Rostant Wayne G, Mason Janet S, de Coriolis Jean-Charles, Chapman Tracey
School of Biological Sciences University of East Anglia Norwich NR4 7TJ United Kingdom.
Evol Lett. 2020 Jan 9;4(1):54-64. doi: 10.1002/evl3.153. eCollection 2020 Feb.
Sexual conflict can promote the evolution of dramatic reproductive adaptations as well as resistance to its potentially costly effects. Theory predicts that responses to sexual conflict will vary significantly with resource levels-when scant, responses should be constrained by trade-offs, when abundant, they should not. However, this can be difficult to test because the evolutionary interests of the sexes align upon short-term exposure to novel environments, swamping any selection due to sexual conflict. What is needed are investigations of populations that are well adapted to both differing levels of sexual conflict and resources. Here, we used this approach in a long-term experimental evolution study to track the evolution of female resistance to sexual conflict in the fruit fly . In resource-rich regimes, high-conflict females evolved resistance to continual exposure to males. There was no difference in baseline survival, consistent with the idea that responses evolving under nutritional abundance experienced no trade-offs with resistance. In the poor resource regimes, the ability of high-conflict females to evolve resistance to males was severely compromised and they also showed lower baseline survival than low-conflict females. This suggested high-conflict females traded off somatic maintenance against any limited resistance they had evolved in response to sexual conflict. Overall, these findings provide experimental support for the hypothesis that evolutionary responses to sexual conflict are critically dependent upon resource levels.
性冲突能够推动显著的生殖适应性进化，以及对其潜在高昂代价效应的抗性进化。理论预测，对性冲突的反应会随资源水平的变化而显著不同——资源稀缺时，反应会受到权衡取舍的限制；资源丰富时，则不受此限。然而，这一点很难得到验证，因为在短期接触新环境时，两性的进化利益是一致的，这会掩盖因性冲突产生的任何选择作用。我们需要对那些既适应不同程度的性冲突又适应不同资源水平的种群进行研究。在此，我们在一项长期实验进化研究中采用了这种方法，以追踪果蝇雌性对性冲突抗性的进化。在资源丰富的环境中，处于高度冲突环境下的雌性果蝇进化出了对持续接触雄性的抗性。基线存活率没有差异，这与在营养丰富条件下进化出的反应不会与抗性产生权衡取舍这一观点相符。在资源匮乏的环境中，处于高度冲突环境下的雌性果蝇进化出对雄性抗性的能力严重受损，并且它们的基线存活率也低于处于低度冲突环境下的雌性果蝇。这表明，处于高度冲突环境下的雌性果蝇在体细胞维持方面进行了权衡，以应对它们为应对性冲突而进化出的有限抗性。总体而言，这些发现为性冲突的进化反应严重依赖资源水平这一假说提供了实验支持。
