Social and genetic mating system of a Neotropical cooperative breeder, the Baywing (Agelaioides badius).

CYNTHIA A. URSINO; CHRISTINA RIEHL; M.C. DE MÁRSICO; JUAN C. REBOREDA

Alaska

Congreso; 52th Animal Behavior Society Conference; 2015

Animal Behavior Society

Social and genetic mating system of a Neotropical cooperative breeder, the Baywing (Agelaioides badius). Cynthia Ursino, Christina Riehl, María Cecilia De Mársico and Juan Carlos Reboreda Cooperatively breeding birds show a multiplicity of mating systems, ranging from genetic monogamy to complex patterns of joint-nesting and shared paternity within cooperative groups. Determining the extent of reproductive sharing is necessary to understand the relative importance of direct and indirect components of inclusive fitness in driving helping behaviour. We investigated the mating system of the Baywing (Agelaioides badius), a Neotropical facultative cooperative breeder, using behavioral observations and microsatellite genotyping. In our study population in eastern Argentina, 40% of baywing nests have 1 to 6 helpers that join the breeding pair after the eggs hatched, and the number of helpers often increases after fledging. These observations suggest that helpers do not share paternity with the dominant breeding pair and therefore, Baywings are genetically monogamous. To test this idea, we assessed the genotype of 140 nestlings, 16 putative mothers and 15 putative fathers from 36 nests using eight DNA microsatellite loci. Our findings show that putative mother is the genetic nestling mother and that extra-pair nestlings are rare in the broods (8%). The results support the hypothesis that Baywings are socially and genetically monogamous and suggest that helping behavior in this species is maintained by selective forces other than direct breeding opportunities.