Fig. 4.
Multicellular differentiating strains resist invasion by Cre− cheats. (A) Hypothesized evolutionary outcomes for novel nondifferentiating mutants (red) in unicellular (Top) and multicellular (Bottom) populations. Germ cells are blue and somatic cells are yellow. (B) Growth advantages of differentiating strains (unicellular: yMEW192, multicellular: yMEW208) relative to cheaters (unicellular: yMEW193, multicellular: yMEW209) in minimal media containing 150 nM cycloheximide. Error bars represent 95% CIs of mean growth advantages, determined using data obtained from three biological replicates. Growth advantages of the multicellular strain growing in sucrose minimal medium at 1, 3, and 10 nM β-estradiol are significantly greater than zero (P < 10−3, one-tailed t test); growth advantages of the unicellular strain growing in sucrose are significantly less than zero at all β-estradiol concentrations (P < 10−6, one-tailed t test).