Washington, Oct 12 (Inditop.com) Cheaters may prosper in the short term, but they are doomed to fail, at least in the microscopic world of amoebas, say researchers.
But why? Shouldn’t “survival of the fittest” give the sneaky cheaters an edge? Not necessarily, say researchers. It turns out amoebas that cooperate for the benefit of all – and even die for the cause – bring their own genetic weapons to the fight.
Rice University and Baylor College of Medicine (BCM) researchers are peeling back the layers of strategy that determine how colonies of social amoebas resist the efforts of cheaters to alter the balance of power.
Rice University’s evolutionary biologists Joan Strassmann and David Queller joined forces with BCM geneticist Gad Shaulsky to determine how altruistic mutants help preserve cooperative behaviour by single-celled amoebas.
They found amoebas that thrive on rotting vegetation in forest soil mutate to keep “cheaters” at bay, forcing them out of the reproductive chain.
Amoebas fascinate researchers because so many of them willingly give up their lives to save others – a characteristic seen at all rungs on the ladder of life, but only recently studied at the genetic level.
Commonly known as slime moulds, these amoebas are not slimy, neither are they moulds. They are independent, bacteria-munching creatures that live alone until the food at a particular location runs out.
When that happens, thousands of amoebas clump into a slug and move as a unit towards heat and light – signposts for food.
When they reach their destination, amoebas at the front of the slug sacrifice themselves, turning into a dead, cellulose stalk. The rest of the amoebas pile on, combining to produce spores that sit precariously atop the stalk until wind, insects or other outside forces can carry them to a better place. The whole construct, known as a fruiting body, looks like a tiny balloon on a string.
However, during the journey some amoeba do their best to stay in the back of the slug, thus avoiding the fate of the 20 percent of colony-dwellers that die for the collective good.
The cheaters quite happily take General George S. Patton’s advice to heart: Good soldiers don’t die for their country, they make others die for theirs.
By that logic, the researchers noted the cheaters should dominate. But altruistic amoebas – at least those that survive – seem to know when there’s a fink in the ranks, and draw upon weapons in their genetic code to keep cheaters at bay.
The findings appeared in PLoS One.
