CAREER/RUI: Genetic Basis of Sperm Precedence and Sex-Specific Fitness in Fruit Flies

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9734008 Hughes This project builds upon previous research indicating that genetic variation for male fertility in Drosophila melanogaster is due to one or a few major-effect genes on the third chromosome. Other fitness traits in fruit flies (female fecundity, male mating success, larval viability) seem to be affected by variation at many genes of small or moderate effect, so male fertility is unusual in its genetic determination. An experiment will be conducted to map genes affecting male fertility to specific locations on the chromosome. It is expected that this mapping will eventually lead to the identification of genes causing variation in the trait. Measurement of specific properties of these genes (e.g., average effect, dominance and epistasis) will provide explicit tests of models of the causes of variation. Another experiment involves measuring genetic and environmental contributions to variation for sex-specific fitness. One of the goals of this experiment is to determine whether genes that have beneficial effects on one sex, but deleterious effects on the other (sexually-antagonistic effects) are involved in the maintenance of genetic variation within populations. The second primary emphasis of this project is educational. Undergraduate students will be involved in every phase of the research effort. In addition, new courses and course modules that exploit molecular genetic techniques will be introduced into the undergraduate curriculum. Populations of organisms, including humans, are genetically diverse for traits related to reproduction, developmental rate, lifespan, and disease resistance. Because they largely determine the lifetime reproductive output of an organism, these life-history traits should be subject to very strong forces that eliminate variation. Yet most populations retain substantial variation for these traits. One of the main goals of population genetics is to gain an understanding of the forces responsible for maintaining this variat ion. Genetic diversity can have a direct impact on human health and longevity (when it occurs in humans or in human pathogens), on the productivity of agricultural systems (when it occurs in agriculturally important species), and on the risks of extinction for threatened and endangered species (when it occurs in these species, their pathogens, or their competitors). This proposal describes two related projects designed to investigate the genetic basis of life-history traits, and to test specific theoretical models of the maintenance of genetic diversity. The educational emphasis of this project is focused on undergraduate researchers, and the introduction of new molecular techniques into the classroom.