Genetics Ch. 25

A recessive allele for brittle bones in a deer population has a selection coefficient of 0.9 and a mutation rate of 5 x 10-6. If this allele is at equilibrium in the population, what is its allelic frequency? A. 0.002 B. 0.02 C. 5.55 x 10-6 D. 424 E. 4.5 x 10-6

A. 0.002

In a large, randomly mating population, the frequency of the allele (s) for sickle-cell hemoglobin is 0.028. The results of studies have shown that people with the following genotypes at the beta-chain locus produce the average numbers of offspring shown: What will the frequency of the sickle-cell allele be at equilibrium? A. 0.145 B. 0.17 C. 0.032 D. 0.028 E. 0.855

A. 0.145

For a period of 3 years, Gunther Schlager and Margaret Dickie estimated the forward and reverse mutation rates for five loci in mice that encode various aspects of coat color by examining more than 5 million mice for spontaneous mutations (G. Schlager and M. M. Dickie, 1966, Science 151:205-206). The numbers of mutations detected at the dilute locus are as follows: If the forward and reverse mutations rates are representative of rates in natural populations of mice, what would the expected equilibrium frequency of dilute mutations be? A. 0.85 B. 0.0000034 C. 0.000019 D. 0.15 E. 0.36

A. 0.85

The forward mutation rate for the melanic form (dark grey color) in a population of peppered moths is 5 × 10 -7and the reverse mutation rate is 1 × 10 -9. If the population is in mutational equilibrium, what is the expected allelic frequency of the melanic form? A. 0.998 B. 0.002 C. 0.5 D. 0.0 E. 1.002

A. 0.998

A total of 6129 North American Caucasians were blood typed for the MN locus, which is determined by two codominant alleles, LM and LN. The following data were obtained: Carry out a chi-square test to determine whether this population is in Hardy-Weinberg equilibrium at the MN locus. Round all calculations to two decimal places except the expected numbers of each genotype where you should round to the nearest whole number. A. Chi square = 0.48; the population is in equilibrium. B. Chi square = 3.70; the population is not in equilibrium. C. Chi square = 7.31; the population is not in equilibrium. D. Chi square = 1.20; the population is not in equilibrium. E. Chi square = 0.084; the population is in equilibrium.

A. Chi square = 0.48; the population is in equilibrium.

What assumptions must be met for a population to be in Hardy-Weinberg equilibrium? A. Random mating, large population, gene pool not affected by migration, selection, or mutation B. Nonrandom mating, large population, gene pool not affected by migration, selection, or mutation C. Nonrandom mating, large population, gene pool is continually undergoing change driven by natural selection D. Random mating, large population, gene pool is continually undergoing change driven by natural selection E. Random mating, large population, gene pool is influenced by migration, selection, and mutation

A. Random mating, large population, gene pool not affected by migration, selection, or mutation

Migration begins between two genetically diverse populations. What will happen to the gene pools of these two populations? A. The gene pools will become more similar. B. The gene pools will remain unchanged. C. The gene pools will become less similar. D. The gene pools will diverge via natural selection. E. Mutations that arise in one population will be absent in the other.

A. The gene pools will become more similar.

Briefly describe underdominance. A. The heterozygote has lower fitness than either homozygote. B. One allele has greater fitness than another. C. All alleles have equal fitness. D. The selection coefficients are all zero. E. The heterozygote has greater fitness than either homozygote.

A. The heterozygote has lower fitness than either homozygote.

What factors affect the magnitude of change in allelic frequencies due to migration? A. The proportion of the population due to migrants and the difference in allelic frequencies between the migrant population and the original resident population B. The number of migrants that die before arriving in the new population C. The amount of natural selection that the new migrants impose on the population D. The mutational rate in the migrants' genome as compared to the mutational rate in the original population E. The number of unique mutations in migrant alleles and the fecundity of the migrants

A. The proportion of the population due to migrants and the difference in allelic frequencies between the migrant population and the original resident population

Testing to see if a population is at Hardy-Weinberg equilibrium requires all of the following EXCEPT: A. determining if selection is acting on the population. B. measuring or estimating the genotypic frequencies. C. calculating expected genotypic frequencies based on allele frequencies. D. conducting a statistical test, such as a Chi-square test. E. Actually, all of these are necessary steps.

A. determining if selection is acting on the population.

Depending on the environment and the genotypes involved, selection can produce all of the following effects EXCEPT: A. directional selection and eventual elimination of a recessive allele. B. directional selection and eventual elimination of a dominant allele. C. disruptive selection with the homozygotes being more fit than the heterozygotes. D. stabilizing selection, also known as overdominance. E. Actually, it can produce all of these effects.

A. directional selection and eventual elimination of a recessive allele.

The __________________________ is influenced by a variety of factors such as fluctuations in population size, age structure of the population, sex ratio and variance in individuals' reproductive success. A. effective population size B. mean fitness C. inbreeding coefficient D. migration rate E. mutation rate

A. effective population size

Voles (Microtus ochrogaster) were trapped in old fields in southern Indiana and were genotyped for a transferrin locus. The following numbers of genotypes were recorded, where TE and TF represent different alleles. Tom McHugh/Photo Researchers. Calculate the genotypic and allelic frequencies of the transferrin locus for this population. (In the answers, TE and TF are represented by E and F, respectively.) A. f(EE) = 0.685, f(EF) = 0.286, f(FF) = 0.029, f(E) = 0.828, f(F) = 0.172 B. f(EE) = 0.029, f(EF) = 0.286, f(FF) = 0.685, f(E) = 0.828, f(F) = 0.172 C. f(EE) = 0.685, f(EF) = 0.286, f(FF) = 0.029, f(E) = 0.172, f(F) = 0.828 D. f(EE) = 0.029, f(EF) = 0.685, f(FF) = 0.286, f(E) = 0.172, f(F) = 0.828 E. f(EE) = 0.029, f(EF) = 0.286, f(FF) = 0.685, f(E) = 0.172, f(F) = 0.828

