The rôle of local’and régional processes in structuring larval dragonfly distributions across habitat gradients

Despite the importance of community-structuring processes operating at both local’and régional scales, there is relatively little work examining both forces within a single system. I used a combination of observational’and experimental’approaches to examine the processes structuring larval dragonfly distributions in lentic habitats that encompass a gradient of both permanence and top predator type. I compared the relative vulnerability of species to predators from différent portions of this gradient to assess the rôle of predation as a local force structuring communities. I also assessed the rôle of régional processes on species’ distributions by examining species’ propensity to disperse to and colonize artificial ponds distributed across a landscape. In both studies I contrasted’habitat specialist species, which had larvae restricted to permanent lakes, with habitat generalist species, which had larvae that occur broadly across the habitat permanence and top predator transition. Results from this work suggest that dispersal’and colonization behavior were critical mechanisms restricting the distributions of habitat specialist species, but that predation may act to reinforce this pattern. The habitat specialists dispersed less frequently, colonized artificial ponds less often when they did reach them, and most moved shorter distances than the habitat generalist species. Habitat specialists were also more vulnerable than habitat generalists to an invertebrate top predator with which they do not co-exist. Results from these studies suggest that species distributions can be shaped by processes operating at both régional’and local spatial scales. The rôle of dispersal’and recruitment limitation may be generally underestimated as a force shaping species distributions and community structure across habitat gradients in which there is a transition in both the biotic interactions and the disturbance interval’across that gradient.

  • Genre de document : Revue
  • Type de document : À préciser

  • Auteur principal : McCauley S. J.
  • Date de publication : 1 janvier 2007