Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, Indiana 47405.
Integr Comp Biol. 2005 Nov;45(5):945-51. doi: 10.1093/icb/45.5.945.
Bateman identified two aspects of sexual selection. The first, called Bateman's principle, is that sexual selection favors increased promiscuity of males but not of females as a result of differences in parental investment in gametes. The second is that the variance in mate number of males is the fundamental cause of a sex difference in fitness variance. We argue that Bateman's insight about the source of sexual selection is more fundamental than his speculation about patterns of parental investment. We show that, when the sex ratio is 1:1, the average female must be as promiscuous as the average male, because each copulation involves one male and one female. Because mean male and female promiscuity are tied together in the same manner as mean male and female fitness, a sex difference in mating propensity must be the result of either (1) a sex difference in the covariance between matings and number offspring, or (2) Fisherian run-away sexual selection, wherein female reluctance to mate is a weak form of female choice. We show how female promiscuity can limit the evolution of male promiscuity, turning the central argument of parental investment theory on its head.
贝特曼确定了性选择的两个方面。第一个方面，称为贝特曼原理，是指由于配子投资的差异，性选择有利于雄性的滥交增加，但不利于雌性的滥交。第二个方面是，雄性配偶数量的方差是适应度方差存在性别差异的根本原因。我们认为，贝特曼关于性选择来源的洞察力比他关于亲代投资模式的推测更为根本。我们表明，当性别比例为 1:1 时，平均雌性必须像平均雄性一样滥交，因为每次交配都涉及一只雄性和一只雌性。由于平均雄性和雌性的滥交与平均雄性和雌性的适应度以相同的方式联系在一起，因此交配倾向的性别差异必须是以下两种情况之一的结果：（1）交配与后代数量之间的协方差存在性别差异，或（2）费希尔式的逃逸性性选择，其中雌性不愿意交配是一种较弱的雌性选择形式。我们展示了雌性滥交如何限制雄性滥交的进化，从而颠覆了亲代投资理论的核心论点。
