Recombination during meiosis serves multiple biological roles. Recombination diversifies genomes by shuffling combinations of mutations, thereby increasing genetic variation and enhancing the efficiency of natural selection. In many species, recombination also ensures that chromosomes segregate properly during gametogenesis. Although these roles should impose strong selective constraints on recombination, recombination rate varies among individuals. This unexpected result raises a major unanswered question: what processes govern variation in recombination rate in nature? Importantly, we still lack a basic picture of how the heritable component of recombination rate varies within and between species ? information that is required for understanding how any phenotype evolves. Two clues about potential determinants of natural variation come from recent studies targeting recombination mechanisms. First, the two sexes present contrasting recombination landscapes and meiotic constraints, raising the prediction that males and females will display discordant patterns of inter-individual variation. Second, there is new evidence that the number of DNA double-strand breaks and the proportion of breaks repaired as crossovers also show differences among individuals, suggesting that these traits could explain natural variation in recombination rate. The proposed research will provide a much-needed portrait of natural genetic variation in recombination rate across multiple evolutionary scales. The contributions of sex and key meiotic processes to variation in recombination rate among individuals will be evaluated.
In Aim 1, we will measure polymorphism and divergence in the genome-wide recombination rate during oogenesis and spermatogenesis by applying immunofluorescence cytology to individual mice. Sex-specific, genetic variation in the total number of crossovers will be quantified on geographically global and local scales using a panel of house mice and their relatives. The prediction that recombination rate experiences distinctive evolutionary pressures in the two sexes will be tested through controlled comparisons between females and males across common genomic backgrounds.
In Aim 2, we will use immunofluorescence cytology to profile natural genetic variation in molecular processes that lead to crossovers, including the generation of double-strand breaks, the regulation of recombination intermediates, and the assembly of the synaptonemal complex. By linking these traits to the total number of crossovers in the same set of strains, we will test the hypothesis that the decision between crossover and non-crossover repair is a primary factor in recombination rate evolution. Defects in recombination are a leading cause of fetal loss and a leading genetic cause of developmental disabilities in humans. By examining heritable variation in recombination rate and its potential determinants in natural populations of the house mouse ? a model organism for recombination-related disorders ? this project is relevant to human health.

Public Health Relevance

Defects in recombination ? the physical exchange of DNA during the generation of sperm and eggs ? are a leading cause of spontaneous miscarriage and a leading genetic cause of developmental disabilities. This project will describe how the rate of recombination varies among individuals and will identify determinants of this variation.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM120051-04
Application #
9896869
Study Section
Genetic Variation and Evolution Study Section (GVE)
Program Officer
Janes, Daniel E
Project Start
2017-05-15
Project End
2021-03-31
Budget Start
2020-04-01
Budget End
2021-03-31
Support Year
4
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Wisconsin Madison
Department
Genetics
Type
Schools of Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Schwahn, Denise J; Wang, Richard J; White, Michael A et al. (2018) Genetic Dissection of Hybrid Male Sterility Across Stages of Spermatogenesis. Genetics 210:1453-1465
Hvala, John A; Frayer, Megan E; Payseur, Bret A (2018) Signatures of hybridization and speciation in genomic patterns of ancestry. Evolution :
Dapper, Amy L; Payseur, Bret A (2018) Effects of Demographic History on the Detection of Recombination Hotspots from Linkage Disequilibrium. Mol Biol Evol 35:335-353
Wang, Richard J; Gray, Melissa M; Parmenter, Michelle D et al. (2017) Recombination rate variation in mice from an isolated island. Mol Ecol 26:457-470
Dapper, Amy L; Payseur, Bret A (2017) Connecting theory and data to understand recombination rate evolution. Philos Trans R Soc Lond B Biol Sci 372:
Wang, Richard J; Payseur, Bret A (2017) Genetics of Genome-Wide Recombination Rate Evolution in Mice from an Isolated Island. Genetics 206:1841-1852