1. The narrow-sense heritability of tail length in mice is about 0.6, and the na
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Question
1. The narrow-sense heritability of tail length in mice is about 0.6, and the narrow-sense heritability of litter size is about 0.15. The most likely reason for this difference is:
a. the total phenotypic variance for tail length is higher
b. the phenotypic effect of an allele substitution is lower for genes affecting tail length
c. the environmental variance is likely to be less for litter size than for tail length
d. directional selection has acted more intensely to fix alleles affecting litter size
e. individuals are more likely to be heterozygous for alleles that affect litter size
2. Which of the following is an essential condition in order for genetic hitch-hiking to occur?
a. genetic drift
b. natural selection
c. epistasis
d. recombination
e. pleiotropy
f. both (d) and (e)
3. Consider a population of size Ne with a new mutation that confers a fitness advantage of 1 + s. This new allele will be more likely to go to fixation due to selection if
a. Ne is large.
b. Ne is small.
c. s is small.
d. s is large.
e. both (a) and (d)
4. If the fitness value of an allele at one locus is altered depending on which allele it is paired with at a second locus, this is known as:
a. balancing selection
b. epistasis
c. a selective sweep
d. co-dominance
e. disequilibrium
5. Which of the following is a key assumption that was made in deriving the expression VA=2pqa2?
a. mating occurs at random
b. presence of stabilizing selection
c. "a" represents the mutation rate
d. absence of dominance
e. heterozygotes have superior fitness
f. (c) and (e) are both correct
g. (b) and (c) are both correct
h. (a) and (d) are both correct
i. (a), (b), (c), (d) and (e) are all correct
Explanation / Answer
1. c. the environmental variance is likely to be less for litter size than for tail length
2. c. epistasis
3. a. Ne is large and d. s is large
4. b. epistasis
5. a. mating occurs at random and d. absence of dominance
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