Data from: Human-caused habitat fragmentation can drive rapid divergence of male genitalia

The aim of this study rests on three premises: 1) humans are altering ecosystems worldwide, 2) environmental variation often influences the strength and nature of sexual selection, and 3) sexual selection is largely responsible for rapid and divergent evolution of male genitalia. While each of these assertions has strong empirical support, no study has yet investigated their logical conclusion that human impacts on the environment might commonly drive rapid diversification of male genital morphology. We tested whether anthropogenic habitat fragmentation has resulted in rapid changes in the size, allometry, shape, and meristics of male genitalia in three native species of livebearing fishes (genus: Gambusia) inhabiting tidal creeks across six Bahamian islands. We found that genital shape and allometry consistently and repeatedly diverged in fragmented systems across all species and islands. Using a model selection framework, we identified three ecological consequences of fragmentation that apparently underlie observed morphological patterns: decreased predatory fish density, increased conspecific density, and reduced salinity. Our results demonstrate that human modifications to the environment can drive rapid and predictable divergence in male genitalia. Given the ubiquity of anthropogenic impacts on the environment, future research should evaluate the generality of our findings and potential consequences for reproductive isolation.本研究的立论基础包含三项前提：1）人类活动正在全球范围内改变生态系统；2）环境变异通常会影响性选择（sexual selection）的强度与本质；3）性选择是推动雄性生殖器快速趋异演化的核心动因。尽管上述三项主张均具备坚实的实证支撑，但目前尚无研究对其逻辑推论开展验证：即人类对环境的影响或可普遍推动雄性生殖器形态的快速多样化。本研究针对栖息于巴哈马群岛6处潮汐溪中的3种土著胎生鱼类（胎鳉属 Gambusia），验证了人为生境破碎化是否会导致雄性生殖器的大小、异速生长（allometry）、形态以及计数特征（meristics）发生快速变化。研究发现，在所有受试物种与群岛的破碎化生境中，雄性生殖器形态与异速生长模式均呈现出一致且可重复的趋异现象。通过模型选择框架，我们确定了驱动上述形态格局的三项破碎化生态效应：捕食性鱼类密度下降、同种个体密度升高，以及盐度降低。本研究结果表明，人类对环境的改造能够推动雄性生殖器产生快速且可预测的趋异演化。鉴于人类活动对环境的影响无处不在，未来研究应验证本研究结论的普适性，以及其对生殖隔离的潜在影响。