The 'tragedy of the commons' holds that cheaters have an advantage over cooperators because cheaters benefit from common goods without contributing to them. Studies in yeast suggest a new mechanism to avert such a tragedy.
Adam James Waite and Wenying Shou of the Fred Hutchinson Cancer Research Center in Seattle, Washington, started cultures that had equal amounts of three yeast strains: one that produced adenine and required lysine; another that produced lysine and required adenine, and a third, 'cheating' strain, which required lysine but did not supply any nutrients.
Contrary to expectations, 'cooperative' strains dominated in some cultures, and could occasionally drive cheaters to extinction. Genome sequencing revealed that the dominating strains had adapted to their new environment by accumulating mutations that improved nutrient transport. When these mutations arose in cooperative strains and compensated for the cost of cooperation, the cheaters were outcompeted.
Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1210190109 (2012)