The size of dragonflies and damselflies varies around the globe. These insects are generally larger in temperate areas than in the tropics. According to a new study from Lund University in Sweden, this is caused by a combination of temperatures and the prevalence of predators.
In a large global comparative study of this ancient order of insects, researchers have studied how body size varies geographically and between different species. They compared the size of these insects in the hot tropics with the cooler, temperate regions to quantify geographical variation and understand its causes. This was done by analyzing size data and fossil data for various species of dragonflies and damselflies (two suborders of the order Odonata).
“Two hundred million years ago, these insects were larger in the tropics than in temperate climates. That trend has since reversed, however, and the opposite is now true, with larger species generally found at our northerly latitudes. We believe that this is partly caused by the evolutionary appearance of birds” says Erik Svensson, biologist at Lund University.