title: Breakdown of an ant-plant mutualism follows the loss of large herbivores from an African savanna.
abstract: Mutualisms are key components of biodiversity and ecosystem function, yet the forces maintaining them are poorly understood. We investigated the effects of removing large mammals on an ant-Acacia mutualism in an African savanna. Ten years of large-herbivore exclusion reduced the nectar and housing provided by plants to ants, increasing antagonistic behavior by a mutualistic ant associate and shifting competitive dominance within the plant-ant community from this nectar-dependent mutualist to an antagonistic species that does not depend on plant rewards. Trees occupied by this antagonist suffered increased attack by stem-boring beetles, grew more slowly, and experienced doubled mortality relative to trees occupied by the mutualistic ant. These results show that large mammals maintain cooperation within a widespread symbiosis and suggest complex cascading effects of megafaunal extinction.
authors.affiliation: Department of Zoology, University of Florida, Gainesville, FL 32611, USA. tmpalmer@zoo.ufl.edu
authors.forename: Todd M
authors.initials: TM
authors.lastname: Palmer
authors.forename: Maureen L
authors.initials: ML
authors.lastname: Stanton
authors.forename: Truman P
authors.initials: TP
authors.lastname: Young
authors.forename: Jacob R
authors.initials: JR
authors.lastname: Goheen
authors.forename: Robert M
authors.initials: RM
authors.lastname: Pringle
authors.forename: Richard
authors.initials: R
authors.lastname: Karban
mesh_terms: D000045:Acacia / Q000033:anatomy & histology / Q000254:growth & development; D000818:Animals; D001000:Ants / Q000502:physiology; D001522:Behavior, Animal; D001517:Coleoptera; D017753:Ecosystem; D004606:Elephants; D007313:Insecta; D007630:Kenya; D012418:Ruminants; D013559:Symbiosis