Moorad Jacob A, Promislow Daniel E L, Smith Ken R, Wade Michael J
Department of Genetics, University of Georgia, Athens, GA, USA.
Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA.
Evol Hum Behav. 2011 Mar;32(2):147-155. doi: 10.1016/j.evolhumbehav.2010.10.004. Epub 2011 Jan 14.
Sexual selection, or competition among members of one sex for reproductive access to the other, is one of the strongest and fastest evolutionary processes. Comparative studies support the prediction that sexual selection is stronger in polygamous than in monogamous species. We report the first study of the effect on sexual selection of a change in mating system, from polygyny to monogamy, within a historical human population. Here we show that over the reproductive lifetimes of Utahns born between 1830 and 1894, socially induced reductions in the rate and degree of polygamy correspond to a 58% reduction in the strength of sexual selection. Polygyny conferred a strong advantage to male fitness as well as a weak disadvantage to female fitness. In contrast, mating with multiple males provided little benefit to females in this population. Polygamy benefitted males by increasing reproductive rates and by lengthening reproductive tenure. Each advantage contributed to roughly half of the increased total lifetime reproductive success. This study illustrates both the potency of sexual selection in polygynous human populations and the dramatic influence that short-term societal changes can have on evolutionary processes.
性选择，即同一性别成员之间为获得与另一性别的繁殖机会而展开的竞争，是最强大且最快的进化过程之一。比较研究支持这样的预测：一夫多妻制物种中的性选择比一夫一妻制物种中的更强。我们报告了第一项关于在一个历史人口群体中，交配制度从一夫多妻制转变为一夫一妻制对性选择影响的研究。我们在此表明，在1830年至1894年出生的犹他州人的整个生殖寿命期间，社会因素导致的一夫多妻率和程度的降低，对应着性选择强度降低了58%。一夫多妻制给男性的生育适应性带来了很大优势，给女性的生育适应性带来了微弱劣势。相比之下，在这个群体中与多个男性交配给女性带来的益处很少。一夫多妻制通过提高生殖率和延长生殖期而使男性受益。每一项优势对男性一生总生殖成功率增加的贡献大致各占一半。这项研究既说明了一夫多妻制人类群体中性选择的效力，也说明了短期社会变化对进化过程可能产生的巨大影响。
