Breakthrough could aid extinction prevention
Declining species in deteriorating habitats become extinct, almost inevitably, after reaching a “tipping point” in their demise, but a researcher at the University of South Carolina and his partner have found a way of predicting that elusive point, which could lead to improved measures of protection.
A paper in this week’s journal Nature demonstrates that the approach of the tipping point can be predicted using simple signatures in the dynamics of declining populations, such as changes in the variation and symmetry of the species.
Blaine Griffen, assistant professor of marine science and biology at USC, and John Drake of the University of Georgia, used zooplankton to detect subtle fluctuations in a population that can provide early warning signals for extinction. Anticipating those tipping points in time to act preventatively has remained elusive.
Their experiment imposed deteriorating environmental conditions over several months on laboratory populations of the small, freshwater plankton, daphnia magna. They followed the populations throughout this time and documented “critical slowing down,” a phenomenon found in physics, but which also may be used to develop new techniques for assessing the viability of populations, the researchers reported.
“As the environment deteriorated, a population would cross a tipping point, after which it quickly declined to extinction,” Griffen said. “Our goal was to use simple population patterns to predict the approach of this tipping point. If we can predict it far enough in advance, we may be able to act preventatively to reduce the risk of extinction before it is too late.”
The researchers were able to get a lead time of eight generations of warning that a population was in serious trouble, he said. The findings are significant because of the large numbers of species currently at risk of extinction due to environmental degradation.
“There is good evidence that we are currently experiencing the Earth’s sixth major extinction event,” Griffen said. “It appears to be an accelerating process, and we need to slow it down and prevent it whenever possible. One of the keys to doing that is understanding the process enough to predict it. With so many extinctions, we’ve been able to document the process, but by then it’s too late.”