Rapid speciation via the evolution of pre-mating isolation in the Ibera Seedeater

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 southern capuchino seedeaters, a recent, rapid radiation characterized by variation in male plumage coloration and song. Although these two species co-occur without obvious ecological barriers to reproduction, we document behaviors indicating species recognition by song and plumage traits and strong assortative mating associated with genomic regions underlying male plumage patterning. Plumage differentiation likely originated through the reassembly of standing genetic variation, indicating how novel sexual signals may quickly arise and maintain species boundaries.

Automated summary

Behavioral isolation can drive speciation by allowing the gradual accumulation of reproductive barriers between co-occurring organisms. In the case of two bird species within the southern capuchino seedeaters, behaviors indicating species recognition through song and plumage traits, as well as strong assortative mating related to genomic regions underlying male plumage patterning, suggest how novel sexual signals can quickly arise and maintain species boundaries.