From clover to lizards, a city’s nonhuman residents evolve in human-scale time
AUSTIN, TEXAS — Cities have become great unintentional experiments in evolution. Urban life can alter the basic biological traits of its plant and animal residents, down to the taste of leaves or the stickiness of toes, researchers reported at the 2016 Evolution conference.
For white clover (Trifolium repens), leaf taste matters as a defense against grasshoppers and other predators, Kenneth Thompson of the University of Toronto Mississauga said June 19. Variations in two genes let clover booby-trap its leaves and stem to release a warning burst of cyanide when bitten. A little taste doesn’t kill a nibbler but can send it spitting away to another plant.
Clover’s cyanide-doping genes are more common in warmer locations. So in Toronto, Thompson expected the elevated temperatures typical of cities to mean more bitter clover downtown than toward the outskirts. He was startled to find just the opposite. The results couldn’t be