Rapid speciation via the evolution of pre-mating isolation

Behavioral isolation can catalyze speciation and permit the slow accumulation of additional reproductive barriers between co-occurring organisms. We illustrate how this process occurs by examining the genomic and behavioral bases of pre-mating isolation between two bird species (Sporophila hypoxantha and the recently discovered S. iberaensis) that belong to the capuchino seedeaters, a recent, rapid radiation characterized by variation in male plumage coloration and song. Though these two species co-occur without ecological barriers to reproduction, we document strong assortative mating and behaviorally-mediated species recognition associated with genomic regions underlying male plumage patterning. Plumage differentiation originated through the reassembly of standing genetic variation, indicating how novel sexual signals can quickly arise and maintain species boundaries.行为隔离（behavioral isolation）可推动物种形成，促使同域分布生物间逐步积累额外的生殖隔离屏障。本研究通过剖析两种食籽雀类鸟类（Sporophila hypoxantha与新近发现的S. iberaensis）的交配前隔离（pre-mating isolation）的基因组与行为基础，阐释了该过程的发生机制；这两个物种均隶属于头巾食籽雀类（capuchino seedeaters）——一个以雄鸟羽色与鸣唱多样性为典型特征的近期快速辐射演化类群。尽管二者同域分布且不存在生殖相关的生态屏障，本研究仍记录到强烈的正选型交配（assortative mating）现象，以及与调控雄鸟羽色模式的基因组区域相关的、由行为介导的物种识别机制。羽色分化源自现存遗传变异（standing genetic variation）的重新组合，这揭示了新型性信号如何快速产生并维系物种界限。