Plastic changes in seed dispersal along ecological succession: theoretical predictions from an evolutionary model
Résumé
1 We use a deterministic model to explore theoretically the ecological and evolutionary relevance of plastic changes in seed dispersal along ecological succession. Our model describes the effect of changing disturbance regime, age structure, density and interspecific competition as the habitat matures, enabling us to seek the evolutionarily stable reaction norm for seed dispersal rate as a function of time elapsed since population foundation. 2 Our model predicts that, in the context of ecological succession, selection should generally favour plastic strategies allowing plants to increase their dispersal rate with population age, contrary to previous predictions of models that have assumed genetically fixed dispersal strategies. 3 More complex patterns can evolve showing periods with high production of dispersing seeds separated by periods of intense local recruitment. These patterns are due to the interaction of individual senescence with change in ecological conditions within sites. 4 Evolution of plastic dispersal strategies affects the patterns of density variation with time since foundation and accelerates successional replacement. An interesting parallel can be drawn between the evolution of age-specific dispersal rates in successional systems and the evolution of senescence in age-structured populations. 5 Seed dispersal plasticity could be a potential mechanism for habitat selection in plants and have implications for range expansion in invasive species because recently founded populations at the advancing front may show different patterns to those in the established range.