Dwyer Greg, Morris William F
Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA.
Am Nat. 2006 Feb;167(2):165-76. doi: 10.1086/498944. Epub 2005 Dec 12.
Many mobile organisms exhibit resource-dependent movement in which movement rates adjust to changes in local resource densities through changes in either the probability of moving or the distance moved. Such changes may have important consequences for invasions because reductions in resources behind an invasion front may cause higher dispersal while simultaneously reducing population growth behind the front and thus lowering the number of dispersers. Intuiting how the interplay between population growth and dispersal affects invasions is difficult without mathematical models, yet most models assume dispersal rates are constant. Here we present spatial-spread models that allow for consumer-resource interactions and resource-dependent dispersal. Our results show that when resources affect the probability of dispersal, then the invasion dynamics are no different than if resources did not affect dispersal. When resources instead affect the distance dispersed, however, the invasion dynamics are strongly affected by the strength of the consumer-resource interaction, and population cycles behind the wave front lead to fluctuating rates of spread. Our results suggest that for actively dispersing invaders, invasion dynamics can be determined by species interactions. More practically, our work suggests that reducing invader densities behind the front may be a useful method of slowing an invader's rate of spread.
许多移动生物表现出资源依赖型移动，即移动速率通过移动概率或移动距离的变化来适应局部资源密度的变化。这种变化可能对入侵有重要影响，因为入侵前沿后方资源的减少可能导致更高的扩散率，同时降低前沿后方的种群增长，从而减少扩散者的数量。如果没有数学模型，很难直观地了解种群增长与扩散之间的相互作用如何影响入侵，但大多数模型都假设扩散率是恒定的。在此，我们提出了允许消费者 - 资源相互作用和资源依赖型扩散的空间传播模型。我们的结果表明，当资源影响扩散概率时，入侵动态与资源不影响扩散时并无不同。然而，当资源影响扩散距离时，入侵动态会受到消费者 - 资源相互作用强度的强烈影响，波前后方的种群周期会导致扩散速率波动。我们的结果表明，对于主动扩散的入侵者，入侵动态可能由物种相互作用决定。更实际地说，我们的工作表明，降低前沿后方的入侵者密度可能是减缓入侵者扩散速率的一种有效方法。
