1. Which of the following statements about genetic drift are true? a. Genetic dr
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Question
1. Which of the following statements about genetic drift are true?
a. Genetic drift occurs more slowly and has a greater effect in small populations, as compared to large populations.
b. Genetic drift is the change in the frequency of an allele in a population that occurs because of random chance.
c. Genetic drift can only impact existing alleles and reduces allelic variation in a population.
d. Genetic drift is the change in the frequency of an allele in a population that occurs because the allele provides a reproductive advantage.
2. A hypothetical population of a trout lives in a lake in California. The fish in this population have two color phenotypes, brown and white. Both phenotypes are relatively equal in the population. In this species, scale color is controlled by different alleles for the same gene. The population in the lake is isolated from other populations of trout as there are no rivers or streams connecting the lake to other bodies of water. One winter, a rockslide on a cliff bordering the lake kills half of the fish living in the lake. By random chance, the majority of the fish killed in the rockslide have the white phenotype. Several years later, a scientist studying the population of trout in the lake observes that there are no more white fish present in the lake. What is most likely responsible for the change in phenotypic frequency of trout in the lake?
a. genetic drift
b. gene flow
c. natural selection
d. allopatric speciation
3. Which of the following best describes macroevolution?
a. evolutionary changes over a long time that encompass entire groups of species
b. gene frequency changes within a population over a short period of time
c. differential reproductive success within a population based on trait variation
d. two interacting species reciprocally affect the other's evolution
Explanation / Answer
1. Both a and b are correct as genetic drift influences more of a small population compared to a large population and the process of change in allelic frequency is a random process.
2. The population of white trout went considerably down was due to a chance event in which most of the white population died (can be due to several reasons, say brown trouts have better ability to escape the rockslide, due to minor variations in phenotype). Since the population of white tout was almost nil , shows that natural selection has played its role in determining the kind of species that has to survive in a Californian lake (option a).
3. Option a as macroevolution occurs on a larger time scale and encompasses entire group of species.
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