A. f(EE) = 0.685, f(EF) = 0.286, f(FF) = 0.029, f(E) = 0.828, f(F) = 0.172

The human MN blood type is determined by two codominant alleles, LM and LN. The frequency of LM in Eskimos on a small Arctic island is 0.80. If the inbreeding coefficient for this population is 0.05, what are the expected frequencies of the M, MN, and N blood types on the island? A. f(MM) = 0.648, f(MN) = 0.304, f(NN) = 0.048 B. f(MM) = 0.648, f(MN) = 0.048, f(NN) = 0.304 C. f(MM) = 0.64, f(MN) = 0.32, f(NN) = 0.04 D. f(MM) = 0.64, f(MN) = 0.304, f(NN) = 0.04 E. f(MM) = 0.048, f(MN) = 0.304, f(NN) = 0.648

A. f(MM) = 0.648, f(MN) = 0.304, f(NN) = 0.048

Jean Manning, Charles Kerfoot, and Edward Berger studied the frequencies at the phosphoglucose isomerase (GPI) locus in the cladoceran Bosmina longirostris. At one location, they collected 176 animals from Union Bay in Seattle, Washington, and determined their GPI genotypes by using electrophoresis (J. Manning, W. C. Kerfoot, and E. M. Berger, 1978, Evolution 32:365-374). Determine the genotypic and allelic frequencies for this population. A. f(S1S1) = 0.023, f(S1S2) = 0.216, f(S2S2) = 0.761, f(S1) = 0.13, f(S2) = 0.87 B. f(S1S1) = 0.023, f(S1S2) = 0.761, f(S2S2) = 0.216, f(S1) = 0.87, f(S2) = 0.13 C. f(S1S1) = 0.023, f(S1S2) = 0.216, f(S2S2) = 0.761, f(S1) = 0.87, f(S2) = 0.13 D. f(S1S1) = 0.761, f(S1S2) = 0.216, f(S2S2) = 0.023, f(S1) = 0.87, f(S2) = 0.13 E. f(S1S1) = 0.761, f(S1S2) = 0.216, f(S2S2) = 0.023, f(S1) = 0.13, f(S2) = 0.87

A. f(S1S1) = 0.023, f(S1S2) = 0.216, f(S2S2) = 0.761, f(S1) = 0.13, f(S2) = 0.87

In a large, randomly mating population, the frequency of the allele (s) for sickle-cell hemoglobin is 0.028. The results of studies have shown that people with the following genotypes at the beta-chain locus produce the average numbers of offspring shown: What will the frequency of the sickle-cell allele (s) be in the next generation? A. 0.027 B. 0.032 C. 0.040 D. 0.028 E. 0.020

B. 0.032

Color blindness in humans is an X-linked recessive trait. Approximately 10% of the men in a particular population are color blind. If mating is random for the color-blind locus, what is the frequency of the color-blind allele in this population? A. 0.1% B. 10% C. 5% D. 1% E. 18%

B. 10%

Full color (D) in domestic cats is dominant over dilute color (d). Of 325 cats observed, 194 have full color and 131 have dilute color. How many of the 194 cats with full color are likely to be heterozygous? A. 97 B. 151 C. 36 D. 43 E. 194

B. 151

The frequency of allele A in a population is 0.8 and the frequency of allele a is 0.2. If the population mates randomly for this locus, give all the possible matings among the genotypes at this locus and the expected proportion of each type. A. AA × AA = 0.0625; AA × Aa = 0.1250; AA × aa = 0.0625; Aa × Aa = 0.2500; Aa × aa = 0.0625; aa × aa = 0.0625 B. AA × AA = 0.4096; AA × Aa = 0.4096; AA × aa = 0.0512; Aa × Aa = 0.1024; Aa × aa = 0.0256; aa × aa = 0.0016 C. AA × AA = 0.05; AA × Aa = 0.10; AA × aa = 0.05; Aa × Aa = 0.20; Aa × aa = 0.05; aa × aa = 0.05 D. AA × AA = 0.4096; AA × Aa = 0.2048; AA × aa = 0.0256; Aa × Aa = 0.1024; Aa × aa = 0.0128; aa × aa = 0.0016

B. AA × AA = 0.4096; AA × Aa = 0.4096; AA × aa = 0.0512; Aa × Aa = 0.1024; Aa × aa = 0.0256; aa × aa = 0.0016

. If variation of heritable traits is the basis of all evolution, which of the following would NOT contribute to the evolution of a population? A. A maternally inherited allele B. DNA mutations in somatic cells acquired during adulthood C. A new combination of alleles resulting from meiotic recombination D. DNA mutations in gamete producing cells E. Migration bringing novel alleles into a population

B. DNA mutations in somatic cells acquired during adulthood

In which of the following scenarios would you expect the greatest impact of genetic drift on differences in allele frequencies among a group of ten populations? A. Each population starts with a size of 100 and allele frequencies of p = 0.5 and q = 0.5 [[Genetic drift can be measured as the variance in allele frequency among populations. This can be calculated as pq/2N. This scenario does not produce the highest amount of variance. Remember, genetic drift will be highest when population sizes are small.] B. Each population starts with a size of 20 and allele frequencies of p = 0.5 and q = 0.5 C. Each population starts with a size of 1000 and allele frequencies of p = 0.5 and q = 0.5 D. Each population starts with a size of 100 and allele frequencies of p = 0.9 and q = 0.1 E. Each population starts with a size of 20 and allele frequencies of p = 0.9 and q = 0.1

