1 Individuals within the same species are not identical.
2 The environment presents many different challenges to an individual’s ability to survive and reproduce.
3 Organisms tend to produce more offspring than their environment can support; thus, individuals of a species often compete with one another to survive.
4 Individuals within a population that are better able to cope with the challenges of their environment tend to leave more offspring than those less suited to the environment.
5 The traits of the fittest individuals those best suited to a particular environment tend to increase.
EX. A species of fish lay thousands of eggs. Each individual will have slightly, different variations. Fishes may differ in color, fins, tail size, and speed. A fast fish will have a skin color, so it will blend in with the surrounding, survive, and reproduce than a slow fish with a more obvious coloring. These adaptations carry several generations will produce a change in the species.
EX. Darwin's finches are an excellent example of the way in which species' gene pools have adapted in order for long term survival via their offspring. The Darwin's Finches diagram below illustrates the way the finch has adapted to take advantage of feeding in different ecological niches. Their beaks have evolved over time to be best suited to their function. For example, the finches that eat grubs have a thin extended beak to poke into holes in the ground and extract the grubs. Finches that eat buds and fruit would be less successful at doing this, while their claw like beaks can grind down their food and thus give them a selective advantage in circumstances where buds are the only real food source for finches.
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