Dominants – Or Not?

So, you have some communities of ants. You notice that some communities are more diverse than others. In one community, certain species of ants are more common, while in another, different species are more common. How can you explain this coexistence and variation? Dominance hierarchies, perhaps?

Ants at war. Image: Alex Wild

Dominance hierarchies have played a key role in ant ecology for many years. These hierarchies describe the relative ability of each species in a community to dominate over others, and tend to be constructed as a single, linear list. In other words, Species A is dominant over Species B which is dominant over Species C which is dominant over blah blah blah. Such a dominance structure is thought to impact species coexistence and variation in community composition across different habitats.

But wait! A recent review and discussion by Dr. Katie Stuble and colleagues challenges this paradigm of dominance hierarchies, suggesting that myrmecologists must improve and move beyond the use of such hierarchies to better explain the processes that structure ant communities. The researchers argue that the most common metrics employed to assess dominance (based on factors ranging from one-on-one aggression to control of food baits) differ in their ecological implications and, critically, are inconsistent in their findings when used on identical sets of data. Furthermore, the concept of a strict dominance hierarchy is unlikely to adequately describe the dynamic and complex nature of real ecological communities. They also offer some suggestions for enhancing future work, including explicitly defining “dominance” and incorporating network theory in studies of dominance, as well as abandoning any uniform application of dominance hierarchies altogether. Check out the paper for more!