Data from: Experimental evidence for the evolution of the mammalian baculum by sexual selection

Male genitalia exhibit a taxonomically widespread pattern of rapid and divergent evolution. Sexual selection is generally believed to be responsible for these patterns of evolutionary divergence, although empirical support for the sexual selection hypothesis comes mainly from studies of insects. Here we show that sexual selection is responsible for an evolutionary divergence in baculum morphology among populations of house mice Mus domesticus. We sourced mice from three isolated populations known to be subject to differing strengths of postcopulatory sexual selection and bred them under common-garden conditions. Mice from populations with strong postcopulatory sexual selection had bacula that were relatively thicker compared with mice from populations with weak selection. We used experimental evolution to determine whether these patterns of divergence could be ascribed to postcopulatory sexual selection. After 27 generations of experimental evolution, populations of mice subjected to postcopulatory sexual selection evolved bacula that were relatively thicker than populations subjected to enforced monogamy. Our data thereby provide evidence that postcopulatory sexual selection underlies an evolutionary divergence in the mammalian baculum and supports the hypothesis that sexual selection plays a general role in the evolution of male genital morphology across evolutionary diverse taxonomic groups.

雄性生殖器在众多分类类群中普遍呈现快速趋异演化的特征。性选择通常被认为是驱动这类演化趋异的核心机制，但目前性选择假说的实证依据主要来源于昆虫类群的研究。本研究证实，性选择是家小家鼠（Mus domesticus）不同隔离种群间阴茎骨（baculum）形态演化趋异的成因。我们从三个已知受不同强度交配后性选择（postcopulatory sexual selection）的隔离种群中采集家鼠，并在共同培育环境条件下进行繁育。相较于交配后性选择强度较弱的种群，来自强交配后性选择种群的小鼠，其阴茎骨相对更为粗壮。我们通过实验演化（experimental evolution）探究这类形态趋异是否可归因于交配后性选择：经过27代实验演化后，经受交配后性选择的小鼠种群，其阴茎骨相较于强制单配制（enforced monogamy）种群的个体，相对更为粗壮。综上，本研究数据证实，交配后性选择是哺乳类阴茎骨演化趋异的内在驱动因素，并支持性选择在跨演化多样性的分类类群的雄性生殖器形态演化中发挥普遍作用这一学术假说。