Systematics of the Tawny-Bellied Seedeater (Sporophila hypoxantha). I. Geographic Variation, Ecology, and Evolution of Vocalizations

Abstract. Geographically isolated populations diverging in vocalizations and habitat use are prime candidates for diversification along the speciation/differentiation continuum. The Tawny-bellied Seedeater (Sporophila hypoxantha) is relatively widespread, thus potentially variable across its range. We investigated geographic variation in vocalizations, habitat use, and migratory behavior, identifying five regiolects (song variants encompassing extensive subpopulations of a species and all individuals within this large range), which correspond with different patterns of habitat use but arose independently of migratory behavior. Given the low level of genetic divergence in the capuchinos, a subset of the genus Sporophila that includes S. hypoxantha, the phylogenetic potential for learning in the genus, the fast temporal changes evident within regiolects (chronolects), the existence of environmental sound assimilation, and the singing of subsongs by young males, we conclude that geographic variation is due m...