Causes of Y-Chromosome Degeneration

University Of Iowa, Iowa City IA

Investigators

Abstract

0075295 McAllister A morphologically and functionally distinct pair of sex chromosomes provides a basis for gender determination in many organisms. One chromosome (X) is shared between the two genders, and contains a normal set of functional genes; the other (Y) is restricted to one gender, and has few genes. These differences arise through a repeatable evolutionary process, because pairs of sex chromosomes have arisen multiple times from pairs of identical chromosomes (autosomes), a transition that has been demonstrated for the X-Y pair in humans. This project involves molecular and genetic analyses of Drosophila americana americana, a species with a chromosomal rearrangement that has recently transformed a pair of its autosomes into neo-sex chromosomes. The long-term objective of the study is to reveal the forces influencing loss of gene function on the male-limited neo-Y chromosome of D. a. americana. Studies will characterize the pattern of sequence variation in the region adjacent to the centromere of these neo-sex chromosomes, because this region is subjected to a gradient of restricted recombination. These data will lead to a better understanding of the relationship between recombination and the forces of mutation, selection and genetic drift. The study of Y chromosomes provides a model system for demonstrating the consequences of restricted recombination, which has implications for understanding factors influencing asexual reproduction and evolution within closely-linked regions of the genome.