Cool. And Hot!

Bacteria adapt to sun irradiation by altering cell membranes.

'Evolution Canyons' I and II are in Israel. They are similar, each with a hot south-facing slope and a cooler north-facing slope. The sun-exposed 'African' south-facing slopes get eight times more solar radiation than the shady, green, lush 'European' north-facing slopes. Scientists studied 131 strains of Bacillus simplex and found that bacteria on different slopes have evolved differently, forming different 'ecotypes' of the same species.

How did they do it?

"Bacteria respond to temperature by altering their fatty acid composition in a constitutive, long-term fashion," said Dr Sikorski. We found that 'African' ecotypes from the hot slopes had more heat-tolerant fatty acids and 'European' ecotypes from the cool slopes had more cold-tolerant fatty acids in their membranes."