Ant genomics sheds light on the molecular regulation of social organization

Abstract

Ants are powerful model systems for the study of cooperation and sociality. In this review, we discuss how recent advances in ant genomics have contributed to our understanding of the evolution and organization of insect societies at the molecular level.

Figure 1

Phylogeny of the extant Formicidae. The figure highlights the subfamilies containing species with sequenced genomes (in blue). The heights of triangles are proportional to the number of described species in each subfamily (also indicated in parentheses). Branch lengths are proportional to the estimated divergence. The colored squares below the names of the sequenced species (on the right) indicate whether their genomes have been used to investigate the six topics discussed in this review (only the genome papers and all non-review publications citing the genome papers were considered). (Figure adapted from [81].)

Figure 2

Diagram of a typical ant colony representing the six topics discussed in this review. (1) Morphological caste determination. In most ant species, a switch during larval development triggers alternative trajectories toward different female castes. Only the queen and one-worker caste are represented here, but some species also have different morphological worker castes. (2) Division of labor. Different groups of workers perform different tasks. Here, some workers nurse the brood inside the nest, whereas others forage for food outside. (3) Chemical communication. Ants rely on chemical communication for many aspects of their social organization. (4) Social immunity. Ants use both behavioral and physiological defenses to limit the transmission of pathogens and diseases in their societies. (5) Social structure. Ant species differ in the number of queens found in one nest, as well as the number of males that the queens mate with (not shown here). In some cases, these numbers vary between colonies of the same species. (6) Mutualism. Many ant species engage in mutualistic interactions with other organisms. Here, some ants tend and protect aphids in exchange for the sugary honeydew they produce.

Figure 3

Pie chart representing the publication volume associated with each topic discussed in this review since the publication of the seven ant genomes. The numbers correspond to the number of studies investigating each topic, including the original genome papers and all publications on social insects citing the genome papers (reviews excluded). The category 'other' incorporates studies of topics that were not discussed in this review (such as sex determination, aging, circadian rhythms, invasiveness, metabolism and neurobiology), as well as studies focusing on social insects but not in a sociobiological context.