Fig. 1

Experimental design: 10 replicate populations were founded by 202 isofemale lines from a natural Drosophila simulans population collected in Florida and maintained at a constant population size (1250 flies) with non-overlapping generations in a hot environment (red) fluctuating between 18 and 28 °C on a 12/12 h cycle. At generation 110 four replicates of the evolved populations were used to generate imbalanced pairwise mixed populations (3 replicates for each combination) and maintained in the same hot environment (18°/28°C) for 29 generations (blue). Pool-Seq of the admixed populations at generation F1, F20 and F29 and the parental populations (at generation F110, F120, and F130) was used to estimate genome-wide allele frequencies