Evolution Of Host Parasite Relationships - 1178 Words

Betsy Gladden Evolution Case Study #1 Dr. Amanda Duffus The Evolution of Host-Parasite Relationships Since Darwin’s â€Å"dangerous† idea in the nineteenth century, the causes and significances of evolution have been investigated unceasingly. One evident example of evolution is between parasite and host relationships, in which host and parasite partners maximize their own fitness, by evolving to reduce the fitness of the other. Parasites are hypothesized to evolve and cause hosts to evolve, as well as promoting sexual recombination. There are two major hypotheses of evolution pertaining to host-parasite relationships: the Red Queen hypothesis and the Red King model. The Red Queen hypothesis claims that there is a†¦show more content†¦Scientist Van Valen used this as a metaphor for the evolutionary race saying that species keep running (evolving) to stay in the same place, but if they stop, they become extinct. This theory has been consistently added to and built upon by G. Bell in 1982, who applied it to host and parasite relationships, showing how evolution a ffects genotype frequencies and that changes come from maintaining sexual reproduction. (Lively, 2010) The Red Queen hypothesis demonstrates how species rely on competition for initiating evolution, and how there is a domino effect of change causing change. (Barnett and Hansen, 1996) In studies done by Barnett and Hansen (1996) using an organizational approach, evidence was found for Red Queen evolution in that organizations exhibited less failure if there was more competition. The research used banks as a model, and the results showed that in places only one existed, there was an advantage of a monopoly, but did not have any experience when exposed to competition. (Barnett and Hansen, 1996) The Red Queen hypothesis also shows that selection favors hosts that have rare resistance alleles. There also is research that shows generation time affects selection for sex, in that the longer it takes to reproduce, the more opportunity there is for evolution. The Red Queen hypothesis suggests that when in regard to parasite and host relationships, when parasites are low in number, the costs of sex outweigh the benefits and