Extrapolating lab study on yeast: species may evolve around deadly environmental change within 50-100 generations

If however survival conditions are optimal, like a gradual increase of the environmental stressor, ‘modest’ inter-population contact – and indeed if such extrapolation from a microorganism to a blue whale would be as legitimate as the researchers in their Science publication risk to suggest.

By closely monitoring and comparing the fate of 2000 populations of baker´s yeast two biologists from the Canadian McGill University conclude that evolution may – under above-mentioned ideal circumstances – outpace environmental change to prevent extinction: “Adaptation was surprisingly frequent and rapid in small peripheral populations.”

We recently reported on rather more pessimistic new findings, published in Proceedings of the Royal Society B, that indicate organisms may have genetic boundaries that form a natural limit to the amount of environmental change that ‘quick evolution’ can buffer. In this study the stressor was temperature rise, and the maximum tolerance among different populations of a specific copepod was found to be as small as +0.5 degrees Celsius.

In the Science study the stressor was an increase of salt to the yeast environment. The real world environmental problems of modern times – which culminate in the biodiversity crisis and a possible sixth mass extinction – are usually not caused by a gradual increase of one single environmental stressor, but rather many parallel ones, which may cause synergistic damage and which would require a multidimensional evolutionary response.

Besides, for many larger species, the changes that are currently happening within this perhaps maximum evolution speed of 50 to 100 generations may already be too much to survive – we would after all still be talking a timeframe of centuries. And many large species have fewer populations to play around with in this planetary-scale experiment than these two Canadian researchers had yeast colonies in their Quebec laboratory.

© Rolf Schuttenhelm | www.bitsofscience.org

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