Investigating the Determinants of Fight Dynamics in the Minotaur Beetle Typhaeus Typhoeus

Abstract

It is widely accepted that the main determinants of contest outcome are resource value, residency status, and resource holding potential, with each of these playing an important role in determining contest behaviour. Examples of resource holding potential are morphological traits such as body size and weaponry. Animals that possess weaponry can exhibit different morphotypes, such as size difference in horns, which can lead to differences in contest behaviour, with larger morphotypes engaging in head-to-head combat, while smaller morphotypes can avoid combat altogether. One such species that possess weapons in the form of horns and engages in physical combat, is the minotaur beetle Typhaeus typhoeus. This beetle species is thought to exhibit male dimorphism, and we used a switch-point regression analysis to determine whether this species does have multiple male morphotypes. We studied whether resource holding potential in the form of horn length had a significant effect on contest outcome, by setting up fighting trials. We also studied how residency and resource value affect contest dynamics, such as fight duration, latency and the number of fights that occurred. Using electron microscopy, we studied this species’ setiferous sex patches and how their morphology affects contest dynamics. We found evidence to suggest that Typhaeus typhoeus males do exhibit two male morphotypes, and that contest dynamics were significantly affected by resource holding potential, resource value, and residency, but that there was minimal effect of setiferous sex patch morphology on contest dynamics.

Date of Award	2026
Original language	English
Awarding Institution	University of Plymouth
Supervisor	Sarah Lane (Director of Studies (First Supervisor)) & David Bilton (Other Supervisor)