Jouni Laakso - Ecology and Evolutionary Biology

Antagonistic species interactions and the evolution of bacterial virulenceAcademy

Research Fellow Jouni Laakso

The evolution of bacterial virulence has traditionally been studied from the narrow perspective of the host-pathogen interaction. However, viewing bacteria and the host as organisms embedded within an evolving community can provide us new insight into the process by which the bacteria evolve to infect multicellular organisms. Many important pathogens have to defend themselves against viral and protozoan enemies during the free-living phase the life cycle.

The evolution of defences against viruses and protozoa is also known to have correlated consequences on the virulence traits of bacteria. There is very limited experimental evidence on the sign and magnitude of these effects. Moreover, there is a need to develop theoretical understanding on the eco-evolutionary dynamics of bacteria under simultaneous threat from viral and protozoan enemies. This would help in predicting the conditions where environmentally driven bacterial diseases are evolving.

The project models the evolutionary and ecological dynamics of facultative pathogenic bacteria exposed to viruses and protozoa. The modelling aims to analyse the evolutionary processes, which modify bacterial life histories, with special emphasis on virulence traits. The models combine two qualitatively different and relatively well-established community modules: the virus-bacteria and protozoa-bacteria interactions under same theoretical framework. The models are developed and tested in concert with long-term evolutionary experiments. The experiments expose facultatively pathogenic bacteria to phages and predatory protozoa. To evaluate the evolutionary changes in bacterial virulence, the strains are used to infect insect hosts. Mortality of the infected hosts will be followed and the bacterial flora will be recovered for further analyses of genetic changes.

The co-operating partners include prof. Veijo Kaitala (Helsinki), Acad. prof. Johanna Mappes (Jyväskylä Centre of Excellence in Evolution Research) and Prof. Jaana Bamford’s group (Centre of Excellence in Virus Research), and Dr. Angus Buckling (Univ. of Oxford).