Luxor4u

Mad Dilys wrote:I've bred all kinds of farm animals pets and birds, so of course I believe a lot of change can come about by adapting to the environment.

I also know from my gardening that sudden and unexpected mutations occur. That is a universe away from what is commonly known as Evolution in my opinion It's rather like the management of the NHS who draw the lines then try to get the dots to fit them.

And that's exactly the basis of evolution!

Darwin didn't know anything about the process by which life forms changed. He worked out that species changed, and that those better adapted to their environment survived whilst other died out. Survival of the fittest and all that. What he didn't know was the mechanism which allowed diversity ...the chance mutation of genes during sexual reproduction.

I also know from my gardening that sudden and unexpected mutations occur. That is a universe away from what is commonly known as Evolution in my opinion

But that is exactly what evolution is, minor changes that occur in all species that are either detrimental or enhance the chances of survival, it is called natural selection. A classic modern example would be Elephants, due to ivory hunting and poaching all the big tuskers will be shot. Those animals became the dominant bulls simple because of their huge tusks and the ability to fight other males for the right to mate and so the dominant feature became large tusks in Elephants. With the eradication of these large tusked males the smaller tusked males will be able to mate, these smaller tusked males will then pass on the small tusk gene to their offsprings and be less attractive as a source of ivory and as such will have a better chance of survival, this trait will continue and eventually result in all Elephants having smaller tusks as is happening today when bulls carry far less ivory than say 100 years ago. In nature once a mutation has occurred and failed to be beneficial it is rarely if ever repeated in that same species, the only exception I can think of is the large teeth in canines such as the sabre toothed Tiger which seems to have occurred several times throughout the millennia.

Edit: You beat me to it Newcastle

Actually Horus, we're talking about slightly different mechanisms for evolutionary change.

Your example is the commonest.....environmental changes "selecting" one gene (small tusk) as opposed to another (large tusk).

I was alluding rather to the completely random mutation of genes which can occur...and result in a beneficial, adverse or neutral change (in survival rates) for the life form in question. An example of this might be the arrival of drug resistant bugs, where a random change in the bug's genetic makeup enables it to survive the onslaught of antibiotics.