► Investigation Two Summary – Genetic Variation and Natural Selection

► Investigation Two Summary – Learning Goals

1. Genetic variation is responsible for all the different traits that an individual possesses. In our example, there was genetic variation in the trait of bone density. Before the weather turned much colder, all the penguins were living happily. However, when the environment changed, some individuals were more adapted to the environment than others. Thus, they were more likely to survive and pass on their genes.

2. If members of a species did not have different traits no natural selection could exist because all the members of that species would be equally adapted to each environmental pressure. However, there is genetic variation in populations and some individuals are more adapted to their surrounds than others. The ones that survive are more likely to pass on their genes.

3. Environmental pressures can affect the population because some members are more adapted to the new environment than others. In the experiment, penguins with more dense bones survived at a higher rate because they were more equipped to deal with the shortage of food. The environmental pressure can be natural causes (such as temperature and sunlight) or human causes (such as pesticide exposure or antibiotic exposure).