Sexual selection is predicted to influence population persistence because skew in male reproductive success may facilitate the purging of mutation load. We manipulated the strength of sexual selection in populations of Indian meal moths, Plodia interpunctella, by adjusting adult sex ratios to be either male- or female-biased, leading to strong and weak sexual selection in males, respectively. After between 19 and 22 generations of experimental evolution, we examined whether mutation load differed between these populations by enforcing successive generations of inbreeding, tracking extinction events, offspring viability and assaying the effect of inbreeding on male mating success and female choice. We found no effect of the strength of sexual selection on the rate of extinction or offspring viability. We did, however, find changes in both male mating success and female choice, with both being influenced by the sex ratio treatment and the number of generations of inbreeding. Males from male-biased populations were more successful at mating with stock females, and mating success declined rapidly with inbreeding regardless of sex ratio treatment. Females from male-biased populations were less likely to mate with stock males at the onset of the experiment, but tended to mate more frequently with increasing inbreeding compared to females from female-biased populations. Our results demonstrate that while mating behaviors have diverged between male-biased and female-biased lines mutation loads remained similar. This suggests that the benefits of sexual selection to population fitness may be low or slow to accumulate under the benign environmental conditions in which these populations evolved.

中文翻译：

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强烈的性选择无法防止飞蛾因近亲繁殖而灭绝

预计性选择会影响种群持久性，因为雄性生殖成功的偏差可能有助于清除突变负荷。我们通过将成年性别比例调整为偏向男性或偏向女性来控制印度粉蛾 Plodia interpunctella 种群的性选择强度，从而分别导致男性的性选择强和弱。经过 19 到 22 代的实验进化后，我们通过实施连续几代的近交、跟踪灭绝事件、后代的生存能力以及分析近交对雄性交配成功和雌性选择的影响来检查这些种群之间的突变负荷是否不同。我们发现性选择的强度对灭绝率或后代生存能力没有影响。然而，我们做到了，发现男性交配成功和女性选择的变化，两者都受到性别比例处理和近亲繁殖代数的影响。来自偏向男性群体的雄性在与种群雌性交配方面更成功，并且无论性别比例处理如何，近亲繁殖的交配成功率迅速下降。在实验开始时，偏向雄性种群的雌性不太可能与普通雄性交配，但与偏向雌性种群的雌性相比，随着近亲繁殖的增加，它们交配的频率往往更高。我们的研究结果表明，虽然交配行为在男性偏向和女性偏向的系之间有所不同，但突变负荷仍然相似。