Figure 9.

Amount of southern immigrant alleles received by a northern population over generations. Absolute number of immigrant alleles into a population located at the extreme northern latitude (+0.5 dotted circle in Figure 1) and coming from southern latitudes (-0.5 to -0.1). Only gene flow between populations is represented here. Numbers on the y-axis are counts of alleles at a given generation (x-axis). Counts of alleles were monitored at three strengths of assortative mating and three levels of environmental cline. All simulations were conducted under the island migration model with moderate gene flow (Nm = 5.1). The red lines indicate strong assortative mating (ρ = 0.8), the blue line indicates moderate assortative mating (ρ = 0.3), the black line random mating (ρ  = 0), and the purple line strong assortative mating under an extreme environmental cline (ρ = 0.8, k_E = 3). Lines are mean values of 50 replicates for each evolutionary scenario.