SYMP 18-2 - Eco-evolutionary dynamics of coexistence via neighbor-dependent selection

Thursday, August 11, 2011: 8:30 AM
Ballroom E, Austin Convention Center
David A. Vasseur, Ecology & Evolutionary Biology, Yale University, New Haven, CT, Priyanga Amarasekare, Department of Ecology and Evolution, University of California, Los Angeles, Los Angeles, CA, Volker H.W. Rudolf, Department of Ecology & Evolutionary Biology, Rice University, Houston, TX and Jonathan Levine, Institut f. Integrative Biologie

Classical mechanisms which allow coexistence of competing species typically focus on niche differences as a means to weaken interspecific competition relative to intraspecific competition; however, empirical demonstrations of this mechanism have proven difficult.  Recently it has been proposed that species-level selection can allow coexistence when the optimal traits for existing in conspecific neighborhoods exhibit a tradeoff with those which are optimal for existing in heterospecific neighborhoods.  We formulate a general model of this phenomenon where the coefficients of a Lotka-Volterra competition model are governed by a quantitative trait which is under selection in one species. 


We demonstrate that this ‘neighbor-dependent’ selection can stabilize coexistence when it is not otherwise possible; coexistence arises from an intransitive competitive loop, formed by two species and neighbor-dependent selection acting one of the species’ traits.  Furthermore, we analyze the general conditions necessary for this outcome to arise.  Given recent evidence for evolution on time-scales commensurate with ecological dynamics, selection may be a widespread, fundamentally important mechanism, for achieving species coexistence.


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