The evolution of a social circulatory system


Our lab takes an integrative approach to understanding how socially exchanged fluids evolve and how they can be co-opted by evolution to influence physiology and behavior.

We use social insects as a model system because many (but not all!) social insects engage in the mouth-to-mouth fluid exchange behavior, trophallaxis. In species that do engage in this behavior, every individual in the colony is connected through this network of fluid exchange. The exchanged fluid is full of growth proteins, hormones, RNA and small molecules. Some of these components, when fed to larvae by trophallaxis, can influence development!

This provides a means for how social insect communities can collectively decide on the colony’s developmental progression by transmitted cues and signals over the social circulatory system. 


  • Evolution of a social fluid

    Socially exchanged fluids like milk and seminal fluid are hotbeds of evolutionary innovation. They provide a private communication channel to influence members of the same species!

    In social insects that engage in trophallaxis, we’ve shown that the contents of trophallactic fluid, when fed to larvae, can influence their development.

    By pairing proteomics, behavioral observations and bioinformatic tools, we harness the variation present across different forms of social insects to see how the trophallactic fluid has evolved over different natural histories, different colony types, and different modes of caste determination.

  • What (who) controls larval development?

    How do communities regulate their own growth and development? An ant colony rearing new workers has different rearing goals throughout the colony’s lifetime. A founding colony needs to rear many new workers quickly with few resources, while a mature colony will invest more in fewer individuals, splitting the colony’s effort between rearing new queens for dispersal and new workers for colony maintenance. From LeBoeuf et al 2016 we know that ant workers pass many growth-related proteins and an important insect growth hormone, Juvenile Hormone, to larva during feeding. This is a fascinating potential means of long-term self-regulation in ant colonies. In this project we use an automated system to track behavior, social fluid exchange and larval growth in groups of ants and larvae whose food is supplemented with these potentially growth-influencing components. We are working to disentangle the black box of ant larval development, collective control of colony development and explore implications for other types of long-term decisions made by groups. 

Department of Biology

Chemin du Musée 10, PER04
CH-1700 Fribourg 


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