The evolution of sheep immunity in response to nematode infection
Friday 11th November, 2016 16:00-17:00 Maths 204
Nematode infections in livestock affect ruminants like cows, sheep pigs, and goats. These macro-parasites mature and reproduce within the host's abomasum. Once infected the host experiences a relative protein deficiency that prohibits its growth and also lowers its productivity. In some extreme cases, where the animal is heavily infected, the infection can lead to the host's death . These effects incur huge losses to the animal production sector. Many hosts mount relatively weak levels of immunity in response to the infection, 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 contradicts the Darwinian natural selection theory which states that evolution shapes 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 larval-pool 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 nematode infection of sheep.