Cloning to the rescue?
BQ: So the question: could cloning put a stop to mutational meltdown of species?
A: Our DNA is much like a book in that it has information encoded in a useful manner. The nucleotides that make up our DNA can be thought of as simple building blocks, much like legos. On their own, they don't do seem like very much, but when looked at as a whole, you can have a variety of different structures—a castle, an airplane, whatever the building blocks create when all assembled together. You could also have a random mess. (See Figure 1—Cloning.)
Our DNA is made up of
A = adenine
C = cytosine
G = guanine
T = thymine
We can view these as being A,C,T, and G, four simple letters in the "book" of our DNA/genome. Like any letters in a book, they have to be in a specific sequence or they start to make the entire thing make less sense. We have shown before that harmful mutations always grow far faster than beneficial mutations, and that for every beneficial mutation, it is inextricably bound up in a massive genome filled with many times as many harmful mutations. Because of this, the net information (useful "letters" in a "good" sequence) must always decline.
Dr. John Sanford, former evolutionist and Cornell professor of applied genetics, was very concerned about the genetic degradation of the human genome, and he believed that cloning might be the answer. In plant species, he knew that clonal selection provided the surest and fastest way to improve populations. However, Muller's Ratchet still applied; even for clones, each cell division adds mutations and there is no mechanism to remove these mutations
Consider this: clones often exhibit severe genetic damage, such as "pre-aging." Why? One major reason is that the cells from which they've been cloned have undergone many divisions and reproductions. Each time, minute mutations (harmful damage almost exclusively) build up, at a rate of at least one mutation per division. Each cell, then, becomes "unique," because it is no longer the same as the pure original from which its lineage derived.
From the above, we can see that when we clone populations, the clones carry over the original genetic mutational load (they are just like the "page" from which they are copied, and have all the same errors). In a sense, these clones are then "pre-aged." Aging occurs within generations of our own cells. When we look at cloning and see the genetic defects, we're actually looking at a foreshadow of where future species are going: downhill in future generations. Just like clones have the damage from mutations, so will we. In fact, every one of us and every one of our cells is a mutant. We can conclude that cloning will not solve evolution's biggest problem: genetic entropy.
(Note that germ cells undergo far fewer generational divisions/reproductions, so we don't see the future genetic damage that awaits us as "deep-time" organisms if we look at only immediate sexually-reproduced offspring; cloning "speeds it up.")
See also: K Higgins and M. Lynch, "Metapopulation extinction caused by mutation accumulation." A Eyre-Walker and P Keightley, "High genomic deleterious mutation rates in Hominids."
(PN234)
