Boynton, Primrose J , Peterson, Celeste N , Ellison, Aaron , Farley, Katherine B , Pringle, Anne .
Competitive outcomes between yeasts that inhabit carnivorous plant pitchers are limited by founding population size.
In reconsidering Baas Becking's "everything is everywhere" hypothesis, microbiologists have taken a keen interest in biogeography. Dispersal limitation and competitive outcomes can work together to influence microbial distributions. We used yeasts that inhabit leaves of Sarracenia purpurea, the purple pitcher plant, to investigate these two processes. We first isolated yeasts from pitcher plant water and identified them using sequences from the large ribosomal subunit; we found a variety of ascomycete and basidiomycete yeasts inhabiting these pitchers. Next, to investigate the impact of dispersal limitation on competitive outcome, we selected three phenotypically distinct isolates for competition in microcosms. Microcosms were inoculated with different relative numbers of cells to simulate different numbers of propagules that might land inside a S. purpurea pitcher. We predicted a clear competitive hierarchy that could be overcome by high dispersal. As expected, competitive ability in these three yeasts followed a transitive hierarchy. In addition, competitive ability improved with inoculum size in most cases. However, inoculum size showed little effect on the competitive ability of the competitive dominant. In this system dispersal and competition appear to interact, but the competitive dominant can overcome even relatively large competing founding populations. These results suggest that strong niche-based interactions are balanced with competitive-dispersal tradeoffs in the pitcher plant yeast system. Further work will examine tradeoffs between competitive and dispersal abilities in the field.
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1 - Harvard University, Department of Organismic and Evolutionary Biology, 16 Divinity Ave, Cambridge, MA, 02138, USA
2 - Massachusetts Institute of Technology, Biology, 31 Ames St, Cambridge, MA, 02139, United States
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Presentation Type: Oral Paper:Papers for Topics
Location: Cottonwood B/Snowbird Center
Date: Monday, July 27th, 2009
Time: 1:15 PM