Three demographic scenarios simulated by msABC. a Isolation model; b Early gene flow model; c Late gene flow model. Na: Effective population size of the most recent common ancestor. NBt: Effective population size of B. thoracicus. NBs: Effective population size of B. sonorivox. mBt: Migration rate from B. sonorivox to B. thoracicus. mBs: Migration rate from B. thoracicus to B. sonorivox. T1: Divergence time between B. thoracicus and B. sonorivox. T2: Time of gene flow disappearance. PP: Posterior probability of each model.