A test of hybrid growth disadvantage in wild, free-ranging species pairs of threespine sticklebacks (Gasterosteus aculeatus) and its implications for ecological speciation

Ecological speciation is the evolution of reproductive isolation as a direct or indirect consequence of divergent natural selection. Reduced performance of hybrids in nature is thought to be an important process by which natural selection can favour the evolution of assortative mating and drive speciation. Benthic and limnetic sympatric species of threespine stickleback (Gasterosteus aculeatus) are adapted to alternative trophic niches (bottom browsing versus open water planktivory, respectively) and reduced feeding performance of hybrids is thought to have contributed to the evolution of reproductive isolation. We tested this “hybrid-disadvantage hypothesis” by inferring growth rates from otoliths sampled from wild, free-ranging benthic, limnetic, and hybrid sticklebacks from two lakes. There were significant differences in growth rate between lakes, life-history stages, and among years (maximum P = 0.02), as well as interactions between most factors, but not between hybrid and parenta...

生态物种形成（Ecological speciation）是指由歧化自然选择的直接或间接后果所驱动的生殖隔离演化过程。自然选择若要推动选型交配的演化并促成物种形成，野外环境中杂种生存适配度降低通常被认为是关键过程之一。三脊刺鱼（threespine stickleback，Gasterosteus aculeatus）的底栖与敞水同域物种，分别适应了两种截然不同的营养生态位：底栖啃食与敞水浮游生物食性，而杂种摄食能力下降被认为对生殖隔离的演化起到了推动作用。本研究通过对两个湖泊中野生自由活动的底栖型、敞水型及杂种三脊刺鱼的耳石样本进行分析以推断其生长速率，对这一“杂种劣势假说（hybrid-disadvantage hypothesis）”进行了验证。研究结果显示，不同湖泊、不同生活史阶段以及不同年份间的生长速率均存在显著差异（最大P=0.02），多数因子间也存在交互作用，但杂种与parenta...