Fig. 2.

Demographic parameter estimates with 95% confidence intervals for four models of allopolyploid speciation in Capsella. Four models were investigated: stepwise population size change, no gene flow (A); stepwise population size change, asymmetrical gene flow (B); exponential population size change, no gene flow (C); and exponential population size change, asymmetrical gene flow (D). Model C was preferred based on Akaike’s information criterion (AIC) and Akaike’s weight of evidence (w). Estimates of the N_e for C. grandiflora (Cg), C. orientalis (Co), and C. bursa-pastoris [subgenome A (Cbp A) and subgenome B (Cbp B)] are given in thousands of individuals, and estimates of the timing of the origin of C. bursa-pastoris [T₁(Cbp)] and the split between C. grandiflora and C. orientalis [T₁(Cg-Co)] are given in thousand years before present (kya). Note that for models with exponential population size change, N_e corresponds to the current N_e. Confidence intervals are given in parentheses.