As it turns out, the most boldly-colored and bad-tasting species are also the most physically fit, the authors report this week in the journal Proceedings of the National Academy of Sciences.
In forests in Colombia, Ecuador, Venezuela, and Panamá, Santos subjected nearly 500 poison frogs - representing more than 50 species - to a frog fitness test. He measured their oxygen uptake during exercise using a rotating plastic tube, turning the tube like a hamster wheel to make the frogs walk.
Santos estimated the frogs' metabolic rates while at rest, and again after four minutes of exercise. The result? The most dazzling and deadly species had higher aerobic capacity than their drab, nontoxic cousins.
"They're better able to extract oxygen from each breath and transport it to their muscles, just like well-trained athletes," Santos said."
J.C. Santos, D.C. Cannatella. Phenotypic integration emerges from aposematism and scale in poison frogs. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1010952108