Division of Biology, Kansas State University, Manhattan, Kansas, 66506.
Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, 60637.
Evolution. 2019 Jun;73(6):1200-1212. doi: 10.1111/evo.13742. Epub 2019 May 7.
Divergence of genital traits among lineages has the potential to serve as a reproductive isolating barrier when copulation, insemination, and fertilization are inhibited by incompatibilities between female and male genitalia. Despite widespread evidence for genital trait diversity among closely related lineages and coevolution of female and male genitalia within lineages, few studies have investigated genital evolution during the early stages of speciation. We quantified genital variation in replicated population pairs of Poecilia mexicana with ongoing ecological speciation between sulfidic (H S containing) and nearby nonsulfidic habitats. These analyses revealed rapid and correlated divergence of female and male genitalia across evolutionarily independent population pairs exposed to divergent selection regimes. Both sexes exhibited convergent evolution of genital traits among populations inhabiting similar habitat types. Our results demonstrate that genital evolution can occur during the early stages of speciation-with-gene-flow, potentially as a result of variation in the intensity of sexual conflict among populations. Our results suggest genitalia may contribute to early stages of divergence and challenge the generality of previously suggested mechanisms of genital evolution in poeciliids.
生殖特征的分歧在交配、授精和受精因雌雄生殖器之间的不兼容而受到抑制时，有可能成为生殖隔离的屏障。尽管有广泛的证据表明近亲谱系之间存在生殖特征的多样性，并且在谱系内雌性和雄性生殖器也存在共同进化，但很少有研究调查生殖进化在物种形成的早期阶段。我们对正在进行硫化物（含 H2S）和附近非硫化物生境之间生态物种形成的墨西哥脂鲤重复种群对的生殖器进行了量化。这些分析揭示了在暴露于不同选择条件的进化独立种群对中，雌性和雄性生殖器的快速和相关分化。两性都表现出栖息在相似生境类型的种群之间的生殖器特征的趋同进化。我们的研究结果表明，生殖进化可以发生在具有基因流的物种形成的早期阶段，这可能是由于种群之间性冲突强度的变化。我们的研究结果表明，生殖器可能有助于早期的分化，并挑战以前在脂鲤科中提出的生殖器进化机制的普遍性。
