by Emily Greenhalgh
From the Dodo bird to the Chinese river dolphin, loss of environment, often from human interference, has left a slew of endangered and extinct species on planet Earth. Very often, this extinction occurs before humans have enough warning to do anything about it.
But what if scientists could predict when a species was in danger of reaching extinction in time to do something to change it?
John M. Drake, PhD from the University of Georgia and Blaine D. Griffen, PhD from the University of South Carolina released their research in this month’s Nature that has the potential to do just that. The paper focuses on populations of water fleas (Daphnia magna) in the lab that are put under environmental stress until they reach a point from which the populations cannot recover. This is known as the tipping point.
The scientists put the fleas under stress by decreasing their food supply over a period of 416 days. They compared those populations with populations that were well fed and unstressed. The results allowed scientists to model a phenomenon known as “critical slowing down,” (CSD), something previously never studied within biological environments. Drake and Griffen saw that when a population approaches its tipping point, it takes a long time to recover from even a small disturbance.
Over the course of the experiment, the test group went extinct. The well-fed control group never reached a tipping point, but instead stayed healthy. The scientists found that by looking at a variety of indicators, such as randomness of distribution and skewness within the population, they could detect when a population was going to reach CSD and therefore predict its tipping point.
Using their indicators, the researchers saw evidence of the approaching tipping point of populations as early as eight generations before it happened -- five generations sooner than ecologists conventionally can report.
Of course, the field of biology is an ever evolving and complex science, and even Drake points out that “nature is a bit more complicated than the lab.” Yet he still believes that using early warning indicators to predict tipping points in ecosystems could eventually become a valuable conservation tool. One he hopes will be used by the International Union for the Conservation of Nature (IUCN) in determining and protecting endangered species.
The idea for searching for CSD within a threatened population is good, but its not a major leap. Dr. Christopher Schneider, Assistant Director for Boston University’s Center of Ecology and Conservation Biology says that while searching for indicators of CSD “wouldn’t be a criteria that [the IUCN] could put across the board,” the required baseline data does exist for some taxa.
With continued practical research, scientists may be able to detect threatened populations far enough in advance of their tipping point that they never fall over the edge and into extinction.
