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Kronauer studies social evolution and behavior within complex societies. The sophisticated behavior, communication, and division of labor within ant colonies make these social insects ideal model systems for this work. His lab uses an integrative approach to understand how natural selection shapes the evolution of insect societies and how social life is regulated at the level of genes, brains, individuals, and colonies.

Insect societies are socially integrated to such an extent that they are often portrayed as “superorganisms,” in which different morphological or behavioral castes have different functions and coordinate their actions, similar to the cells and tissues of an organism. The Kronauer lab uses ants to study how complex animal societies evolved from solitary ancestors, and the molecular mechanisms controlling caste development and division of labor. The group also explores how ants produce, perceive, and process social signals, and how the composition and network structure of social groups affects group-level properties and fitness.

The lab uses molecular genetics and neuroscience in combination with quantitative behavioral and morphological measurements under controlled laboratory conditions. In particular, the researchers are developing and using the clonal raider ant Ooceraea biroi as a new model system for social behavioral genetics. The clonal raider ant is a powerful model system because it uniquely combines the rich biology of social insects with unparalleled experimental accessibility. The unusual biology of this species makes it possible for Kronauer’s team to control and replicate the size, genetic composition, and age structure of colonies—three central factors affecting individual behavior, division of labor, and social networks in ants. The team has sequenced the species’ genome and has developed protocols for genome editing, along with automated tracking setups that allow precise quantification of individual and group behavior.

The lab’s recent results reveal that a massive expansion in odorant receptors allows ants to perceive the many chemical cues they use to communicate, and that genetic ablation of these receptors results in the collapse of ant societies. Kronauer’s team has also found that insulin signaling regulates reproductive activity in response to social signals, suggesting a molecular mechanism for the evolution of reproductive division of labor and ant sociality. Finally, the lab has shown that behavioral division of labor and improved colony performance emerge automatically with increasing group size, identifying some of the factors that make sociality adaptive. They also found that changes in group size underlie changes in group behavior in various other contexts, from foraging to collective decision making. Finally, they recently discovered that a novel type of social fluid creates dependencies across different ant developmental stages, thereby acting as a glue for the colony’s social fabric.

Lately, the lab has been studying how genetic factors and the nervous system contribute to behavior, with the ultimate aim to understand how ants communicate and assume different behavioral roles at the level of the brain, and how these interactions translate into emergent properties at the group-level. These insights will inform our understanding of how social behavior evolves and is regulated.

Kronauer is a faculty member in the David Rockefeller Graduate Program and the Tri-Institutional M.D.-Ph.D. Program.