Consider the diagram below showing the gene pool of a population over 20 generations.

a. Using the information above, explain how natural selection can lead to the differences in genotypes seen in this population over time. Populations of the lizard species Anolis sagrei are found on the many islands of the Bahamas.There is natural variation between the phenotypes of individuals within each population. In 2004, a hurricane killed many A. sagrei lizards on one of the islands of the Bahamas.Over the next three years, the scientists measured the genetic diversity within the population and found there was lower genetic diversity.

b. Explain the reasons for the lower genetic diversity of the A. sagrei lizards on the island being studied compared with the population on an unaffected island.

C.Describe the effect of having reduced genetic diversity for a species.

Retinitis pigmentosa (RP) is an autosmoal recessive trait that results in progressive blindness in humans. On the island of Tristan da Cunha in the Atlantic Ocean, the frequency of the allele causing RP is four times greater in its population of a few hundred individuals than in the original British population from which it was colonised in the early 1800s. No natural disasters have occurred on the island since it was colonised.

d. Explain the process that is most likely responsible for this observation related to allele frequency?