Evolutionsbiologie
Transition between mutualistic and parasitic interactions using
The intimate and long-lasting association between two different species represents one of the most fascinating
biological phenomena, because they rely on complex and well-coordinated molecular interactions of two partners
with usually different interests. To date, the exact causes and the underlying mechanisms, which determine the
nature of the symbiotic interaction, are still only poorly understood. Such knowledge would in general help to
understand how and why different species interact with each other in nature. It may also contribute to our
comprehension of the evolution of harmful parasitic agents with potentially medical importance. This study focuses
on a detailed experimental analysis of symbiotic interactions and the transitions between them, using the nematode
Caenorhabditis elegans as the model host and the Gram-negative enterobacterium Photorhabdus
luminescens as the model symbiont. Two main questions are addressed: i) What biotic and abiotic factors cause
a microorganism to be nice or nasty? ii) How are the different outcomes of the association mediated at the molecular
level in both the host and the symbiont, i.e. which host and which symbiont genetic factors contribute to this
interaction?
