Use the following information to answer the next three questions: 1) A new speci

Question

Use the following information to answer the next three questions:

1) A new species of lizards in the American northwest have been discovered. A researcher at UTSA counted the different varieties and observed that out of 500 lizards, 96 were black (BB), 185 were brown (bb), and 219 were spotted (Bb). What is the chi-square value, df, and is this population in Hardy-Weinberg equilibrium?

2) In the same population of lizards, each genotype has the following # of viable offspring:

BB = 110, Bb = 180, and bb = 75.

What is the relative fitness for each? Give answer to the nearest 2 decimal places.

WBB =

WBb =

Wbb =

What is the selection coefficient for each?

SBB =

SBb =

Sbb =

3) Which of the following best describes the population of lizards in the previous problem? May have more than one answer, select all that apply.

a) underdominance

b) directional selection

c) overdominance

d) disruptive selection

e) stabilizing selection

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4) Tay-Sachs disease (TC) is an autosomal recessive disorder that is fatal in children (usually by age 5). It causes a progressive degeneration of the central nervous system, and is especially prevalent in people of Eastern European and Askhenazi Jewish descent. In the Askhenazi Jewish population, about 1 in 4500 babies are born with the disorder.What is the frequency of individuals in the Askhenazi Jewish population that do not carry the allele for TC?

Explanation / Answer

answer no 1,

observed gene frequencies

BB(p2) = 96/500 = 0.192

Bb (2pq) = 185/500 = 0.37

bb (q2) = 219/500 = 0.438

ALLELE FREQUENCIES:

Freq of B = p = p2 + 1/2 (2pq) = 0.192 + 1/2 (0.37) = 0.192 + 0.185 = 0.377

Freq of b = q = 1-p = 1 - 0.192 = 0.808.

EXPECTED GENOTYPE FREQUENCIES (assuming Hardy-Weinberg):

BB(p2) = (0.192)2 = 0.036

Bb (2pq) = 2 (0.192)(0.438) = 0.168

bb (q2) = (0.438)2 = 0.191

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