Intra-specific variability and fecundity: Potential impact on competition interactions and species coexistence in plant communities

Plant intra-specific variability blurs mean species differences and can modify local competition outcome. We tested implications of this process in plant communities with a two species meta-population model. Several juveniles of each species competed on patches of homogeneous environment. Competitive ability was drawn for each juvenile in a distribution corresponding to its species and the best juvenile on a patch won it whatever its species.

Variability did not favour coexistence systematically. It benefited to the species with lower mean competitive ability because it allowed it to produce a fraction of very competitive individuals and this effect was multiplied when fecundity was high. In cases of high fecundity and high variability, a species with lower mean competitive ability could indeed both colonize more sites and win more local contests than its competitor.

Intra-specific variability can have a huge impact on community dynamics and should be taken into account to describe species strategies.