B. Each population starts with a size of 20 and allele frequencies of p = 0.5 and q = 0.5

What proportion of the populations shown in Figure 25.13 reached fixation for either one of the alleles by generations 10, 25, and 30? A. G10 = 0.0, G25 = 0.0, G30 = 0.0 B. G10 = 0.0, G25 = 0.2, G30 = 0.4 C. G10 = 0.1, G25 = 0.2, G30 = 0.3 D. G10 = 0.0, G25 = 1.0, G30 = 2.0

B. G10 = 0.0, G25 = 0.2, G30 = 0.4

You have determined that a trait within a population is not in Hardy-Weinberg equilibrium. You have also determined that mutation, migration and natural selection are not present for this trait. What factor is keeping this trait out of Hardy-Weinberg equilibrium? A. Random mating B. Genetic drift C. Multiple alleles D. Segregation E. Founder effect

B. Genetic drift

Describe the effects of inbreeding on a population. A. Inbreeding increases overall genetic diversity in a population but decreases homozygosity. B. Inbreeding increases homozygosity and reduces heterozygosity in a population. C. Inbreeding increases heterozygosity and reduces homozygosity in a population. D. Inbreeding both increases heterozygosity and homozygosity in a population. E. Inbreeding increases the number of carriers in a population for recessive disorders but decreases the number of individuals affected.

B. Inbreeding increases homozygosity and reduces heterozygosity in a population.

On the African savannah, every generation 15 male water buffalos migrate from their original large herd to a second herd. If the allelic frequency of an allele for small ears was higher in the first herd than the second, what will happen to that allelic frequency in both herds over time? A. It will decrease in the first herd and increase in the second herd. B. It will stay the same in the first herd and increase in the second herd. C. It will increase in the first herd and decrease in the second herd. D. It will decrease in both herds. E. It will stay the same in both herds.

B. It will stay the same in the first herd and increase in the second herd.

Examine Figure 25.15. Which evolutionary forces cause an increase in genetic variation within populations but cause a decrease in genetic variation between populations. A. Migration B. Migration and some types of natural selection C. Mutation D. Genetic drift E. Some types of natural selection

B. Migration and some types of natural selection

Examine Figure 25.15. Which evolutionary forces cause an increase in genetic variation both within and between populations? A. Genetic drift B. Mutation and some types of natural selection C. Mutation D. Migration E. Some types of natural selection

B. Mutation and some types of natural selection

Briefly describe directional selection. A. The heterozygote has greater fitness than either homozygote. B. One trait or allele is favored by natural selection. C. The selection coefficients are all zero. D. All alleles have equal fitness. E. The heterozygote has lower fitness than either homozygote.

B. One trait or allele is favored by natural selection.

From the individuals in your genetics class, the following phenotypes and corresponding genotypes were counted for tasters versus non-tasters of the chemical compound phenylthiocarbamide (PTC), where P and p represent different alleles: PP (severe tasters) 11 Pp (mild tasters) 18 pp (non-tasters) 20 Calculate the genotypic frequencies of the PTC-taste locus for this population. A. P = 0.41, p = 0.59 B. PP = 0.22, Pp = 0.37, pp= 0.41 C. PP = 0.11, Pp= 0.18, pp = 0.20 D. PP = 0.17, Pp = 0.48, pp= 0.35 E. PP = 0.45, Pp = 0.37, pp = 0.82

B. PP = 0.22, Pp = 0.37, pp= 0.41

What is effective population size? A. The population size that includes breeding and nonbreeding individuals B. The effective number of breeding adults in the population C. The effect of unexpected natural selection due to chance events D. The population size that results when you account for migrating males that contribute alleles to multiple different populations E. The population size that includes just the female members of the population

B. The effective number of breeding adults in the population

In Figure 25.10, each blue dot represents one copy of the A allele and each red dot represents each copy of the a allele. How and why did the frequency of Ain population II change after migration? A. The frequency of A in population II increased because natural selection favors the migrants with the A allele from population I. B. The frequency of A in population II increased because the migrants came from a population with a much higher frequency of the A allele. C. The frequency of the A allele in population II decreased because the migrants made up such a small fraction of population II. D. The frequency of A in population II increased because the migrants made up such a large fraction of population II. E. The frequency of A in population II decreased because the migrants came from a population with a much lower frequency of the A allele.

B. The frequency of A in population II increased because the migrants came from a population with a much higher frequency of the A allele.

The fruit fly Drosophila melanogaster normally feeds on rotting fruit, which may ferment and contain high levels of alcohol. Douglas Cavener and Michael Clegg studied allelic frequencies at the locus for alcohol dehydrogenase (Adh) in experimental populations of D. melanogaster (D. R. Cavener and M. T. Clegg, 1981, Evolution 35:1-10). The experimental populations were established from wild-caught flies and were raised in cages in the laboratory. Two control populations (C1 and C2) were raised on a standard cornmeal-molasses-agar diet. Two ethanol populations (E1 and E2) were raised on a cornmeal-molasses-agar diet to which was added 10% ethanol. The four populations were periodically sampled to determine the allelic frequencies of two alleles at the alcohol dehydrogenase locus, AdhS and AdhF. The frequencies of these alleles in the experimental populations are shown in the graph. Cavener and Clegg measured the viability of the different Adh genotypes in the alcohol environment and obtained the following values: Genotype Relative viability AdhF/AdhF 0.932 AdhF/AdhS 1.288 AdhS/AdhS 0.596 Using these relative viabilities, what are the relative fitnesses for the three genotypes. Note: F is being used for the AdhF allele and S is being used for the AdhS allele. A. WFF = 0.1.56, WFS = 2.161, WSS = 1 B. WFF = 0.724, WFS = 1, WSS = 0.463 C. WFF = 0.463, WFS = 1, WSS = 0.724 D. WFF = 1, WFS = 0.724, WSS = 0.639 E. WFF = 1.381, WFS = 1, WSS = 2.161

