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Replying to post 23 by Still small]
Still small:
�I agree with you that either through selective breeding or via environmental changes that we arrive at various species, illustrated by your excellent example of the various dog breeds from the (grey) wolf. By the combination of different alleles, we get long hair, medium hair, short hair, etc. As the particular breed gets established, the genome becomes relatively stable but the differences between breeds is an example of, as you said, loss. That is a loss of genetic information, not new mutations. I was in full agreement with you until you said -
'But over the course of time new mutations will occur and more variation will be introduced.'
�As I indicated in a previous post, test results show the vast majority of mutations are deleterious or neutral and very few are beneficial. The natural accumulation of even mildly deleterious mutations eventually weakens the species to a point of extinction outweighing beneficial accumulation effects unless intelligent intervention occurs by breeders to avoid the problems.�
You have overlooked an important point about deleterious mutations:
In nature they don't survive. They die or are otherwise unsuccessful at leaving descendants. The species is culled and only the successful survivors and breeders pass on their genes. The unsuccessful mutations, the unfortunate combinations of genes, don't have descendants.
Still small:
�Even so, the practice of selective breeding for certain traits (species/breeds) can and does lead to certain mutational problems. For example - German Shepherds, Rottweilers, Bulldogs, Great Danes, Saint Bernards, Neapolitan Mastiffs and Retrievers, the larger breeds, are prone to suffer from hip dysphasia. Breeds including Dalmations, Newfoundlands, the Bichon Frise and Miniature Schnauzers can suffer from urinary bladder stones. Breeds including the English Bulldog, French Bulldog, Boston terrier, Pug, Pekingese, Shih Tzu and Cavalier King Charles Spaniel tend to suffer from Brachycephalic Syndrome (brachycephalic literally means “short-headed,�) resulting in respiratory complication. This selective breeding, the loss of genetic information and the genetic loading of deleterious mutations eventually weakens the species to the point of extinction. “
And indeed, most dog breeds
would go extinct in the wild. They only survive because there are humans in their environment who tend to cull the undesirable mutts by not breeding them (spay and neuter) or by providing the support they need to survive.
Still small:
�Whilst there may be instances of a beneficial mutation, overall, genetic mutation has a negative effect for survival which is contrary to the expectations of ToE.�
Genetic mutation provides variability. Most mutations are neutral, many are negative, and only a very few may be positive. (You probably have a hundred or more differences in your own genome that neither of your parents possessed. Mutation is that common.) But it is the positive and neutral mutations that survive to breed, and that is exactly what the theory of evolution proposes and
what is observed.
And note, that in my previous post I had a cooler climate selecting for thicker fur, more body fat and shorter limbs to facilitate the retention of heat, a warmer climate would have selected for thinner fur, less body fat and longer limbs so that the survivors would be more efficient at shedding excess heat.
So if the climate changed again, back to warmer, those cold adapted little mammals would likely go extinct because of their decreased variability, as have around 99.9% of all known species.
That is why evolution isn't about progress. It is about stability. And since the environment changes, and that change may include population density, the stability is not static but dynamic. As a species we have to adapt to our own population and the other environmental changes that are inevitable.
Another point: The early ancestors of Latimeria, the coelocanths, used to live quite close to the surface. A few adapted to the ocean depths where conditions are slow to change. So, having adapted to a stable environment, any change would likely be counted as deleterious. And any attempt to re-colonize their former environment, would be almost impossible because those environments are now inhabited by species adapted to them with whom Latimeria could not compete. Persons who do not understand this label coelocanths as primitive or un-evolved.
Is there any other confusion or misunderstanding that I can try to clear up? Is some further explanation necessary?
