List of strains used in this study.

a<p>: Determined in previous studies <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002810#pgen.1002810-Lin1" target="_blank">[51]</a>, <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002810#pgen.1002810-Litvintseva1" target="_blank">[52]</a>, <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002810#pgen.1002810-Litvintseva2" target="_blank">[53]</a>.</p>b<p>: <i>ade2 ura5</i>; one of the two parental strains used in the laboratory cross.</p>c<p>: <i>ADE2 URA5</i>; one of the two parental strains used in the laboratory cross; also included in the population genetics analyses of natural isolates.