B. WFF = 0.724, WFS = 1, WSS = 0.463

Genotypes of leopard frogs from a population in central Kansas were determined for a locus (M) that encodes the enzyme malate dehydrogenase. The following numbers of genotypes were observed: What would the expected frequency of genotypes be if the population were in Hardy-Weinberg equilibrium? A. f(M1M1) = 0.390, f(M1M2) = 0.300, f(M2M2) = 0.127, f(M1M3) = 0.068, f(M2M3) = 0.105, f(M3M3) = 0.009 B. f(M1M1) = 0.127, f(M1M2) = 0.390, f(M2M2) = 0.300, f(M1M3) = 0.068, f(M2M3) = 0.105, f(M3M3) = 0.009 C. f(M1M1) = 0.127, f(M1M2) = 0.195, f(M2M2) = 0.300, f(M1M3) = 0.034, f(M2M3) = 0.053, f(M3M3) = 0.009 D. f(M1M1) = 0.105, f(M1M2) = 0.390, f(M2M2) = 0.127, f(M1M3) = 0.009, f(M2M3) = 0.300, f(M3M3) = 0.068 E. f(M1M1) = 0.300, f(M1M2) = 0.390, f(M2M2) = 0.127, f(M1M3) = 0.105, f(M2M3) = 0.068, f(M3M3) = 0.009

B. f(M1M1) = 0.127, f(M1M2) = 0.390, f(M2M2) = 0.300, f(M1M3) = 0.068, f(M2M3) = 0.105, f(M3M3) = 0.009

The genetic effects of migration include all of the following EXCEPT to: A. counter the effect of genetic drift. B. make populations less heterogeneous. C. counter the effects of selection. D. allow new alleles to spread. E. Actually, all of these are effects of migration.

B. make populations less heterogeneous.

In the plant Lotus corniculatus, cyanogenic glycoside protects the plant against insect pests and even grazing by cattle. This glycoside is due to a simple dominant allele. A population of L. corniculatus consists of 77 plants that possess cyanogenic glycoside and 56 that lack the compound. What is the frequency of the dominant allele responsible for the presence of cyanogenic glycoside in this population? A. p = 0.42 B. p = 0.35 C. p = 0.76 D. p = 0.58 E. p = 0.65

B. p = 0.35

Sampling error produced by _______________________ tends to ______________________ of genetic drift in a population. A. a genetic bottleneck; decrease the effect B. the founder effect; increase the effect C. fluctuations in population size; have no effect on the role D. variation in reproductive success; have limited effect on the role E. nonrandom mating; delay the effect

B. the founder effect; increase the effect

The Hardy-Weinberg equilibrium requires all of the following assumptions EXCEPT: A. mating is random. B. the population is small. C. no selection is taking place. D. there is no immigration or emigration. E. Actually, it requires all of these assumptions.

B. the population is small.

The fruit fly Drosophila melanogaster normally feeds on rotting fruit, which may ferment and contain high levels of alcohol. Douglas Cavener and Michael Clegg studied allelic frequencies at the locus for alcohol dehydrogenase (Adh) in experimental populations of D. melanogaster (D. R. Cavener and M. T. Clegg, 1981, Evolution 35:1-10). The experimental populations were established from wild-caught flies and were raised in cages in the laboratory. Two control populations (C1 and C2) were raised on a standard cornmeal-molasses-agar diet. Two ethanol populations (E1 and E2) were raised on a cornmeal-molasses-agar diet to which was added 10% ethanol. The four populations were periodically sampled to determine the allelic frequencies of two alleles at the alcohol dehydrogenase locus, AdhS and AdhF. The frequencies of these alleles in the experimental populations are shown in the graph. Cavener and Clegg measured the viability of the different Adh genotypes in the alcohol environment and obtained the following values: Genotype Relative viability AdhF/AdhF 0.932 AdhF/AdhS 1.288 AdhS/AdhS 0.596 If a population has an initial frequency of p = f (AdhF) = 0.5, what will the expected frequency of AdhF be in the next generation on the basis of these fitness values? A. 0.50 B. The allele frequency of the AdhF allele cannot be determined from this information. C. 0.54 D. 1.0 E. 0.46

C. 0.54

Consider a population of inbreeding humans, in which the inbreeding coefficient is 0.6. At locus A, there are 215 individuals with genotype AA, 58 with Aa,and 190 with aa. How much will the frequency of heterozygotes decrease after an additional generation of mating? A. 15% B. 0.3% C. 30% D. None. This trait is exhibiting Hardy-Weinberg equilibrium. E. 37%

C. 30%

Blue eyes are recessive to brown eyes in humans. If the frequency of blue-eyed individuals in a population is 16%, we can calculate that the frequency of the allele for blue eyes is: A. 16%. B. 32% C. 40% D. 48% E. None of the above.

C. 40%

A population of cats has the following genotypes for an X-linked coat-color trait (O for the dominant brown allele, o for the recessive orange allele): Brown homozygous females: 30 Brown heterozygous females: 75 Orange females: 10 Brown males: 50 Orange males: 65 What are the allele frequencies in this population? A. = 0.51, o = 0.49 B. = 0.43, o = 0.57 C. = 0.54, o = 0.46 D. = 0.59, o = 0.41 E. = 0.40, o = 0.35

C. = 0.54, o = 0.46

What determines the allelic frequencies at mutational equilibrium? A. Reverse mutation rates B. The selection coefficients C. Both forward and reverse mutation rates D. Migration of new alleles into the gene pool E. Forward mutation rates

C. Both forward and reverse mutation rates

Define genetic drift. A. Change in the number of alleles in a population due to geological events B. Change in allele frequencies due to an increase in the mutation rate C. Change in allele frequencies due to sampling error or chance events D. Movement of an exotic species into a new habitat, resulting in hybridization with native species E. Change in allele frequencies due to disproportionate natural selection against aging members of a population

C. Change in allele frequencies due to sampling error or chance events

Assume that the phenotypes of lady beetles shown in Figure 25.1 are encoded by the following genotypes: Phenotype Genotype All black BB Some black spots Bb No black spots bb Use a chi-square test to determine if the lady beetles shown are in Hardy-Weinberg equilibrium. Round all calculations to two decimal places. A. Chi square = 0.05; the population is in equilibrium. B. Chi square = 0.50; the population is in equilibrium. C. Chi square = 4.45; the population is not in equilibrium. D. Chi square = 3.84; the population is in equilibrium. E. Chi square = 10.97; the population is not in equilibrium.

