Almost every time I have a discussion like this we seem to be unable to agree on a definition. Please give me your definitions for speciation, evolution, natural selection in you next post to bring some clarity.
Speciation: a species that has been split into two reproductively isolated populations, and each population evolves in different ways to the point where members from two different groups would not reproduce even if they were brought into contact with each other. For example, if there was a population of spiders, but flooding created a river which thereafter flowed through the middle of their range, dividing them into two different groups, each group would be reproductively isolated. Members of one group would not be able to reach members of the other group and so they couldn't interbreed. Each group would continue evolving in their own way, and would face different pressures. For example, one group might have to face a species of predatory lizard that the other group, protected by the river, did not face. Over time, the two different populations of spider would evolve differences, and many generations later, the differences would mean that a spider from Group A would not mate with a counterpart from Group B, even if a researcher collected specimens from both groups and put them in the same box. They might have evolved physical differences which make them physically incompatible, or they might have evolved different mating behaviour, meaning one spider would simply not see the other as a potential mate.
Evolution: The way animals change over many generations as they face different pressures in their environment. One of the things that causes the change is natural selection, described below. And I cannot emphasize enough, it is a change over many generations. An individual animal will NOT evolve.
Natural selection: Each individual in a population is born with a unique set of traits. It might have slightly better stamina than others in the group, or slightly poorer eyesight. These traits create benefits or disadvantages in the individual. If a benefit means that the animal has a better chance of surviving long enough to reproduce, the genes that cause this trait have a good chance of being passed to the offspring. This means that the trait will appear in more and more individuals as the offspring grow and have offspring of their own and pass on the genes yet again. However, if a trait causes a disadvantage in an animal, then it might end up meaning the individual is more likely to die before it can reproduce. And so, the genes that cause these disadvantages are much less likely to be passed on, because any animal that has them isn't likely to produce any offspring to pass them on to. So, genes that create advantages are more likely to be selected by the natural pressures to spread throughout the population, and traits that cause disadvantages are more likely to be removed from the population by killing the individuals who have them before they can pass them on.
I think just about anyone who understands these concepts would agree with what I have written here, I hope this clears it up for you.