Abstracts (first author)
Inbreeding dependent trade-offs in the ant Formica exsecta
Trade-offs between different defence mechanisms and life-history traits are known to exist. Especially interesting are the ones involving immune defences, as surviving infections is paramount for any organism. The capability to respond to stressors depends on the phenotypic plasticity of an organism. It is assumed that inbreeding decreases the adaptability of organisms to environmental stresses (e.g. dealing with pathogens, oxidative stress). Recent evidence from many insects highlights the importance of Reactive Oxygen Species (ROS) in insect immunity by regulating potential pathogens and keeping commensal gut flora under control. Although the release of these free radicals is an extremely effective defence against intruders, it is also harmful to the organism itself, as it causes oxidative stress. This is a situation where cellular production of ROS overwhelms its antioxidant capacity, leading to damage of various macromolecules (e.g. lipids, proteins, DNA). Dealing with this self-inflicted injury is essential, but requires extra resources for anti-oxidant production. In a multi-infection scenario, the capability of an organism to deal with multiple stressors may give a crucial advantage in comparison to less adaptive phenotypes. Here, we study how ants with different inbreeding levels cope with bacterial and fungal parasites, being previously exposed to oxidative stress via feeding with ROS. Dietary intake of extra ROS may lead to better survival against gut penetrating entomopathogenic bacteria, but may at the same time leave fewer resources to fight against fungal pathogens. We use oral infection with the pathogenic bacterium Serratia marcescens, and the exposure to the generalist fungal pathogen Metarhizium brunneum to study the trade-offs between ROS responses and the immune response in workers of F. exsecta. Comparing inbred colonies and outbred colonies reveals differences in the expression of various antioxidant and immunity related responses.