Thursday, September 16, 2010

yeast banksters....,

The Scientist | Yeast colonies with mooches, thieves and cheats actually grow faster and larger than colonies without these freeloading individuals, according to a study published 15th September in PLoS Biology, challenging the widely held belief that cheaters bring only bad news to cooperating populations.

Researchers found that when some yeast cheat their neighbors out of glucose, the entire population grows faster. "This is a most surprising result," said Laurence Hurst of the University of Bath in the UK, who coauthored the study. "The theory of cooperation was one of the best worked theories in all of evolution. Everyone assumed that it had to be the case that the world is better off when everyone cooperates."

The results may explain why yeast populations tolerate the presence of cheaters, added Michael Travisano, a biologist at the University of Minnesota, who was not involved in the research -- "because a mixed strategy is to everyone's benefit."

Most yeast secrete invertase, which hydrolyzes sucrose into fructose and glucose, their preferred food. However, some yeast are known to cheat the system. Cheater yeast don't secrete invertase and therefore don't contribute to the glucose production, yet they still eat the glucose that is generated by the rest of the population.

According to the theory of cooperation, which states that organisms are better off when everyone cooperates, yeast populations should be best off when all the yeast produce invertase. This would maximize the availability of glucose, which should enable more yeast growth. But when Hurst and his colleagues grew yeast populations with both producers and non-producers of invertase, this is not what they saw. Instead, the yeast grew the fastest and saw the highest population numbers when a proportion of the population was cheating.