Data from: The evolution of sexual imprinting through reinforcement

Reinforcement is the process whereby assortative mating evolves due to selection against costly hybridization. Sexual imprinting could evolve as a mechanism of reinforcement, decreasing hybridization, or it could potentially increase hybridization in genetically purebred offspring of heterospecific social pairs. We use deterministic population genetic simulations to explore conditions under which sexual imprinting can evolve through reinforcement. We demonstrate that a sexual imprinting component of female preference can evolve as a one-allele assortative mating mechanism by reducing the risk of hybridization, and is generally effective at causing trait divergence. However, imprinting often evolve to be a component rather than the sole determinant of female preference. The evolution of imprinting has the unexpected side effect of homogenizing existing innate preferences, because the imprinted preference neutralizes any innate preference. We also find that the weight of the imprinting component may evolve to a lower value when migration and divergent selection are strong and the cost of hybridization is low; these conditions render hybridization adaptive for immigrant females because they can acquire locally adaptive genes by mating with local males. Together, these results suggest that sexual imprinting can itself evolve as part of the speciation process, and in doing so has the capacity to promote or retard divergence through complex interactions.

生殖强化（Reinforcement）是指通过对代价高昂的异种杂交（hybridization）进行选择，进而推动选型交配（assortative mating）演化的过程。性印记（sexual imprinting）既可能作为生殖强化的机制演化，以降低异种杂交的发生概率，也有可能在异种社会配对的遗传纯合后代中提升杂交风险。我们采用确定性种群遗传模拟（population genetic simulations），探究性印记可通过生殖强化完成演化的条件。研究表明，雌性偏好（female preference）中的性印记组分可作为单等位基因选型交配机制（one-allele assortative mating mechanism）演化，通过降低杂交风险发挥作用，且通常可有效促成性状分歧（trait divergence）。然而，性印记往往会演变为雌性偏好的组成部分，而非唯一决定因素。性印记的演化会带来一项意想不到的附带效应：它会抹平现有的先天偏好（innate preference），因为印记偏好会中和所有先天偏好。我们还发现，当迁移（migration）与歧化选择（divergent selection）强度较高、异种杂交成本较低时，性印记组分的权重可能会演化至更低水平；在这类条件下，迁入雌性（immigrant females）的异种杂交行为反而具备适应性，因为它们可通过与本地雄性交配获得本地适应性基因（locally adaptive genes）。综上，上述结果表明，性印记本身可作为物种形成（speciation）过程的一部分完成演化，并通过复杂的交互作用，兼具推动或延缓性状分歧的能力。