Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA.
Mol Ecol. 2012 Aug;21(15):3879-92. doi: 10.1111/j.1365-294X.2012.05644.x. Epub 2012 May 31.
Understanding how reproductive barriers evolve during speciation remains an important question in evolution. Divergence in mating preferences may be a common first step in this process. The striking colour pattern diversity of strawberry dart frog (Dendrobates pumilio) populations has likely been shaped by sexual selection. Previous laboratory studies have shown that females attend to male coloration and prefer to court with males of their own colour, suggesting that divergent morphs may be reproductively isolated. To test this hypothesis, we used molecular data to estimate pedigree relationships from a polymorphic population. Whereas in the laboratory both red and yellow females preferred to court with males of their own phenotype, our pedigree shows a pattern of assortative mating only for red females. In the wild, yellow females appear to be less choosy about their mates, perhaps because they incur higher costs associated with searching than females of the more common red phenotype. We also used our pedigree to investigate the genetic basis for colour-pattern variation. The phenotype frequencies we observed were consistent with those expected if dorsal background coloration is controlled by a single locus, with complete dominance of red over yellow. Our results not only help clarify the role of sexual selection in reducing gene flow, but also shed light on the mechanisms underlying colour-pattern variation among sympatric colour morphs. The difference we observed between mating preferences measured under laboratory conditions and the pattern of mate choice observed in the wild highlight the importance of field studies for understanding behavioural reproductive isolation.
了解生殖障碍在物种形成过程中是如何进化的，仍然是进化研究中的一个重要问题。交配偏好的差异可能是这个过程的常见第一步。草莓箭毒蛙（Dendrobates pumilio）种群引人注目的颜色图案多样性很可能是由性选择塑造的。以前的实验室研究表明，雌性会关注雄性的颜色，并更喜欢与自己颜色的雄性交配，这表明不同形态的雄性可能在繁殖上是隔离的。为了验证这一假说，我们使用分子数据从一个多态种群中估计了系谱关系。虽然在实验室中，红色和黄色的雌性都更喜欢与自己表型的雄性交配，但我们的系谱显示只有红色雌性存在交配偏好的选择性。在野外，黄色雌性似乎对它们的配偶不太挑剔，也许是因为它们在寻找配偶方面的成本比更常见的红色表型的雌性更高。我们还利用我们的系谱来研究颜色图案变异的遗传基础。我们观察到的表型频率与如果背部背景颜色由单个基因座控制，红色对黄色完全显性的情况一致。我们的研究结果不仅有助于澄清性选择在减少基因流方面的作用，还揭示了同域颜色形态之间颜色图案变异的潜在机制。我们在实验室条件下测量的交配偏好与在野外观察到的交配选择模式之间的差异，强调了野外研究对于理解行为生殖隔离的重要性。
