title: Species-specific seed dispersal in an obligate ant-plant mutualism.
abstract: Throughout lowland Amazonia, arboreal ants collect seeds of specific plants and cultivate them in nutrient-rich nests, forming diverse yet obligate and species-specific symbioses called Neotropical ant-gardens (AGs). The ants depend on their symbiotic plants for nest stability, and the plants depend on AGs for substrate and nutrients. Although the AGs are limited to specific participants, it is unknown at what stage specificity arises, and seed fate pathways in AG epiphytes are undocumented. Here we examine the specificity of the ant-seed interaction by comparing the ant community observed at general food baits to ants attracted to and removing seeds of the AG plant Peperomia macrostachya. We also compare seed removal rates under treatments that excluded vertebrates, arthropods, or both. In the bait study, only three of 70 ant species collected P. macrostachya seeds, and 84% of observed seed removal by ants was attributed to the AG ant Camponotus femoratus. In the exclusion experiment, arthropod exclusion significantly reduced seed removal rates, but vertebrate exclusion did not. We provide the most extensive empirical evidence of species specificity in the AG mutualism and begin to quantify factors that affect seed fate in order to understand conditions that favor its departure from the typical diffuse model of plant-animal mutualism.
authors.affiliation: Department of Entomology, WM Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America.
authors.forename: Elsa
authors.initials: E
authors.lastname: Youngsteadt
authors.forename: Jeniffer Alvarez
authors.initials: JA
authors.lastname: Baca
authors.forename: Jason
authors.initials: J
authors.lastname: Osborne
authors.forename: Coby
authors.initials: C
authors.lastname: Schal
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001000:Ants / Q000502:physiology*; D001181:Arthropods; D005247:Feeding Behavior; D008954:Models, Biological; D010568:Peru; D010944:Plants / Q000469:parasitology*; D012639:Seeds / Q000469:parasitology* / Q000502:physiology*; D013045:Species Specificity; D013559:Symbiosis; D014714:Vertebrates