Changes in the pathogen composition and immune response during range expansion of successful crayfish invaders

Funding: Croatian science foundation  (HRZZ)

Project leader: Sandra Hudina
Institution: Department of Biology, Faculty of Science, University of Zagreb
Duration: 60 months (April 2018 – March 2023)
Invasive species impair ecosystem function and services across a range of ecosystems worldwide and prediction and management of successful invaders represents a global challenge. Rapid dispersal is an important determinant of invasion success. Pathogens may greatly impact invasion success since they influence the ecology and evolution of their hosts. Due to altered pathogen pressures and ecological /evolutionary processes arising from dispersal, altered immune investment is likely to occur during range expansion. Lower pathogen prevalence and potentially lower transmission rates at low densities of available hosts at invasion fronts might reduce the need for strong immune response. On the other hand, in a novel environment, individuals may experience a broader range of pathogens which would require increased immune investment. Additionally, immune investment may be altered through energy trade-offs with life-history traits promoting dispersal and population growth at invasion fronts. Since individuals at the invasion front could benefit from both elevated and decreased immune response, it is not immediately obvious which of these opposing tendencies will prevail during range expansion. We will test these issues using a successful group of freshwater invaders – non-indigenous crayfish. Firstly, we will compare diversity and abundance of crayfish associated microbiota (with emphasis on selected pathogens) and the intensity of immune response in individuals of the invasive signal crayfish (Pacifastacus leniusculus) from the invasion core and invasion fronts in the expanding population in the Korana River, Croatia. Secondly, we will perform an extensive laboratory study using parthenogenetic marbled crayfish (Procambarus virginalis) in order to identify the effects of population density, pathogen presence, and immune response on individual growth and reproduction. Based on this input, we aim to quantify potential energy allocation trade-offs between immune function and life-history traits promoting invasion success using dynamic energy budget modelling. This comprehensive framework which combines field and experimental research with modelling will allow us to assess population-level consequences of immune response alterations and their role in invasion success of a species.