This stacking image of the ant, Leptothorax acervorum carrying won honorable mention in the 2014 Nikon Small World competition. Leptothorax acervorum is a model system used to study ant colonies with multiple queens. Female reproductives leave the nest and mate with males from other nests. A successful mated queen will typically follow one of two options. She will drop to the ground near her home nest and hope to be “adopted”. Adopted queens are carried into the nest by workers. Alternatively the a mated queen can disperse to initiate a new colony. The success rate of new colony initiation is low.
Scientists have asked, “Why has sociality evolved many times in the Hymenoptera. One answer proposes that genetic relatedness is key. Male Hymenoptera have only one set of chromosomes. Every female progeny of the male with a single queen will be on average 3/4 genetically identical. The half of their genes that come from the male are 100% identical. The half of the genes that come from the queen are 50% identical. Thus, sociality may be genetically favorable because workers would benefit more from raising sisters (which are 3/4 identical) than raising their own offspring which would share only 50% identity. When societies such as Leptothorax acervorum have multiple queens, this answer no longer applies because the relatedness of sisters is less than half on average. Leptothorax acervorum is studied as a model of a society with low relatedness of workes.