Bachelor- / Master-Thesis

Chemical mimicry and sexual dimorphism in mites

05.03.2026, Abschlussarbeiten, Bachelor- und Masterarbeiten

Bulb mites show a dramatic male dimorphism, developing either into deadly fighters or harmless scramblers, raising the question of why the ill-equipped scramblers still persist in nature. This project explores whether scramblers escape aggression from fighter males by chemically mimicking females, using detailed analyses of their surface chemical profiles. By linking behaviour and chemistry, you will uncover the mechanisms that maintain these surprising alternative tactics.

Bulb mites (Rhizoglyphus robini) are tiny soil living arthropods that breed quickly and are easily maintained in the lab, making them an exciting model for studying evolution, behaviour, and genetics. Their most striking feature is a male dimorphism: some males develop into heavily armed fighters with enlarged legs used in lethal combat, while others become scramblers that avoid aggression. These branching male developmental pathways depend on both genetics and environmental conditions, with larger, healthier juveniles typically becoming fighters and smaller individuals developing as scramblers.
A key unresolved evolutionary question is why scramblers persist in natural populations despite fighters gaining clear advantages in male–male competition. One compelling hypothesis is that scramblers survive by chemically mimicking female cuticular surface profiles to avoid being attacked by fighters. Intriguingly, complementing genetic studies suggest that fatty acid synthase genes are potentially linked to the male dimorphism, which, in turn, play also a major role in the production of the chemical surface profiles.
This project aims to test that idea by:
• Comparing and quantifying cuticular surface profiles of fighters, scramblers, and females
• Experimentally exposing fighters to individuals or dummies coated with different cuticular surface profile extracts
• Exploring how fatty acid synthase (FAS) genes contribute to the surface profiles as well as the male morph development

Together, these integrative approaches will allow us to investigate how behavior, chemistry, and genetics interact to maintain alternative reproductive strategies—offering a fascinating window into how diversity evolves and persists in natural populations.

Time frame:
This project can be started year-round, start date flexible, project time can be adjusted according to the type of thesis, internship, “Forschungspraktikum” etc.

Requirements:
Self-sufficient, reliable and precise work ethic in the lab. Experience with analytical chemistry not required as this will be taught in the project, but some experience with data analysis through statistical programs such as R would be beneficial.

Kontakt: jan.buellesbach@tum.de

Mehr Information

https://www.lss.ls.tum.de/pii/team/dr-jan-buellesbach/