DOI
10.1038/nature07921

Summary

In this paper the game theory model of “snowdrift” is applied to Saccharomyces cerevisiae, used as a model for animal cooperation and competition. For the budding yeast Saccharomyces cerevisiae to grow on sucrose, the disaccharide must first be hydrolysed by the enzyme invertase. This hydrolysis reaction is performed outside the cytoplasm. In this paper the author demonstrated that the vast majority of the monosaccharides created by sucrose hydrolysis diffuse away before they can be imported into the cell, serving to make invertase production and secretion a cooperative behaviour. A mutant “cheater” strain that does not produce invertase is able to take advantage of and invade a population of wild-type cooperator cells. The experimental observation of coexistence between cooperator and cheater strains in a well-mixed environment makes sucrose metabolism in yeast a particularly clear example of the snowdrift game. A model of the cooperative interaction incorporating nonlinear benefits explains the origin of this coexistence.

Relevance for Complex Systems Knowledge
In this paper is possible to observe how a purely theoretical and mathematical model can accurately explain microbial behavior and the complex interactions between organisms than could not be explained otherwise.

Point of Strength
The point of strength of this paper is that the author chose a commonly used model organism (S. cerevisiae), and used the game theory approach to study one of its metabolic pathways.