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 precedence for sympatric males in competitive in vitro fertilization experiments, potentially owing 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 pre-zygotic 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进程中可发挥关键作用。当生物个体适应截然不同的生境时，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，但生态物种形成早期阶段的交配后生殖隔离演化机制仍不甚明晰。针对来自两个湖泊与两条河流的分化型三刺棘鱼（three-spined stickleback）生态型，我们观察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。有趣的是，在竞争性体外受精实验中，这类差异并未使同域雄性呈现出生态型特异性的配子竞争优势，这一现象可能源于拮抗补偿效应的作用。但我们观察到间接证据表明，跨生态型合子的发育受到阻碍，这或许暗示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的作用相对有限，但研究结果也表明，遗传不相容性可能在生态物种形成的早期阶段就已产生。