Figure 1
Three models of allopatric isolation. (A) Classic vicariance where a large ancestral population is broken up into two isolated sister populations. (B) Marine vicariance or "soft vicariance" where two ancestral populations with effective sizes (θ τ )1 and (θ τ )2 are connected by high to moderate gene flow (M 1 = 1.0 to 100.0 migrants per generation) until τ V , when M 1 decreases to 0.0 – 1.0 migrants per generation (M 2 ). (C) Isolation by colonization, where one of the sister populations is founded by a very small number of individuals (θ τ )2 that come from a larger source population (θ τ )1 at the time of colonization, τ C .