Germinators: Amoeba Farmers and Other Organisms That Grow Their Own Food [Slide Show]
New research shows how a social slime mold species seeds its own food, giving ants, termites and other fungal harvesters steep competition for surprising agriculture adaptations
Credits: SCOTT SOLOMON
TERMITES Although human's agricultural technology might have surged ahead of other farming organisms in the 10,000 years it has been around, some termites have been cultivating fungus species for tens of millions of years. During that time, the fungi species have had an extended period to become a particularly fine-tuned cultivar. A 2009 study found that African
Termitomyces mushrooms, which were likely domesticated by termites some 30 million years ago, have adapted to have only one genotype per termite colony, so that spores gathered from different sources would not compete as they grow into mushrooms on top of termite mounds. WIKIMEDIA COMMONS
ANTS Some ant species are colonized by a parasitic fungus that turns them into zombie vehicles for spore dispersal. But dozens of ant species have arrived at a more harmonious relationship with various fungal species. Perhaps the most well-known examples, leaf-cutter ants (of the genera
Acromyrmex and Atta), actively maintain colonies of Lepiotaceae family fungus by both supplying it with fresh-cut leaves and clearing out mold. "They're really fascinating," Brock says of ant farmers. WIKIMEDIA COMMONS
BEETLES "Insects were farming way before humans," says Debra Brock, a graduate researcher at Rice University's Department of Ecology and Evolutionary Biology. Ambrosia beetles cultivate their fungal food on trees. When they land on a tree, the beetles deposit spores of the ambrosia fungi, which helps to transform the tree's wood into nutrient-rich food that is eaten by the beetle offspring's larvae.
DAMSEL FISH Some fish are particularly picky eaters, and one species of damselfish (
Stegastes nigricans) has been found to help their preferred food, the Polysiphonia alga, grow by weeding out competing species of algae. "Because this alga is highly susceptible to grazing and is competitively inferior to other algae, it survives only within the protective territories of this fish species, suggesting an obligate mutualism between damselfish and their cultivated alga," the authors of a 2010 study on the relationship concluded. WIKIMEDIA COMMONS Advertisement
SNAILS To a casual observer, the marsh periwinkle (
Littoraria irrorata) marine snail might seem to be feeding on marsh grass as it glides over the surface. But researchers reported in 2003 that this snail is actually engaging in a "facultative, farming mutualism," according to their study. The snails instead seem to be making the grass surface more appealing for invasive fungus, which the snail then consumes. WIKIMEDIA COMMONS
SOCIAL AMOEBA Some lines of the social amoeba species
Dictyostelium discoideum have recently been found to carry out a primitive form of farming. Rather than eating all of their bacterial food supply like most of their species, the farming single-celled organisms start their aggregation phase before food has run out. Taking bits of bacteria with them as they coalesce into slug form, the amoebae then transport their nutritional source to a new habitat and "seed" it along with their own spores. SCOTT SOLOMON Advertisement Expertise. Insights. Illumination.
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