Exam 18: Evolution of Populations

Genetic drift has a greater effect on

Although millions of prairie chickens once occupied Illinois, in 1993 only 50 remained. Starting in 1992, scientists moved almost 300 prairie chickens from large populations in other states to Illinois to _____ Illinois prairie chicken populations.

Allele frequency refers to the rate of mutation in a population.

In the Hardy-Weinberg equation, ____________________ represents the predicted frequency of the heterozygous genotype.

Genetic drift causes random changes in ____________________ frequency.

A new allele spreads from one large population to another as a result of genetic flow.

The increase in antibiotic resistance in E. coli as a result of treating healthy animals with antibiotics is an example of ____________________ driving evolution.

Which of the following is not a reason that farmers give antibiotics to their livestock?

Compared to a large mainland population, genetic drift in a small island population is

The Hardy-Weinberg equation predicts the following genotype frequencies for a particular gene: BB = 0.36, Bb = 0.48, and bb = 0.16. The population you are studying exhibits the following frequencies: BB = 0.42, Bb = 0.5, and bb = 0.08. What can you conclude?

The shell of a particular species of snail exhibits anywhere from 3 to 10 coils when mature. Over a series of three years, a scientist counts the number of coils in the shells of all the mature individuals in a population of snails. Year after year, the most common phenotype is 7 coils. Snails with 3 coils or 10 coils are very rare. This is an example of _____ selection.

A gene has two alleles, D and D. The frequency of the D allele is 0.2. What is the frequency of the d allele?

The fur in a species of mice ranges from white to black (intermediate phenotypes are different shades of gray). A population of these mice lives in an environment that contains both regions of white sand and regions of black lava rocks. When a scientist examines the frequencies of the different alleles in the population, she finds that, although white mice and black mice are common, gray mice are rare. This is an example of _____ selection.

In any given population the genotype frequency is usually the same as the allele frequency.

If the phenotypic distribution of a population starts out as shown in the graph on the left and ends as shown in the graph on the right, you can conclude that the population is undergoing directional selection.

Genetic drift can result in the fixation of a harmful allele in a small population.

____________________ is the only mechanism of evolutionary change that is not influenced by chance events.

In a population of 100,000 flies, 30,000 have the AA genotype, 20,000 carry the Aa genotype, and 50,000 have the aa genotype. What is the frequency of the A allele?

When a population shrinks, causing low genetic variation or the fixation of a harmful allele, a genetic ____________________ has occurred.

Two populations of geese live near each other. As time passes, the populations are becoming more genetically alike. This is probably due to ____________________.