C. Chi square = 4.45; the population is not in equilibrium.

A population of water snakes is found on an island in Lake Erie. Some of the snakes are banded and some are unbanded; banding is caused by an autosomal allele that is recessive to an allele for no bands. The frequency of banded snakes on the island is 0.4, whereas the frequency of banded snakes on the mainland is 0.81. One summer, a large number of snakes migrate from the mainland to the island. After this migration, 20% of the island population consists of snakes that came from the mainland. If both the mainland population and the island population are assumed to be in Hardy-Weinberg equilibrium for the alleles that affect banding, what is the frequency of the allele for bands on the island and on the mainland before migration? A. Island frequency = 0.63, mainland frequency = 0.37 B. Island frequency = 0.9, mainland frequency = 0.63 C. Island frequency = 0.63, mainland frequency = 0.9 D. Island frequency = 0.20, mainland frequency = 0.8 E. Island frequency = 0.40, mainland frequency = 0.81

C. Island frequency = 0.63, mainland frequency = 0.9

How would you respond to someone who said that models are useless in studying population genetics because they represent oversimplifications of the real world? A. Models oversimplify very few aspects of the real world and are reliable in their predictive powers in almost 100% of cases. B. While models have not produced any useful data to date, virtually all population geneticists believe that a breakthrough is imminent and worth working toward. C. Models provide reasonable predictions about the effects of different factors on the gene pool of a population. D. Models do not have to oversimplify any facet of the real world; this misconception comes from the fact that people often choose simpler models because they take less time to produce data. E. Models rely on equations to describe a process; these equations can produce robust answers regardless of whether or not the underlying assumptions of the model are accurate.

C. Models provide reasonable predictions about the effects of different factors on the gene pool of a population.

Define natural selection. A. The differential age at which natural death occurs B. The process that decreases the frequency of adaptive traits in a population C. The differential reproductive success of genotypes D. The survival of the most aerobically and physically fit phenotypes E. Selection by natural events, human intervention, or genetic drift that results in a disproportionate amount of a certain genotype

C. The differential reproductive success of genotypes

Briefly describe overdominance. A. One allele has greater fitness than another. B. The selection coefficients are all zero. C. The heterozygote has greater fitness than either homozygote. D. All alleles have equal fitness. E. The heterozygote has lower fitness than either homozygote.

C. The heterozygote has greater fitness than either homozygote.

Most black bears (Ursus americanus) are black or brown in color. However, occasional white bears of this species appear in some populations along the coast of British Columbia. Kermit Ritland and his colleagues determined that white coat color in these bears results from a recessive mutation (G) caused by a single nucleotide replacement in which guanine substitutes for adenine at the melanocortin 1 receptor locus (mcr1), the same locus responsible for red hair in humans (K. Ritland, C. Newton, and H. D. Marshall, 2001, Current Biology 11:1468-1472). The wild-type allele at this locus (A) encodes black or brown color. Ritland and his colleagues collected samples from bears on three islands and determined their genotypes at the mcr1 locus. Wendy Shattil/Alamy. Give the genotypic frequencies expected if the population is in Hardy-Weinberg equilibrium. Round the expected numbers of each genotype to the nearest whole number. A. f(AA) = 0.621, f(AG) = 0.471, f(GG) = 0.389 B. f(AA) = 0.483, f(AG) = 0.276, f(GG) = 0.241 C. f(AA) = 0.384, f(AG) = 0.471, f(GG) = 0.144 D. f(AA) = 0.384, f(AG) = 0.144, f(GG) = 0.471 E. f(AA) = 0.144, f(AG) = 0.471, f(GG) = 0.384

C. f(AA) = 0.384, f(AG) = 0.471, f(GG) = 0.144

In a large, randomly mating population, the frequency of an autosomal recessive lethal allele is 0.20. What will the frequency of this allele be in the next generation if the lethality takes place before reproduction? A. f(q) = 0.33 B. f(q) = 0.04 C. f(q) = 0.17 D. f(q) = 0.64 E. f(q) = 0

C. f(q) = 0.17

When an allele has reached a frequency of 1, it is said to have reached A. nonequilibrium B. dominance C. fixation D. completion E. stasis

C. fixation

All of the following describe effects of natural selection EXCEPT: A. it promotes adaptation. B. it reflects differential survival and reproduction according to phenotype. C. it always produces an equilibrium. D. it can lead to unstable equilibria. E. Actually, it is described by all of these.

C. it always produces an equilibrium.

Full color (D) in domestic cats is dominant over dilute color (d). Of 325 cats observed, 194 have full color and 131 have dilute color. If these cats are in Hardy-Weinberg equilibrium for the dilution locus, what is the frequency of the dilute allele? A. q = 0.133 B. q = 0.365 C. q = 0.635 D. q = 0.403 E. q = 0.773

C. q = 0.635

In German cockroaches, curved wing (cv) is recessive to normal wing (cv+). Bill, who is raising cockroaches in his dorm room, finds that the frequency of the gene for curved wings in his cockroach population is 0.6. In the apartment of his friend Joe, the frequency of the gene for curved wings is 0.2. One day Joe visits Bill in his dorm room, and several cockroaches jump out of Joe's hair and join the population in Bill's room. Bill estimates that now, 10% of the cockroaches in his dorm room are individual roaches that jumped out of Joe's hair. What is the new frequency of the curved wing phenotype among cockroaches in Bill's room? A. 0.69 B. 0.20 C. 0.5 D. 0.31 E. 0.4

D. 0.31

The forward mutation rate for piebald spotting in guinea pigs is 8 × 10-5; the reverse mutation rate is 2 × 10-6. If no other evolutionary forces are assumed to be present, what is the expected frequency of the allele for piebald spotting in a population that is in mutational equilibrium? A. 0.00004 B. 0.02 C. 0.80 D. 0.98 E. 0.000006

D. 0.98

A Mendelian population is one that: A. is a group of interbreeding members of a species. B. evolves through changes in its gene pool. C. meets Hardy-Weinberg equilibrium conditions. D. A and B. E. All of the above.

