O.K., if we've got that down, here's the basic explanation, for blu.
The question we are answering, remember, is how do we get new species? How does a new species come about?
We could use any kind of example: fish, birds, lizards, flowers. Let's say fish. Say you have an insignificant species of fish--call it Fishius blua. Say it's 3" long, brown with some yellowish and greenish speckles, eats aquatic bugs, lays around 50 eggs every 3 moths, and it takes 2 months to reach maturity. O.K.? Now say of those 50 eggs 10 of them reach maturity, cuz it's tough on a fish. Of those, they will all look basically alike to us, but if you look close there are little variations--size, shade, number of speckles, and other differences that we can't see--immunity, speed, eye-sight. Just tiny variations. But since they're all the same species, all those variations keep getting mixed back into the pool, so they keep getting distributed around and the whole species changes either not at all, or together.
O.K. but say something happens so one lake full of Fishius blua gets cut off from the group. Like an earthquake changes the river drainage or whatever. Now they're isolated. And that lake is a little different--little colder, has a fungus that prefers yellow speckles and a predator that can't see greenish ones, etc. So over time, the green speckles will predominate, maybe the bigger ones tend to survive better, and it works better to lay 60 eggs, etc.
Now let 100 years go by, which is 600 generations of Fishius. At this point, the two groups look pretty different. They're a different size, different color, reproduce a little differently. It's a very slow and gradual process. At some point the two groups can no longer breed together. At that point Biologists say, "Whoa, Nelly. We're going to call the separate group a different species. And since my name is Tristesse, I shall call it Fishius tristessa." Voila--a new species.
That's how ToE says we get new species.
What say you, blu?