An Integrative Analysis of Gene Conversion

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Meiosis, the reductive division of the genome in preparation for fertilization, is a critical phase in the life-cycle of sexually reproducing organisms. During meiosis homologous chromosomes interact resulting in the heritable rearrangement of DNA, through reciprocal exchange between homologous chromosomes (crossing over, CO) or gene conversion (GC). In most eukaryotes these events ensure proper chromosome segregation, facilitate DNA repair and provide a basis for genetic diversity. Detailed models describing recombination mechanisms have been proposed and measurements of the frequency, and distribution of GC events can be used to test the accuracy of these models. Meiotic recombination also causes the breakdown linkage disequilibrium (LD), the non-random association of sets of alleles at linked loci, over evolutionary time which population geneticists use to better understand how species, their phenotypes, and their genomes evolve. Recent models suggest that GC may be as important as CO in breaking down LD in some genomic regions. The immediate goals of this project are to measure GC frequency at multiple loci in two distinct organisms, the plant Arabidopsis thaliana and the metazoan Drosophila melanogaster. The investigators will also make population genetic estimates of recombination at the same loci and compare these estimates with direct measurements of GC and CO in order to refine population genetic models of recombination and its effect on genome wide patterns of LD. The long-term goal of the project is to understand how meiotic recombination operates in multi-cellular organisms and how it influences genome variation and evolution. In addition to deepening our understanding of a classic genetic problem - gene conversion - this proposal also provides broader impact by building truly interdisciplinary collegial partnerships, creating a platform for participation by junior scientists from underrepresented groups and emphasizing graduate level education in the form of first-hand research and collaboration.