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.

雄性生殖器在各分类类群中普遍呈现快速趋异演化的模式。学界普遍认为性选择是造成这类演化趋异的核心驱动因素，但目前性选择假说的实证依据主要来自昆虫类群的研究。本研究证实，性选择是家鼠（Mus domesticus）不同种群间阴茎骨（baculum）形态演化趋异的驱动因素。我们采集了三个已知受不同强度交配后性选择作用的隔离种群家鼠，并在同质园（common-garden）饲养条件下开展繁育实验。结果发现，相较于交配后性选择较弱的种群，来自性选择较强种群的家鼠，其阴茎骨相对更为粗壮。我们借助实验演化手段，验证这类形态趋异是否由交配后性选择导致。经过27代实验演化后，经受交配后性选择的小鼠种群，其阴茎骨相对强制单配偶制种群的个体更为粗壮。综上，本研究数据证实交配后性选择是哺乳动物阴茎骨演化趋异的核心驱动因素，并支持“性选择在不同演化类群的雄性生殖器形态演化中发挥普遍作用”这一科学假说。