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 professors Marie-Josée Fortin and Rowe raised juvenile dragonfly larvae (Leucorrhinia intacta) in aquariums or tanks along with their predators. The two groups were separated so that while the dragonflies could see and smell their predators, the predators could not actually eat them.
"What we found was unexpected -- more of the dragonflies died when predators shared their habitat," says Rowe. Larvae exposed to predatory fish or aquatic insects had survival rates 2.5 to 4.3 times less than those not exposed.
On the edge: Disease and habitat loss is decimating wild amphibian populations globally, with more than 200 species needing urgent intervention through captive breeding, says Dr. Simon Clulow. In a south-eastern suburb in Melbourne, there’s a zoo. It has no visitors, and there are no animals anywhere inside it. Rather, the Australian Frozen Zoo houses living cells and genetic material from Australian native and rare and exotic species. This place, and others like it, could be a big part of the future of conservation. Department of Biological Sciences’ Simon Clulow and his colleagues make the case for ‘biobanking’ in a recent piece in Conservation Letters. Clulow is keen to stress that this doesn’t mean getting rid of conventional zoos or captive breeding programs. “Captive breeding has had some wonderful successes, and there will always be a huge place for it,” he says. PhD student and lead author Lachlan Howell agrees. “It was captive breeding that brought the giant panda back from
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