New research shows that the loss of biodiversity can increase the risk of “extinction cascades”, where an initial species loss leads to a domino effect of further extinctions.
The researchers, from the University of Exeter, showed there is a higher risk of extinction cascades when other species are not present to fill the “gap” created by the loss of a species.
Even if the loss of one species does not directly cause knock-on extinctions, the study shows that this leads to simpler ecological communities that are at greater risk of “run-away extinction cascades” with the potential loss of many species. The study is published ahead of print on 21 February in the journal Proceedings of the National Academy of Sciences.
With extinction rates at their highest levels ever and numerous species under threat due to human activity, the findings are a further warning about the consequences of eroding biodiversity.
“Interactions between species are important for stability,” said Dr Dirk Sanders, of the Centre for Ecology and Conservation at the University of Exeter. “And because species are interconnected through multiple interactions, an impact on one species can affect others as well.
Dr Dirk Sanders, lead author, Centre for Ecology & Conservation and Environment and Sustainability Institute, College of Life and Environmental Sciences, University of Exeter, Cornwall, United Kingdom
“It has been predicted that more complex food webs will be less vulnerable to extinction cascades because there is a greater chance that other species can step in and buffer against the effects of species loss,” Sanders added.
“In our experiment, we used communities of plants and insects to test this prediction.”
The researchers removed one species of wasp and found that it led to secondary extinctions of other, indirectly linked, species at the same level of the food web. This effect was much stronger in simple communities than for the same species within a more complex food web.
How extinction cascades work
The loss of a predator can initiate a cascade, such as in the case of wolves, where their extinction on one mountain can cause a large rise in the number of deer. This larger number of deer then eats more plant material than they would have before. This reduction in vegetation can cause extinctions in any species that also relies on the plants, but are potentially less competitive, such as rabbits or insects.
(Source: University of Exeter new release, 19.02.2018)