Halliday T J D, Goswami A
Department of Genetics, Evolution, and Environment, University College London, Gower Street, London WC1E 6BT, UK
Department of Genetics, Evolution, and Environment, University College London, Gower Street, London WC1E 6BT, UK Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK.
Biol Lett. 2016 Aug;12(8). doi: 10.1098/rsbl.2016.0051.
The fossil record of the earliest Cenozoic contains the first large-bodied placental mammals. Several evolutionary models have been invoked to explain the transition from small to large body sizes, but methods for determining evolutionary mode of trait change depend on input from tree topology and divergence dates. Different dating methods may therefore affect inference of evolutionary model. Here, we fit models of body mass evolution onto dated phylogenies of Cretaceous and Palaeogene mammals, comparing the effect of dating method on interpretation of evolutionary model. Among traditional palaeontological dating approaches, an Ornstein-Uhlenbeck model with high alpha parameters is recovered as best-fitting when minimum-age dating is used, while branch-sharing methods are highly sensitive to topology. Release or release-radiate models are preferred when Bayesian fossilized birth-death method is used, but when using stochastic cal3 dating of trees, a model of increased evolutionary rate without a release in constraint at the Cretaceous-Palaeogene boundary has highest support. These results demonstrate unambiguously that choice of dating method is critical for interpretation of continuous trait evolution, and that care must therefore be taken to consider these effects in macroevolutionary studies.
最早的新生代化石记录包含了首批大型胎盘哺乳动物。人们提出了几种进化模型来解释从小型到大型体型的转变，但确定性状变化进化模式的方法取决于系统发育树拓扑结构和分歧时间的输入。因此，不同的定年方法可能会影响进化模型的推断。在这里，我们将体重进化模型应用于白垩纪和古近纪哺乳动物的定年系统发育树上，比较定年方法对进化模型解释的影响。在传统的古生物学定年方法中，当使用最小年龄定年时，具有高α参数的奥恩斯坦-乌伦贝克模型被认为是最拟合的，而分支共享方法对拓扑结构高度敏感。当使用贝叶斯化石出生-死亡方法时，释放或释放-辐射模型更受青睐，但当对系统发育树使用随机cal3定年时，在白垩纪-古近纪边界没有约束释放的进化速率增加模型得到的支持最高。这些结果明确表明，定年方法的选择对于连续性状进化的解释至关重要，因此在宏观进化研究中必须谨慎考虑这些影响。
