A web page created by Palomar College provides great information on what constitutes support that a species has evolved. The site offers four different pieces of evidence which illustrates the concept that evolution actually exists. According to the site, evolution has been proven to exist based upon these four ideas:
1) the fossil record of change in earlier species;
2) the chemical and anatomical similarities of related life forms;
3) the geographic distribution of related species;
4) the recorded genetic changes in living organisms over many generations.
According to the "Human Evolution Evidence" (on the Smithsonisan's website for the National Museum of Natural History), proof of evolution has been found in the evolution of human beings based upon changes regarding the size of the brain and body (over 6 million years).
One final site stated that proof of evolution through the similarities of animals. These similarities show that many of these "different" animals have similar ancestors. For example, the wolf, dog, and fox all share a common ancestor. Likewise, the horse, donkey, and zebra all share a common ancestor. In the case of the zebra, the stripes illustrate that a species adapts to the environment in which it lives.