Apr 13
Seminar by Jesse Weber, Assistant Professor of Integrative Biology, University of Wisconsin-Madison: Parasite lost (and found): the genetics and ecology of coevolution between threespine stickleback fish and tapeworm parasites
Parasitic worms infect all vertebrate taxa, but little is known about how the evolution of host immunity and parasite infectivity shape natural infection variation. To fill this knowledge gap, the Weber Lab studies a small fish with abundant ecological and genetic resources, the threespine stickleback (Gasterosteus aculeatus), and one of its cestode (i.e., tapeworm) parasites. We have established lab-based protocols to hybridize evolutionarily diverged populations of hosts as well as divergent parasites, expose fish to controlled doses of these pathogens, and assay host immunity and parasite viability. We also apply modern genetic approaches to dissect the molecular mechanisms underlying this natural infection variation. This seminar will present data showing that sticklebacks repeatedly evolved to block the initial establishment and subsequent growth of cestodes, but the mechanisms of resistance vary across populations. Moreover, because parasite resistance often results in extensive autoimmunity, many fish populations have instead evolved to tolerate infections via shared changes in a single immune gene. The talk will end by explaining ongoing projects that address how the parasite is evolving to counter host resistance, and how we are using natural experiments to understand the broad impacts of immune evolution on stickleback biology.