PARENT SESSION
Contributed Oral Session 25: Aquatic Trophic Systems II
Monday, August 8, 1:30 PM - 5:00 PM, Meeting Room 518 A, Level 5, Palais des congrès de Montréal
Dispersal limitation and local performance: Interactions across life-history stages and consequences for species' distributions in anisopteran odonates.
McCauley, Shannon*,1, 1 University of Michigan, Ann Arbor, MI, USA
ABSTRACT- In many freshwater taxa, species' distributions are related to a habitat permanence gradient that is associated with a transition in the top predator community. Most studies of species' distributions across this gradient have focused on the role of trade-offs in local performance. However, for species which have limited abilities to withstand habitat drying, dispersal limitation may also be an important mechanism determining their ability to utilize habitats which dry regularly. I assessed the relative importance of local performance and dispersal limitation and how these processes may interact to determine species distributions in dragonfly species. I used a contrast of habitat specialist species restricted to permanent lakes with large bodied fish as top predators, and species with generalist distributions, occurring across the permanence and top predator gradient, to assess the role of local performance and dispersal limitation mechanisms in shaping species' distributions. I compared one aspect of local performance in habitat specialists and generalists - their vulnerability to alternative top predator types. I also compared larval traits expected to affect this and other aspects of local performance including larval activity levels and growth rates. I experimentally contrasted the effects of dispersal limitation in habitat specialists and generalists and related dispersal behavior to adult morphology. Dispersal limitation is a dominant mechanism structuring the breadth of species' distributions in these species. However, larval traits associated with species restricted to permanent lakes with large bodied fish predators were negatively related to adult traits that facilitate dispersal. These results suggest that traits affecting performance in different life-history stages may reinforce each other to shape species' distributions in this system.
Key words: dispersal, local performance, Odonata, habitat gradients