Figure 3.
Speciation models and estimated divergence times. (a) The single isolation-mixing (SIM) model, equivalent to conventional allopatry. Divergence times under SIM should be relatively uniform across loci. (b) Estimated divergence time between the East and West populations (Tmin) under the SIM model. The shades in the background correspond to cycles of isolation and migration depicted in (c). Note that, in four of the five species, the divergence spans multiple cycles. (c) The mixing-isolation-mixing (MIM) cycles model in which the cycles correspond to the geographical record of potential gene flow (Fig. 1b). Under the MIM model, the level of divergence would vary from locus to locus, depending on when migration happened.