The role of asymmetric dispersal in metapopulations

Metapopulations consist of a number of sub-populations connectedthrough the dispersal of migrants. In many theoretical approachesoften rather simple dispersal patterns are investigated, whiletypically complex dispersal patterns are observed in nature. Thisespecially is the case for larvae dispersal in marine environmentsdriven by ocean currents.In a recent work Vuilleumier and Possingham investigate the role ofsymmetry in dispersal patterns and draw the conclusion, thatasymmetric dispersal has a distinct negative impact on populationviability. Our results based on artificial dispersal patterns,however, suggest that symmetry actually only could have a vanishingimpact. The simulation results are in good agreement with tests onrealistic dispersal patterns of mussel larvae in the Baltic Sea.We demonstrate the importance of artificially generated dispersalpatterns for the disentanglement of the complexity intrinsic tonatural systems. Although many aspects of larvae dispersal might notyet have been understood we can draw the conclusion, that asymmetrymight not be as severe as expected by Vuilleumier and Possingham. Thatis of course good news for many systems of biological relevance.