Saturday, June 2, 2012

Observing the dynamics of a collapsing ecosystem

I think I heard a distinguished mathematical ecologist claim that there are very few actual systems which do behave like the simple textbook models.
Hence, I was very interested to see in Science this week a really nice experimental paper

Generic Indicators for Loss of Resilience Before a Tipping Point Leading to Population Collapse 
by Lei Dai, Daan Vorselen, Kirill S. Korolev, and Jeff Gore
Theory predicts that the approach of catastrophic thresholds in natural systems (e.g., ecosystems, the climate) may result in an increasingly slow recovery from small perturbations, a phenomenon called critical slowing down. We used replicate laboratory populations of the budding yeast Saccharomyces cerevisiae for direct observation of critical slowing down before population collapse. We mapped the bifurcation diagram experimentally and found that the populations became more vulnerable to disturbance closer to the tipping point. Fluctuations of population density increased in size and duration near the tipping point, in agreement with the theory.
Our results suggest that indicators of critical slowing down can provide advance warning of catastrophic thresholds and loss of resilience in a variety of dynamical systems.
Below is the "phase diagram" of the model.
It is interesting that the work was done in a Physics department.

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