Ecological and evolutionary genetics of Puffinus spp.

Three distinct molecular genetic techniques were applied at different levels in the evolutionary hierarchy to investigate the reproductive ecology, population biology and systematics of species in the shearwater genus Puffinus, with particular emphasis on the short-tailed shearwater, P. tenuirostris, or Tasmanian muttonbird. Genetic relationships between mated pairs of adult short-tailed shearwaters and the single offspring in the nest were analysed by multilocus DNA fingerprinting. The human polycore minisatellite probe, 33.6, revealed sufficient variation in shearwater DNA to allow individualspecific identification. In addition this probe hybridised to a large minisatellite restrictionfragment derived from the female W chromosome, which allowed the identification of sex of adults and nestlings in this sexually monomorphic species. Analysis of DNA fingerprint profiles from 107 nestlings and one or both of the attendant adults in each case, in two independent studies, revealed 13 cases where a nestling was not related to one of the attendant adults. Although four of these unrelated adults could be accounted for by sampling errors, the remaining nine cases all involved the male in each nest and were more likely to have resulted from extra-pair copulations involving the attendant female and an unknown, extra-pair male. These results suggest that although short-tailed shearwaters exhibit strong pair fidelity and social monogamy, some birds are engaging in an alternative mating strategy that may substantially enhance both male and female reproductive success. Future estimates of life-time reproductive success in this species will have to allow for the small percentage of paired males that are unrelated to the nestlings that they are providing care for.