View Program - 2022 Population, Evolutionary, and Quantitative Genetics Conference

A central goal of evolutionary genetics research is understanding the influence of biotic and abiotic processes on genetic variation in natural populations. While previous work has found extensive variation in the degree of recombination rate plasticity between chromosomal regions, a genome-wide survey of this phenomenon is lacking. Here, we have used a classic genetic crossing scheme to conduct a large-scale backcross between wild type strains with multiple replicates reared at control and heat stress temperatures (21°C and 26°C, respectively). We then isolated DNA and performed low coverage (~0.8x) whole-genome sequencing of a pilot set of 38 F₁ female parents and 730 progeny using plexWell384 kits. We used data from the F₁ parents to validate our predicted set of ancestry informative markers. We then used the software ancestryinfer to map reads and identify crossover locations between the two parental genomes in each of the progeny. These results guided the construction of genetic maps in each experimental condition for a fine-scale comparison of recombination rates. Our goal is to identify regions of the chromosome that are more sensitive to these short-term changes in recombination due to heat stress. While the majority of plasticity studies show an increase in recombination in response to stress, this result is not consistent. Therefore, these data will provide insight into how chromosomal features might correspond to specific directional changes in recombination. In concert, we have conducted a thorough re-analysis of 24 published recombination maps of the target species, Drosophila pseudoobscura, and close relatives to identify regions of the chromosome that are more sensitive to long-term changes in recombination rate. By comparing these short-term and long-term chromosomal regions that are sensitive to recombination rate changes, our work will determine the role of the environment in driving recombination differences within- and between-species. Moreover, because recombination rates often correlate with population genetic signatures of diversity and divergence, our comprehensive portrait of genome-wide recombination plasticity will inform population genetic studies aimed at explaining the heterogenous genome landscape.

Genome-wide recombination rate plasticity in response to heat stress in Drosophila pseudoobscura