Kinship and fine-scale genetic structure in a cooperatively breeding bird, the Grayish Baywing (Agelaioides badius)

CAMPAGNA LEONARDO; LOVETTE IRBY; MAHLER BETTINA; DE MÁRSICO MARÍA CECILIA; ROJAS RIPARI JUAN MANUEL; REBOREDA JUAN CARLOS

Congreso; North American Ornithological Conference VII; 2020

Cooperative breeding is a reproductive system in which one or more adults (helpers) assist others in rearing their offspring. In birds, cooperative breeding occurs in 9% of species and it is associated to remarkable variation in mating systems and patterns of social organization. Determining the genetic relationships within and among social groups is a necessary step to understand the conditions under which helping behavior can evolve and be maintained. We used ddRAD sequencing to study the social organization and fine-scale genetic structure in a Neotropical facultative breeder, the Greyish Baywing (Agelaioides badius). During southern breeding seasons (Nov-Feb) 2015-2016, 2016-2017 and 2017-2018, we sampled blood from adults and nestlings at 33 nests in a population from eastern Argentina. Helpers were mostly males (90%, n = 21), and based on bioinformatics analyses of 523 SNPs, they were previous offspring of the breeding pair (5 males, 24%), first-order relatives of the breeding male (9 males, 43%), or they were unrelated to both breeders (5 males and 2 females, 33%). Helpers did not gain paternity/maternity in the nests where they assisted and we did not detect any clear genetic structure at fine spatial scale (i.e., kin neighborhoods) in the study population. The results suggest that cooperative breeding in Greyish Baywings occurs primarily within family groups and it could be driven by kin selection. However, the occurrence of unrelated helpers also suggests that non-reproductive direct benefits such as increased access to resources may influence helping behavior in this species.