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Viral evolution is a subfield of evolutionary biology and virology that is specifically concerned with the evolution of viruses. [ 1 ] [ 2 ] Viruses have short generation times, and many—in particular RNA viruses —have relatively high mutation rates (on the order of one point mutation or more per genome per round of replication).
Viral phylodynamics is the study of how epidemiological, immunological, and evolutionary processes act and potentially interact to shape viral phylogenies. [1] Since the term was coined in 2004, research on viral phylodynamics has focused on transmission dynamics in an effort to shed light on how these dynamics impact viral genetic variation.
New groups of viruses might have repeatedly emerged at all stages of the evolution of life. [16] There are three major theories about the origins of viruses: [16] [17] Regressive theory Viruses may have once been small cells that parasitised larger cells. Eventually, the genes they no longer needed for a parasitic way of life were lost.
Further, the viral origins of the modern eukaryotic nucleus may have relied on multiple infections of archaeal cells carrying bacterial mitochondrial precursors with lysogenic viruses. [4] The viral eukaryogenesis hypothesis depicts a model of eukaryotic evolution in which a virus, similar to a modern pox virus, evolved into a nucleus via gene ...
Ewald is known for his "theory of virulence”, suggesting that "the deadlier the germ, the less likely it is to spread", [1] and his theory that many common diseases of unknown origin are likely the result of chronic low-level infections from viruses, bacteria or protozoa.
After cross-species transmission of a virus, rapid evolution and positive selection are expected. [47] Several studies found only weak signs of adaptive evolution early in the COVID-19 pandemic. [c] Kang et al. wrote that SARS-CoV-2 had exhibited relatively little genetic variation by 2021. [47]
In 2005, human T lymphotropic viruses 3 and 4 were discovered. [124] In 2008 the WHO Global Polio Eradication Initiative was re-launched with a plan to eradicate poliomyelitis by 2015. [125] In 2010, the largest virus, Megavirus chilensis was discovered to infect amoebae. [126] These giant viruses have renewed interest in the role viruses play ...
A founder virus can introduce a different phenotype for the ensuing evolution. Evolution of viruses in nature and as disease agents can be viewed as succession of mutant spectrum alterations, subjected to expansions and reductions of population size in a continuous interplay of positive and negative selection and random drift.