Costs of resistance limit the effectiveness of cooperation enforcement in social amoebae

Cooperative groups face a dilemma, in that some individuals gain social benefits without payingthe costs, termed cheating. One possibility is that cheating can be countered by genetic changesto suppress or resist it. To test the effectiveness of this mechanism, we evolved strains of thesocial amoeba Dictyostelium that resist cheating. We found that resistance evolved readily, butadaptation to one cheater left strains less well-adapted to other cheaters. To assess the genetic basis of cheater resistance, we used Illumina whole genome sequencing to identify mutations in a single isolate from each evolved line.