Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3B2, Canada.
Curr Biol. 2012 Feb 7;22(3):204-8. doi: 10.1016/j.cub.2011.12.020. Epub 2012 Jan 5.
Whether the changes brought about by sexual selection are, on the whole, congruent or incongruent with the changes favored by natural selection is a fundamentally important question in evolutionary biology. Although a number of theoretical models have assumed that sexual selection reinforces natural selection [1, 2], others assume these forces are in opposition [3-5]. Empirical results have been mixed (see reviews in [1, 6-8]) and the reasons for the differences among studies are unclear. Variable outcomes are expected if populations differ in their evolutionary histories and therefore harbor different amounts and types of segregating genetic variation. Here, we constructed populations of Drosophila melanogaster that differed in this regard to directly test this hypothesis. In well-adapted populations, sexually successful males sired unfit daughters, indicating sexual and natural selection are in conflict. However, in populations containing an influx of maladaptive alleles, attractive males sired offspring of high fitness, suggesting that sexual selection reinforces natural selection. Taken together, these results emphasize the importance of evolutionary history on the outcome of sexual selection. Consequently, studies based on laboratory populations, cultured for prolonged periods under homogeneous conditions, may provide a skewed perspective on the relationship between sexual and natural selection.
性选择带来的变化在整体上与自然选择所偏好的变化是一致还是不一致，这是进化生物学中一个基本的重要问题。尽管一些理论模型假设性选择加强了自然选择[1,2]，但另一些模型假设这些力量是对立的[3-5]。实证结果喜忧参半（见综述[1,6-8]），而且研究之间差异的原因尚不清楚。如果种群在进化历史上存在差异，因此拥有不同数量和类型的可分离遗传变异，那么预期会出现不同的结果。在这里，我们构建了在这方面存在差异的黑腹果蝇种群，以直接检验这一假设。在适应性良好的种群中，性成功的雄性会生育出不适应环境的雌性后代，这表明性选择和自然选择是相互冲突的。然而，在含有大量不利等位基因流入的种群中，有吸引力的雄性会生育出适应能力强的后代，这表明性选择加强了自然选择。总之，这些结果强调了进化历史对性选择结果的重要性。因此，基于在同质条件下长时间培养的实验室种群进行的研究，可能会对性选择和自然选择之间的关系产生有偏差的观点。
