Modelling frugivore-mediated seed dispersal

[摘要] ENGLISH ABSTRACT : Seed dispersal is the movement of seeds away from parent plants, and is acrucial ecological process for plant reproduction, persistence and spatial distribution. Specific interest in frugivorous seed-dispersal has increased due toits importance for plant temporal and spatial dynamics under global change.Empirical studies confirm that the interaction between fleshy-fruited plantsand frugivores is mutualistic and can be fully beneficial for both partners provided that the dispersal cost is low. The animals benefit is quite obvious (food)while plants benefit is seed dispersal leading to reduced level of plant aggregation among other benefits. Based on pair-approximation method, we herepropose a process-based mechanistic model of frugivorous seed-dispersal thatcaptures the dynamics of the global and local densities of plants and the densityof frugivores. The model considers three essential components of frugivorousseed-dispersal, including the strength of plant-frugivore mutualistic interaction, dispersal efficiency of frugivores and germination probability of seeds.Our theoretical findings agree with previous empirical studies that seed dispersal decreases plant intraspecific competitions by reducing the level of plantclustering. Results show that efficient frugivorous animals allow conditionalpersistence of plants with low fecundity and natural dispersal ability. Otherwise, inefficient animal seed-dispersers, with high dispersal risks, will act asseed predators, leading to global extinction of plants. Finally, results show theanimals benefit (increased density equilibrium of animals) from plant-frugivoremutualistic interaction. Interestingly, our results provide broad theoretical evidence for the paramount importance of the existence of furgivore species intropical forests.

[发布机构] Stellenbosch University