Data from: Sexual selection and assortative mating: an experimental test

Mate choice and mate competition can both influence the evolution of sexual isolation between populations. Assortative mating may arise if traits and preferences diverge in step, and, alternatively, mate competition may counteract mating preferences and decrease assortative mating. Here, we examine potential assortative mating between populations of Drosophila pseudoobscura that have experimentally evolved under either increased (‘polyandry’) or decreased (‘monogamy’) sexual selection intensity for 100 generations. These populations have evolved differences in numerous traits, including a male signal and female preference traits. We use a two males: one female design, allowing both mate choice and competition to influence mating outcomes, to test for assortative mating between our populations. Mating latency shows subtle effects of male and female interactions, with females from the monogamous populations appearing reluctant to mate with males from the polyandrous populations. However, males from the polyandrous populations have a significantly higher probability of mating regardless of the female's population. Our results suggest that if populations differ in the intensity of sexual selection, effects on mate competition may overcome mate choice.择偶偏好与配偶竞争均可影响种群间性隔离的演化进程。若性状与偏好同步分化，便可能产生选型交配（Assortative mating）；反之，配偶竞争可能抵消择偶偏好，降低选型交配的发生概率。本研究以经历100代实验演化的伪暗果蝇（Drosophila pseudoobscura）种群为研究对象，这些种群分别在性选择强度升高（多配性（polyandry））与降低（单配性（monogamy））的条件下繁育。上述种群已在诸多性状上演化出差异，涵盖雄性信号与雌性偏好相关性状。本研究采用两雄一雌实验设计，使择偶偏好与配偶竞争均可对交配结果产生影响，以此检验各实验种群间是否存在选型交配。实验结果显示，交配潜伏期体现出雌雄个体间交互作用的细微效应：来自单配种群的雌性似乎不愿与多配种群的雄性交配。但无论雌性所属种群为何，多配种群的雄性均具有显著更高的交配成功率。本研究结果表明，若不同种群的性选择强度存在差异，则配偶竞争带来的效应可能盖过择偶偏好的作用。