D. A and B.

The Hardy-Weinberg equation can be extended to describe frequencies for: A. X-linked alleles. B. multiple alleles. C. multiple loci. D. A and B. E. All of the above.

D. A and B.

The Hardy-Weinberg equation implies: A. genotypic frequencies are determined by genotypic frequencies. B. populations that meet the equation are not evolving. C. a single generation of assortative mating will produce the predicted frequencies. D. A and B. E. All of the above.

D. A and B.

The effect of mutation on allele frequencies is usually small because: A. mutations are relatively rare. B. mutations can be backward or forward. C. mutations are usually selected against because they generally interfere with function. D. A and B. E. All of the above.

D. A and B.

The Barton Springs salamander is an endangered species found only in a single spring in the city of Austin, Texas. There is growing concern that a chemical spill on a nearby freeway could pollute the spring and wipe out the species. To provide a source of salamanders to repopulate the spring in the event of such a catastrophe, a proposal has been made to establish a captive breeding population of the salamander in a local zoo. You are asked to provide a plan for the establishment of this captive breeding population, with the goal of maintaining as much of the genetic variation of the species as possible in the captive population. What strategy would NOT likely be effective in mitigating the loss of genetic variation in the captive population? A. Regularly introducing new individuals from the wild into the captive population B. Limiting matings among individuals that are related C. Keeping the captive population as large as possible D. Adding a mutagenic chemical to the captive population E. Keeping the sex ratio as close to 50:50 as possible

D. Adding a mutagenic chemical to the captive population

What factors affect the rate of change in allelic frequency due to natural selection? A. None of the above is correct. B. The dominance relationships between the alleles C. The allelic frequencies themselves affect the rate of change D. All of the above are correct. E. The difference in fitness between the different genotypes

D. All of the above are correct.

If you have data on genotype frequencies at a locus for a population, what steps would you follow to determine if these genotypes are in Hardy-Weinberg equilibrium? A. Use the Hardy-Weinberg law to calculate allele frequencies from the observed genotype frequencies; compare to the genotypic frequencies expected under Hardy-Weinberg equilibrium B. Calculate allele frequencies from the observed genotype frequencies; compare to the genotypic frequencies expected under Hardy-Weinberg equilibrium C. Use the Hardy-Weinberg law to calculate allele frequencies from the observed genotype frequencies; use the allele frequencies to calculate the expected number of genotypes under Hardy-Weinberg equilibrium; conduct a chi-square test D. Calculate allele frequencies from the observed genotype frequencies; use the allele frequencies to calculate the expected number of genotypes under Hardy-Weinberg equilibrium; conduct a chi-square test E. You are unable to determine if the population is in Hardy-Weinberg equilibrium without additional data.

D. Calculate allele frequencies from the observed genotype frequencies; use the allele frequencies to calculate the expected number of genotypes under Hardy-Weinberg equilibrium; conduct a chi-square test

There are two different, isolated populations of pronghorn antelope. Over 95% of herd A was killed during a disease outbreak, but its population quickly bounced back. Herd B was never exposed to the disease. The two herds currently have equal numbers. A completely different disease is likely to affect both populations this year. Which population would you be more concerned about surviving the disease? A. Both herds equally B. Herd B C. Neither herd D. Herd A E. Not enough information is provided to answer this question.

D. Herd A

Pikas are small mammals that live at high elevation in the talus slopes of mountains. Most populations located on mountaintops in Colorado and Montana in North America are isolated from one another because the pikas don't occupy the low-elevation habitats that separate the mountaintops and don't venture far from the talus slopes. Thus, there is little gene flow between populations. Furthermore, each population is small in size and was founded by a small number of pikas. A group of population geneticists propose to study the amount of genetic variation in a series of pika populations and to compare the allelic frequencies in different populations. On the basis of the biology and the distribution of pikas, predict what the population geneticists will find concerning the within- and between-population genetic variation. A. Little of genetic variation between populations and little of genetic variation within populations B. Little of genetic variation between populations and large genetic variation within populations C. Large genetic variation between populations and large genetic variation within populations D. Large genetic variation between populations and little of genetic variation within populations E. This will be no genetic variation within or between populations since genetic drift will have fixed the same allele in each population.

D. Large genetic variation between populations and little of genetic variation within populations

The Barton Springs salamander is an endangered species found only in a single spring in the city of Austin, Texas. There is growing concern that a chemical spill on a nearby freeway could pollute the spring and wipe out the species. To provide a source of salamanders to repopulate the spring in the event of such a catastrophe, a proposal has been made to establish a captive breeding population of the salamander in a local zoo. You are asked to provide a plan for the establishment of this captive breeding population, with the goal of maintaining as much of the genetic variation of the species as possible in the captive population. What factors are NOT likely to lead to a loss of genetic variation in the captive population? A. Genetic drift over time in the captive population B. None. All of these will likely lead to a loss of genetic variation. C. Inbreeding in the captive population D. Lower rate of mutation in the captive population E. A founder effect in the establishment of the captive population

D. Lower rate of mutation in the captive population

A ____________________________ is a group of interbreeding, sexually reproducing individuals that have a common set of genes. A. gene pool B. clonal lineage C. species complex D. Mendelian population E. pedigree

D. Mendelian population

If a population is exhibiting positive assortative mating for one coat-color trait, what effect will this have on two other traits: a closely linked trait for disease susceptibility and a second, unlinked, coat-color trait. A. Both traits will also show positive assortative mating. B. There will be no effect on the disease susceptibility trait; the other coat-color trait will also show positive assortative mating. C. There will be no effect on either trait. D. Only the closely linked disease susceptibility trait will be affected. E. The closely linked disease susceptibility trait will be affected while the other coat-color trait will show negative assortative mating.

