In species with low Nm, the rate of coalescence during the scattering phase is very fast since lineages have low probability of emigrating from the sampled deme and high probability of coalescence due to the small N. Once all the lineages are dispersed in the array of demes, there will be two possible outcomes: i) in equilibrium model, we shift to the collecting phase, where the rate of coalescence drops since lineages will hardly fall in the same deme again; ii) in non-equilibrium model, with the parameters we have simulated here, there will be very few (if any) coalescence events during the collecting phase and the transition will be directly from the scattering to the ancestral phase. Both the collecting and the ancestral phases have a rate of coalescence lower than the scattering phase, which determines the observed recent drop in Ne for all simulated scenarios. Remarkably, the decline in Ne is much stronger in equilibrium model, since the rate of coalescence is much lower in the collecting than in the ancestral phase (Figures 4, 5, S1, S2 and S3). Low Nm species will therefore have only two coalescence phases, the scattering and either the collecting (in equilibrium model) or the ancestral (in non-equilibrium model) which is why the signature of the ancestral expansion is lost.