Latitudinal gradients in colony size for social insects: Termites and antsshow different patterns

On the basis of a comparison of Nearctic and Neotropical ants, social insec ts have been proposed to show a latitudinal gradient in colony size. Furthe r, the "fasting endurance hypothesis," which predicts larger colonies in ar eas with extended periods of low food availability, was proposed as the mec hanism driving the gradient. To test the generality of the pattern and its mechanism, we examined the relationships between termite colony size and bo th latitude and annual evapotranspiration, a measure of plant productivity. We found no evidence that colony size increases with increasing latitude o r decreasing plant productivity. We conclude that the pattern identified fo r ants cannot be generalized to include social insects as a whole. As is th e case for ecogeographic gradients in insect body sizes, a pattern that is reported for one taxon may not be consistent for other taxa at the global l evel.