Questions on "Random" Mutations

There's absolutely no reason why we couldn't breed either tigers or lizards. There's considerable variety already in tigers, with the world's largest wild cat, the Siberian tiger, already significantly different from the others. The Sumatran tiger has been in isolation on its island since the last ice age as well, so there's probably quite a lot of variety to go on.However, nature has already done this in a sense, and the big roarer cats, lions, tigers and leopards, are the end products. All can produce offspring with the others in captivity, and some of the hybrid females are fertile, which means that we could possibly play with introducing lion and leopard genes into some of our new tiger breeds.What we see in these cats is the result of nature, over perhaps about 2 million years, doing what we've done with dogs (and domestic cats). The genetic differences must be more profound in the wild cats, because the male hybrids seem to be invariably sterile.The real natural equivalent of our dog breeds could perhaps be the differences within lions, tigers and leopards. There are visible and behavioural differences between African and Asian lions, the Snow Leopard and tropical leopards, and the Siberian Tiger and other tigers as mentioned above.The big roarer cats are a very good example of varying degrees of divergence from a (relatively speaking) recent common ancestor. Evolution, Martin, whether you like it or not!

I think Dr. A's reading of what Martin meant was accurate, Ned. As you say, NS is reshaping the gene pool over time. It does not "just remove extremities". It could be said to remove extremities, if we used the word extremities to mean "characteristics disadvantageous to the organism in any particular environment". However, it's Martin's use of the words "just" and "purely" which give the clue to his meaning.NS can clearly be a conservative force, and a force for change.