Why Big Ant Colonies Have Thinner Armor
If you have ever watched a colony grow from a queen and a handful of workers into hundreds of ants, you might wonder how much each worker costs the colony. A study in Science Advances puts a number on one part of that cost: the cuticle, the protective outer layer of the body.
Arthur Matte, a PhD student at the University of Cambridge who began the work at the Okinawa Institute of Science and Technology, and Evan Economo, now at the University of Maryland, measured cuticle and body volume in more than 500 ant species using a large set of 3D X-ray scans. Colony sizes in the dataset run from tens of individuals to millions.
The cuticle is nutritionally expensive because it needs nitrogen and minerals. Across species, cuticle investment ranged from about 6 percent to 35 percent of body volume. Species that put less into the cuticle tended to have larger colonies, and lower investment was also linked to higher diversification rates, a rough measure of evolutionary success.
The authors' interpretation is that collective defence, disease control, foraging and division of labour reduced the need for heavy individual armour. That may have created a feedback loop in which thinner cuticles made larger colonies possible. They also suggest that lower nitrogen needs may have helped ants settle nutrient-poor habitats, though why this drives speciation is still unknown.
I like that the study frames cheap, replaceable workers as a strength of the colony. Termites might have followed a similar path, but the authors note that this remains untested.
Source: Phys.org (University of Maryland)
Arthur Matte, a PhD student at the University of Cambridge who began the work at the Okinawa Institute of Science and Technology, and Evan Economo, now at the University of Maryland, measured cuticle and body volume in more than 500 ant species using a large set of 3D X-ray scans. Colony sizes in the dataset run from tens of individuals to millions.
The cuticle is nutritionally expensive because it needs nitrogen and minerals. Across species, cuticle investment ranged from about 6 percent to 35 percent of body volume. Species that put less into the cuticle tended to have larger colonies, and lower investment was also linked to higher diversification rates, a rough measure of evolutionary success.
The authors' interpretation is that collective defence, disease control, foraging and division of labour reduced the need for heavy individual armour. That may have created a feedback loop in which thinner cuticles made larger colonies possible. They also suggest that lower nitrogen needs may have helped ants settle nutrient-poor habitats, though why this drives speciation is still unknown.
I like that the study frames cheap, replaceable workers as a strength of the colony. Termites might have followed a similar path, but the authors note that this remains untested.
Source: Phys.org (University of Maryland)
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