The evidence of micro-evolution can be seen today even in humans. Take for example the wisdom teeth. Since we now have easy access to cooked meals that are easier to chew we actually lost the need to have that extra set of teeth. There are people who don't have those molars anymore, they are underdeveloped or they may be there but they remain hidden for their entire life. It is expected that in the future this set of molars will be gone from the entire population. But you have to understand that this process is dictated be genes. You have to give the gene that inhibits the formation of this set of molars to spread around. Other examples are the length of your body hair, the places where it grows, the shape of our eyes, the color of our skin. These differences exist because of the environments in which people have lived for long periods of time.
I remember watching a documentary about a species of lizard that had wings(a membrane between their legs) which it used to glide around to get from one tree to another. Some of them got to another island where the winds were stronger from what I can remember. This resulted in the wings of that lizard population to shrink because there wasn't a need for the bigger wing size.
A good example to seeing the kind of changes between one population to another is to look at birds. You have species of birds who live on different islands that are somewhat close. Those species of birds look very similar to each other but they have adapted to their specific island. One may have bigger claws while another one has a longer beak. They are all variations of a common ancestor.