9623970 Langley Meiosis is the biological process in which a diploid organism produces haploid gametes (i.e. eggs or sperm). It is traditionally assumed that each chromosome of a given homologous pair has an equal probability of being transmitted into a gamete. Violations of this assumption in which certain chromosomes are transmitted more or less frequently are referred to as segregation distortion. Examples of segregation distortion are found in a wide variety of organisms and can profoundly influence the dynamics, levels and patterns of genetic variation in natural populations. Genes whose function is to ensure chromosome transmission through meiosis would seem to be ideal candidates to exhibit segregation distortion. Yet, for a variety of reasons, the study of this class of genetic loci has been neglected by population geneticists. The research funded by this award takes advantage of recent advances in the understanding of the genes and the mechanisms of meiosis in the model organism, Drosophila melanogaster, to address this the gap in our fundamental understanding of segregation distortion. In this project, variation in the fidelity of chromosome transmission through female meiosis for will be assessed for fifty African X chromosomes. This experiment is designed to detect deviations from the assumption of equal probability of transmission into gametes. A series of X-linked genes which act during meiosis will then be surveyed. Specific polymorphisms detected during this survey will be correlated with the observed variation in chromosome transmission. Finally, the effects of telomeres, centromeres and polymorphic candidate loci on a chromosome's "transmission phenotype" will be directly measured through a series of genetic assays. The mechanisms of segregation distortion revealed in this work are important to applied as well as theoretical genetics, impacting genetic engineering, gene therapy, and breeding programs to improve plant and animal resources.
