Reelo
5°170
"Unlike many other types of mutation, SHM affects only individual immune cells, and the mutations are not transmitted to offspring."[/I]) Furthermore what you have explained is already inherent in living creatures, there is no evidence that this is due to some sort of adaptation to environment, it doesnt matter where an Aa Aa type couple is, there children can be AA Aa or aa in the cold, dry, wet or hot environment. Linking environmental adaptaion to reproduction is what we need for evolution, which is not proved (yet theory).
Evolution does not work with the goal of adaption in mind. It's random. Whatever the reasons for a creature's modified genes are, they are random. If an advantage is created, fine. If not, too bad.
Linking environmental adaption to evolution is not necessary. Let's take the Mammoth as an example. It's ancestors, some form of elephants (even though science doesn't call em that way, but let's just do) spread across Africa and Eurasia. Let's assume they had a very light fur (well, not fur, but like young elephants today, some form of thin hair). Now, when in Eurasia the Ice Ages came, they didn't develop wool because it was cold. Changes in density of body hair are natural, some have more, some have less (like some men going bald and others not) independently of climate, just because of genetic drift (the first part of evolution). As it got colder, the ones with denser body hair (which they DIDN'T develop because it was cold, it was just a random factor) endured better, lived longer and produced more offspring. Also, some of them could digest small grass and lichen better than others. They also had an advantage. It is only logical that over time, the offspring of the better adapted (BY CHANCE) pre-mammoths outnumbered the others. And thus over time, you get some creature that has dense wool and can eat grass and lichen instead of shrubs and tree-leafs: the Mammoths. No need for breeding across-species, it all happens within a single genepool.
Take dogs for example. There are hundreds of dog races across the world, and a lot of them are VERY different. A chihuahua and a german sheperd, for example, or a terrier and an afghan. Yet they all come from the common wolf, they are interbreedeable and they can breed with wolves (genetically at least) Yet just by the look of them, you could never think that a chihuahua was related to the wolf. Here, the randomnes factor of nature has been replaced by the selective breeding of humans, but the underlying principle is exactly the same. The selective process just hasn't gone on long enough for the different breeds to not be interbreedeable anymore. But in 50.000 yeras or more, I wouldn't be surprised.
Nobody would compare an S.U.V. to a Ferrari, but they both have a common ancestor: the horse-drawn coach. At one point in time, a motor was developped which replaced horses. If it had sucked, compared to horses, it wouldn't have survived (people wouldn't have bought it) but it seemed better. Different types of motor-powered cars began to show up, and if a particular model appealed to an audience (a niche, in nature's terms) it stayed. If it sucked, nobody would buy it and production would cease. Over time, different types of cars could be recognized, each with their own set of defining characteristics, until they were as different as an SUV and a Ferrari. Evolution right there...