On the impact of dispersal asymmetry on metapopulation persistence

TL;DR

This study systematically investigates how dispersal asymmetry affects metapopulation persistence, revealing that asymmetry alone does not necessarily harm persistence and should be considered alongside other dispersal properties.

Contribution

It provides a detailed analysis disentangling dispersal symmetry from other factors, challenging previous assumptions about negative effects of asymmetry.

Findings

Asymmetry alone does not negatively impact persistence.

Dispersal symmetry should be studied in context with other dispersal properties.

Previous studies may have confounded effects of asymmetry with other factors.

Abstract

Metapopulation theory for a long time has assumed dispersal to be symmetric, i.e. patches are connected through migrants dispersing bi-directionally without a preferred direction. However, for natural populations symmetry is often broken, e.g. for species in the marine environment dispersing through the transport of pelagic larvae with ocean currents. The few recent studies of asymmetric dispersal concluded, that asymmetry has a distinct negative impact on the persistence of metapopulations. Detailed analysis however revealed, that these previous studies might have been unable to properly disentangle the effect of symmetry from other potentially confounding properties of dispersal patterns. We resolve this issue by systematically investigating the symmetry of dispersal patterns and its impact on metapopulation persistence. Our main analysis based on a metapopulation model equivalent to previous studies but now applied on regular dispersal patterns aims to isolate the effect of dispersal symmetry on metapopulation persistence. Our results suggest, that asymmetry in itself does not imply negative effects on metapopulation persistence. For this reason we recommend to investigate it in connection with other properties of dispersal instead of in isolation.