The trade-off between quality and quantity is a classic economic dilemma, but a team of British, American, and Japanese researchers is now highlighting its relevance in biology. Their study suggests that this dilemma has likely played a crucial role in shaping the evolutionary path of ants, one of the planet’s most prolific species.
The research indicates that as ant societies expanded in numbers and complexity, they didn’t only produce smaller workers; they also made them more cost-effective.
The Cost of Armor
In the insect realm, the exoskeleton, known as the cuticle, is essential. It acts as a defense against predators, pathogens, and dehydration, while also providing a structure for muscle attachment. However, building a durable cuticle demands significant resources, such as nitrogen and rare minerals like zinc and manganese. While forgoing protection could be deadly for an individual insect, ants have seemingly evolved a successful strategy to mitigate this risk.
“There’s this question in biology of what happens to individuals as societies they are in get more complex?” remarked Evan Economo, an entomologist at the University of Maryland and co-author of the study. “For example, the individuals may themselves become simpler because tasks that a solitary organism would need to complete can be handled by a collective.”
Economo’s team proposed that in social insects, such as ants, the cost of producing protective cuticles might be outweighed by the benefits to the colony as a whole. The notion was that in a colony of 10,000 workers, losing a few to predators would not have significant repercussions, making extensive defensive investments in each worker inefficient. To explore this hypothesis, they investigated whether ant species with large, specialized workforces have reduced their investment in individual workers' exoskeletons.
Scanning Superorganisms
To evaluate their theory, the researchers embarked on an extensive comparative study of ant anatomy. “We worked with scans of ant specimens and species from all over the world to capture the global diversity of ants,” Economo explained. The team utilized a comprehensive database known as Antscan, which includes three-dimensional X-ray microtomography images of ants from around the globe.