A community genetics perspective on plant competition.
Dinnage, Russell*,1, Zhou, Alice1, Johnson, Marc1, Hunter, Mark2, 1 University of Toronto, Toronto, ON2 University of Michigan
ABSTRACT- Plant competition is a major factor affecting the coexistence of species and the structure of plant communities. Theory predicts that genetic diversity within plant populations can promote species coexistence, but there are few empirical tests of the ecological consequences of such genetic variation for competitive interactions. In a series of greenhouse and field experiments, we tested for genetic variation in aboveground and belowground growth of a native plant (Oenothera biennis), and the consequences of this genetic variation for the performance of competing plant species. In greenhouse experiments, O. biennis was genetically variable for growth rate and its allocation to aboveground and belowground biomass. This genetic variation affected the growth rate of shoots and the allocation to belowground biomass of the exotic grass Bromus inermis. However, the effects of genetic variation in O. biennis on the performance of B. inermis varied with soil nutrients (i.e. a genotype X fertilizer interaction). In a field experiment, O. biennis reduced the biomass of competing herbaceous plants, but there was no effect of genetic variation in O. biennis on the biomass of competing plants. These results show the potential for genetic variation in plants to affect competitive interactions among species, but variation in O. biennis is unlikely to have ecological consequences for natural communities.
Key words: competition, plant ecology, plants
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