Project 4

Decoding the chemical signals behind conflict in a clonal ant society

Supervisors: 
Dr. Yuko Ulrich (main supervisor)
Lise Meitner Group Leader, Max Planck Institute for Chemical Ecology
Dr. Markus Knaden (co-supervisor)
Group Leader, Max Planck Institute for Chemical Ecology

Background: 
Animal societies must regulate internal conflict to remain cohesive and function. Kin selection theory predicts that reproductive conflict should be reduced when group members are closely related. In the clonal raider ant Ooceraea biroi, colonies are queenless and made of genetically identical workers that reproduce synchronously as part of a stereotyped colony cycle. Despite the lack of genetic variation, aggression among nestmates is regularly observed, and it is directed almost exclusively at intercastes: individuals with queen-like traits, including larger body size, eyes, and more ovarioles. Intercaste aggression has been proposed to act as policing of individuals that reproduce out of phase with the colony cycle, but the cues that elicit it remain unknown. In many social insects, fertility status is signalled by chemical cues, which mediate both reproductive regulation and policing. Identifying the chemical and sensory bases of intra-colony aggression in O. biroi will shed light on the proximate mechanisms that maintain social cohesion.

Project description: 
This project will investigate the chemical and sensory bases of intercaste aggression in O. biroi, integrating behavioural ecology, chemical ecology, and (depending on progress) neuroethology. You will (1) quantify aggressive interactions to characterise the behavioural and physiological correlates of aggression; (2) analyze and compare the chemical profiles of aggressed and non-aggressed intercastes, as well as workers across the colony cycle using analytical chemistry to identify candidate compounds; and (3) test the behavioural activity of these compounds in custom, quantitative bioassays. Depending on your interests and progress, the project can be extended to examine how these cues are detected and processed by the olfactory system, taking advantage of the genetic tools available in O. biroi. The project combines expertise in ant behaviour, olfaction and chemical ecology in the Ulrich and Knaden groups. At the institute, you will have access to state-of-the-art facilities and equipment, expert service groups for mass spectrometry and microscopy, and world-class colleagues in insect chemical ecology, neuroethology, and evolutionary biology.

Candidate profile: 
- Proactive, dynamic, and curious
- Strong critical thinking skills
- Excellent communication and organizational skills
- Proficiency in written and spoken English 
- Experience with chemical analyses or behavioural assays in insects is beneficial but not necessary

Reading: 
1.    Teseo, S., Kronauer, D. J. C., Jaisson, P. & Chaline, N. Enforcement of Reproductive Synchrony via Policing in a Clonal Ant. Curr. Biol. 23, 328–332 (2013).
2.    Hart, T. et al. Sparse and stereotyped encoding implicates a core glomerulus for ant alarm behavior. Cell 186, 3079-3094.e17 (2023).
3.    Piqueret, B. et al. Offspring chemical control of adult reproductive transitions in a social insect. Proceedings of the National Academy of Sciences 123, e2526776123 (2026).