Abstract Diversification in sexual signals is often taken as evidence for the importance of sexual selection in speciation. However, in order for sexual selection to generate reproductive isolation between populations, both signals and mate preferences must diverge together. Furthermore, assortative mating may result from multiple behavioral mechanisms, including female mate preferences, male mate preferences, and male–male competition; yet their relative contributions are rarely evaluated. Here, we explored the role of mate preferences and male competitive ability as potential barriers to gene flow between 2 divergent lineages of the tawny dragon lizard, Ctenophorus decresii, which differ in male throat coloration. We found stronger behavioral barriers to pairings between southern lineage males and northern lineage females than between northern males and southern females, indicating incomplete and asymmetric behavioral isolating barriers. These results were driven by both male and female mate preferences rather than lineage differences in male competitive ability. Intrasexual selection is therefore unlikely to drive the outcome of secondary contact in C. decresii, despite its widely acknowledged importance in lizards. Our results are consistent with the emerging view that although both male and female mate preferences can diverge alongside sexual signals, speciation is rarely driven by divergent sexual selection alone.

中文翻译：

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不同的雄性和雌性配偶偏好并不能解释蜥蜴谱系之间的早期物种形成

摘要 性信号的多样化通常被视为性选择在物种形成中的重要性的证据。然而，为了使性选择在种群之间产生生殖隔离，信号和配偶偏好必须同时发散。此外，分类交配可能由多种行为机制引起，包括女性择偶偏好、男性择偶偏好和雄性竞争；然而，他们的相对贡献很少被评估。在这里，我们探讨了配偶偏好和雄性竞争能力作为黄龙蜥蜴 Ctenophorus decresii 两个不同谱系之间基因流动的潜在障碍的作用，它们的雄性喉咙颜色不同。我们发现南方雄性和北方雌性之间的配对行为障碍比北方雄性和南方雌性之间更强，表明存在不完整和不对称的行为隔离障碍。这些结果是由男性和女性的配偶偏好而不是男性竞争能力的血统差异驱动的。因此，尽管其在蜥蜴中的重要性得到广泛承认，但性内选择不太可能驱动 C. decresii 中二次接触的结果。我们的结果与新出现的观点一致，即尽管男性和女性的配偶偏好会随着性信号而发生分歧，但物种形成很少仅由不同的性选择驱动。这些结果是由男性和女性的配偶偏好而不是男性竞争能力的血统差异驱动的。因此，尽管其在蜥蜴中的重要性得到广泛认可，但性内选择不太可能驱动 C. decresii 中二次接触的结果。我们的结果与新出现的观点一致，即尽管男性和女性的配偶偏好会随着性信号而发生分歧，但物种形成很少仅由不同的性选择驱动。这些结果是由男性和女性的配偶偏好而不是男性竞争能力的血统差异驱动的。因此，尽管其在蜥蜴中的重要性得到广泛承认，但性内选择不太可能驱动 C. decresii 中二次接触的结果。我们的结果与新出现的观点一致，即尽管男性和女性的配偶偏好会随着性信号而发生分歧，但物种形成很少仅由不同的性选择驱动。