Question

Which is a phenomenon that can result from directional selection? a. There is an increase in the number of different breeds of dog. b. There is an increase in the number of giraffes with long necks in areas of Africa where low-growing trees have died. c. There is an increase in garter snakes with different coloration patterns found in backyard gardens.

Answer 1

Answer:  Option B

Explanation:

Differential selection took place during the time when all the long necked giraffe survived in the area of Africa and all the giraffe that has short neck died.

Directional selection can be defined as the type of the selection in which the the most extreme phenotype is selected over the other phenotype.

In this case when the grasses having short height was consume then the giraffes having long neck was selected over short neck.

Answer 2

Answer:

B) There is an increase in the number of giraffes with long necks in areas of Africa where low-growing trees have died

Explanation:

The directional selection is one of the ways of the natural selection in which the natural selection selects or favours the most extreme trait of the species and the extreme trait show higher fitness than the normal or average trait.

In the given question, the case of Giraffe necks shows directional selection as the normal length of the neck is not favoured by the environment but the extreme trait that is long neck is favoured by the environment and the selection shifted to that level.

Thus, Option-B is the correct answer.