Oral presentation- Open Session 12th International Mammalogical Congress

High parasite infection level in non-native invasive species – It is just a matter of time (#361)

Andrzej Zalewski 1 , Marta Kołodziej-Sobocińska 1 , Agnieszka Niemczynowicz 1 , Wiesław Babik 2 , Marcin Brzeziński 3
  1. Mammal Research Institute, Polish Academy of Sciences, Białowieża, Podlaskie, Poland
  2. Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
  3. Faculty of Biology, University of Warsaw, Warszawa, Poland

The Enemy Release Hypothesis (ERH) is often used to explain the success of non-native species invasions. Growing evidence indicates that parasite or pathogen species richness increases over time in invasive non-native species. However, this increase should not directly translate into release from enemy pressure as infection intensity of parasites (number of parasites per host) has a more profound impact on host fitness. The changes in intensity of parasitic infections in invasive non-native species have not yet been thoroughly analysed in newly colonized areas. The goal of this study was to determine whether gastrointestinal parasite (nematodes and trematodes) infection intensity has increased with time since the populations of American mink (Neovison vison) were established and how parasite-mediated selection might drive mink major histocompatibility complex (MHC) diversity. We tested the ERH by substituting space for time, evaluating parasite abundance in American mink at sites along a chronosequence of mink invasion history. Nematode and trematode abundance increased with time since mink introduction and mink populations established 30-35 years ago had similar parasite abundance to native populations. The rate of increase in infection intensity varied among demographic groups of mink (sex and age). Our results provide evidence that non-native species are released from enemy pressure only in the first phase of invasion. The delay in parasite infection may explain the dynamics of invasive non-native species populations during expansion. Examination of parasite abundance and MHC genes provide an improved understanding of the mechanisms driving MHC diversity.