PS 57-16 - The effects of species richness and endophyte infection on invasion of Festuca arundinacea

Thursday, August 11, 2011
Exhibit Hall 3, Austin Convention Center
Emily A. Drystek, Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, Hafiz Maherali, Integrative Biology, University of Guelph, Guelph, ON, Canada and Kathryn A. Yurkonis, Department of Biology, University of North Dakota, Grand Forks, ND

Characteristics of the invader and community can influence the likelihood of an invasion occurring. Invasion by exotic species may be deterred by high resident community diversity. However, equally diverse communities may not be equally resistant to invasion. The dominance of species in communities structured by selection prevents complete resource use, leaving resources open for invaders. Invasion should then be higher in communities structured by selection relative to communities structured by complementarity.  The association with the endophyte Neotyphodium coenophialum increases the competitive ability of the invasive host Festuca arundinacea over non-infected counterparts. Taken together we would expect invasion to be highest in communities with endophyte infected invaders that are also structured by selection.

To determine whether endophyte infection influenced invasion success we used 10 tallgrass prairie species to create experimental communities and mimicked natural invasion with propagules of infected and uninfected F. arundinacea. To test whether community invasibility was influenced by selection or complementarity we manipulated the composition and species richness (1,2,4,8) of the experimental communities subject to invasion and calculated selection and complementarity values for each community.


Manipulating the species richness of experimental communities effectively formed a diversity gradient. The net primary productivity of the resident communities was dependent on the diversity. The level of invasion of F. arundinacea was dependent on the diversity and productivity of the resident community. Invader success was affected by the endophyte status of the invader. The level of selection in a community was dependant on diversity but not the level of complementarity. Understanding how the properties of diverse communities like selection and complementarity affect invasion may provide a new way for biodiversity experiments to examine controls over invasion.

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