PARENT SESSION
Oral Session #75: Evolutionary Ecology -- Life histories, interactions.
Presiding: S. Armbruster
Thursday, August 8. 9:00 AM to 11:30 AM. Graham Meeting Room, TCC.
Phylogenetic repulsion in the assembly of Floridean oak communities.
Cavender-Bares, J*,1, Ackerly, D2, Baum, D3, Bazzaz, F4, 1 Smithsonian Environmental Research Center, Edgewater, MD2 Stanford University, Stanford, CA3 University of Wisconsin, Madison, WI4 Harvard University, Cambridge, MA
ABSTRACT- Understanding the maintenance of biodiversity requires establishing the factors that influence the composition of ecological communities. In order for species to coexist within a community, they need to be able to cope with the abiotic factors present and thus need to be phenotypically similar in ways that allow persistence in a given environment. At the same time, they need to be sufficiently differentiated in ecologically meaningful ways to prevent competitive exclusion. Communities that are dominated by multiple species of a single genus are challenging to explain because phylogenetically similar species are often ecologically similar as well, and consequently relatively few close relatives should be able to coexist without competitive exclusion. A range of forest communities in north central Florida are dominated by oaks; up to six different species occur together. By examining the community structure with respect to phylogenetic relationships in these communities, we found that oak species co-occurring within communities are more distantly related than expected by chance and that the most closely related species seldom occur in the same communities. Also, traits important for habitat differentiation into particular disturbance and resource regimes evolve rapidly while other traits have sufficient phylogenetic inertia to disfavor the co-occurrence of close relatives. These conserved traits may influence density-dependent mortality and allow complementarity among distantly related congeners that occur together, thereby promoting the phylogenetically non-random patterns of community composition. This scale-dependent pattern of phylogenetic repulsion may be more widespread than previously considered and is likely to be important in maintaining biological diversity within communities.
KEY WORDS: Quercus