D. Only the closely linked disease susceptibility trait will be affected.

Genotypes of leopard frogs from a population in central Kansas were determined for a locus (M) that encodes the enzyme malate dehydrogenase. The following numbers of genotypes were observed: Calculate the allelic frequencies for this population. A. f(M1) = p = 0.16, f(M2) = q = 0.34, f(M3) = r = 0.048 B. f(M1) = p = 0.36, f(M2) = q = 0.032, f(M3) = r = 0.064 C. f(M1) = p = 0.096, f(M2) = q = 0.548, f(M3) = r = 0.356 D. f(M1) = p = 0.356, f(M2) = q = 0.548, f(M3) = r = 0.096 E. f(M1) = p = 0.548, f(M2) = q = 0.096, f(M3) = r = 0.356

D. f(M1) = p = 0.356, f(M2) = q = 0.548, f(M3) = r = 0.096

Orange coat color of cats is due to an X-linked allele (XO) that is codominant with the allele for black (X+). Genotypes of the orange locus of cats in Minneapolis and St. Paul, Minnesota, were determined, and the following data were obtained: Calculate the frequencies of the XO and X+ alleles for this population. A. f(XO) = 0.24, f(X+) = 0.76 B. f(XO) = 0.74, f(X+) = 0.26 C. f(XO) = 0.23, f(X+) = 0.77 D. f(XO) = 0.26, f(X+) = 0.74 E. f(XO) = 0.45, f(X+) = 0.55

D. f(XO) = 0.26, f(X+) = 0.74

Since random mating is an assumption of the Hardy-Weinberg equilibrium, non-random mating can confound it, as in all of the following cases EXCEPT: A. inbreeding. B. positive assortative mating. C. negative assortative mating. D. loss of heterozygosity. E. Actually, all of these are forms of non-random mating.

D. loss of heterozygosity.

A population of water snakes is found on an island in Lake Erie. Some of the snakes are banded and some are unbanded; banding is caused by an autosomal allele that is recessive to an allele for no bands. The frequency of banded snakes on the island is 0.4, whereas the frequency of banded snakes on the mainland is 0.81. One summer, a large number of snakes migrate from the mainland to the island. After this migration, 20% of the island population consists of snakes that came from the mainland. After migration has taken place, what is the frequency of the banded allele on the island? A. 0.9 B. 0.81 C. 0.63 D. 0.20 E. 0.68

E. 0.68

Tay-Sachs disease is an autosomal recessive disorder. Among Ashkenazi Jews, the frequency of Tay-Sachs disease is 1 in 3600. If the Ashkenazi population is mating randomly for the Tay-Sachs gene, approximately what proportion of the population consists of heterozygous carriers of the Tay-Sachs allele? A. 1 in 600 B. 1 in 60 C. 1 in 17 D. 1 in 1800 E. 1 in 30

E. 1 in 30

Color blindness in humans is an X-linked recessive trait. Approximately 10% of the men in a particular population are color blind. What proportion of the women in this population is expected to be color blind? A. 10% B. 18% C. 5% D. 0.1% E. 1%

E. 1%

The sum of all genotypic frequencies always equals A. 0.25. B. 0. C. 2. D. 0.5. E. 1.

E. 1.

Color blindness in humans is an X-linked recessive trait. Approximately 10% of the men in a particular population are color blind. What proportion of the women in the population is expected to be heterozygous carriers of the color-blind allele? A. 10% B. 0.1% C. 5% D. 1% E. 18%

E. 18%

What is a Mendelian population? A. A group of asexually reproducing individuals that do not share a common gene pool B. A group of sexually reproducing individuals that produce offspring with a 3:1 dominant-to-recessive phenotype ratio C. A group of sexually reproducing individuals that undergo natural selection in order to maintain a 9:3:3:1 dominant-to-recessive phenotype ratio D. A group of asexually reproducing individuals that share a common gene pool, with unchanging genotype frequencies E. A group of sexually reproducing individuals sharing a common gene pool, with (under certain conditions) predictable genotype frequencies

E. A group of sexually reproducing individuals sharing a common gene pool, with (under certain conditions) predictable genotype frequencies

As population genetics is studied, all of the following are of interest EXCEPT: A. genotype frequencies. B. allele frequencies. C. phenotype frequencies. D. mutation rates. E. Actually, all of these are of interest.

E. Actually, all of these are of interest.

The Hardy-Weinberg equation is described by all of the following EXCEPT: A. it requires that there be only two alleles. B. it applies to traits determined by only a single locus. C. it predicts that allele frequencies will not change over time. D. it predicts that genotype frequencies will be predictable after a single generation. E. Actually, all of these describe the equation.

E. Actually, all of these describe the equation.

Factors that can cause microevolutionary changes away from equilibrium include all of the following EXCEPT: A. mutation. B. migration. C. genetic drift. D. natural selection. E. Actually, all of these factors can cause microevolution.

E. Actually, all of these factors can cause microevolution.

Genetic drift: A. affects populations in bottlenecks. B. is important in founder effects. C. has little role in large populations. D. leads to allele fixation. E. All of the above.

