Fitness of incompatible relative to compatible strains following competition.

Independent cultures of compatible (kMLH1-kPMS1, EAY3242) and incompatible (cMLH1-kPMS1, EAY3236) strains were grown for the indicated number of transfers in YPD + 1.2 M NaCl. Fitness values were separately determined after competition experiments in which evolved cultures were randomly mixed at a 1:1 ratio and grown for an additional 24 hours in YPD or YPD + 1.2 M NaCl (see examples of the raw data in S2 Fig). Fitness (w) [34,35] was calculated as w = ((pt/qt)/(po/qo))1/t, where t equals the number of generations after 24 hrs of competition (7 generations), po and qo are the number of incompatible and compatible cells, respectively at 0 hrs, and pt and qt are the number of incompatible and compatible cells, respectively, at 24 hrs. n is the number of unique competitions performed for each data set. One-way ANOVA [36] was used to test whether mean fitness values are different in YPD + 1.2M NaCl vs. YPD.
Fitness of incompatible relative to compatible strains following competition.