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Evolution to the rescue

From Nature’s Research Highlights:

Environmental degradation threatens to wipe out countless species unless natural selection can help them to adapt fast enough to fend off ultimate doom — a process known as ‘evolutionary rescue’.

Theory predicts that large populations are necessary to keep extinction at bay, but the mathematical models had never been tested. Graham Bell and Andrew Gonzalez of McGill University in Montreal, Canada, (Bell and Gonzalez, Ecol. Lett., 2009)exposed hundreds of populations of baker’s yeast (Saccharomyces cerevisiae) to deadly salt concentrations. Consistent with prediction, the microbial populations crashed before rapidly bouncing back, and recovery occurred only when the population had started out above a threshold size.