Frugivore choice and escape from pre-dispersal seed predators: the case of Dialium guianense and two sympatric primate species in southern Mexico

Seed predation and dispersal play key roles in the regeneration of tropical trees. Pre-dispersal predation may cause high mortality in seed crops. Seeds may escape pre-dispersal predation when ingested with the fruit pulp and moved away from the parent trees by frugivores. In southern Mexico, we investigated if seed traits (i.e., length, width, and mass) and seed damage by insects on Dialium guianense differed according to seed source: from the tree crowns, the ground, and from howler ( Alouatta pigra ) and spider monkey ( Ateles geoffroyi ) feces. We counted the number of seeds with circular entrance and/or exit holes in their tegument. Ingested seeds were larger, heavier, and wider than non-ingested seeds. Seeds ingested by the howler were, however, significantly larger than those ingested by the spider monkey. Damaged seeds showed the lowest values for all seed traits. The proportion of damage declined significantly from seeds on the ground (37 %), to seeds in spider monkey feces (29 %), to seeds from tree crowns (11 %), and finally to seeds in howler monkey feces (7 %). Fruit selection by primates influences dispersal quality differently, even when feeding on the same plant species. The howler monkey may increase the reproductive success of D. guianense by selecting larger and predation-free seeds/fruits.