The evolution of sheep immunity in response to nematode infection
Friday 24th February, 2017 16:00-17:00 Maths 204
Many hosts mount relatively weak levels of immunity in response to nematode infections, whilst only a few hosts mount a higher immune response required to lower the infectivity of the parasites. The immune responses mounted against the infective agents have moderately to highly heritable levels, hence the host’s immunity is shaped by evolution. The variance in the immune strengths amongst the host population contradict the natural selection process which works to evolve organisms to be better adapted to their environments which in this case is to produce the “best” immune responses against the infection. In the disease infection system, there is a collective larvalpool thus the few individuals mounting a higher immune response may end up bearing a greater burden in regulating the parasite numbers. We study the consequence of sheep displaying varying immunity strategies in the Teladorsagia circumcincta infection; this is done so as to understand the heterogeneity. We have developed a sheep - weight infection model and used adaptive dynamics theory to determine the position and nature of the “evolutionary singular” points with a view of determining the evolutionary behaviour of the host’s immunity.