SYSTEMATICS OF THE TAWNY-BELLIED SEEDEATER (SPOROPHILA HYPOXANTHA). I. GEOGRAPHIC VARIATION, ECOLOGY, AND EVOLUTION OF VOCALIZATIONS

ARETA JI; REPENNING M

THE CONDOR

COOPER ORNITHOLOGICAL SOC

Año: 2011 vol. 113 p. 664 - 677

0010-5422

Geographically isolated populations diverging in vocalizations and habitat use are prime candidates fordiversification 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 subpopulationsof a species and all individuals within this large range), which correspond with different patterns of habitat usebut arose independently of migratory behavior. Given the low level of genetic divergence in the capuchinos, a subset ofthe genus Sporophila that includes S. hypoxantha, the phylogenetic potential for learning in the genus, the fast temporalchanges evident within regiolects (chronolects), the existence of environmental sound assimilation, and the singingof subsongs by young males, we conclude that geographic variation is due mostly to learning, the genetic makeupof the various populations having little effect. The occurrence of allopatric habitat-related regiolects with little (if any)morphological differentiation, suggests that this constitutes a plausible step toward the evolution of new species in thecapuchinos. These results highlight the importance of habitat use and vocalizations in understanding the evolutionarydifferentiation and diversification of the seedeaters and suggest that their explosive radiation has been stronglyinfluenced by the interplay of habitat choice, migratory behavior, and vocal differentiation.