Figure 2. Different scenario of divergence between L. planeri and L. fluviatilis.

Five models with different parameters are tested and compared. Two null models: stict Isolation (SI) and Panmixia (PAN). Three models of migration: isolation with constant migration (IM), ancient migration (AM) and secondary contact (SC). The following parameters are shared by all models: τ_div : number of generations since divergence time. θ_A, θ_Lf, θ_Lp: effective population size of the ancestral population, of L. fluviatilis and L. planeri respectively. τ_isol is the number of generations since the two ecotypes have stopped exchanging genes. τ_sc is the number of generations since the two ecotypes have entered into a secondary contact after a period of isolation. M₁₂ and M₂₁ represent the number of migrants expressed in 4.Nm units per generation with m the proportion of population made of migrants from the other populations.