Have you heard about this? The harsh spotlight of agricultural fame has been taken off the social insects by the paper in Nature last month. It turns out that amoebae of the species Dictyostelium discoideum treat their food bacteria like leafcutter ants treat the fungi they eat. In fact, the single-celled wonders might be called “farmers.”
Did you know there were social amoebae? When levels of their “prey bacteria” get low, the amoebae gather together to form what is called a migrating slug (see video below). The clustered amoebae move a certain distance, and then form a towering fruiting body, with a thin stalk supporting a round sorus at the top. The cells within the sorus form spores, which disperse.
Be patient for the first 30 seconds of the video. The amoebae have been deprived off food. It takes a bit of time, but then they form the slug. I wonder if the stragglers that try to catch up to the main slug should be called “sluglets?” 🙂 (You’ll see what I’m talking about.)
When the “farmer” amoebae are ready to disperse, rather than eating absolutely all the bacteria available to them, they leave some. The bacteria are incorporated into the amoebae, into the slug, and carried via spores to the new area. Once at a suitable location to grow, the farmers “seed” the area with the bacteria, thus ensuring a certain food supply.
Non-farming clones of the same species of amoeba, on the other hand, consume all of the bacteria in the original area. Whether there will be food where their spores land is left to chance.
A fascinating species. And thanks to SN for bringing this to my attention,
Brock, D.A., T.E. Douglas, D.C. Queller, and J.E. Strassmann. (2011). Primitive agriculture in a social amoeba. Nature. 469: 393-396.