Field experiments show contradictory short‐ and long‐term myrmecochorous plant impacts on seed‐dispersing ants. (30th July 2018)

• Record Type: Journal Article
• Authors: Warren, Robert J.; Elliott, Katherine J.; Giladi, Itamar; King, Joshua R.; Bradford, Mark A.
• Is Part Of: Ecological entomology. Volume 44:Number 1(2019)
• Page Start: 30
• Page End: 39
• Publication Date: 2018-07-30
• Subjects: Animal–plant interactions -- Aphaenogaster -- commensalism -- dispersal -- herbaceous -- mutualism -- species interactions -- woodland; Insects -- Ecology -- Periodicals; Entomology -- Periodicals; 595.7
• DOI: 10.1111/een.12666
• Languages: English
• ISSNs: 0307-6946

Abstract

Abstract : 1. Some interactions previously described as mutualistic were revealed to be commensal or parasitic in subsequent investigations. Ant‐mediated seed dispersal has been described as a mutualism for more than a century; however, recent research suggests that it may be commensal or parasitic. Plants demonstrably benefit from ant‐mediated seed dispersal, although there is little evidence available to demonstrate that the interaction benefits long‐term ant fitness. 2. Field experiments were conducted in temperate North America focused on a key seed‐dispersing ant. All herbaceous plants were removed from a forest understorey for 13 years, and supplemented ant colonies with large elaiosome‐bearing seeds aiming to examine potential long‐ and short‐term myrmecochorous plant benefits for the ants. 3. If elaiosome‐bearing seeds benefit ants, suggesting a mutualistic relationship, it is expected that there would be greater worker and/or alate abundance and greater fat reserves (colony lipid content) with seed supplementation (short‐term) and in areas with high understorey herb abundance. 4. Short‐term seed supplementation of ant colonies did not result in an increase with respect to numbers or fat stores, although it did prompt the production of colony sexuals, which is a potential fitness benefit. In the long term, however, there was no positive effect on the ants and, instead, there were negative effects because the removal of elaiosome‐bearing plants corresponded with greater colony health. 5. The data obtained in the present study suggest that the ant–plant interaction ranged from occasionally beneficial to neutral to overall negative for the ant partner. Such results did not support considering the interaction as a mutualism. Collectively, the data suggest the need to reconsider the nature of the relationship between these ants and plants. Abstract : There is ample evidence indicating that plants benefit from ant‐mediated seed dispersal, where plants receive seed‐dispersal services in return for food provided as a seed appendage; however, evidence suggesting that the interaction benefits ants is less conclusive. More than a decade of understorey herb removal and field seed addition experiments suggest that ant‐mediated seed‐dispersal ranged from occasionally beneficial to negative for the ant partner. Overall, the data obtained in the present study suggest the need to reconsider the nature of the relationship between these ants and plants that was previously described as mutualistic.