Reinforcement can occur when maladaptive hybridization in sympatry favors the evolution of conspecific preferences and target traits that promote behavioral isolation. In many systems, enhanced behavioral isolation is due to increased female preference for conspecifics. In others, behavioral isolation is driven by male preference, and in other systems both sexes exert preferences. Some of these patterns can be attributed to classic sex-specific costs and benefits of preference. Alternatively, sex differences in conspecific preference can emerge due to asymmetric post-zygotic isolation (e.g., hybrid offspring from female A × male B have lower fitness than hybrid offspring from female B × male A), which can lead to asymmetric behavioral isolation (e.g., female A and male B are less likely to mate than female B and male A). Understanding reinforcement requires understanding how conspecific preferences evolve in sympatry. Yet, estimating conspecific preferences can be difficult when both sexes are choosy. In this study, we use Lucania killifish to test the hypothesis that patterns of reinforcement are driven by asymmetric post-zygotic isolation between species. If true, we predicted that sympatric female L. goodei and sympatric male L. parva should have lower levels of behavioral isolation compared to their sympatric counterparts, as they produce hybrid offspring with the highest fitness. To address the problem of measuring behavioral isolation when both sexes are choosy, we inferred the contribution to behavioral isolation of each partner using assays where one sex in the mating pair comes from an allopatric population with potentially low preference, while the other comes from a sympatric population with high preference. For one hybrid cross direction, we found that both female L. parva and male L. goodei have high contributions to behavioral isolation in sympatry. In the other hybrid cross direction, we found that only female L. goodei contribute to behavioral isolation. Sympatric male L. parva readily engaged in hybrid spawnings with allopatric L. goodei females. These results indicate that both asymmetric post-zygotic isolation and the traditional sex-specific costs to preference likely affect the nature of selection on conspecific preferences and target traits.

中文翻译：

---

卢卡尼亚kill鱼的不对称增强：两性选择时评估生殖隔离

当适应障碍中的适应不良杂交有利于特定的偏好和目标性状的进化，从而促进行为隔离时，就会发生强化。在许多系统中，增强的行为隔离是由于女性对特定物种的偏好增加。在另一些情况下，行为隔离是由男性的偏好驱动的，而在其他系统中，两性都发挥了偏好。这些模式中的某些可以归因于经典的针对特定性别的成本和偏好收益。或者，由于不对称的合子后隔离（例如，雌性A×雄性B的杂种后代的适应性低于雌性B×雄性A的杂种后代），会出现同种异性的性别差异，这可能导致行为不对称（例如，女性A和男性B的交配可能性要小于女性B和男性A）。理解强化需要理解特定的偏好在交联中如何演变。然而，当两性都挑剔时，估计特定偏好会很困难。在这项研究中，我们使用Lucania ania鱼检验了以下假设：强化模式是由物种之间的不对称合子后分离驱动的。如果为真，我们预测与同胞同龄人相比，同胞雌性古德氏菌和同胞雄性帕尔瓦氏菌应该具有较低的行为隔离水平，因为它们产生具有最高适应性的杂交后代。为了解决在两性都选择的情况下衡量行为隔离的问题，我们使用以下分析推论出每个伴侣对行为隔离的贡献：在交配对中，一种性别来自可能具有较低偏好的异源种群，另一种来自同胞高度优先的人口。对于一个混合横向，我们发现两个女性L.鹟和男性L. goodei在同域对行为隔离作出的重大贡献。在另一个杂种交叉方向上，我们发现只有雌性古德酵母有助于行为隔离。同域公L.麦穗鱼容易从事与异地杂交spawnings L. goodei女性。这些结果表明，不对称的合子后隔离和传统的针对性别的偏好成本都可能影响针对特定偏好和目标性状的选择的性质。