title: Changes in the gradient percolation transition caused by an Allee effect.
abstract: The establishment and spreading of biological populations depends crucially on population growth at low densities. The Allee effect is a problem in those populations where the per capita growth rate at low densities is reduced. We examine stochastic spatial models in which the reproduction rate changes across a gradient g so that the population undergoes a 2D-percolation transition. Without the Allee effect, the transition is continuous and the width w of the hull scales as in conventional (i.e., uncorrelated) gradient percolation, w ∝ g(-0.57). However, with a strong Allee effect the transition is first order and w ∝ g(-0.26).
authors.affiliation: Institute for the Chemistry and Biology of the Marine Environment, Carl von Ossietzky Universität, Carl-von-Ossietzky-Straße 9-11, 26111 Oldenburg, Germany.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Gastner
authors.forename: Beata
authors.initials: B
authors.lastname: Oborny
authors.forename: Alexey B
authors.initials: AB
authors.lastname: Ryabov
authors.forename: Bernd
authors.initials: B
authors.lastname: Blasius
mesh_terms: D005843:Geography; D008962:Models, Theoretical; D011157:Population Dynamics; D011336:Probability; D013269:Stochastic Processes