Experimental evolution studies are a means of testing evolutionary theory under carefully designed, reproducible experiments.
For these reasons, bacteriophages (i.e. viruses that infect bacteria) are especially favored by experimental evolutionary biologists.
Bacteriophages, and microbial organisms, can be frozen in stasis, facilitating comparison of evolved strains to ancestors.
Understanding whether the majority of genetic interactions are synergistic or antagonistic will help solve such problems as the evolution of sex.
Virulence is the negative impact that a pathogen (or parasite) has on the Darwinian fitness of a harboring organism (host).
For phage, virulence results either in reduction of bacterial division rates or, more typically, in the death (via lysis) of individual bacteria.
A number of theory papers exist on this subject, especially as it applies to the evolution of phage latent period.
However, the reader should be warned that virulence is often used as a synonym for "not temperature", a usage which is neither employed here nor to be encouraged generally.
Muller’s ratchet is the gradual, but irreversible accumulation of deleterious mutations in asexual organisms.
Prisoner's dilemma is a part of game theory which involves two individuals choosing to cooperate or defect, reaping differential rewards.
However, the reader should be warned that virulence is often used as a synonym for "not temperate", a usage which is neither employed here nor to be encouraged generally.