PARENT SESSION
Contributed Oral Session 160: Biodiversity: Communities
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 519 A, Level 5, Palais des congrès de Montréal
Landscape design and the structuring of local and metacommunity richness.
Cadotte, Marc*,1, 1 University of Tennessee, Knoxville, TN, USA
ABSTRACT- A growing paradigm in community ecology is that communities are structured by local and regional processes. Local processes, such as competition and predation, are thought to limit species membership, while regional processes, dispersal and evolution, are thought to increase membership. Recent studies have shown that dispersal can actually have negatively impact richness. Using protozoan microcosm landscapes, I examine how dispersal structures communities under different landscape designs. I explicitly manipulate dispersal pathways and rates. The three pathways were: 1) species disperse to all local communities with equal probability; 2) a distance gradient with differing probabilities based on distance; and 3) pathways where species have to disperse through neighboring communities. I show that the rate and pathway can have important impacts for species richness at local and metacommunity scales. Local and metacommunity richness did not differ between pathways at low dispersal rates, but did at high dispersal rates. Landscapes forcing species to disperse through neighboring communities maintained higher richness than landscapes allowing species to disperse throughout the landscape. Further, Pathways allowing dispersal to all communities showed a spike in richness during the experiment followed by a rapid decline in local richness, while the neighbor-only pathway maintained relatively constant richness. These results indicate that dispersal, as a regional process, can have differing impacts depending on how often and where species move. Metacommunity dynamics likely have scale dependent processes which make it difficult to attribute patterns solely to regional or local processes.
Key words: metacommunity, dispersal, local vs. regional processes, spatial scale