The recombination landscape of introgression in yeast
In this study, we look at patterns of recombination and introgression at the population level by crossing two pairs of Holarctic Saccharomyces uvarum strains. One pair of strains was isolated from natural environments in North America and the other pair was isolated from European fermentation environments (Almeida et al., 2014). The S. uvarum strains isolated from European fermentation environments each carry introgression from their sister species, Saccharomyces eubayanus, which is approximately 6% divergent from S. uvarum (Almeida et al., 2014; Langdon et al., 2020; Nespolo et al., 2020). The diploid F1 genome of these strains is heterozygous for nine different introgressions which make up approximately 10% of the genome (Figure 1B). The strains from the North American cross do not carry S. eubayanus introgression, thus allowing us to assess the impact of introgression on the recombination landscape. We obtained whole genome sequencing data from individual meiotic events from the first offspring generation of each cross and used this data to detect CO and NCO events along the genome (Figure 1A). From these maps, we aim to understand (i) how patterns of CO and NCO differ between closely related strains, (ii) how regions of introgression differ in their CO and NCO patterns, and (iii) how these different patterns affect shuffling of alleles locally and at the chromosome level. Understanding these objectives will provide us novel insights into how introgression impacts the recombination landscape.