Host-parasite Dynamic
Selective pressure between two species can include host-parasite coevolution. This antagonistic relationship leads to the necessity for the pathogen to have the best virulent alleles to infect the organism and for the host to have the best resistant alleles to survive to parasitism. As a consequence, allele frequencies vary through time depending on the size of virulent and resistant populations (fluctuation of genetic selection pressure) and generation time (mutation rate) where some genotypes are preferentially selected thanks to the individual fitness gain. Genetic change accumulation in both population explains a constant adaptation to have lower fitness costs and avoid extinction in accordance with the Red Queen's hypothesis suggested by Leigh Van Valen in 1973.
Read more about this topic: Evolutionary Arms Race
Famous quotes containing the word dynamic:
“We Americans have the chance to become someday a nation in which all radical stocks and classes can exist in their own selfhoods, but meet on a basis of respect and equality and live together, socially, economically, and politically. We can become a dynamic equilibrium, a harmony of many different elements, in which the whole will be greater than all its parts and greater than any society the world has seen before. It can still happen.”
—Shirley Chisholm (b. 1924)