Question

Natural selection can move a population beyond its initial range of variation because

a. sudden increases in mutation rates are often induced by selection.

b. under genetic drift there is less variation and under selection there is more.

c. selection can expose hidden variation.

d. selection usually increases the randomness of mating, thus increasing variation.

Which of the following is true of continuously varying characters?

a. They allow for blending of the effects of two genes, the blended version passed on to offspring.

b. They are likely to expose the genetic variation underlying a trait.

c. They always hide genetic variation.

d. They do not help to explain how variation is maintained.

Which of the following decreases genetic variation?

a. mutation

b. selection

c. recombination

d. gene flow

Which of the following is true of geneticists at the beginning of the twentieth century?

a. They thought that inheritance was fundamentally discontinuous.

b. They argued that Mendelian genetics supported Darwin’s idea that adaptation occurs through the accumulation of small variations.

c. They agreed that evolution was proceeded by the gradual accumulation of small changes.

d. They believed that genes had no discernible effect on phenotypes.

Which of the following statements is correct?

a. Hidden variation is not always present in continuously evolving traits.

b. Selection causes genotypic frequencies to reach equilibrium in one generation, and the distribution of phenotypes does not change.

c. Selection can lead to cumulative, long-term change.

d. Genetic variation is always expressed as phenotypic variation.

Answer 1

Natural selection can move a population beyond its initial range of variation because selection can expose hidden variation. It means that though selection favours one phenotype, but other allele (for different phenotype) can be eliminated completely because favoured gene largely masks the effects of the other gene.