To explain this kind of collapse, ecologists have long theorized that populations suffering a decline in environmental conditions (such as overfishing) appear stable until they reach a tipping point where the population plummets. Recovery from such collapses is nearly impossible.
“This is thought to underlie lots of sudden transitions — in populations, ecosystems or climate regime shifts,” says Jeff Gore, an assistant professor of physics at MIT.
Gore and his students have now offered the first experimental validation of this theory. They showed that in populations of yeast subject to increasingly stressful conditions, populations became less and less resilient to new disturbances until they reached a tipping point at which any small disruption could wipe out a population.
“In the wild, you do see things change suddenly, and this model is a reasonable explanation, but it’s very hard to prove that this is happening,” Gore says. “This is the kind of thing we can do in the laboratory that you can’t do in the wild.”