Radcliffe Institute for Advanced Study, Harvard University, Cambridge, Massachusetts 02138, USA.
Am Nat. 2010 Dec;176 Suppl 1:S45-60. doi: 10.1086/657058.
Darwin's Origin of Species is often criticized for having little to say about speciation. The complaint focuses in particular on Darwin's supposed failure to explain the evolution of the sterility and inviability of interspecific hybrids. But in his chapter on hybridism, Darwin, working without genetics, got as close to the modern understanding of the evolution of hybrid sterility and inviability as might reasonably be expected. In particular, after surveying what was then known about interspecific crosses and the resulting hybrids, he established two facts that, while now taken for granted, were at the time radical. First, the sterility barriers between species are neither specially endowed by a creator nor directly favored by natural selection but rather evolve as incidental by-products of interspecific divergence. Second, the sterility of species hybrids results when their development is "disturbed by two organizations having been compounded into one." Bateson, Dobzhansky, and Muller later put Mendelian detail to Darwin's inference that the species-specific factors controlling development (i.e., genes) are sometimes incompatible. In this article, I highlight the major developments in our understanding of these interspecific genetic incompatibilities--from Darwin to Muller to modern theory--and review comparative, genetic, and molecular rules that characterize the evolution of hybrid sterility and inviability.
达尔文的《物种起源》经常因其对物种形成几乎没有什么可说的而受到批评。这种抱怨特别集中在达尔文据称未能解释种间杂种的不育性和生存力的进化上。但是，在他关于杂交的章节中，达尔文在没有遗传学的情况下，尽可能接近现代对杂种不育性和生存力进化的理解。特别是，在调查了当时已知的种间杂交和由此产生的杂种之后，他确立了两个事实，尽管现在被认为是理所当然的，但在当时却是激进的。首先，物种之间的不育性障碍既不是造物主特别赋予的，也不是自然选择直接青睐的，而是随着种间分歧的偶然副产品而进化的。其次，物种杂种的不育性是由于它们的发育“受到两种已组合成一种的组织的干扰”而导致的。贝特森、多布赞斯基和穆勒后来将孟德尔的细节推断为控制发育的物种特异性因素（即基因）有时是不相容的。在本文中，我强调了我们对这些种间遗传不兼容性的理解的主要进展——从达尔文到穆勒到现代理论——并回顾了表征杂种不育性和生存力进化的比较、遗传和分子规则。
