Accelerating invasion rates result from the evolution of density-dependent dispersal
Authored by Calvin Dytham, Justin MJ Travis, Tim G benton, Karen Mustin
Date Published: 2009
DOI: 10.1016/j.jtbi.2009.03.008
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Abstract
Evolutionary processes play an important role in shaping the dynamics of
range expansions, and selection on dispersal propensity has been
demonstrated to accelerate rates of advance. Previous theory has
considered only the evolution of unconditional dispersal rates, but
dispersal is often more complex. For example, many species emigrate in
response to crowding. Here, we use an individual-based model to
investigate the evolution of density dependent dispersal into empty
habitat, such as during an invasion. The landscape is represented as a
lattice and dispersal between Populations follows a stepping-stone
pattern. Individuals carry three `genes' that determine their dispersal
strategy when experiencing different population densities. For a
stationary range we obtain results consistent with previous theoretical
studies: few individuals emigrate from patches that are below
equilibrium density. However, during the range expansion of a previously
stationary population, we observe evolution towards dispersal strategies
where considerable emigration occurs well below equilibrium density.
This is true even for moderate costs to dispersal, and always results in
accelerating rates of range expansion. Importantly, the evolution we
observe at an expanding front depends upon fitness integrated over
several generations and cannot be predicted by a consideration of
lifetime reproductive success alone. We argue that a better
understanding of the role of density dependent dispersal, and its
evolution, in driving population dynamics is required especially within
the context of range expansions. (C) 2009 Elsevier Ltd. All rights
reserved.
Tags
Dynamics
Metapopulation
Demographic stochasticity
Consequences
Mutations
Species range
Define fitness
Wave-front
Expanding population
Kin
competition