The social amoeba Dictyostelium discoideum can farm symbiotic bacteria for food by carrying them from generation to generation. New research shows that these bacteria can also protect the amoeba from environmental toxins.
Some wild clones of social amoebas farm the bacteria they eat, but this is a losing strategy if nonfarming amoebas can steal the farmers’ crops. To make the strategy work, the farmers also carry bacteria that secrete chemicals that poison free riders. The work suggest farming is complex evolutionary adaptation that requires additional strategies, such as recruiting third parties, to effectively defend and privatize the crops, the Washington University in St. Louis scientists say.