Gender-Specific Fitness and Intersexual Developmental Conflict in a Fruit Fly (Drosophila) Model System

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This research investigates a process by which natural selection can lead to gender-specific dysfunction. Males and females need to accomplish different biological functions, yet nearly 90% of the genome is expressed in both sexes. In a recent pilot experiment the entire genome of the common fruit fly (Drosophila melanogaster) was cloned and then identical copies of the same genomes were expressed in both males and females. Genomes that produced the highest Darwinian fitness in females produced low fitness in males, and visa versa. This intersexual reversal suggests that genes that are favored in one sex and disfavored in the other sex are common in the genome of the fruit fly. Because all animals express many of the same genes, the observed intersexual genetic conflict may be widespread. In the proposed research cytogenetic cloning will be used to measure: i) the functional significance of sexually antagonistic genetic variation, ii) its distribution among chromosomes, iii) its transmission dynamics between generations, and iv) the traits that mediate intersexual genetic conflict. The experiments are relevant to hereditary factors that mediate gender-specific impairment (e.g., sterility). In the past it has been assumed that harmful genetic variation was maintained solely by recurrent mutation or genetic drift. This research evaluates a new source for the genetic polymorphisms that are responsible for gender-specific dysfunction.