geological timescales, as does the nature of the environments that it preserves. Even so, patterns in the fossil evidence allow us to assess the incompleteness of the fossil record. While the molecular clock can be used to extend the time estimates from fossil species to lineages not represented in the fossil record, fossils are the only source of information concerning absolute (geological) times in molecular dating analysis. We review different ways of incorporating fossil evidence in modern clock dating analyses, including node-calibrations where lineage divergence times are constrained using probability densities and tip-calibrations where fossil species at the tips of the tree are assigned dates from dated rock strata. While node-calibrations are often constructed by a crude assessment of the fossil evidence and thus involves arbitrariness, tip-calibrations may be too sensitive to the prior on divergence times or the branching process and influenced unduly affected by well-known problems of morphological character evolution, such as environmental influence on morphological phenotypes, correlation among traits, and convergent evolution in disparate species. We discuss the utility of time information from fossils in phylogeny estimation and the search for ancestors in the fossil record. This article is part of the themed issue ‘Dating species divergences using rocks and clocks’.