Social amoebae have evolved resistance to cheaters, which makes sure that the amoebae work together for the good of the group, say scientists published in Nature last week.
Social amoebae, such as Dictyostelium, co-operate together to form multicellular, fruiting bodies when they reproduce. However, as always some try to cheat the system and reap the benefits without any of the costs, in this case getting more of their fair share of spores into the fruiting bodies than the other Dictyostelium. Cheats must pay though, with lower fitness and can be discriminated against by the other amoebae.
The scientists randomly mutated a group of Dictyostelium and then mixed them with a strain of cheating amoebae (called cheater C). Most of the mutant amoebae got cheated on by the cheater C’s, and died out. However, during this process cheater-resistant strains evolved (called resistant to cheater C), and started to grow. The resistant strains turned out to be noble amoebae, they didn’t take advantage of the weaker mutant strains that had already been bullied by the cheater C’s. The evolution of cheater-resistant strains helps preserve co-operative behaviour in the social amoebae and reduces the number of cheaters in a population. So the moral of this story is…..cheats don’t always prosper and sometimes it is better to work together for the good of society.