Darwin And Wallace's Theory Of Evolution

In the content of Natural Selection, published by Darwin and Wallace, the theorem of evolution is clearly defined: Creatures will evolve by natural selection. Nature selects, the fittest survives. We can not only see the evidence of the fossils of the horse in a long time scale, but we can see the short-time evolution on cichlid fish.
Another support is the evolutionary tree. It shows us all the creatures has its own ancestors, and then we can find the similarity or the common point in either gene or external features.
And the mechanism of evolution is now well adapted to the gene biology like DNA analysis with the modern technology. With the concrete evidence and the use in modern medical technology, we can totally confirm that evolution is