Reinforcement shapes clines in female mate discrimination in Drosophila subquinaria

Reinforcement of species boundaries may alter mate recognition in a way that also affects patterns of mate preference among conspecific populations. In the fly Drosophila subquinaria, females sympatric with the closely related species D. recens reject mating with heterospecific males as well as with conspecific males from allopatric populations. Here we assess geographic variation in behavioral isolation within and among populations of D. subquinaria and use cline theory to understand patterns of selection on reinforced discrimination and its consequences for sexual isolation within species. We find that selection has fixed rejection of D. recens males in sympatry, while significant genetic variation in this behavior occurs within allopatric populations. In conspecific matings sexual isolation is also asymmetric, and stronger in populations that are sympatric with D. recens. The clines in behavioral discrimination within and between species are similar in shape and are maintained by str...生殖强化（Reinforcement）对物种边界的强化作用，可能会改变配偶识别机制，进而影响同种种群间的配偶偏好模式。在亚奎果蝇（Drosophila subquinaria）中，与近缘物种recens果蝇（D. recens）同域分布的雌性个体，会拒绝与异种雄性交配，同时也会拒绝来自异域种群的同种种群雄性。本研究针对亚奎果蝇种群内部及种群间的行为隔离地理变异展开评估，并借助渐变群理论（cline theory）解析强化配偶识别的选择模式及其对物种种内性隔离的影响。研究发现，自然选择已使同域种群固定了对recens果蝇雄性的拒交行为，而在异域种群中，该行为存在显著的遗传变异。在同物种交配场景下，性隔离同样表现出不对称性，且在与recens果蝇同域分布的种群中，性隔离强度更高。物种种内及种间的行为识别渐变群在形态上相似，且由str...维持。