Multi-locus DNA fingerprinting supports genetic monogamy in Florida scrub-jays

Extensive behavioural and pedigree data on a colour-marked population of Fl orida scrub-jays (Aphelocoma coerulescens) suggested that this cooperativel y breeding species is monogamous, with extremely rare exceptions in which m ales have two mates. We used multi-locus DNA fingerprinting to test these o bservations by determining genetic parentage. Despite restricted dispersal and high relatedness between behavioural parents and non-breeding members o f the group, DNA fingerprints provided sufficient variability to determine parentage unambiguously in almost all cases. We found no evidence of extra- pair fertilisation of females or egg dumping, and confirmed a suspected cas e of polygyny in which a mother and daughter laid and incubated in the same nest. Our results confirm that detailed behavioural data allow accurate as signment of genetic parentage in this species. In Florida scrub-jays, large territory size may limit opportunities for cuckoldry, and persistent inten se competition for limited breeding space may lead to low variance in the q uality of established male breeders. These factors would reduce both the op portunity for, and benefits of engaging in extra-pair fertilisations. Delay ed dispersal and cooperative breeding in this species have not evolved as a venues for direct reproduction by unpaired individuals.