EAGER: Test for local adaptation of recombination rate

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Genetic recombination is fundamentally important to many genetic and evolutionary processes, including segregation, repair of double-strand breaks in DNA, removal of detrimental mutations, adaptation, and speciation. Prior research has shown that rates of gene recombination vary among individuals and populations, and are also modulated by temperature and other environmental factors in many species. Despite being the subject of over a hundred years of investigation, no study has tested the fundamental hypothesis of whether gene recombination rates exhibit adaptation to local environments. This project will examine variation in wild populations of the fruit fly, Drosophila pseudoobscura, and identify genomic regions undergoing rapid selection-driven evolution in recombination rates. This novel project is the first step in identifying the kind of natural selection that creates adaptation and species divergence in recombination rates. Additionally this project funds a partnership with a minority-serving high school and includes curriculum development to teach genetics in K-16 schools. This project builds on decades of research on wild populations of Drosophila pseudoobscura to provide a critical "first-look" at whether recombination rates have adapted to local populations and potentially open the door to testing the nature of such adaptation. The primary goal of the proposed research will be to contrast variation within and between several natural populations of D. pseudoobscura in nucleotide sequence vs. recombination rate when tested in a constant environment. Significantly higher differentiation among populations in recombination rate would suggest that this phenotype has adapted to local environments, whereas lower differentiation in recombination rate would demonstrate that there has been broad stabilizing selection in this trait across the species range. The secondary goal of the research will be to test whether rates exhibited in nature are sometimes initially maladaptive in particular populations as a result of environmental modulation, and adaptation occurs within populations to mitigate the maladaptive rates induced by plasticity to the environment. Such "genetic compensation" has been inferred for other traits, but never suggested or tested with respect to recombination, despite its ubiquitous importance in inheritance, adaptation, and speciation.