Data from: Cast adrift on an island: introduced populations experience an altered balance between selection and drift

A long-standing question in evolutionary biology is what becomes of adaptive traits when a species expands its range into novel environments. Here we report the results of a study on an adaptive colour pattern polymorphism (stripes) of the coqui frog following its introduction to Hawaii from Puerto Rico. We compared population differentiation (φ'ST and FST) for the stripes locus —which underlies this colour pattern polymorphism— with neutral microsatellite loci to test for a signature of selection among native and introduced populations. Among native populations, φ'ST and FST for stripes were lower than expected under the neutral model, suggesting uniform balancing selection. Alternatively, among introduced populations, φ'ST and FST for stripes did not differ from the neutral model. These results suggest that the evolutionary dynamics of this previously adaptive trait have become dominated by random genetic drift following the range expansion.

进化生物学领域一个长期存在的核心问题是：当物种将其分布范围拓展至全新环境时，其适应性性状会发生何种演化。我们在此报告一项针对从波多黎各引入夏威夷的科奎蛙（coqui frog）适应性体色多态性——条纹性状——的研究结果。我们针对构成该体色多态性基础的条纹相关基因座，对比其与中性微卫星基因座的种群分化程度（φ'ST与FST），以检验本土种群与引入种群间是否存在选择信号。在本土种群中，条纹相关基因座的φ'ST与FST值低于中性模型下的预期值，表明存在均匀的平衡选择。而在引入种群中，条纹相关基因座的φ'ST与FST值与中性模型并无显著差异。上述结果表明，这一原本具有适应性的性状在分布范围拓展后，其演化动态已转为由随机遗传漂变主导。