Evolutionary processes in planktonic metacommunities.
Tessier, Alan*,1, Leibold, Mathew2, Cáceres, Carla3, 1 National Science Foundation, Arlington, VA2 University of Texas at Austin, Austin, TX3 University of Illinois at Urbana-Champaign, Urbana, IL
ABSTRACT- The plankton of lakes and ponds has long provided theoretical inspiration and an empirical test bed for community ecology. Planktonic species also have served as models for evolutionary ecologists studying local adaptation, especially in response to variation in trophic interactions. More recently, a focus on dispersal promises to merge these two perspectives by explicitly considering the evolution of metapopulations in response to food web structure in metacommunities. A motivation for this synthesis is growing recognition that species trait variation shaped by ecological selection can feedback to modify ecological interactions. This leads to the question of whether the evolution of traits within metapopulations can shape the structure of metacommunities. We consider the situation of coexisting Daphnia species whose relative abundance and habitat use is determined by a keystone predator. We review evidence for adaptive trait variation in body size and behavior among lake populations of these species. An enclosure experiment is used to quantify the impact of this trait variation within one species on competitive interactions among species. Results show that the ecological relevance of trait variation to competition among species depends strongly on the presence of a common predator. Finally, we consider an important lesson from metapopulation evolution: local adaptation of populations can shape traits determining breeding system, gene flow, and dispersal rates. The consequences of such trait variation to ecological dynamics within metacommunities are potentially large. Evidence for population differentiation in breeding system in Daphnia populations is used to illustrate this point.
Key words: trait evolution, keystone predation, competition, breeding system
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