Meeting Abstract
In songbirds that hybridize, extrapair parentage may confound analysis of key fitness consequences such as hatching success if the species-level genotypes of extrapair parents differ from those of social parents. Our research on black-capped and Carolina chickadees in southeastern Pennsylvania has revealed rapid northward hybrid zone movement associated with climate change; hatching success has changed correspondingly, with fewer eggs hatching in populations experiencing interbreeding, but whether the patterns are obscured by extrapair parentage is unknown. Using eight species-diagnostic single nucleotide polymorphism (SNP) markers, we genotyped 54 breeders and 137 nestlings from 30 nests over 2 years in one hybrid-zone population (at Hawk Mountain Sanctuary) and conducted parentage analysis to identify extrapair offspring (EPO). At least 30% of nestlings had genotypes that could not be explained by those of their social parents and were therefore EPO, even though species-diagnostic SNPs yield low detection power. Therefore, extrapair mating does potentially confound analysis of hatching success at Hawk Mountain. Work in progress focuses on using these results to refine analysis of hatching success in this hybrid-zone population.
