Speciation
Speciation is when two or more species evolve from one parent species. This contributes to Evolution in a few ways. First you need to know how speciation works. Speciation occurs when there is a physical barrier is placed between the same species. This barrier prevents the species to breed with the other across the barrier. Over time the species eventually start to form different genes from the other side to help it survive in its environment. If the barrier ever disappears then the two species will not be able to breed because of the different genes each species has.
Example: One type of finches are living in the same area with now barrier to prevent them from breeding. They have the ocean to the west and mountains to the east. Soon a hurricane hits the population from the west and drives some of the birds over the mountains. Over time the finches that are over the mountains start to adapt and change to their new surroundings. Their beaks become longer and more curved, their feathers become darker then they already were. 1 million years later and somehow the mountains flatten out to be a large plain. The two species of birds cannot breed now because of the differences in their genes.
Because Speciation occurs evolution is possible. With a barrier between two different species, one or both species can change over time to benefit from the environment. That is one reason why the finches Darwin brought back from his journey's were so different. They all had different color and patterns on their feathers and different kinds of beaks. Yet, you are still able to trace all of them to the same ancestor. It is because of speciation that each finch was different in their own kind of way and there is no way to be able to breed them with such differences in the genes.
