Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia 24061, USA.
Am Nat. 2011 Jul;178(1):53-63. doi: 10.1086/660283.
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 and result 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 nonlocal dialects in two allopatric populations of rufous-collared sparrows (Zonotrichia capensis) in the Andes Mountains of Ecuador. Here we show that female sparrows prefer their natal song dialect to the dialect of an allopatric population that is just 25 km away and separated by an unsuitable higher-elevation habitat (pass of 4,200 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.
除了热带地区观察到的物种多样性很高之外，同一物种的种群在表型特征和中性遗传标记方面，在短地理距离上也存在分歧。种群之间的分歧表明，生殖隔离和最终物种形成的进化潜力巨大。在鸟类中，通过文化传播，歌曲可以快速进化，并产生地域方言，这可能是通过雌性偏好的变化来实现生殖隔离的一个关键组成部分。我们在厄瓜多尔安第斯山脉的两个隔离种群中，检查了栗腹沙雀（Zonotrichia capensis）的雌性和雄性对本地和非本地方言的行为反应。在这里，我们发现雌性麻雀更喜欢自己出生地的方言，而不喜欢来自仅 25 公里远且被不合适的高海拔栖息地（海拔 4200 米的山口）隔开的种群的方言，从而为种群之间的合子前生殖隔离提供了证据。雄性对所有同种方言的领地行为反应相似，与距离无关，因此雄性的领地行为对于估计生殖隔离没有任何意义。这项研究为热带鸟类中非常短距离的基于文化的合子前隔离提供了新的证据。
