Complex foraging ecology of the red harvester ant and its effect on the soil seed bank

• Published in: Acta oecologica (Montrouge) 2018-01, Vol.86, p.57-65
• Main Authors: Luna, Pedro, García-Chávez, Juan Héctor, Dáttilo, Wesley
• Format: Article
• Language: English
• Subjects: Biotic interactions; Granivory; Networks; Tehuacán-Cuicatlán Valley; Thorny shrub
• ISSN: 1146-609X; 1873-6238
• DOI: 10.1016/j.actao.2017.12.003

Granivory is an important interaction in the arid and semi-arid zones of the world, since seeds form an abundant and nutritious resource in these areas. While species of the genus Pogonomyrmex have been studied in detail as seed predators, their impact on seed abundance in the soil has not yet been explored in sufficient depth. We studied the impact of the harvesting activities of the ant Pogonomyrmex barbatus on seed abundance in the soil of the Zapotitlán valley, Mexico. We found that P. barbatus activity significantly impacts the abundance of seeds in the soil, which is lower in the sites where P. barbatus forages than it is in sites with no recorded foraging. We also found that P. barbatus distributes intact seeds of three tree species, two of which are nurse plants, and could consequently be promoting the establishment of these species. Using tools derived from graph theory, we observed that the ant-seed interactions exhibit a nested pattern; where more depredated seed species seem to be the more spatially abundant in the environment. This study illustrates the complex foraging ecology of the harvester ant P. barbatus and elucidates its effect on the soil seed bank in a semi-arid environment. •Pogonomyrmex barbatus reduces the abundance of seeds in the soil where it forages, in a semi arid ecosystem.•Intact seeds from nurse trees are redistributed by this ant.•Nestedness is a property of the interactions between P. barbatus nests and resources.