that asymmetric dispersal links resulted in higher extinction risk. Another very recently published work investigates metapopulation viability for a selection of asymmetric dispersal patterns and supports the findings of previous works [@Vuilleumier10].

The main objective with this study is to isolate the effect of dispersal asymmetry from other properties of the metapopulation network. When changing the degree of symmetry of dispersal networks this generally may simultaneously influence the number of isolated patches and other aspects of the network such as the balance of dispersal in the individual patches [see e.g. Figure 4 in @Vuilleumier06]. Since metapopulations are known to be sensitive in particular to the density of the dispersal network [@Barabasi04Review], the existence of closed cycles of dispersal [@Armsworth02], and the hierarchy of dispersal in directed networks [@Bode08; @Artzy-Randrup10] these secondary implications could confound any effect of asymmetric dispersal. We resolve the problem by restricting our main analysis to *regular* networks.

In this paper we in particular analyse the effect of asymmetric dispersal on metapopulation persistence in more detail, with an initial focus on regular dispersal networks. We employ models of synthetic dispersal patterns and demonstrate that asymmetric dispersal per se may not lead to an increase in metapopulation extinction 