Model shows how even thriving species can go extinct

By Dana Kobilinsky

Leatherback sea turtles (Dermochelys coriacea) like this one are among the most endangered species in the world, but recent research suggests that even large populations are at risk from extinction when environmental fluctuations such as drought occur. ©USFWS

Physicists may not be the scientists you’d expect to tackle conservation issues, but a group of them recently used modeling technique to show how species — even ones that are thriving— may be vulnerable to extinction.

In a new study published in the European Physical Journal B, a team of researchers determined how fluctuations in environmental factors like water supply and temperature could impact wildlife populations.

The team, including lead author Thomas Vojta, a physics professor at Missouri University of Science and Technology, used a computational model that looked at the behavior of a biological population over many generations. They determined how fluctuations in the environment affected factors such as procreation and competition for resources — factors that can cause populations to become extinct.

“What we have is an abstract model that describes broad trends in behavior,” Vojta said. “If we want to apply this to a particular species, we need much more biological information on the species.”

Using the model, Vojta and his colleagues found that environmental disturbances, such as a few years of drought or unusually high temperatures, could cause enormous variations in population size and eventually lead to sudden population collapses, even in populations that started with high numbers. The team also found that environmental fluctuations make extinction much more likely.

People might think large populations would be more resilient to these environmental changes, Vojta said, but their model showed that populations that seem to be thriving “can still be killed off by a chain of ecological bad years.”

While it might be difficult to predict exactly if and when these environmental fluctuations occur, Vojta said, scientists can understand the probability of events like droughts occurring and adjust conservation efforts accordingly.

“We need to be extremely cautious in looking at a population over a short amount of time and concluding that the population is doing OK,” he said. “Even if a population has been stable for extended periods, it doesn’t meant that it’s really going to be OK in the future.”

Dana KobilinskyDana Kobilinsky is a science writer at The Wildlife Society. Contact her at dkobilinsky@wildlife.org with any questions or comments about her article. You can follow her on Twitter at @DanaKobi.

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