The Early Ant Gets the Canned Sardine with Oil

If you’re anything like us, you’ve been spending a lot of time lately wondering about ant species coexistence. How can there possibly be 13,384 species of ants, when so many species have overlapping niches in space, food resources, and other traits? Shouldn’t the most competitive ant species ultimately drive all the others to extinction?

One of 13,384 known species of ants. How? Image: Alex Wild

Luckily, we have scientists like Dr. Flávio Camarota, a postdoctoral researcher at George Washington University who decided to address this question head-on. As reported in a paper published online in Behavioral Ecology and Sociobiology earlier this week, Camarota and collaborators investigated an arboreal (tree-living) ant community in tropical Brazil, to determine if arboreal ant species’ overlap in food resources is maintained through a trade-off between resource discovery ability and competitive ability. In other words, the researchers wanted to know: Are some ant species really good at competing with other ant species, while different ant species are particularly good at finding resources more quickly than the best competitor ant species? Myrmecologists typically call this the “discovery-dominance trade-off”. Such a trade-off is often invoked as a potential mechanism that might allow for multiple species to coexist, similar to how differences in business strategy or products may allow for a higher diversity of businesses in a given part of a human town.

A high diversity of businesses in a small human town.

How did Camarota and colleagues go about exploring this question? At their field site in Brazil, Reserva Ecológica do Panga, they utilized food baits (which we’ve discussed before!) on many trees – 175, to be exact. They chose delicious and effective canned sardine with oil as their bait. For each observation, over a period of 3 hours, the researchers documented the number of ant workers at each bait, and the identity of the species. They were then able to use these observations to compare the ability of each species to discover a resource first and to maintain control of a resource once it was controlled.

To the surprise of anyone strongly adhering to the discovery-dominance trade-off hypothesis, the researchers did not find the expected trade-off. Instead, their results support what they coin the “discovery-defense strategy”: whichever species arrives at a food resource first is able to maintain control of that food resource even as other species arrive. Camarota and colleagues argue that this strategy also has an equalizing effect that prevents any species from dominating in a community, as no one species will always be superior to all others – each of the other species will always get to some resources first at least some of the time.

Nom, nom, nom. Image: Alex Wild

So there you have it! The early ant gets the worm canned sardine with oil.