Discussion

Parasites are ubiquitous. They impact both ecological dynamics as well as adaptive evolution of their hosts. Focusing on a series of infection experiments using the three-spined stickleback as a model host species, we will report about various molecular bases of resistance whether genetics or epigenetics. Furthermore, we describe how parasites and the evolution of parasite resistance in this fish host can mediate eco-evolutionary feedbacks altering prey communities impacting the selection pressure on subsequent host generations. Given the high parasite abundance in natural populations, and the rapid evolution of resistance, we argue that the neglect of parasites in ecosystem studies is unwarranted since they act as cryptic but crucial part in eco-evolutionary dynamics.