Study Demonstrates That One Extinction Leads to Another

http://www.sciencedaily.com/releases/2012/08/120814213500.htm

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A parasitic wasp attacks an aphid in the first study to prove the theory that the extinction of one predator can lead to the extinction of another. (Credit: Dirk Sanders)

ScienceDaily (Aug. 14, 2012) — When a carnivore becomes extinct, other predatory species could soon follow, according to new research. Scientists have previously put forward this theory, but a University of Exeter team has now carried out the first experiment to prove it.

Published August 15, 2012 in the Royal Society journal Biology Letters, the study shows how the demise of one carnivore species can indirectly cause another to become extinct. The University of Exeter team believes any extinction can create a ripple effect across a food web, with far-reaching consequences for many other animals.

The research adds weight to growing evidence that a 'single species' approach to conservation, for example in fisheries management, is misguided. Instead the focus needs to be holistic, encompassing species across an entire ecosystem.

The researchers bred two species of parasitic wasps, along with the two types of aphids on which each wasp exclusively feeds. They set up tanks with different combinations of the species and observed them for eight weeks. In tanks that did not include the first species of wasp, the second went extinct within a few generations. In tanks in which they co-existed, both wasp species thrived.