E. All of the above.

A population of rabbits was divided up based upon the color of their fur, represented by a single locus with two alleles (B for the dominant brown allele, and b for the recessive white allele): BB (brown fur) 100 Bb (brown fur) 88 bb (white fur) 25 Calculate the allelic frequencies of the fur color locus for this population of rabbits. A. B = 0.75, b = 0.32 B. BB= 0.47, Bb = 0.41, bb = 0.12 C. B = 0.47, b = 0.53 D. B = 0.44, b = 0.27 E. B = 0.68, b = 0.32

E. B = 0.68, b = 0.32

The fruit fly Drosophila melanogaster normally feeds on rotting fruit, which may ferment and contain high levels of alcohol. Douglas Cavener and Michael Clegg studied allelic frequencies at the locus for alcohol dehydrogenase (Adh) in experimental populations of D. melanogaster (D. R. Cavener and M. T. Clegg, 1981, Evolution35:1-10). The experimental populations were established from wild-caught flies and were raised in cages in the laboratory. Two control populations (C1 and C2) were raised on a standard cornmeal-molasses-agar diet. Two ethanol populations (E1 and E2) were raised on a cornmeal-molasses-agar diet to which was added 10% ethanol. The four populations were periodically sampled to determine the allelic frequencies of two alleles at the alcohol dehydrogenase locus, AdhS and AdhF. The frequencies of these alleles in the experimental populations are shown in the graph. One the basis of these data, what conclusion might you draw about the evolutionary forces that are affecting the Adh alleles in these populations? A. Directional selection is occurring in favor of the AdhS allele and against the AdhF allele. B. The bottleneck effect has occurred and caused a decrease in frequency of the AdhS allele. C. Genetic drift is causing the AdhF allele to increase in frequency because of a founder effect. D. The presence of ethanol has increased the rate that the AdhS allele mutates into the AdhF allele. E. Directional selection is occurring in favor of the AdhF allele and against the AdhS allele.

E. Directional selection is occurring in favor of the AdhF allele and against the AdhS allele.

Examine Figure 25.15. Which evolutionary forces cause a decrease in genetic variation both within and between populations? A. Mutation B. Migration C. Migration and some types of natural selection D. Genetic drift E. Some types of natural selection

E. Some types of natural selection

What is random mating? A. The frequency of two genotypes mating will be determined by the amount of natural selection on the recessive phenotype. B. The frequency of two genotypes mating will be the difference of their respective frequencies in the population. C. The frequency of two genotypes mating will be the sum of their respective frequencies in the population. D. The frequency of two genotypes mating will be the square root of their respective frequencies in the population. E. The frequency of two genotypes mating will be the product of their respective frequencies in the population.

E. The frequency of two genotypes mating will be the product of their respective frequencies in the population.

Most black bears (Ursus americanus) are black or brown in color. However, occasional white bears of this species appear in some populations along the coast of British Columbia. Kermit Ritland and his colleagues determined that white coat color in these bears results from a recessive mutation (G) caused by a single nucleotide replacement in which guanine substitutes for adenine at the melanocortin 1 receptor locus (mcr1), the same locus responsible for red hair in humans (K. Ritland, C. Newton, and H. D. Marshall, 2001, Current Biology 11:1468-1472). The wild-type allele at this locus (A) encodes black or brown color. Ritland and his colleagues collected samples from bears on three islands and determined their genotypes at the mcr1 locus. Wendy Shattil/Alamy. What are the frequencies of the A and G alleles in these bears? A. f(A) = 0.69, f(G) = 0.31 B. f(A) = 0.47, f(G) = 0.53 C. f(A) = 0.38, f(G) = 0.62 D. f(A) = 0.74, f(G) = 0.26 E. f(A) = 0.62, f(G) = 0.38

E. f(A) = 0.62, f(G) = 0.38

Two chromosomal inversions are commonly found in populations of Drosophila pseudoobscura: Standard (ST) and Arrowhead (AR). When treated with the insecticide DDT, the genotypes for these inversions exhibit overdominance, with the following fitnesses: What will the frequencies of ST and AR be after equilibrium has been reached? A. f(AR) = 0.31, f(ST) = 0.53 B. f(AR) = 0.42, f(ST) = 0.58 C. f(AR) = 0.47, f(ST) = 0.62 D. f(AR) = 0.38, f(ST) = 0.53 E. f(AR) = 0.58, f(ST) = 0.42

E. f(AR) = 0.58, f(ST) = 0.42

If a large, randomly mating, isolated (no migration in or out) population of toads lives in a pond polluted with high concentrations of a mutagen (a chemical that mutates DNA), and a particular trait is not undergoing natural selection, is it likely that this trait is in a state of Hardy-Weinberg equilibrium? No Not enough information Yes

No

Give the Hardy-Weinberg expected genotypic frequencies for an autosomal locus with three alleles, designated A1, A2, and A3. f(A1A1) = p2 f(A1A2) = 2pr f(A2A2) = q2 f(A1A3) = 2pq f(A2A3) = 2pr f(A3A3) = r2 f(A1A1) = p2 f(A1A2) = q2 f(A2A2) = r2 f(A1A3) = 2pq f(A2A3) = 2pr f(A3A3) = 2rq f(A1A1) = p2 f(A1A2) = 2pq f(A2A2) = q2 f(A1A3) = 2qr f(A2A3) = 2pr f(A3A3) = r2 f(A1A1) = p2 f(A1A2) = 2pq f(A2A2) = q2 f(A1A3) = 2pr f(A2A3) = 3qr f(A3A3) = r3 f(A1A1) = p2 f(A1A2) = 2pq f(A2A2) = q2 f(A1A3) = 2pr f(A2A3) = 2qr f(A3A3) = r2

f(A1A1) = p2 f(A1A2) = 2pq f(A2A2) = q2 f(A1A3) = 2pr f(A2A3) = 2qr f(A3A3) = r2