03 Sep '13 17:49>3 edits
I came across this piece:
http://en.wikipedia.org/wiki/Muller%27s_ratchet
“....Geneticists have long bet on the success of sexual reproduction over asexual reproduction based in a large part on the process known as Muller's ratchet, the mechanism by which a genome accrues deleterious and irreversible mutations after the host organism has lost its ability to carry out the important gene-shuffling job of recombination ...”
But this seems to me total nonsense because, if it was true, bacteria and viruses would have become extinct long ago! In fact, I would guess most species would have become extinct in just the last hundred years or so! It seems obvious to me that, regardless of whether there is sexual or asexual reproduction, natural selection would continually weed out any deleterious mutations before any of them became widespread in a specie's genome. So I looked up this so-called “ Muller's ratchet” effect just to check my facts:
http://en.wikipedia.org/wiki/Muller%27s_ratchet
I was appalled to find highly flawed reasoning being used throughout the Muller's ratchet theory as explained in the above!
For example, it says:
“Asexual reproduction compels genomes to be inherited as indivisible blocks so that once the least mutated genomes in an asexual population begin to carry at least one deleterious mutation, no genomes with fewer such mutations can be expected to be found in future generations”
-which is obviously false because 1, why should the individual with the least mutated genome have to have at least one deleterious mutation? ( -answer, no reason! ) and, 2, why should, suddenly and miraculously, ALL individuals of a population have one deleterious mutation before natural selection has a chance to weed it out? Obviously, any deleterious mutation generally starts off with just ONE (or at least only a few) individual having it and, in the many generations that follow, there would be ample opportunity for natural selection to weed it out WELL before it has a chance to spread to the whole population! Plus, even if such a mutation miraculously DID spread to the whole population and to every individual, what is stopping any individuals then being born with that mutation mutated back to its none deleterious version and then natural selection selecting for those individuals that don't have that deleterious mutation until, once again, the population is free of such a deleterious mutation? -this theory just makes no sense at all!
http://en.wikipedia.org/wiki/Muller%27s_ratchet
“....Geneticists have long bet on the success of sexual reproduction over asexual reproduction based in a large part on the process known as Muller's ratchet, the mechanism by which a genome accrues deleterious and irreversible mutations after the host organism has lost its ability to carry out the important gene-shuffling job of recombination ...”
But this seems to me total nonsense because, if it was true, bacteria and viruses would have become extinct long ago! In fact, I would guess most species would have become extinct in just the last hundred years or so! It seems obvious to me that, regardless of whether there is sexual or asexual reproduction, natural selection would continually weed out any deleterious mutations before any of them became widespread in a specie's genome. So I looked up this so-called “ Muller's ratchet” effect just to check my facts:
http://en.wikipedia.org/wiki/Muller%27s_ratchet
I was appalled to find highly flawed reasoning being used throughout the Muller's ratchet theory as explained in the above!
For example, it says:
“Asexual reproduction compels genomes to be inherited as indivisible blocks so that once the least mutated genomes in an asexual population begin to carry at least one deleterious mutation, no genomes with fewer such mutations can be expected to be found in future generations”
-which is obviously false because 1, why should the individual with the least mutated genome have to have at least one deleterious mutation? ( -answer, no reason! ) and, 2, why should, suddenly and miraculously, ALL individuals of a population have one deleterious mutation before natural selection has a chance to weed it out? Obviously, any deleterious mutation generally starts off with just ONE (or at least only a few) individual having it and, in the many generations that follow, there would be ample opportunity for natural selection to weed it out WELL before it has a chance to spread to the whole population! Plus, even if such a mutation miraculously DID spread to the whole population and to every individual, what is stopping any individuals then being born with that mutation mutated back to its none deleterious version and then natural selection selecting for those individuals that don't have that deleterious mutation until, once again, the population is free of such a deleterious mutation? -this theory just makes no sense at all!