Effects of Fruiting Neighborhood, Plant Traits, and Fruit Traits on Frugivore Visitation and Fruit Removal for an Understory Palm

Abstract

Seed dispersal services are key to maintaining healthy forest ecosystems, yet our understanding of the factors that influence visitation and frugivory between conspecific plants remains incomplete. Although fruiting neighborhood, plant traits, and fruit traits have been shown to individually influence frugivory, few studies have concurrently evaluated the relative importance of these factors. We address this knowledge gap by simultaneously assessing multiple factors thought to influence frugivory. Specifically, we evaluated how the fruiting neighborhood, defined as the number of fruiting palms in a 35 m radius, and relevant traits at the level of individual plants (e.g., height, crop size) and fruits (e.g., fruit and seed size, water and sucrose content) influenced frugivore visitation and the number of fruits removed per visit in a common understory palm in Northwestern Ecuador, Synechanthus warscewiczianus. A higher number of conspecific fruiting neighbors exhibited a decrease in visitation, suggesting competition among palms that share frugivore mutualists for dispersal services. However, the number of fruits removed per frugivore visit appeared to be affected by crop size and fruit traits of individual palms. Larger crop and fruit sizes were positively associated with the number of fruits removed per visit and indicates frugivore satiation is not a main determinant of fruit consumption during visits. Taken together, our results suggest larger-scale factors like fruiting neighborhood may affect a frugivore's decision to visit a palm, yet finer-scale fruit traits may drive fruit removal once a palm is selected, thereby influencing variation in seed dispersal services at the individual plant level.