Mortality During Dispersal an the Stability of a Metapopulation
We use a coupled map lattice to investigate the dynamics of a system of populations linked by dispersal, when dispersal incurs an additional mortality cost. Considering a single isolated population first, we show analytically that imposing an additional mortality term can stabilise the non-trivial steady state only under certain conditions. We demonstrate algebraically that in the absence of mortality during dispersal, linking a number of similar populations does not affect whether or not the equilibrium will be stable, although it can affect the nature of any unstable dynamics. Adding a fixed mortality rate during dispersal has a strong stabilising effect on system dynamics. We show analytically that for any combination of intrinsic reproduction parameters, a range of dispersal rates and dispersal mortalities can be found which together act to stabilise the equilibrium. Our results are shown numerically to be robust against a number of perturbations. Hence dispersal mortality has a strong stabilising effect on dynamics. In natural systems, some losses during long-distance dispersal are likely, and so we suggest that this factor could be an important determinant of the strength of observed population fluctuations. Copyright 1997 Academic Press Limited
Ruxton
GD
Division of Environmental & Evolutional Biology, Graham Kerr Building, Glasgow, G12 8QQ, U.K.
Gonzalez-Andujar
JL
Perry
JN