Germination success of seeds ingested by <italic>Saguinus bicolor</italic>.

Frugivory and seed dispersal are fundamental ecological interactions influencing plant population dynamics and distribution. Still, understanding how the ingestion of seeds by fruit-eating animals affects seedling emergence performance remains poorly documented. Seed dispersal through animal ingestion can either promote or hinder germination. In this study, we assessed how seed ingestion by <italic>Saguinus bicolor</italic>, a critically endangered primate from the Brazilian Amazon, affects germination rate and germinability. As primate seed ingestion often improves seed germination, we predicted that germination rate and germinability would be higher in seeds defecated by the tamarins if compared to hand-extracted seeds. Of the 23 species, five did not germinated in either the control or gut-passage treatments. Among the ones that germinated, nine had an average increase in germinability, two decreased in germinability, and seven had a neutral effect. The germination rate increased in four species, reduced in eight species and had a neutral effect in six of the species. Most of the seeds that passed through the tamarins' digestive tract successfully germinated, demonstrating that seed ingestion by pied tamarins can benefit the plant populations by dispersing viable seeds through the landscape. [ABSTRACT FROM AUTHOR]