Data from: Anthropogenic ecosystem fragmentation drives shared and unique patterns of sexual signal divergence among three species of Bahamian mosquitofish

When confronted with similar environmental challenges, different organisms can exhibit dissimilar phenotypic responses. Therefore, understanding patterns of phenotypic divergence for closely related species requires considering distinct evolutionary histories. Here, we investigated how a common form of human-induced environmental alteration, habitat fragmentation, may drive phenotypic divergence among three closely-related species of Bahamian mosquitofish (Gambusia spp.). Focusing on one phenotypic trait (male coloration), having a priori predictions of divergence, we tested whether populations persisting in fragmented habitats differed from those inhabiting unfragmented habitats, and examined the consistency of the pattern across species. Species exhibited both shared and unique patterns of phenotypic divergence between the two types of habitats, with shared patterns representing the stronger effect. For all species, populations in fragmented habitats had fewer dorsal-fin spots. In contrast, the magnitude and trajectory of divergence in dorsal-fin color, a sexually selected trait, differed among species. We identified fragmentation-mediated increased turbidity as a possible driver of these trait shifts. These results suggest that even closely related species can exhibit diverse phenotypic responses when encountering similar human-mediated selection regimes. This element of unpredictability complicates forecasting the phenotypic responses of wild organisms faced with anthropogenic change - an important component of biological conservation and ecosystem management.

当面临相似的环境挑战时，不同生物会表现出迥异的表型响应。因此，解析近缘物种的表型分化模式，需要考量其各自独特的演化历史。本研究聚焦于人类活动引发的常见环境扰动类型——生境破碎化（habitat fragmentation），探究其如何驱动三种近缘巴哈米亚食蚊鱼（Gambusia spp.）的表型分化。本研究以雄性体色这一表型性状为核心，基于预先提出的分化假说，检验了生境破碎化种群与未破碎化栖息地种群的表型差异，并分析了该模式在三个物种间的一致性。三个物种在两类生境中均表现出共有与特有的表型分化模式，其中共有模式的效应强度更高。所有物种的破碎化栖息地种群的背鳍斑点数量均更少。与之形成对比的是，作为性选择性状的背鳍颜色，其分化的幅度与方向在物种间存在差异。本研究推断，生境破碎化引发的浊度升高可能是这些性状变化的驱动因素。上述结果表明，即便近缘物种在面临相似的人为选择压力时，也可能表现出多样的表型响应。这种不可预测性增加了预测野生生物面对人为环境变化时表型响应的难度——而这正是生物保护与生态系统管理的核心议题之一。