a bbhosted.cuny.edu y>STUDENTS ANTH 260: E Take Test: Problem Set 2-20 After exa

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a bbhosted.cuny.edu y>STUDENTS ANTH 260: E Take Test: Problem Set 2-20 After examining Pikachu mating strategies and survival rates you disoover that Pikachus with three stripes have a very few babies, while Pikachus with no stripes rarely survive to adulthood. Pikachu with two stripes soom to survive and reproduce better than other phenotypes. What mode of natural selection is affecting the Pikachu population? Oa Balancing selection Ob. Directional selection for the recessive phenotype OG Purifying selection Od. Disruptive selection Oe Frequency-dependent selection Ot sexual lection QUESTION 6 Eventually, you estimate that the relative fitness of Pikachus with no stripes is 0.1, the relative fitness of Pikachus with three stripes is 0.4. Pikachus with two stripes have the fitness of 1. Determine how the frequency of N alilele will change. Determine the selection coefficients (s) for Pikachus with no stripes and for Pikachus with three stripes. Oa 0.9 and 0.1 Ob 0.5 and 0.5 Oc. 0.25 and 0.75 Od. 0 and 1 00.0.4 and 0.1 Of 0.9 and 0.6 Chick Save and Submit to save and submit. Cliek Save All Ansuers to saee oll isuirs

Explanation / Answer

Question 5.

Balancing selection: Multiple alleles are maintained in the gene pool at unexpectedly large concentrations. ( not applicable here)

Directional Selection for recessive phenotype: this type of selection shows a clear advantage to the recessive phenotype. (not applicable here)

Purifying selection (also called negative selection) is the selective removal of alleles that are harmful or deleterious. In this type of selections, carriers of the harmful gene produce fewer and fewer offspring in each generation and the frequency of the allele is greatly reduced. (applicable here)

In disruptive selection, extreme values for a trait are favored over intermediate values. In this case, however, that is not true since the intermediate value is reproducing better.

Frequency-dependent selection is an evolutionary process by which the fitness of a phenotype depends on its frequency relative to other phenotypes in a given population. In positive frequency-dependent selection, the fitness of a phenotype increases as it becomes more common. (This could be applicable here.)

Sexual selection is not applicable here.

If multiple options can be selected, Purifying selection and frequency-dependent selection are both correct. If only one option, then the frequency-dependent selection is correct because it is more evident than purifying selection.

Question 6.

The formula to be used is: Selection coefficient = 1- fitness

The relative fitness is the fitness in comparison to the fitness of the fittest allele. ( 1 here.)

s (no stripes) = 1-0.1 = 0.9

s (3 stripes) = 1- 0.4 = 0.6

f option is correct.

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