Question

1-Why is the host/pathogen relationship often described as an arms race or according to the Red Queen hypothesis?

2-Why are phylogenies useful for the study of disease? What are challenges in creating accurate phylogenies and dating divergence times?

3-What do phylogenies suggest about the domestic origins hypothesis?

Answer 1

1) The Red Queen hypothesis is an evolutionary hypothesis which proposes that organisms must constantly adapt, evolve, and proliferate not merely to gain reproductive advantage, but survive while pitted against ever evolving organism opposes in an ever-changing surroundings. This hypothesis explains the "Law of Extinction''. This is explained by the coevolution of species. At other times, species have evolved cooperatively by assuming adaptive coevolutionary dependencies. These complementary relationships form during the symbiosis, which direct punctuated advantages specialized enough to ensure a greater survivability and fitness rate for both species, coupled. So, an adaptation in a population of one species (e.g. parasites) change the natural selection pressure on a population of another species (e.g. hosts), which give rise to common antagonistic coevolutions.

An evolutionary arms race, which is appropriate for the explanation of the natural processes with dynamics similar to arms races. in evolutionary arms race is a struggle between competing sets of co-evolving genes, traits, or species, which increase adaptations and counter-adaptations against each other, that resembles to an arms race. The co-evolving gene sets may be in different species, as in an evolutionary arms race between a parasite and its host. Alternatively, the arms race occur between members of the same species due to Red Queen effects.

Selective pressure between two species can include host-parasite coevolution. This antagonistic relationship leads to the requirement for the pathogen to have the best virulent alleles, which infect the organism and for the host to have resistant alleles to survive parasitism. Allele frequencies are changed during time, these are depending on the size of virulent and resistant populations and generation time where some genotypes are preferentially selected to the individual fitness gain. Genetic change growth in both population explains a constant adaptation to have lower fitness costs and avoid extinction in unity with the Red Queen's hypothesis.