viral evolution 2016
Post on 16-Apr-2017
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Theories of Viral Evolution
Analysis of viral genetic material suggests viruses DO NOT come from a single common ancestor.
Three hypotheses to explain the origin of viruses:
1. Devolution (Regression) Hypothesis
• Viral ancestors were cellular organisms similar to bacteria.• Evolved into obligate parasites • Parasites lost cellular components as it was
more efficient to reproduce without.•
2. Escapist (Progressive) Hypothesis
•Genetic material from a free living (non-parasitic) cell “escaped” wrapped in protein coat• Explains viral-host specificity (viruses are able to
attack and take over host because they came from them)
3. Self-Replication (Co-evolution) Hypothesis
• Particles with the ability to self-replicate evolved alongside the cells• As new cell types evolved, new viruses that
could target that cell evolved (co-evolution)
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