Ant Factor: How Tiny Insects Shape Biodiversity

GW researchers studying arboreal ants in a Florida forest explored fundamental questions on the ways resource availability and competition impact biodiversity.

October 2, 2023

Turtle ant on a branch

Turtle ant worker moving between nests.

It’s a fundamental question of biodiversity research: How do many different species manage to coexist in one place?

Now, a team of researchers, including scholars from George Washington University’s Columbian College of Arts and Sciences (CCAS), have drawn a new robust biodiversity picture—thanks to a kingdom of ants.

Their study, published in the journal “Proceedings of the Royal Society B: Biological Sciences,” explores the tensions between resource availability and competition among arboreal ants in the Dagny Johnson Key Largo Hammock Botanical State Park in Key Largo, Florida. 

The Dagny Forest contains the largest contiguous tract of West Indian tropical hardwood hammock in the United States. It is also home to 84 protected species of plants and animals.

“The ant species we examined in this study only live in this unique patch of land off the tip of Florida and the Florida Keys. So, understanding what determines how many species are in this rare environment is a key question for conservation efforts,” said Max Adams, the study’s first author and a former postdoc at GW. 

The team, including senior author Scott Powell, a CCAS associate professor of biology, traveled to the Dagny Forest and focused on specific trees where the ants make nests in pockets of dead wood. They identified 176 poisonwood trees and observed the community of ants living there over two years, between 2020 and 2022. 

The researchers found that the same dynamics of resource availability and competition that exist at large scales—on a continent or within a large forest, for example—also exist at the very small scales of these ant communities.

Observing these interactions in three different scales, the researchers discovered that resource availability and competition often flip-flopped in importance. For example:

  • At the scale of the whole tree, resource availability was more important than competition. Determining how many species live in one tree is dependent on the amount of dead wood available, they found. 
  • Zooming in on the network of ants inside the tree, researchers found that resource availability remained a key determining factor, but competition among different ant species began to come into play. Here, the species started to directly compete with one another, by moving and bumping up against each other, the researchers observed.  
  • Looking even closer at an individual ant nest—or ant home—competition was the solely important factor. The ants moved resources depending upon how dangerous their neighbors were.  

“This research reveals that both resource availability and competition among species are important for maintaining biodiverse communities, and that the relative importance of these two processes is dependent on the scale at which we examine biodiversity patterns,” Powell said. “It also suggests that in our ongoing efforts to support and preserve biodiversity on a changing planet, important aspects of biodiversity scale up from fine-grained interactions with resources and among species at local scales.”

This authors said their findings will help conservationists promote biodiversity in Dagney and other forests, an effort that may improve the health of both the forests and the species that live there. The research team also said their work reinforces the model of a healthy forest, noting that the dead wood within a habitat is critical for every species within that community.

The research was funded by the National Science Foundation. Researchers at Smithsonian Tropical Research Institute, Cary Institute of Ecosystem Studies, Harvey Mudd College and University of York contributed to the study.