Heard Stephen B, Mooers Arne Ø
Department of Biology, University of New Brunswick, Fredericton, Canada.
Syst Biol. 2002 Dec;51(6):889-97. doi: 10.1080/10635150290102591.
Current models of diversification with evolving speciation rates have trouble mimicking the extreme imbalance seen in estimated phylogenies. However, these models have not incorporated extinction. Here, we report on a simple simulation model that includes heritable and evolving speciation rates coupled with mass extinctions, Random (but not selective) mass extinctions, coupled with evolving among-lineage variation in speciation rates, increase imbalance of postrecovery clades. Thus, random mass extinctions are plausible contributors to the imbalance of modern clades. Paleontological evidence suggests that mass extinctions are often random with respect to ecological and morphological traits, consistent with our simulations. In contrast, evidence that the current anthropogenic mass extinction is phylogenetically selective suggests that the current extinction episode may be qualitatively different from past ones in the way it reshapes future biotas.
当前具有不断演变的物种形成速率的多样化模型难以模拟估计系统发育中出现的极端不平衡。然而，这些模型并未纳入灭绝因素。在此，我们报告一个简单的模拟模型，该模型包括可遗传且不断演变的物种形成速率以及大规模灭绝。随机（而非选择性）的大规模灭绝，再加上物种形成速率在谱系间不断变化，会增加恢复后分支的不平衡性。因此，随机大规模灭绝可能是导致现代分支不平衡的原因。古生物学证据表明，大规模灭绝在生态和形态特征方面往往是随机的，这与我们的模拟结果一致。相比之下，当前人为导致的大规模灭绝具有系统发育选择性的证据表明，当前的灭绝事件在重塑未来生物群的方式上可能与过去的事件在性质上有所不同。
