Zink Robert M, Klicka John
Bell Museum, University of Minnesota, St. Paul, Minnesota 55108, USA.
Evolution. 2006 Feb;60(2):411-2; discussion 413-4.
Johnson and Cicero (2004) claimed that inspection of a distribution of uncorrected mitochondrial DNA avian sister-taxon distances illustrated that the late Pleistocene was an important time for avian speciation. They believed this finding to be at odds with conclusions of Klicka and Zink (1997). However, both studies document recent speciation events. More germane to the discussion is what is meant by an "important" time for speciation, which we take to mean above some baseline diversification rate. We constructed a null distribution of sister-taxon distances based on a model of constant speciation and extinction rates. The empirical distribution of sister-taxon distances in Johnson and Cicero (2004) did not differ from the null model. Therefore, our analysis of Johnson and Cicero's data suggests that the late Pleistocene was no more important for avian speciation than any other time during this time period.
约翰逊和西塞罗（2004年）声称，对未校正的线粒体DNA鸟类姐妹分类群距离分布的检查表明，晚更新世是鸟类物种形成的重要时期。他们认为这一发现与克利卡和津克（1997年）的结论不一致。然而，两项研究都记录了近期的物种形成事件。与讨论更相关的是，物种形成的“重要”时期是什么意思，我们认为这意味着高于某个基线多样化率。我们基于恒定物种形成和灭绝率模型构建了姐妹分类群距离的零分布。约翰逊和西塞罗（2004年）中姐妹分类群距离的经验分布与零模型没有差异。因此，我们对约翰逊和西塞罗数据的分析表明，晚更新世对鸟类物种形成的重要性并不高于该时期的任何其他时间。
