THE GENETIC MATING SYSTEM OF A TROPICAL TANAGER

We describe the genetic mating system of Cherrie's Tanager (Ramphocelus costaricensis) in southwestern Costa Rica. Our data represent the first analysis of the genetic mating system of any member of the tanager family, Thraupidae. For 59 nestlings sampled from 32 broods over two years, the social mother was the genetic mother for all but two nestlings. These two unmatched nestlings were in the only brood we observed of four young, which is double the modal brood size. We identified social fathers for 55 nestlings from 31 broods. Of these young, 49% of the nestlings in 55% of the broods resulted from extra-pair matings. Our data on Cherrie's Tanager do not support the prediction that asynchronously breeding, tropical species will have low levels of extra-pair fertilizations and highlight the need for more genetic studies of tropical species.