Results
We gathered information on 1,614 interactions between 34 primate species, in six subfamilies and three families, and 960 plant species in 311 genera and 98 families across Neotropical rainforests. Primates were the exclusive seed dispersers of 627 (65%) species (in 233 genera) (Fig. 1). Birds overlapped 147 plant species with primates (in 80 genera), bats 48 (in 32 genera), ungulates 17 (in 16 genera), and small mammals 9 (in nine genera). Finally, 112 plant species (in 68 genera) were found to be dispersed by more than one vertebrate group plus primates. The most exclusively primate-dispersed family was Sapotaceae (70 species, or 5.5% of the total 1,273 species), followed by Menispermaceae (22 species, or 5% of the 440 species), and Moraceae (44 species, or 3.7% of the 1,180 species) (Figure S6).
We detected a strong evidence of a coupled evolutionary history among primates and plants based on seed dispersal interactions (R= 0.99, p<0.001). The residual contribution to the overall magnitude of the signal varied among interacting species.
Specialization or generalization of each plant and primate species (quantified by the number of interaction partners) predicted the CS of their interactions: the most interacting primates (those presenting highest degrees) had the shortest residual distances, thus contributing more to the CS (t = -8.76, p < 0.001). In turn, the most interacting plants were those with the largest residual distances, contributing less to the CS (t = 2.5, p = 0.01, Figure S7). Primate functional traits (degree of frugivory: F = 4.65, p = 0.03; feeding guild: F = 7405.30, p < 0.001), but not plant traits (fruit length: F = 0.21, p = 0.65; seed diameter: F = 0.13, p = 0.72), determined the magnitude of the influence of the interaction on the overall CS.
At the continental scale, major frugivore primates (Ateles ,Lagothrix and Brachyteles ) and the frugivore-folivores (Alouatta ) contributed more to the strength of the CS, followed by the omnivores (Cebus andS a p ajus ) and frugivore-insectivores (Leontopithecus and Saguinus ). On the other hand, mostly seed predators (Cacajao ,Chiropotes and Callicebus species) showed the largest Procrustean residual values, with the smallest contribution to the signal as expected (Fig. 2, Table S8.a and Figure S8.a, Tables S9).
The continental pattern was consistent when broken-down at the regional/biome scale. We found a strong CS on primate-fruit interactions in the Atlantic forest (R= 0.98, p< 0.001), the Amazon forest (R= 0.99, p= 0.014), and in Mesoamerican forests (R= 0.98, p= 0.008). The contribution by each primate feeding guild in Amazon followed the continental pattern, while in the Atlantic Forest folivores contributed slightly more than frugivores, and in the Mesoamerica omnivores had the greatest contribution to CS (Fig. 3, Tables S8.b and Figure S8.b).