Adaptation to Experimental Alterations of the Operational Sex Ratio in Populations of Drosophila Melanogaster
Adaptation to Experimental Alterations of the Operational Sex Ratio in Populations of Drosophila Melanogaster
复制标题
果蝇种群中操作性性别比实验性改变的适应
DOI：
--
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
G. Hurst
中科院分区：
文献类型：
--
作者：
M. Reuter;Jon R. Linklater;L. Lehmann;Kevin Fowler;T. Chapman;G. Hurst
摘要理论预测，男性通过增加对睾丸质量的投资以转移更大的射精来适应精子竞争。实验和比较数据支持这一预测。然而，精子竞争在睾丸大小进化中的相对重要性仍然难以捉摸，因为实验只改变精子竞争，而比较方法将其与其他变量，特别是男性交配率混淆。我们采用实验进化的方法研究了精子竞争和雄性交配率的相对重要性。我们将黑腹果蝇种群的性别比例为1：1，4：1，和10：1（女性：男性）。雌性偏好降低精子竞争，但增加雄性交配率和精子消耗。经过28代的进化，10：1处理的雄性比其他处理的雄性有更大的睾丸。因此，睾丸大小的演变是对交配率和精子消耗的反应，而不是精子竞争。此外，我们的实验表明，漂移与性别比例失真限制适应;睾丸大小只在人口中的性别比例偏差的影响，有效的人口规模已被补偿增加的数值大小的进化。我们讨论了这些结果与生殖进化，遗传漂变在自然和实验种群，自然性别比例扭曲的后果。
Abstract Theory predicts that males adapt to sperm competition by increasing their investment in testis mass to transfer larger ejaculates. Experimental and comparative data support this prediction. Nevertheless, the relative importance of sperm competition in testis size evolution remains elusive, because experiments vary only sperm competition whereas comparative approaches confound it with other variables, in particular male mating rate. We addressed the relative importance of sperm competition and male mating rate by taking an experimental evolution approach. We subjected populations of Drosophila melanogaster to sex ratios of 1:1, 4:1, and 10:1 (female:male). Female bias decreased sperm competition but increased male mating rate and sperm depletion. After 28 generations of evolution, males from the 10:1 treatment had larger testes than males from other treatments. Thus, testis size evolved in response to mating rate and sperm depletion, not sperm competition. Furthermore, our experiment demonstrated that drift associated with sex ratio distortion limits adaptation; testis size only evolved in populations in which the effect of sex ratio bias on the effective population size had been compensated by increasing the numerical size. We discuss these results with respect to reproductive evolution, genetic drift in natural and experimental populations, and consequences of natural sex ratio distortion.