Friberg U, Arnqvist G
Department of Ecology and Environmental Science, Section of Animal Ecology, Umeå University, Sweden.
J Evol Biol. 2003 Sep;16(5):797-811. doi: 10.1046/j.1420-9101.2003.00597.x.
The evolution of female mate choice, broadly defined to include any female behaviour or morphology which biases matings towards certain male phenotypes, is traditionally thought to result from direct or indirect benefits which females acquire when mating with preferred males. In contrast, new models have shown that female mate choice can be generated by sexual conflict, where preferred males may cause a fitness depression in females. Several studies have shown that female Drosophila melanogaster bias matings towards large males. Here, we use male size as a proxy for male attractiveness and test how female fitness is affected by reproducing with large or small males, under two different male densities. Females housed with large males had reduced lifespan and aged at an accelerated rate compared with females housed with small males, and increased male density depressed female fitness further. These fitness differences were due to effects on several different fitness components. Female fitness covaried negatively with male courtship rate, which suggests a cost of courtship. Mating rate increased with male size, whereas female fitness peaked at an intermediate mating rate. Our results suggest that female mate choice in D. melanogaster is, at least in part, a by-product of sexual conflict over the mating rate.
雌性配偶选择的进化，广义上定义为包括任何使交配偏向某些雄性表型的雌性行为或形态，传统观点认为这是雌性与偏好的雄性交配时获得的直接或间接利益所致。相比之下，新模型表明，雌性配偶选择可能由性冲突产生，即偏好的雄性可能导致雌性适合度降低。多项研究表明，雌性黑腹果蝇会使交配偏向体型较大的雄性。在此，我们以雄性体型作为雄性吸引力的指标，测试在两种不同雄性密度下，与体型大或小的雄性繁殖时雌性适合度如何受到影响。与和体型小的雄性关在一起的雌性相比，和体型大的雄性关在一起的雌性寿命缩短且衰老加速，而雄性密度增加会进一步降低雌性适合度。这些适合度差异是由于对几个不同适合度组成部分的影响。雌性适合度与雄性求偶率呈负相关，这表明存在求偶成本。交配率随雄性体型增加，而雌性适合度在中等交配率时达到峰值。我们的结果表明，黑腹果蝇中的雌性配偶选择至少部分是交配率上性冲突的副产品。
