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Lfabarum_stinging
Endosymbiont-mediated coevolution in an insect host-parasitoid system
Antagonistic coevolution between hosts and parasites may be the driving force behind many important evolutionary phenomena, including the maintenance of genetic polymorphism. It was found recently that coevolution between aphid hosts and their hymenopteran parasitoids is strongly influenced by facultative endosymbiotic bacteria that increase host resistance. This challenges existing models of host-parasite coevolution by adding another layer of complexity. We develop models describing the expected dynamics of such symbiont-mediated coevolution and we study this process empirically from the level of individual genotypes up to the level of the biological community, using the black bean aphid, Aphis fabae, and its parasitoid Lysiphlebus fabarum as a study system.
isopods
Defensive Actinobacteria in aquatic and terrestrial isopods
Pathogens and parasites favour the evolution of a wide diversity of defences including the production of secondary metabolites synthesized by symbionts. Actinobacteria, the prime producers of antibiotics, protect diverse insects against pathogenic fungi. How widespread these symbiotic interactions are and how a host may benefit from Actinobacteria remains largely unexplored. This project, financed by the Czech Ministry of Education, Youth and Sports (International Mobility of Researchers MSCA-IF IV), and in collaboration with Institute of Soil Biology (Biology Centre CAS, Ceske Budejovice), tests the role of Actinobacteria-conferred protection against pathogenic fungi in the freshwater isopod Asellus aquaticus and the terrestrial isopod Porcellio scaber using amplicon sequencing, in vitro cultivation of microbes and dietary manipulation.

A_pisum
Defensive symbiosis in the wild – the role of symbiont-conferred resistance in natural host-parasitoid communities
It has become increasingly clear that numerous insects rely on heritable bacterial endosymbionts for protection against parasitoids. Although a large body of laboratory work is consistent with such defensive symbionts having a pervasive influence on host-parasitoid interactions, a realistic appreciation of their relevance has to come from field studies. This project is a rigorous attempt to investigate the ecological and evolutionary role of defensive symbionts in natural aphid-parasitoid communities.
A_astaci
Detection of aquatic diseases from eDNA in water samples
Aquatic diseases like the crayfish plague or proliferative kidney disease (PKD) contribute to the decline of numerous freshwater species and pose an important threat to fish and crayfish stocks. The current management of aquatic diseases is re-active rather than pro-active in that detected outbreaks trigger measures and recommendations aimed at preventing further spread of the disease. In collaboration with Hanna Hartikainen's lab at Eawag and the "Koordinationsstelle Flusskrebse Schweiz" (KFKS) we are developing a combined eDNA assay for a set of aquatic diseases that are of concern in Switzerland. The goal is to have a rapid and cost-effective tool for a comprehensive risk assessment to enable a more pro-active management of aquatic diseases.
L_fabarum_by_SS
The evolution of thelytoky in parasitoids of the genus Lysiphlebus
The evolutionary maintenance of sex remains one of the big unresolved questions in biology. A promising system to study this question empirically are aphid parasitoids of the genus Lysiphlebus. They comprise sexual (arrhenotokous) and asexual (thelytokous) lineages, and asexual reproduction is unconfounded with hybridisation, polyploidy or the possession of parthenogenesis-inducing microbes. Crossing experiments demonstrated that thelytoky has a simple genetic basis and is inherited as a single-locus recessive trait, but the responsible genes are still unknown. In collaboration with Casper van der Kooi and Tanja Schwander from the University of Lausanne, we are trying to elucidate the genetic basis of thelytoky in L. fabarum.


Austropotamobius_torrentium
Population genetics and conservation of native freshwater crayfish
Native freshwater crayfish in Europe are endangered due to habitat degradation, competition by introduced crayfish species, and a deadly disease (crayfish plague) vectored by these introduced species. Remaining populations of native crayfish are largely restricted to small and disconnected tributaries. The massive fragmentation of streams and rivers by man-made barriers prevents genetic exchange between them as well as the recolonization of streams after local extinctions. We use population genetic methods to study the genetic structure and diversity of the remnant populations of stone crayfish (Austropotamobius torrentium) and white-clawed crayfish (A. pallipes), with the aim of aiding and informing conservation measures for these endangered species.