Abstract

Seed predation and dispersal play key roles in the regeneration of tropical trees. Seeds may escape pre-dispersal predation when ingested with the fruit pulp and moved away from the parent trees by frugivores. Frugivore species may influence dispersal quality differently even when feeding on the same fruit species. In southern Mexico, we investigated if seed traits (i.e., length, width, and mass) and germination success differed among seeds ingested by howler monkeys (Alouatta pigra), spider monkeys (Ateles geoffroyi), and non-ingested seeds. For this, we recorded the germination rate and percentage of seeds from five tropical tree species, including the following: Ampelocera hottlei , Brosimum lactescens , Dialium guianense, Spondias mombin and Spondias radlkoferi. Furthermore, only for D. guianense we determined if there was a primate selection towards seeds with no insect damaged. Results showed that traits of seeds ingested by howler monkeys differed from those ingested by spider monkeys and non-ingested seeds; while seeds ingested by spider monkeys were similar to non-ingested seeds. Howlers consumed on average the larger seeds. For all five tree species, germination rate was greatest for seeds ingested by howler monkeys. The proportion of damaged seeds declined significantly from non-ingested seeds (48 %), to seeds in spider monkey feces (29 %), and finally to seeds in howler monkey feces (7 %). Fruit selection by primate species influences dispersal quality differently, even when feeding on the same plant species. Howler monkeys may increase the reproductive success of the studied tree species by selecting larger and predation-free seeds/fruits.

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