How do biological systems develop and how are they influenced by genetic and environmental cues? Early Independence Awardee, Dr. Waring “Buck” Trible, explored these questions using ants. Ants make a good species to study this question because they develop into distinct classes depending on the genetic and environmental cues they receive. Using this system, the group was able to identify a novel supergene that gave ants that would normally be workers, queen-like traits. Supergenes represent a relatively unexplored area of genetics that consist of a set of genes within a single chromosomal region which are inherited as one and function together to create complex traits.
Ants typically have two types of females– queens and workers. These distinct classes differ in their size, presence or absence of wings, and social behavior. Some ants, like those used for this study (Ooceraea biroi), have evolved to produce only female worker ants from a single parent that are mostly genetically identical to each other and do not have queens. However, Dr. Trible and colleagues identified ants from a line of these worker clones that have reacquired queen-like properties. These ‘queen-like mutant’ (QLM) ants developed wings and functioned as a social parasite exploiting the other worker ants for childcare, foraging, and general support. Researchers sought to determine how these complex social and developmental traits of the QLM ants arose.
The team evaluated environmental, social, and genetic factors in the ants and determined that genetic differences were driving the QLM behavioral traits. In addition, they found that the characteristics observed were not those of a true queen ant, but a new ant type resembling both queen and worker. They identified a large region on one of the ant’s chromosomes, or genetic material, that differed between the QLM ants and their worker-like relatives. The genetic difference originated recently in evolution and likely in the span of a single generation. They speculated that this region contains a supergene responsible for the queen-like development and social behavior observed. The properties identified in the QLM ants support the idea of a novel supergene and provide evidence for how a single mutation within a supergene region could enable rapid evolution. While humans are not likely to have a QLM supergene, understanding how supergenes arise, function, and impact biological systems could provide valuable insights into human biology, development, and disease.
Reference: Trible W, Chandra V, Lacy KD, Limón G, McKenzie SK, Olivos-Cisneros L, Arsenault SV, Kronauer DJC. A caste differentiation mutant elucidates the evolution of socially parasitic ants. Curr Biol. 2023 Mar 27;33(6):1047-1058.e4. doi: 10.1016/j.cub.2023.01.067. Epub 2023 Feb 28. PMID: 36858043; PMCID: PMC10050096.