Ants farm root aphid clones in subterranean rooms.
The yellow meadow ant, Lasius flavus, farms root aphids for sugar (honeydew) and nitrogen (protein). In turn these species of aphids have developed distinctive traits never found in free living species such as the 'trophobiotic organ' to hold honey dew for the ants. New research published in BioMed Central's open access journal BMC Evolutionary Biology shows that over half of ant mounds contained only one of the three most common species of aphid, and two thirds of these has a single aphid clone. Even in mounds which contained more than one species of aphid 95% of the aphid chambers contained individuals of a single clone.
Aphid farming by ants is considered to be mutualistic. The ants cultivate and protect the aphids which in turn provide food for the ants. In farming mutualism, monocultures may reduce competition and are perhaps the result of husbandry (caused by the ants selecting the best aphids for their needs).
Researchers from the University of Copenhagen, University of Groningen and Rockefeller University used DNA microsatellite analysis to look at the genetic similarity of the three most common species of root aphids (Geoica utricularia, Tetraneura ulmi, and Forda marginata) within L. flavus nests, soil samples within nests, and single aphid chambers.