The explosion of phylogenetic studies not only provides a clear snapshot of biodiversity, but also makes it possible to infer how the diversity has arisen (see for example, Purvis and Hector, 2000; Harvey et al., 1996; Nee et al., 1996; Mace et al., 2003). To this aim, variation in speciation and extinction rates have been investigated through their signatures in the shapes of phylogenetic trees (Mooers and Heard, 1997). This issue is of great importance, as fitting stochastic models to tree data would help to understand underlying macroevolutionary processes. Although the prevailing view is that it does not represent phylogenies so well, the most popular model of phylogenetic trees is a branching process introduced by Yule, in which lineages split at random (Yule, 1924). Here we report the study of one major database of published

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哪些随机过程描述了生命之树？系统发育树不平衡的大规模研究

系统发育研究的爆炸式增长不仅提供了生物多样性的清晰快照，而且可以推断多样性是如何产生的（例如，参见 Purvis 和 Hector，2000；Harvey 等，1996；Nee 等，1996 ；梅斯等人，2003 年）。为此，物种形成和灭绝率的变化已经通过它们在系统发育树形状中的特征进行了研究（Mooers 和 Heard，1997 年）。这个问题非常重要，因为将随机模型拟合到树数据将有助于理解潜在的宏观进化过程。尽管流行的观点是它不能很好地代表系统发育，但最流行的系统发育树模型是由 Yule 引入的分支过程，其中谱系随机分裂（Yule，1924）。在这里，我们报告了对已发表的一个主要数据库的研究