Department of Ecology and Evolutionary Biology and Museum of Zoology, University of Michigan, Ann Arbor, MI 48109.
Proc Natl Acad Sci U S A. 2013 Sep 17;110(38):15354-9. doi: 10.1073/pnas.1305529110. Epub 2013 Sep 3.
The rate at which speciation occurs varies greatly among different kinds of organisms and is frequently assumed to result from species- or clade-specific factors that influence the rate at which populations acquire reproductive isolation. This premise leads to a fundamental prediction that has never been tested: Organisms that quickly evolve prezygotic or postzygotic reproductive isolation should have faster rates of speciation than organisms that slowly acquire reproductive isolation. We combined phylogenetic estimates of speciation rates from Drosophila and birds with a method for analyzing interspecific hybridization data to test whether the rate at which individual lineages evolve reproductive isolation predicts their macroevolutionary rate of species formation. We find that some lineages evolve reproductive isolation much more quickly than others, but this variation is decoupled from rates of speciation as measured on phylogenetic trees. For the clades examined here, reproductive isolation--especially intrinsic, postzygotic isolation--does not seem to be the rate-limiting control on macroevolutionary diversification dynamics. These results suggest that factors associated with intrinsic reproductive isolation may have less to do with the tremendous variation in species diversity across the evolutionary tree of life than is generally assumed.
物种形成的速度在不同的生物种类中差异很大，通常被认为是由影响种群获得生殖隔离速度的物种或进化枝特异性因素导致的。这一前提导致了一个从未被检验过的基本预测：与那些缓慢获得生殖隔离的生物相比，快速进化出合子前或合子后生殖隔离的生物应该具有更快的物种形成速度。我们结合了果蝇和鸟类的系统发育估计的物种形成率，以及一种分析种间杂交数据的方法，来检验个体谱系进化生殖隔离的速度是否可以预测它们在宏观进化上形成物种的速度。我们发现，一些谱系的生殖隔离进化速度比其他谱系快得多，但这种变化与系统发育树上测量的物种形成率是脱钩的。对于这里研究的进化枝，生殖隔离——尤其是内在的、合子后隔离——似乎不是控制宏观进化多样化动态的限速因素。这些结果表明，与内在生殖隔离相关的因素与人们普遍假设的那样，与生命之树中物种多样性的巨大差异关系不大。
