Figure 1.

Spatial settings of populations, environmental and selection gradients. Fifty-five populations of 500 individuals each were spread homogeneously on a 5 × 11 grid along 11 latitudinal positions. E represents the environmental effect at a given latitude (see Soularue and Kremer (2012) for more details). Co- and countergradient divergent selection were mimicked by assigning different Z_opt values at different latitudes. In the cogradient case, Z_opt values are positively correlated to latitudes, as the E values. In countergradient settings, Z_opt values are negatively correlated to latitudes, and hence are negatively correlated to the E values. Both examples correspond to k_E=2 and to . We considered mostly cases with ω²=50 and , some cases were explored with ω²=5 or . Finally, uniform selection was simulated with .