table of contents table of contents

Knowledge of the origin and evolution of viruses could provide a better …

Home » Biology Articles » Evolutionary Biology » Origin and evolution of viruses: EscapedDNA/RNA sequences as evolutionaryaccelerators and natural biological weapons » Viruses as evolutionary accelerators

Viruses as evolutionary accelerators
- Origin and evolution of viruses: EscapedDNA/RNA sequences as evolutionaryaccelerators and natural biological weapons

The model of living beings evolving based on genome changes and the ability to adapt to positive and/or negative selection pressures is widely accepted among evolutionists. However, it is hard to imagine that the evolution of life is based on accidental and isolated gene mutations and that this model of evolution finally brought about the form of life we know today. One of key arguments against a model of evolution based on the accidental changes of isolated genes is the simple fact that gene mutation is a relatively rare event and hence, according to this model, evolution would be very slow. Many evolutionists argue that life on the Earth would still be at the bacteria and seaweed stage, if genetic changes were based only on accidental changes of isolated genes. Considering the fact that most mutations are sources of negative selective pressure, the minor percentage of accidental mutations of genes that might cause positive selective pressure, theoretically, could not result in the evolution of living beings and the diversity of species that we know today. Certainly, this opinion does not completely exclude participation of accidental isolated gene changes in the evolutionary processes, but the influence of these events on the evolution of life probably is minimal and marginal [3,4,6].

With the exception of the mutations of isolated genes, several different mechanisms can lead to genome changes. These mechanisms are recombination, transposition, translocations, inversions, deletions, duplications, transduction and other unpredictable, chaotic and yet unremarkable genetic events which, in contrast to mutations, lead to great changes of genome. Significant genetic changes can probably result in ‘‘great evolutionary displacement’’ and acceleration of evolutionary processes. Incidentally, this hypothesis might represent an acceptable explanation for the many ‘‘missing links’’ in palaeontology and the state of our knowledge regarding the origin of life and species. Put quite simply, what we call the ‘‘missing links’’ probably never existed, due to ‘‘rapid’’ and large-scale changes which, for as yet unknown reasons, have implicated, from time to time, every living creature in the last billion years. Consequently, we can conclude that the evolution of living beings probably has not been based on gradual and ‘‘fine’’ passing forms. In this story, viruses could be an important factor in the theory of ‘‘rapid and big evolutionary steps’’ based on great changes of genome. Several mechanisms might be included in this evolutionary scheme: (i) horizontal transmission of genes between individuals of identical or even different species; (ii) vertical transmission of genes and bi-directional vertical transmission between mother and offspring in viviparous species; (iii) genome destabilization and induction of new changes of genome; (iv) increasing genome instability. Finally, the advantages of the rapid evolution of living beings and a possible link of this phenomenon with viruses could be an acceptable explanation for the ‘‘symbiotic’’ connection of the genomic ability to emit DNA/RNA sequences and/or de novo created viruses. This phenomenon could lead to evolutionary conservation of genome instability as a universal genome characteristic [6,7].

Recombination is a far more powerful way for DNA to change. This model of genome remodelling takes whole blocks of genes and moves them to different locations. These new locations could be elsewhere in the same genome or in the genome of a different host. One of recombination mechanisms is transduction by viruses that works in both prokaryotic and eukaryotic organisms. The discovery that large blocks of genetic instructions can be swapped and transferred among living beings is a clue that the insertion of new genes could be the mechanism that assists evolution. If viruses can transfer eukaryotic genes across species boundaries, and can install their own genes into their hosts, the case for the new mechanism is even stronger. Viruses do just that [1,3,4,6,7].


rating: 4.39 from 18 votes | updated on: 16 Feb 2009 | views: 37437 |

Rate article: