Data from: The contribution of post-copulatory mechanisms to incipient ecological speciation in sticklebacks

Ecology can play a major role in species diversification. As individuals are adapting to contrasting habitats, reproductive barriers may evolve at multiple levels. While pre-mating barriers have been extensively studied, the evolution of post-mating reproductive isolation during early stages of ecological speciation remains poorly understood. In diverging three-spined stickleback ecotypes from two lakes and two rivers, we observed differences in sperm traits between lake and river males. Interestingly, these differences did not translate into ecotype-specific gamete preference for sympatric males in competitive in vitro fertilization experiments, potentially due to antagonistic compensatory effects. However, we observed indirect evidence for impeded development of inter-ecotype zygotes, possibly suggesting an early stage of genetic incompatibility between ecotypes. Our results show that prezygotic post-copulatory mechanisms play a minor role during this first stage of ecotype divergence, but suggest that genetic incompatibilities may arise at early stages of ecological speciation.

生态学在物种多样化过程中可扮演核心角色。当个体适应迥异的栖息环境时，生殖隔离屏障可能在多个层面逐步演化。尽管交配前生殖隔离屏障已被广泛研究，但生态物种形成（ecological speciation）早期阶段的交配后生殖隔离演化机制仍有待深入解析。针对源自两个湖泊与两条河流的趋异三棘刺鱼（three-spined stickleback）生态型，我们观测到湖泊与河流种群的雄性个体在精子性状上存在显著差异。值得注意的是，此类差异并未在竞争性体外受精实验中催生针对同域雄性配子的生态型特异性偏好，这一结果可能由拮抗补偿效应所导致。然而，我们发现了生态型间合子发育受阻的间接证据，这或许表明不同生态型之间已出现早期遗传不相容性。本研究结果显示，在生态型分化的初始阶段，合子前交配后机制所起到的作用相对微弱，但同时提示遗传不相容性可能在生态物种形成的早期阶段便已形成。