The evolution and genetic basis of species differences in meiotic recombination rate

The rate of recombination is a key parameter in genetics and evolution. Recombination shapes genomic patterns of DNA diversity, controls the fates of new mutations in populations, determines the resolution of genetic mapping experiments, and ensures the orderly segregation of homologous chromosomes at meiosis. Despite its biological significance, recombination rates vary markedly among individuals, between populations, and across species. This variation is evident over a range of physical scales of measurement, including single recombination hotspots and entire genomes. Although the mechanisms of recombination hotspot evolution have begun to unravel, the evolution and genetic basis of megabase and genome scale recombination rate remain poorly understood.;In this thesis, I characterize evolutionary variation in broad and genome scale recombination rate among mammals, focusing on house mice belonging to the Mus musculus species complex. I use existing genetic linkage maps and leverage powerful cytological methods to estimate the rate of recombination across whole genomes. I construct genetic linkage maps from experimental mapping populations to assess patterns of broad scale recombination rate variation I show that more closely related mammalian species have more similar genomic recombination rates. However, this phylogenetic pattern disappears when closely related murid rodent taxa are examined, hinting at temporal scale sensitive processes of genomic recombination rate evolution. Closely related subspecies of house mice provide an especially exemplary case of rapid recombination rate evolution. Two subspecies, M. m. castaneus and M. m. musculus differ in their global recombination rate by ∼30% and display significant differences in genetic map length across orthologous genomic intervals, pointing to variation in megabase-scale recombination rates. To identify the genetic basis of the rapid phenotypic divergence between M. m. castaneus and M. m. musculus, I use a quantitative trait locus mapping approach in an experimental inter-subspecific F2 mapping population. I identify 8 QTL for genomic recombination rate, including a large effect X-linked locus. Taken together, the work described in this thesis provides a refined picture of evolutionary variation in genomic recombination rate over several scales of divergence and provides an initial portrait of the genetic architecture of this important quantitative trait.