Marginal posterior probability density for each of the population size ( θ , written as q in panel A), splitting time ( t ) and migration rates ( m ) parameters under a multi-population model (IMa2) for three major diploid species A. asiatica -2x, A. asplenifolia -2x and A. setacea -2x. In panel A & C, the number "0" stands for A. asiatica-2x, "1" for A. asplenifolia-2x, "2" for A. setacea-2x, "3" for the common ancestral population of A. asiatica-2x and A. asplenifolia-2x, and "4" for the ancestral population common to all three species. In panel B, t0 refers to the splitting time of A. asiatica-2x and A. asplenifolia-2x, and t1 represents the time when A. setacea-2x split from the ancestor of A. asplenifolia-2x and A. asiatica-2x. In panel C, " > " indicates direction of migrants, e.g., m0 > 1 refers to migration from 0 (A. asiatica) to 1 (A. asplenifolia). Each curve is the sum of 10 curves from the analysis of 10 independent MCMC simulations.