What happens when an organism evolves?

Answer 1

The nature of organisms is that they don't stop evolving. Evolution is a gradual process that is not noticeable except over hundreds of generations. Mutation is impossible to prevent. Some mutations result in introduction or exaggeration of bad characteristics - these organisms die and generally do not reproduce, thus removing these characteristics from the gene pool. Some organisms can become perfectly adapted to the environment they live in - no further evolution is necessary for them to live exactly as-is. But the human timeframe is distorted - we tend to think of that environment in terms of a few hundred years, or more commonly, our own lifetimes. Organisms that have perfectly adapted will continue to change and evolve and the beneficial changes that remain may allow them to extend their area of colonisation. This may change them enough to form new species. There is also the fact that the environment changes and evolves also. Nothing stays the same forever. This is the main reason that organisms do not stop evolving - they continue to change and adapt to the environment as it changes around them. If they did not do this, they would die. I will avoid turning this topic into a theological debate, but one of the arguments for evolution is that it has been proven that the environment does change. If organisms did not adapt to their environment, they would die out.