Genetic Parentage in Red-Winged Blackbirds: Tests of Alternative Reproductive Strategies

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This project seeks to test several hypotheses about the ecological factors affecting the genetic parentage of red-winged blackbirds (Agelaius phoeniceus). This work will improve our understanding of the process of evolution and the genetic structure of populations. Because in many animals, especially birds, individuals often mate outside the observed social bonds, the factors influencing genetic parentage will ultimately influence how evolution proceeds and which genes are represented within a population. Only the use of genetic markers can uncover the effects of such extra-bond matings. Previous genetic methods for analyzing parentage have not provided enough genetic information to completely analyze parentage. This study will expand on those previous methods by using a new technique, known as DNA fingerprinting, which can assay highly variable regions of the genome. These regions provide information sufficient to determine completely the parentage of every offspring. This study will combine behavioral observations of free- living redwings with these new genetic analyses of parentage to achieve several goals. First, the study will uncover the effects on genetic parentage of when a female breeds relative to other females. Second, the effects of male behavior on genetic parentage will be tested by increasing male presence on the territory through supplemental feeding and by decreasing male presence by temporary removals. Third, the genetic parentage of young raised on territories will be analyzed in light of the characteristics of territory location and quality. Fourth, the effects of female mating behavior on genetic parentage will be assessed by detailed observations of females and subsequent analysis of parentage. Finally, the impact of variation in genetic parentage on parental behavior and on the action of selection in natural populations will be documented. Upon completion, this study will provide information on a number of ecological factors that might affect genetic parentage. This information will be incorporated into general concepts about the ecology and evolution of reproductive and about the influence of such behavior on population structure.