Evolution of virulence in specific host-parasite system, the three-spined stickleback and the tapeworm Schistocephalus solidus

CLUSTER: „Evolutionary genetics of three-spined stickleback – parasite interactions“

Dr. Martin Kalbe

Max-Planck-Institut für Evolutionsbiologie 

Dr. Jörn Peter Scharsack

This project aims to investigate the hypothesis that evolving host-parasite systems are influenced by environmental conditions. It is based on the concept that the host x parasite genotype interactions (GxG) are modified by an additional variable, namely the interaction with the environment (GxGxE). It will make use of coevolved and non-coevolved populations of an ecological model host-parasite system, the three-spined stickleback (Gasterosteus aculeatus) and the tapeworm Schistocephalus solidus. Due to the wide geographical distribution of sticklebacks and their tapeworm parasite, this system is ideal to study the effect of temperature as a key environmental factor on the immunological and genetic interactions of host-parasite associations from different climatic regions. Furthermore, the high specificity of the parasite toward its stickleback host enables us to study in detail genotype-genotype interactions in different locally adapted host-parasite combinations. In laboratory experiments crosswise infection of sympatric and allopatric host-parasite combinations will be performed. Infected and uninfected stickleback will be exposed to different temperature regimes, mimicking selective pressure by environmental variation. Measurements of the functional basis of stickleback immunocompetence will be complemented by an expression array of stickleback immune-relevant genes. In parallel, candidate genes conferring virulence to S. solidus will be identified and characterized. Ultimately, the project also aims to uncover the genetic underpinnings of virulence in both host and parasite.