Genetic diversity decreased over time. Genetic diversity (H') decreased significantly over the course of the selection experiment. After one social generation, genetic diversity was high both at high and low relatedness with a small but significant difference between high and low relatedness populations. Over the course of the selection experiment genetic diversity decreased significantly more at high relatedness. Genetic diversity was measured as Shannon's Index of Diversity (H') and scaled to the maximum H' possible for eight strains (where pi = 1/8). Bars represent the mean of twelve populations with 95% CI. The numbers in the bars indicate the approximate numbers of vegetative generations (doublings) for each treatment after one and after 10 social generations.