Presgraves Daven C, Yi Soojin V
Department of Biology, University of Rochester, Rochester, NY 14627, USA.
Trends Ecol Evol. 2009 Oct;24(10):533-40. doi: 10.1016/j.tree.2009.04.007. Epub 2009 Aug 5.
Two patterns from large-scale DNA sequence data have been put forward as evidence that speciation between humans and chimpanzees was complex, involving hybridization and strong selection. First, divergence between humans and chimpanzees varies considerably across the autosomes. Second, divergence between humans and chimpanzees (but not gorillas) is markedly lower on the X chromosome. Here, we describe how simple speciation and neutral molecular evolution explain both patterns. In particular, the wide range in autosomal divergence is consistent with stochastic variation in coalescence times in the ancestral population; and the lower human-chimpanzee divergence on the X chromosome is consistent with species differences in the strength of male-biased mutation caused by differences in mating system. We also highlight two further patterns of divergence that are problematic for the complex speciation model. Our conclusions raise doubts about complex speciation between humans and chimpanzees.
大规模DNA序列数据中的两种模式被提出来作为证据，表明人类与黑猩猩之间的物种形成过程很复杂，涉及杂交和强烈的选择。第一，人类和黑猩猩在常染色体上的差异在很大范围内变化。第二，人类和黑猩猩（而非大猩猩）在X染色体上的差异明显更低。在此，我们描述了简单物种形成和中性分子进化如何解释这两种模式。具体而言，常染色体差异的广泛范围与祖先群体中合并时间的随机变化一致；而X染色体上人类与黑猩猩较低的差异与交配系统差异导致的雄性偏向突变强度的物种差异一致。我们还强调了另外两种差异模式，它们对于复杂物种形成模型来说是有问题的。我们的结论对人类与黑猩猩之间的复杂物种形成提出了质疑。
