Evidence of extra-pair paternity in the Tawny-bellied Seedeater (Sporophila hypoxantha)

FACCHINETTI, C.; DI GIACOMO, A. G.; CAMPAGNA, L.; MAHLER, B.; REBOREDA, J.C.

Lund

Congreso; 14th International Behavioral Ecology Congress; 2012

Many studies in the last 30 years have shown that most socially monogamous passerine species are not genetically monogamous and actually obtain extra-pair fertilizations (EPF). The majority of these studies have been conducted on Paleartic and Neartic temperate birds with only a few Neotropical species examined, which interestingly, have relatively low levels of extra pair paternity. The tawny-bellied seedeater (Sporophila hypoxantha) is a sexually dichromatic and socially monogamous passerine that inhabits grassy open and semi-open habitats in Bolivia, Brazil, Paraguay, Uruguay and Argentina. We analyzed the genetic parentage of seedeaters in a population of NE Argentina. We assessed the genotype of 44 nestlings, 16 mothers and 18 putative fathers from 20 nests using four DNA microsatellite loci. According to male assignation to nests, we found that the frequency of extra-pair nestlings ranged between 13% and 44% in 25-50% of the broods. We also tested whether the sex ratio in broods with extra-pair paternity was more male-biased than in broods without extra-pair paternity. We found no differences in sex ratio between broods with and without extra-pair paternity. Our results show that Tawny-bellied Seedeaters are socially but not genetically monogamous and that the frequency of extra-pair paternity in this species is similar to the one of other dichromatic passerines