Department of Biology, McGill University, Montreal, Quebec, Canada.
Biol Lett. 2013 Jun 12;9(4):20130343. doi: 10.1098/rsbl.2013.0343. Print 2013 Aug 23.
The tree-of-life represents the diversity of living organisms. Species extinction and the concomitant loss of branches from the tree-of-life is therefore a major conservation concern. There is increasing evidence indicating that extinction is phylogenetically non-random, such that if one species is vulnerable to extinction so too are its close relatives. However, the impact of non-random extinctions on the tree-of-life has been a matter of recent debate. Here, we combine simulations with empirical data on extinction risk in mammals. We demonstrate that phylogenetically clustered extinction leads to a disproportionate loss of branches from the tree-of-life, but that the loss of their summed lengths is indistinguishable from random extinction. We argue that under a speciational model of evolution, the number of branches lost might be of equal or greater consequences than the loss of summed branch lengths. We therefore suggest that the impact of non-random extinction on the tree-of-life may have been underestimated.
生命之树代表了生物的多样性。因此，物种灭绝以及随之而来的生命之树上的分支丧失是主要的保护关注点。越来越多的证据表明，灭绝在系统发育上是非随机的，因此，如果一个物种容易灭绝，那么它的近亲也是如此。然而，非随机灭绝对生命之树的影响一直是最近争论的话题。在这里，我们将模拟与哺乳动物灭绝风险的经验数据相结合。我们证明，系统发育聚类灭绝会导致生命之树上的分支不成比例地丧失，但它们的总长度的丧失与随机灭绝无法区分。我们认为，在进化的物种形成模型下，丧失的分支数量可能与丧失的总分支长度具有同等或更大的后果。因此，我们认为非随机灭绝对生命之树的影响可能被低估了。
