The stairwayplot showed a nearly similar dynamic for C. amblyrhynchos and C. limbatus, characterized by a strong ancestral expansion (Figure 3). When approaching T=0, both species underwent a bottleneck but of distinct strength. This is consistent with the shape of the normalized SFS, which clearly shows a stronger deficit in low frequency variants for C. limbatus compared to C. amblyrhynchos (Figure 3). Similarly to C. limbatus, C. melanopterus experienced a recent 10-fold population collapse around 20,000 years B.P. starting from a long term constant Ne. However, C. melanopterusshowed no signature of ancestral expansion, consistent to the results obtained by Maisano Delser et al. (2019) using abc-skyline method. Finally, G. cuvier displayed an ancestral expansion around 100,000 years B.P. with Ne reaching ~12,000 before dropping to ~3000 at T ~1,600 years B.P. Remarkably, the ancestral expansion retrieved by the stairwayplot(Figure 3) for both C. amblyrhynchos and C. limbatus overlap with the posterior distribution of TCOL estimated by the SST model (Table 1). This analogy holds too for C. melanopterus, where TCOL could not be properly estimated under the structured model (we obtained a flat posterior distribution, Figure 2) and there was no signature of ancestral expansion in the stairwayplot (Figure 3).