Figure 4.
Competing demographic scenarios of Psittacanthus calyculatus divergence. Five evolutionary scenarios were built and tested using DIYABC: (A) simple split model (scenario 1), in which CALY (Pop1), HYBR (Pop2) and SCHI (Pop3) diverged simultaneously at t1; (B) isolation with admixture model (scenario 2), in which Pop2 (HYBR) was generated by admixture between Pops 1 (CALY) and 3 (SCHI) at t1, then CALY merged with SCHI at t2; (C) hierarchical split model 1 (scenario 3), in which HYBR merged with CALY at t1, then both populations merged with SCHI at t2; (D) hierarchical split model 2 (scenario 4), in which HYBR merged with SCHI at t1, then both populations merged with CALY at t2; (E) hierarchical split model 3 (scenario 5), in which CALY merged with SCHI at t1, then both populations merged with HYBR at t2. The posterior probability of scenarios was assessed using a weighted logistic regression on the 1% of simulated datasets closest to the observed data and, for the best-supported scenario (scenario 2); (F) Results of a logistical model comparing the posterior probability of each scenario with the number of simulations used to calculate it; (G) A model checking procedure was applied using a PCA on test statistic vectors to visualize the fit between the simulated and observed datasets. Note the large cloud of data from the prior and observed datasets centred on a small cluster from the posterior predictive distribution, suggesting that the best-supported scenario explained the observed data well. Prior and posterior probabilities of parameters t1 (H) and ra (=admixture rate) are provided (I).