The extinction of one carnivore species can have a ripple effect across fellow predators, triggering further unexpected knock-on effects on other species, according to a new study.
Conservation biologists from the University of Exeter in the United Kingdom, writing in the journal Current Biology, backed previously held notions and research that demonstrate horizontal extinction cascades.
The research team out of the Centre for Ecology and Conservation at the university used insects - species of aphids and their natural foes, parasitoid wasps - and established experimental communities in 40 four-square-meter field cages outdoors, observing them over spring and summer.
The findings: annihilating one wasp species led to a higher extinction rate in other wasp species, an outcome occurring through shifts in density of the aphid groups.
Once one wasp species was wiped out, its aphid-prey grew in count, crowding out others and giving other wasp species a tough time in locating their specific food sources. This eventually led to the extinction of species hard up for food, the researchers explained.
Study author Dr. Dirk Sanders, associate research fellow at the center, highlighted it as a unique experiment and the first time the workings of horizontal extinction cascades was probed in a large natural setting.
"Usually these research questions are tackled with theoretical approaches and researchers focus on extinctions after the loss of food species," Dr. Sanders observed.
The said extinction cascades, he explained, were typically considered a major biodiversity thread, but that data is difficult to obtain due to varying influences.
The findings are believed to be helpful for researchers in the conservation scene, encouraging the use of a whole system approach that includes looking not just a single species but its fellow ones as well.
About 2,000 animal and plant species are estimated to become extinct each year, without countless conservation initiatives trying to address the problem.
Earlier this year, scientists declared that the planet is, in fact, entering its sixth mass extinction event, threatening a catastrophic loss of animal species and humanity's survival. Many biodiversity benefits, for instance, are expected to be lost within three generations at the current rate that species are disappearing.
"If we want to protect an endangered carnivore species, for example, we might need to protect other predators around it, which is quite an important message," Dr. Sanders said.
Photo: Martin Cooper | Flickr
