Fitness consequences of extra-pair fertilizations

Suny At Albany, Albany NY

Investigators

Abstract

A handicap to understanding how natural selection acts on mating choices by females has been the lack of information on the genetic parents of their young. We ask what genetic benefits, if any, females gain from mating with a male that is not the social mate. The term for this rather common behavior is extra-pair copulation (EPC). One hypothesis is that EPC offspring are genetically superior to other offspring. If so, then EPC offspring should be superior in survival to those of the social mate. Using DNA markers for a jay that lives in Arizona, we identify both genetic parents of each nestling in many broods. We then compare the survival and reproduction of EPC and nonEPC offspring from these broods. A second hypothesis to explain EPC is that females make mistakes that lead to inbreeding, with reduced survival of inbred offspring. A female's risk of complete failure for such reasons or male infertility can be reduced by mating with more than one male. We test the hypothesis that genetic similarity between mother and father assessed using genetic fingerprinting is associated with reduced survival and reproduction in offspring of the more similar parents. Survival and reproduction of each offspring are observed under natural conditions. By testing two popular hypotheses that explain female choice of males this research advances our understanding of the operation of how mating behavior and mating choice evolve. Our research also can help to understand the genetic risks encountered by some endangered species.