Buddy, The adaptation, most of the time, is because the environment of the area of the specie has changed. If an ice age occurs, the animals either adapt to the harsh conditions, or they die. Some adapt as a factor if instinct to survive kicks in, and the changes made by the mother as a member of a specie, a change is registered in the genes and is passed on to those that are born by that animal.
For instance, in the galapagos, there were differences in the environment on each island that provided different food sources for a specie of a bird and as a result, these birds have a different kind of beak depending on what island they lived on.
I don't know the reason why, but the large land tortoises have a different carapace pattern depending on the island where they live.
As you infer, all individuals of a specie will not adapt to accommodate the environment, so those that did adapt, had the change entered into their genes, and their offspring will be born with a slightly different DNA than the ones born of a mother that did not adapt.
The species of all animals will be affected by a great disaster, and in most cases that disaster will be caused by nature, so evolution is affected by nature. I also said that the intervention by humans does not necessarily have any affect on evolution, but then one has to explain what has happened to dogs because of the selected breading by humans over the thousands of years. Look at all of the different breeds of dogs, and bear in mind that all of them came from a common ancestor that either was a wolf, or an entity that was the ancestor of both dogs and wolves. There is still a lot of debate going around about each of those theories.
All bovines have the ancestry of the large Och, and they are all quite different from each other, but there are a number of ways that could have been achieved, one of them being the domestication of bovines thousands of years ago. |
