Population Genetics and Evolution

In an isolated population of 250 dragonflies, blue wing color is dominant to red wing color. If the frequency of the blue allele is 0.8, how many dragonflies are red? Assume that the population is not evolving. A. 10 B. 50 C. 80 D. 160

A. 10 (We need to calculate the number of dragonflies with the homozygous recessive phenotype. The question stem gives us the frequency of the blue allele (p), which we can use to calculate the frequency of the red allele (q) through the formula p + q = 1:0.8 + q = 1q = 0.2 If q = 0.2, then q2 = 0.04, which is the frequency of the homozygous recessive phenotype. To calculate the number of dragonflies with this phenotype, we simply multiply the frequency by the number of dragonflies in the population which yields (0.04)(250) = 10 individuals.)

Which of the following examples best illustrates the bottleneck effect? A. A wildfire consumes all of the aspen trees on the west side of a forest, but the aspens along the southern border are untouched. B. Influenza viruses within a person's nasal cavity are aerosolized during a sneeze and begin to proliferate on a classroom desktop. C. Arctic temperatures begin to rise, melting ice caps and reducing the global polar bear population, but a small number of polar bears with lower heat sensitivity survive. D. A group of rats emigrates from its parent population and joins another population living two miles away, increasing the genetic diversity of the second population.

A. A wildfire consumes all of the aspen trees on the west side of a forest, but the aspens along the southern border are untouched. (The bottleneck effect occurs when population allele frequencies change in response to a random decrease in population size due to external events, such as natural disasters. This best exemplifies the bottleneck effect as the surviving aspen trees were simply "lucky" in the sense that they had no fitness advantage over trees located at the western edge of the forest. The wildfire did not destroy them because it did not enter the southern region. Any changes in population allele frequencies will be due to random chance alone.)

Which of the following are mechanisms of genetic drift? Select all that apply. A. Founder effect B. Gene flow C. Disruptive selection D. Bottleneck effect E. Immigration

A. Founder effect D. Bottleneck effect

Which of the following statements are true about genetic drift? Select all that apply. A. It is a type of selective pressure. B. It causes random changes in allele frequencies. C. It can lead to loss of genetic diversity. D. It has a greater effect in small populations.

B. It causes random changes in allele frequencies. C. It can lead to loss of genetic diversity. D. It has a greater effect in small populations.

Which of the following are reasons why the biological species concept is problematic? Select all that apply. A. It does not account for coevolution. B. It does not apply to organisms that reproduce asexually. C. It does not account for hybrid organisms. D. It does not apply to organisms that are reproductively isolated.

B. It does not apply to organisms that reproduce asexually. C. It does not account for hybrid organisms.

Which of the following causative relationships listed below are correct? Select all that apply. A. Evolution results in fitness. B. Natural selection results in evolution. C. Natural selection results in fitness. D. Fitness results in natural selection.

B. Natural selection results in evolution.

Convergent evolution and parallel evolution of two species differ with respect to: A. the type of trait that is acquired by the two species in question. B. the genetic similarity of the two species in question. C. whether the trait in question was evolved by a common ancestor of the two species. D. whether the two species in question develop similar or different traits.

B. the genetic similarity of the two species in question. (Convergent evolution is what occurs when two very different species independently evolve a similar trait, such as a bird and an insect both evolving wings for flight. Parallel evolution happens when two species with a recent common ancestor evolve a similar trait, such as two species of butterflies evolving similar coloration patterns.)

The allele W, for white wool, is dominant over the allele w, for black wool. If 16% of a sheep population is black, and the population is unaffected by evolutionary forces, what percentage of the population is heterozygous for wool color? A. 36% B. 40% C. 48% D. 60%

C. 48%

Disruptive selection is best defined as: A. a type of natural selection caused by the introduction of new alleles through gene flow. B. a type of genetic drift in which a natural disaster changes allele frequencies at random. C. an evolutionary pressure favoring extreme phenotypes over intermediate phenotypes. D. the retention and overexpression of deleterious recessive alleles due to inbreeding.

C. an evolutionary pressure favoring extreme phenotypes

The presence of any of the following characteristics will prevent a population from attaining Hardy-Weinberg equilibrium EXCEPT: A. natural selection. B. genetic mutation. C. random mating. D. gene flow.

C. random mating.

True or false: Inbreeding results in greater phenotype expression of deleterious recessive alleles than does outbreeding.

True.

True or false: Differential reproduction results in natural selection, which is a mechanism through which evolution occurs.

True. (Differential reproduction occurs when certain traits are more favorable than others within a population and these traits are reproduced more frequently. Since natural selection is the process through which favorable traits are selected and maintained within a population, differential reproduction results in natural selection. Natural selection drives evolution as selection for favorable phenotypes causes the population to evolve in that direction over time.)