I do not think mass extinction plays such an important role in evolution. Ofcourse it will have a huge impact but I think the environment is a much more important factor in evolution. I think isolation played a huge role similar to what you say of mass extinction, imagine a species adapted to very harsh environments somehow comes to another less harsh environment and thrives, maybe hurting or helping the native species. There are so many factors involved with natural selction I don't see how you can say they are not the driving force of evolution, if natural selection does not drive it then what? Mass extinctions? Isn't that natural selection as well anyway, think about it nature selecting species wich survive catastrophic events.
"Whenever I read about evolution, there is always a tie between natural selection and evolution." A tie? Just a tie? The two are practically one in the same. Unless you believe some outside force is directing all things, natural selection is evolution.
"Over time, as organisms become better and better within their local environment, they evolve into a new species that is incompatible with the old species." Within a local environment there would probably be no old species left because they all became the new species. Now over a large environment, or were isolation of species is maintained for many generations, with differing conditions there may be some branching, and incompatibilities may begin. Really there is no "old" species or "new" species unless you travelled back in time and brought an organism into the future.
"Although I agree with natural selection, I do not agree that natural selection evolves new species. Actually, I think that it does the opposite. Natural selection takes what it has available and looks for an optimal solution to the problem." You would be right if there was only one "problem", but the earth varies greatly in climate and terrain, and thats speaking on a very large scale, compared to the origins of evolution wich took place at a subatomic scale, combinations of proteins and nucleotides (if my memory serves me right) imagine all the different combinations of subatomic particles throughout the earth, and there changing all the time, it may as well be infinite.
"So where does evolution come from if not from natural selection? I suspect evolution is driven by mass extinction. If some natural event occurs that wipes out 90% of all organisms on earth, then there is less competition against each other and more competition against the environment." Natural selection is a process that includes competition between species as well as with the environment. And there hasn't always been that much competition, at one point this earth was without life.
"As natural selection starts to take hold once again, the sub-optimal paths are once again pruned, forming new divisions or species.... until the next mass extinction." Natural selection never lost it's hold, mass extinctions are a part of natural selection."Sub-optimal" paths are taken all the time in evolution, natural selection. Organisms are effected and changed by all sorts off things, and not always for the better, or worse, usually it falls in that middle ground, the grey area, most changes are so small and happen over such long periods of time there is never a chance to say wether they are good or bad, "optimal" or "sub-optimal", most changes do not even impact a species survival at all. Parts of organisms can evolve for no reason pertaining to the organisms ultimate survival at all, random mutations allowed to grow because they have no positive or negative impact.
A great book on evolution, though a little dry, is Darwins Dangerous Idea by Daniel Dennet, that is where most of my ideas on evolution came from.
|