Natural Selection

Chase N.

Biology 1001

Section 52

3-5-2011

Natural Selection Exercise

Natural Selection Scenario Essay:

Charles Darwin was the first person to propose the theory of evolution by natural selection. Natural selection takes place within populations over generations. At the core of this theory is the idea, “ different reproductive success” of individuals within the population. No two individuals in a population are perfectly alike, this difference, known as genetic variation, shows the differences in individuals within a population. The individuals that exhibit traits most necessary to survive, will survive and reproduce, this variation among individuals within a population is known as differential reproductive success. Due to limited resources, populations struggle for survival, which ultimately leads to controlling the population size. Individuals that exhibit a high relative fitness are more likely to survive and reproduce. Relative fitness is the measure of relative reproductive success of different genetic variants in a population. Another factor that affects natural selection is adaptation, which describes the heritable traits of individuals that improve reproductive success. A final way that individuals among a population develop new traits is by mutation. Mutations arise when changes in DNA sequence occur within an individual. Mutations can be either beneficial or detrimental.

The hypothetical scenario that we observed in class regarding the size and strength of finch beaks shows the results of natural selection. This change occurred over the course of many generations within the population. The ancestral finch population had small, thin, and relatively weak beaks. Either this population migrated to an area with plants that were stronger and contained seeds that were more difficult to crack, or the plant population in their native area evolved and became stronger with harder seeds. Because of this, the finches with stronger and larger beaks were...