Fig. 7.

The root-variance over M(t) initialised at the unstable equilibrium M_* value (left panel) and at the stable equilibrium M_* value (right panel), plotted as a function of time, and numerically obtained by summing over 10³ realisations of Eq. (40) using the non-Markovian (solid coloured lines) and Markovian (dotted coloured lines) migration processes given by Eqs. (36) and (37), respectively. The dashed coloured lines correspond to the analytic Markovian solution given in Eq. (41).