Idea paper: Airport ecology, an environment without predation pressure drives evolution

Evolutionary changes in organisms are directly observable, and they can occur rapidly in the presence of strong natural selection. Here, we present the “airport ecology” to describe the rapid evolution of animals. The pygmy grasshopper Tetrix japonica exhibits significant variations in pronotum color and markings and is a good model organism for “airport ecology.” There are trade‐offs in black‐spot markings in the pygmy grasshoppers; although it helps in camouflaging and reducing predation pressure, it stimulates overheating, resulting in a reduction in mating opportunities and foraging success under high solar irradiance. Therefore, the frequency of black‐spotted morphs is lower at lower latitudes than at higher latitudes along a latitudinal cline. However, in an airport where predation pressure is reduced by the removal of predatory bird populations, we predict that the frequency of black‐spotted morphs of T. japonica will be lower in habitats without predators than in those with predators at the same latitude; this demonstrates the anthropogenic effect on T. japonica polymorphism. As suggested here, predator‐free environments such as airports are valuable for illustrating the effects of anthropogenic activity on animal evolution. These findings can be extended to several other species that are found around airports and are potentially preferred by avian predators in terms of not only rapid evolution of color polymorphism but also evolution of various life‐history traits.