Data from: Female, but not male, tropical sparrows respond more strongly to the local song dialect: implications for population divergence.

In addition to the observed high diversity of species in the tropics, divergence among populations of the same species exists over short geographic distances in both phenotypic traits and neutral genetic markers. Divergence among populations suggests great potential for the evolution of reproductive isolation and eventual speciation. In birds, song can evolve quickly through cultural transmission resulting in regional dialects, which can be a critical component of reproductive isolation through variation in female preference. We examined female and male behavioral responses to local and non-local dialects in two allopatric populations of rufous-collared sparrows (Zonotrichia capensis) in the Andes of Ecuador. Here we show that female sparrows prefer their natal song dialect to the dialect from an allopatric population just 25 km away and separated by unsuitable higher elevation habitat (pass 4200 m), thus providing evidence of prezygotic reproductive isolation among populations. Males showed similar territorial responses to all conspecific dialects, with no consistent difference with respect to distance, making male territoriality uninformative for estimating reproductive isolation. This study provides novel evidence for culturally-based prezygotic isolation over very short distances in a tropical bird.

除观测到的热带地区极高的物种多样性外，同一物种种群间在较短地理距离内，已在表型性状（phenotypic traits）与中性遗传标记（neutral genetic markers）层面出现分化。种群间的分化暗示了生殖隔离演化乃至最终物种形成的巨大潜力。在鸟类中，鸣唱可通过文化传递快速演化并形成区域方言；而雌性偏好的差异可使这类方言成为生殖隔离的关键组成部分。我们以厄瓜多尔安第斯山脉的两个异域种群棕顶雀鹀（Zonotrichia capensis）为研究对象，检验了雌雄个体对本地与非本地方言的行为响应。研究结果显示，相较于仅相隔25公里且被海拔4200米的不适宜高海拔生境隔开的异域种群的鸣唱方言，雌性棕顶雀鹀更偏好自身出生地的鸣唱方言，这为种群间的合子前生殖隔离（prezygotic reproductive isolation）提供了直接证据。雄性个体对所有同种鸣唱方言均表现出相似的领地响应，未出现随距离变化的一致性差异，因此雄性领地行为无法为生殖隔离的评估提供有效信息。本研究为热带鸟类在极短地理距离内形成基于文化的合子前生殖隔离提供了全新证据。