Kirkpatrick Mark
Department of Zoology, University of Texas, Austin, Texas, 78712.
Evolution. 1996 Dec;50(6):2125-2140. doi: 10.1111/j.1558-5646.1996.tb03603.x.
A model is used to study quantitatively the impact of a good genes process and direct natural selection on the evolution of a mating preference. The expression of a male display trait is proportional to genetic quality, which is determined by the number of deleterious mutations a male carries throughout his genome. Genetic variances and covariances, including the covariance between the preference and male trait that drives the good genes process, are allowed to evolve under an infinitesimal model. Results suggest that the good genes process generates only weak indirect selection on preferences, with an effective selection intensity of a few percent or less. If preferences are subject to direct natural selection of the intensity observed for other characters, the good genes process alone is not expected to exaggerate the male trait by more than a few phenotypic standard deviations, contrary to what is observed in highly sexually selected species. Good genes can, however, cause substantial exaggeration if preference genes are nearly selectively neutral. Alternatively, direct selection on preference genes, acting on mating behavior itself or on the genes' pleiotropic effects, can cause mating preferences and male display traits to be exaggerated by any degree. Direct selection of preference genes may therefore play an important role in species that show extreme sexual selection.
一个模型被用于定量研究优质基因过程和直接自然选择对交配偏好进化的影响。雄性展示性状的表达与基因质量成正比，而基因质量由雄性整个基因组中携带的有害突变数量决定。在一个无穷小模型下，遗传方差和协方差，包括驱动优质基因过程的偏好与雄性性状之间的协方差，被允许进化。结果表明，优质基因过程对偏好仅产生微弱的间接选择，有效选择强度为百分之几或更低。如果偏好受到针对其他性状所观察到的强度的直接自然选择，仅优质基因过程预计不会使雄性性状夸张超过几个表型标准差，这与在高度性选择物种中所观察到的情况相反。然而，如果偏好基因几乎是选择中性的，优质基因可以导致显著的夸张。另外，对偏好基因的直接选择，作用于交配行为本身或基因的多效性效应，可以使交配偏好和雄性展示性状被夸张到任何程度。因此，对偏好基因的直接选择可能在表现出极端性选择的物种中发挥重要作用。
