Data from: Testing for Depéret’s rule (body size increase) in mammals using combined extinct and extant data

Whether or not evolutionary lineages in general show a tendency to increase in body size has often been discussed. This tendency has been dubbed “Cope’s rule” but because Cope never hypothesized it, we suggest renaming it after Depéret, who formulated it clearly in 1907. Depéret’s rule has traditionally been studied using fossil data, but more recently a number of studies have used present-day species. While several paleontological studies of Cenozoic placental mammals have found support for increasing body size, most studies of extant placentals have failed to detect such a trend. Here we present a method to combine information from present-day species with fossil data in a Bayesian phylogenetic framework. We apply the method to body mass estimates of a large number of extant and extinct mammal species, and find strong support for Depéret’s rule. The tendency for size increase appears to be driven not by evolution towards larger size in established species, but by processes related to the emergence of new species. Our analysis shows that complementary data from extant and extinct species can greatly improve inference of macroevolutionary processes.

进化谱系总体上是否存在体型增大的演化趋势，这一科学议题已被广泛探讨。该演化趋势曾被冠以「科普法则（Cope’s rule）」之名，但由于科普本人从未正式提出过该假说，我们建议以1907年首次明确阐述该规律的德佩雷（Depéret）命名，将其更名为「德佩雷法则（Depéret’s rule）」。

德佩雷法则的传统研究多采用化石数据，而近年来已有多项研究借助现生物类群展开相关分析。尽管多项针对新生代有胎盘类哺乳动物的古生物学研究证实了体型增大趋势的存在，但多数针对现生有胎盘类哺乳动物的研究却未能检测到该演化趋势。

本文提出一种可在贝叶斯系统发育框架（Bayesian phylogenetic framework）下，整合现生生物与化石数据信息的分析方法。我们将该方法应用于大量现生及灭绝哺乳动物的体重估算数据，结果为德佩雷法则提供了强有力的支持。体型增大的演化趋势似乎并非源于已有物种种群向更大体型的进化方向，而是由与新物种诞生相关的演化过程所驱动。

本研究分析表明，整合现生与灭绝类群的互补数据，可极大提升宏观进化过程（macroevolutionary processes）推断的准确性与可靠性。