evyy -> RE: Grrrrrrrrr (10/10/2006 10:39:58 PM)
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quote:
I am having a hard time understanding the concept that if mutation can be reversed due to DNA repair; how come this does not apply to genetic drift? AND, if natual selection is the normal in most society; how come DNA repair does not occur there? Basically DNA has some limited ability to repair, but the vast majority of mutations are not 'reversed', a mutation that effects phenotype (ie does something to the organism) becomes an allele in the population, once it is established it can be acted upon by natural selection, this can act against the phenotype of the mutation, which is to say that an individual with that mutation will have less chance to survive and reproduce, and so the mutation can be reduced or eliminated from the population- depending on mode of inheritance, a recessive trait can never be eliminated from any real population. One the other hand the mutation might be beneficial, or, as in the most case, invisible. The DNA will not be repaired because an inherited mutation isn't damage, it's what makes you not a chemosynthetic protocell, DNA replicates, the mutation is part of the DNA. Genetic drift is another matter altogether, if you have any two populations, and sample from then, as you do when gametes are randomly combined, ie, sex, there will be a sampling effect, just like if you flip a coin 10 times you wont always get heads 5, tails 5, if you flip two coins you might get heads 3, tails 7 on one and heads 10 on the other, its just change, which don’t always follow probability. Genetic drift is change that will occur in any two separated populations regardless of mutation and/or natural selection, all it relies on is having more then 1 allele for a trait, which admittedly is a result of some ancestral mutation, but once again that mutation isn’t damage, its just variation
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