Male genitals are highly divergent in animals with internal fertilization. Most studies attempting to explain this diversity have focused on testing the major hypotheses of genital evolution (the lock‐and‐key, pleiotropy, and sexual selection hypotheses), and quantifying the form of selection targeting male genitals has played an important role in this endeavor. However, we currently know far less about selection targeting female genitals or how male and female genitals interact during mating. Here, we use formal selection analysis to show that genital size and shape is subject to strong multivariate stabilizing sexual selection in both sexes of the red flour beetle, Tribolium castaneum. Moreover, we show significant sexual selection on the covariance between the sexes for specific aspects of genital shape suggesting that male and female genitalia also interact to determine the successful transfer of a spermatophore during mating. Our work therefore highlights the important role that both male and female genital morphologies play in determining mating success and that these effects can occur independently, as well as through their interaction. Moreover, it cautions against the overly simplistic view that the sexual selection targeting genital morphology will always be directional in form and restricted primarily to males.

中文翻译：

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红粉甲虫的多元稳定性选择与雄性和雌性生殖器形态的演变

男性生殖器在具有内部受精的动物中高度分化。大多数试图解释这种多样性的研究都集中在测试生殖器进化的主要假设（锁钥、多效性和性选择假设），并且量化针对男性生殖器的选择形式在这一努力中发挥了重要作用. 然而，我们目前对针对女性生殖器的选择或男性和女性生殖器在交配过程中如何相互作用知之甚少。在这里，我们使用正式选择分析来表明生殖器的大小和形状在红粉甲虫 Tribolium castaneum 的两性中都受到强烈的多元稳定性选择的影响。而且，我们在生殖器形状的特定方面显示了两性之间协方差的显着性选择，这表明男性和女性的生殖器也会相互作用以确定交配过程中精囊的成功转移。因此，我们的工作强调了男性和女性生殖器形态在决定交配成功方面的重要作用，并且这些影响可以独立发生，也可以通过它们的相互作用发生。此外，它告诫不要过于简单化的观点，即针对生殖器形态的性选择在形式上总是有方向性的，并且主要限于男性。因此，我们的工作强调了男性和女性生殖器形态在决定交配成功方面的重要作用，并且这些影响可以独立发生，也可以通过它们的相互作用发生。此外，它告诫不要过于简单化的观点，即针对生殖器形态的性选择在形式上总是有方向性的，并且主要限于男性。因此，我们的工作强调了男性和女性生殖器形态在决定交配成功方面的重要作用，并且这些影响可以独立发生，也可以通过它们的相互作用发生。此外，它告诫不要过于简单化的观点，即针对生殖器形态的性选择在形式上总是有方向性的，并且主要限于男性。