Seminar: "Rapid evolution of a costly form of parasite resistance in threespine stickleback" by Dr. Daniel I. Bolnick
Rapid evolution of a costly form of parasite resistance in threespine stickleback
by Dr. Daniel I. Bolnick, Department of Integrative Biology, University of Texas at Austin
The evolution of immunity to parasites requires a delicate balance between costs and benefits. Eliminating or tolerating parasite infection can improve host survival and fecundity. But, the immune responses needed to achieve this goal can be directly or indirectly detrimental to the host. I will describe a dramatic instance of rapid evolution of host immunity. The threespine stickleback has repeatedly evolved immunity to Schistocephalus solidus cestodes, when it colonizes freshwater habitats. This entails both reduced infection success in freshwater stickleback populations, and two-order-of-magnitude reduction in parasite growth in certain populations. My lab has investigated the genetic basis of this resistance, and found that independent genetic processes separately control infection prevention, and parasite growth suppression. The latter entails a severe immunepathology that affects some populations in nature but not others. I will describe what is known of the immunogenetic basis of this recently-evolved resistance, and the ecological context that dictates the severity of associated immunopathology.