"The survival of individual genes over vast geological periods provides more than unimpeachable evidence of the preservative force of natural selection" (72)
What is the significance or the importance of the preservative force of natural selection? Why would it be important for different evolving species?
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ReplyDeleteThe presence of a preservation force is necessary for the evolution of any species. The genes that have withstood the bombardment of mutation have remained for a reason. They are necessary and “central to fundamental, universal processes in the cell” (Carroll 79). Species depend upon these core genes for survival because without them, many necessary cell functions and processes will not work.
ReplyDeleteAlthough mutations are random, evolution is not and is based on the essential goal of survival of the species. Immortal genes, as Carroll discusses are not immune to mutation, small changes in letters still occur (which is possible because of the redundancy of the genetic code) but the key is that the gene endures because that is what code for the necessary proteins.
A report published by Nature studied two species of bacteria living together in a California mine and were found to share large groups of genes. The two species of bacteria were quite different but they shared a common ancestor which passed along these genes to both of the species. They were preserved because the genes were probably either necessary for them to survive in that environment, or because they code for functions that are necessary for survival.
In an experiment in Human Genetics, the RPGR gene in humans and mice showed 28 conserved sequence elements in their sequence. Also, in a study by Tom Paulsen, he noted that humans and chimps each have some “3 billion base units of DNA in their genomes, differing by only 1.2 percent”. These genomes are very similar and that is because humans and chimps are related and came from the same common ancestor. These genes are an example of the presence of a preservation force in nature. Chimps and humans look vastly different but at the same time the preservation of these immortal genes was necessary for the evolution of the 2 species.
Also, on page 81, Carroll looks at a part of a protein involved in making machinery for decoding mRNA in humans, tomatoes, yeast, Archaea, and bacteria. And 13 individual amino acids form this one protein were absolutely maintained throughout evolution showing that they are “effectively immortal”.
Now we can look at genomes from centuries ago and compare them to modern genomes of certain organisms and see what genes are truly fundamental. They way this works is, if a mutation occurs that would change the amino acid and consequentially the gene of something that is necessary for the organism’s survival, this organism will die off because it will not be able to perform some essential function. As Carroll states, mutations have occurred but “these mutations have been purged by selection over and over again” (83). This shows the incredible benefits of natural selection and how it promotes survival and success of a species.
http://www.springerlink.com/content/c2y3kff7kay1akgl/
http://www.seattlepi.com/local/238852_chimp01.html
http://www.bio-medicine.org/biology-news/NYU-scientists-identify-how-development-of-different-species-uses-same-genes-with-distinct-features-4463-1/
Preservative force of natural selection is another aspect of natural selection. I always used to see natural selection as destructive force that destroys everything on their path that is not the fittest. However, natural selection also preserves those genes that are useful to an organism.
ReplyDeleteThe most riveting evidence that supports preservative force of natural selection is the Universal code. On page 75, Carroll writes "Much to our convenience, but also of profound evolutionary significance, this code is, with few minor exceptions, the same in every species”. Universal code is very important piece of evidence that suggests all living organisms came from LUCA (Last Universal Common Ancestor). Without preservative force of natural selection, we wouldn’t be able to keep these useful genetic codes.
Preservative force of natural selection is important for different evolving species because it allows those species to keep their favorable mutations. For example, loss of short wave length opsin gene in many nocturnal species is preserved because they only act during the night. Also, proteins such as insulin, is preserved because this is useful to not only humans but also many other organisms such as pigs and cows. As we can see, natural selection is fine tuning our fittest to our changing environment: it is constantly getting rid of unnecessary components, adding more advantageous components and keeping the best of the best.
http://en.wikipedia.org/wiki/Universal_Code_(biology)
http://www.endocrineweb.com/diabetes/2insulin.html