Ants as Seed Dispersers
Although it is likely most people have experienced ants at a picnic, they may not realize ants are important seed dispersers, a mutualism referred to by ecologists as myrmecochory. Seed dispersal by ants exists worldwide, but the eastern deciduous forests are a hotspot for this ant-plant interaction. Approximately 35 percent of the herbaceous plants in the understory of forests in eastern North America rely on ants for seed dispersal. Plant species that have coevolved myrmecochory have an oil-rich appendage, known as an elaiosome. The elaiosome attracts the ants with chemical cues. Ants pick up the seed by the elaiosome and return with it to their nest where they feed the elaiosome to their brood. The seed either remains in the nest or is taken outside of the nest. Thus, in myrmecochory, ants gain food, and seeds receive dispersal away from their parent plant, protection from seed predators, and a nutrient-rich germination site in or around ant nests.
Additional organisms likely play a role in this interaction. Microbes, such as bacteria and fungi, are abundant in soil and decaying wood environments where ants nest and seeds germinate. Some of these microbes are harmful to plants or ants, so ants and plants have defenses against these pathogens. Each partner in the ant seed dispersal mutualism has the potential to affect the other partner’s microbes. Chloe Lash, a graduate student in the Kwit Lab, is investigating the effects of chemicals and microbes in this mutualism for her dissertation.
Chloe uses advanced chemical identification techniques to investigate plant and ant chemicals and their potential antimicrobial properties. A combination of traditional and next generation sequencing techniques allows Chloe to understand the microbial loads that both ants and seeds encounter and how those microbial communities change when the partners interact with each other. This novel incorporation of chemical and microbial facets into myrmecochory will contribute to understanding the evolution and persistence of the myrmecochory mutualisms and can help scientists predict the consequences of global change-related disruptions.
