Aim of the proposed project is to study spatial and temporal patterns of coevolution in theinvasive garden ant, Lasius neglectus, and its fungal and bacterial hosts. When this antspecies is introduced into new sites, it experiences a loss of adapted parasites, as it is freedfrom its natural parasites (“parasite release”) and encounters new parasites native to theintroduced range that are not yet adapted to the new host species (“disrupted coevolution”).Each introduction thus sets the starting point of a new coevolutionary arms race by buildingnew combinations of hosts and parasites. We will study the outcome of this arms race inpopulations differing in their age, size, genetic diversity and dominance of the invasivegarden ant in the species community, by isolation of field fungal and bacterial parasites. Todetermine the “tightness of coevolution” in the different populations, we will then performinfections of the hosts and parasites sampled from the same and different field populationsunder standardised laboratory conditions, and test for parasite pathogenicity and hostindividual and collective (social) immune defences. We will test both across populations(spatial aspects) and the same populations for two time points in a distance of two years(temporal aspect). We will also perform an experimental evolution study, in which wedetermine the speed of adaptation of fungal (Metarhizium anisopliae) and bacterial (Bacillusthuringiensis) parasites to the invasive garden ant depending on the host genetic diversityand its ecological dominance. We will analyse changes in parasite pathogenicity and thecorresponding genetic changes over time.
