non-regular connectivity matrices we generated always extended to at least $99$ patches for densities above $7$ connections per patch with a strong trend towards $100$ patches with increasing density. For this reason we assume, that the effects described in [@Vuilleumier06] originate from differences in network topology between the investigated connectivity matrices rather than differences in dispersal asymmetry.

@Bode08 investigated the same metapopulation model as in the present work in a slightly different setup ($N=10$, $e=0.4$, and $L/N=2.6$). Instead of simulating individual realisations, the probability of metapopulations to go extinct within $100$ time steps was calculated numerically for different dispersal patterns. This method restricts the analysis to rather small metapopulations of $10$ patches. Extinction probabilities were calculated for metapopulations connected through different dispersal patterns generated by the small world algorithm [see e.g. @Watts98; @Kininmonth09] initiated with a particular symmetric dispersal pattern (Bode, pers.communication). @Bode08 concluded from qualitative graphical analysis of their simulation results[^2], that asymmetry reduces persistence and exhibits a distinct threat to metapopulations.

The discussion of our results in Section \[sec:discussion:interpret\] relates our graphical analysis to the extinction probability in a certain number of time steps[^3], which allows for a comparison of the results. From additional simulation data we received 