Ecological redundancy in seed dispersal systems: a comparison between manakins (Aves: Pipridae) in two tropical forests

LOISELLE BA; BLENDINGER PG; BLAKE JG; RYDER TB

Seed dispersal: Theory and its application in a changing world.

CABI Publishing

Lugar: Wallingford, UK.; Año: 2007; p. 178 - 195

Redundancy in ecological function may enhance ecosystem resilience and buffer ecosystems from disturbance. Forests of western Amazonia are approximately three to four times more species-rich than well-studied wet forest sites in Meso-America. From the perspective of frugivory and seed dispersal processes, one might predict that ecological roles of fruit-eating animals overlap more broadly in the species-rich forests of western Amazonia when compared to wet forest sites in Meso-America. We investigate this hypothesis by comparing overlap in fruit and habitat use by manakins in wet forests of eastern Ecuador and Costa Rica. We measure ecological redundancy in seed dispersers based on overlap in fruit species consumed and overlap in environments that dispersers occupy and, presumably, disseminate seeds into. We found 81 species of plants in the diets of two manakin species in old-growth forests of Costa Rica; their diets overlapped significantly more than expected by chance. In Ecuador, we found 85 species of plants in the diets of four species of manakins. These four species were, for the most part, ecologically equivalent in the quantitative and diversity components of seed-disperser effectiveness because they feed on a similar suite of plant species in similar proportions. In Costa Rica, differential habitat use by manakin species results in a lower ecological redundancy for this component of the seed dispersal process, while there appears to be considerable ecological redundancy among Ecuadorian manakin species in the forest environments where seeds are disseminated. Our prediction that manakins in species-rich forests of Ecuador are more ecologically redundant in their roles as seed dispersers than manakins in relatively less diverse forests of Costa Rica was largely upheld. We  conclude that manakins from species-rich forests overlap more in ecological function than do manakins in less diverse forests and, thus, that these forests may be more resilient to disturbance.