ScienceDaily   — The mere presence of a predator causes enough stress to kill a dragonfly, even when the predator cannot actually get at its prey to eat it, say biologists at the University of Toronto. "How prey respond to the fear of being eaten is an important topic in ecology, and we've learned a great deal about how these responses affect predator and prey interactions," says Professor Locke Rowe, chair of the Department of Ecology and Evolutionary Biology (EEB) and co-principal investigator of a study conducted at U of T's Koffler Scientific Reserve. "As we learn more about how animals respond to stressful conditions -- whether it's the presence of predators or stresses from other natural or human-caused disruptions -- we increasingly find that stress brings a greater risk of death, presumably from things such as infections that normally wouldn't kill them," says Rowe. Shannon McCauley, a post-doctoral fellow, and EEB professo...