Data from: Testing the role of mating preference in a case of incomplete ecological speciation with gene flow

Mating preference can evolve as a side effect of ecological adaptation and simultaneously contribute to speciation in certain scenarios. However, theoretical predictions have been difficult to test experimentally because there has not been any simple way to relate empirical and theoretical parameters. Recently, it has been shown that the r coefficient and other statistics can be used to estimate mating preference in wild-captured mating pairs. In the present work we use these estimators to test whether mating preference has significantly increased in a context favorable for ecological divergence. We perform the study using two groups of samples from populations of the marine gastropod Littorina saxatilis: 1) a group of bimodal populations affected by ecological divergence, and 2) a group of unimodal populations. The results show that mating preference (unlike the trait affected by the preference) does not increase when two ecotypes meet and mate in sympatry, which suggests that mating preference must be controlled by strong stabilizing natural selection, and/or limited by mating cost. This would suggest that mating preference would rarely contribute to speciation under the face of gene flow in these ecotypes.

择偶偏好可作为生态适应的附带演化效应，并在特定情境下同时推动物种形成。然而，由于缺乏将经验参数与理论参数相联结的简便途径，相关理论预测始终难以通过实验验证。近期研究证实，r系数（r coefficient）及其他统计量可用于估算野生捕获交配对中的择偶偏好。本研究借助上述估算方法，检验在利于生态分化的情境中，择偶偏好是否会显著提升。研究以海洋腹足类粗纹滨螺（Littorina saxatilis）的两类种群样本开展实验：1）受生态分化影响的双峰种群；2）单峰种群。结果显示，当两种生态型（ecotype）在同域分布区域内相遇并交配时，择偶偏好（与其所调控的性状不同）并未出现显著提升，这提示择偶偏好可能受到强烈的稳定化自然选择调控，或受交配成本限制。这意味着在这类生态型中，即便存在基因流，择偶偏好也极少会促进物种形成。