There is a whole lot of evidence for what you call 'macro-evolution'. There are mountains of evidence for it. You don't have a clue about this stuff.
I call them different species because we're discussing Biology. You don't know what a family is do you?
Do you think that cats and lions have common ancestors?
Do you think that land snails (pulmonates) evolved from water snails? (don't kid yourself.....That's what you call "macro-evolution")
Do you think that sea slugs evolved from snails? (don't kid yourself.....That's what you call "macro-evolution")
I don't. Why are you writing that sort of bullshit about me?
What is the mechanism for evolution ?
The mechanism is in the interaction of the individuals within species. We, as race of humans are taller and more numerous than we were even 200 years ago.
That is evolution. If you are white and your children are white, that is evolution. Sameness, as well as difference is evolution. It is the path on which a species changes, but the species knows not the path nor does it know the direction or the destination.
We, as humans exist within societies and those societies swell as our ancestors contribute to evolution. The crippling illness of today was the fatal illness of yesterday. Conversely, the fatal illness of today may have been a dormant curiosity in the past.
Life is change and change is what evolution is.
If we go with your theory--I was taught that evolution is just a bit more complicated than that but we'll use your definition here--let's return to the topic of the thread. Is the evolution we can observe all strictly a process of random chance? Or are there other dynamics involved? And if there are other dynamics involved, is it within the range of rational possibility that evolution is part of a larger dynamic that could be called Intelligent Design?