Social insects and social amoebae. - Centre for Ecological Sciences

Social insects and social amoebae 233,-"c ":"'cFigure 6. Dicl)'o.flelium and AcYlo.flelium compared. Semidiagramatic drawings of saggitalsections through the rising cell masses. In AC)'lo.fleliuln (left) all the cells secrete thenon-cellular stalk and then each one turns into a spore. In Diclyo.fleliuln (right) the anteriorcells foml the stalk by first secreting the sheath and then entering at the tip by a "reversefountain" movement. Once insidc, the cells swell and die. The remaining posterior cellsfonn spores. (Diclyo.flelium species are larger than those ~f Acylo.flelium. In order tocompare them, a small Diclyo,flelium is placed alongside a large Acylo.flelium.) FromBonner (1988).It is conceivable that the most significant factor that has driven solitary amoebaeto become social is dispersal (Bonner 1982, ] 988), There is good reason to believethat this has a potent selective force in soil microorganisms, Amoebae feed onbacteria, and their distribution in the soil is bound to be patchy because thedistribution of decaying vegetables or animal matter will be patchy, depending onwhere a beetle died, or where animal droppings fell. If a patch of bacterial foodis discovered by an amoeba, then soon, amongst the rich food, it will proliferate