Sexual selection theory provides a framework for investigating the evolution of traits involved in attracting and competing for mates. Given the sexual function of such traits, studies generally focus on individual interactions (i.e., displays and contests) in explaining trait origin and persistence. We show that ecological factors can strongly influence the adaptive value of these traits, and changes to these factors can lead to rapid evolutionary change. We compared sexually selected traits in the small Indian mongoose (Urva auropunctata) between their sparsely populated native range and four tropical islands to which they were introduced within the last 150 years and where, due to a lack of interspecific competition and predation, they have become invasive and densely populated. Because of a likely increase in encounter rate, we predicted that selection on long‐distance chemical advertisement by males would relax in the introduced range. Accordingly, male, but not female, anal pads (used in scent marking) decreased in size in relation to both time since introduction and population density, and their relationship to body size and condition weakened. Concurrently, as predicted by intensified sperm competition, testis size increased following introduction. The small Indian mongoose thus experienced an inversion in the relative contributions to fitness of two sexual traits, followed by their rapid evolution in line with ecological changes.

中文翻译：

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通过性选择在野生入侵哺乳动物中快速进化

性选择理论提供了一个框架来研究吸引和竞争配偶的特征的进化。鉴于这些性状的性功能，研究通常侧重于解释性状起源和持久性的个体互动（即展示和竞争）。我们表明生态因素可以强烈影响这些性状的适应性价值，这些因素的变化会导致快速的进化变化。我们比较了印度小猫鼬 (Urva auropunctata) 在其人烟稀少的原生范围和过去 150 年内引入它们的四个热带岛屿之间的性选择特征，由于缺乏种间竞争和捕食，它们已成为侵入性和人口稠密。由于遭遇率可能会增加，我们预测男性对远程化学广告的选择会在引入的范围内放松。因此，男性（而非女性）肛垫（用于气味标记）的尺寸随着引入时间和人口密度而减小，并且它们与体型和状况的关系减弱。同时，正如精子竞争加剧所预测的那样，引入后睾丸大小增加。印度小猫鼬因此经历了两种性状对适应性的相对贡献的倒置，随后它们随着生态变化而快速进化。肛门垫（用于气味标记）的尺寸随着引入时间和人口密度而减小，并且它们与体型和状况的关系减弱。同时，正如精子竞争加剧所预测的那样，引入后睾丸大小增加。印度小猫鼬因此经历了两种性状对适应性的相对贡献的倒置，随后它们随着生态变化而快速进化。肛门垫（用于气味标记）的尺寸随着引入时间和人口密度而减小，并且它们与体型和状况的关系减弱。同时，正如精子竞争加剧所预测的那样，引入后睾丸大小增加。印度小猫鼬因此经历了两种性状对适应性的相对贡献的倒置，随后它们随着生态变化而快速进化。