genetics ch 25

What factors affect the rate of change in allelic frequency due to natural selection?

-The dominance relationships between the alleles - The allelic frequencies themselves affect the rate of change - The difference in fitness between the different genotypes

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: Genotype: Average no. offspring: SS 5 Ss 6 ss 0 What will the frequency of the sickle-cell allele (s) be in the next generation?

0.032

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: Genotype: Average no. offspring: SS 5 Ss 6 ss 0 What will the frequency of the sickle-cell allele be at equilibrium?

0.145

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?

0.31

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?

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?

151

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?

18%

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:

40%

Factors that can cause microevolutionary changes away from equilibrium include all of the following:

A. mutation. B. migration. C. genetic drift. D. natural selection.

The effect of mutation on allele frequencies is usually small because:

A. mutations are relatively rare. B. mutations can be backward or forward.

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.

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

Define genetic drift.

Change in allele frequencies due to sampling error or chance events

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: Blood type Number M 1787 MN 3039 N 1303 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.

Chi square = 0.48; the population is in equilibrium.

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.

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

If variation of heritable traits is the basis of all evolution, which of the following would NOT contribute to the evolution of a population?

DNA mutations in somatic cells acquired during adulthood

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.

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

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?

Each population starts with a size of 20 and allele frequencies of p = 0.5 and q = 0.5 Correct! Genetic drift can be measured as the variance in allele frequency among populations. Thi

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?

Exactly! The correct answer is O = 0.54, o = 0.46 Correct! O = [(30 x 2) + 75 + 50]/{[(30 + 75 + 10) x 2] + 50 + 65}, o = [(10 x 2) + 75 + 65]/{[(30 + 75 + 10) x 2] + 50 + 65

Describe the effects of inbreeding on a population.

Inbreeding increases homozygosity and reduces heterozygosity in a population.

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?

Island frequency = 0.63, mainland frequency = 0.9

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?

Lower rate of mutation in the captive population

A ____________________________ is a group of interbreeding, sexually reproducing individuals that have a common set of genes.

Mendelian population

Examine Figure 25.15. Which evolutionary forces cause an increase in genetic variation within populations but cause a decrease in genetic variation between populations. in pop. btwn pop. increase gen.var mut,mig,nat.sel. mut,gen.drft, nat sel. decrease gen.var. gen drft,nat.sel. mig, nat sel.

Migration and some types of natural selection

Briefly describe directional selection.

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.

PP = 0.22, Pp = 0.37, pp= 0.41 Genotypic frequency is the number of individuals with a particular genotype divided by the total number of individuals. PP = 11/(11 + 18 + 20), Pp= 18/(11 + 18 + 20), pp = 20/(11 + 18

______________________ refers to a deviation from expected results due to a limited sample size.

Sampling error

Examine Figure 25.15. Which evolutionary forces cause a decrease in genetic variation both within and between populations? in pop. btwn pop. increase gen.var mut,mig,nat.sel. mut,gen.drft, nat sel. decrease gen.var. gen drft,nat.sel. mig, nat sel.

Some types of natural selection

Define natural selection.

The differential reproductive success of genotypes

Why is it easier to use allelic frequency than genotypic frequency to characterize a population's gene pool?

The gene pool can be described using fewer parameters.

Migration begins between two genetically diverse populations. What will happen to the gene pools of these two populations?

The gene pools will become more similar.

Briefly describe overdominance.

The heterozygote has greater fitness than either homozygote.

Briefly describe underdominance.

The heterozygote has lower fitness than either homozygote.

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

WFF = 0.724, WFS = 1, WSS = 0.463

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.

Yes! The correct answer is B = 0.68, b = 0.32 Correct! Allelic frequency is the number of one allele (2 x # of homozygotes + 1 x # of heterozygotes) divided by the total number of alleles (2 x # of individuals). The allelic frequency of B = (100 x 2) + (88)/(100 + 88 + 25) x 2

If one allele confers fitness over another allele, this is known as ______________ selection.

directional

If the only force acting on a population is mutation, the forward and reverse mutation rates will determine the

eventual equilibrium allele frequencies.

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. Genotype Number AA 42 AG 24 GG 21 What are the frequencies of the A and G alleles in these bears?

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

Give the Hardy-Weinberg expected genotypic frequencies for an autosomal locus with three alleles, designated A1, A2, and A3.

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

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: Genotype Fitness ST/ST 0.47 ST/AR 1 AR/AR 0.62 What will the frequencies of ST and AR be after equilibrium has been reached?

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

The relative reproductive success of a genotype is known as

fitness.

Positive assortative mating for relatedness is also known as

inbreeding.

All genetic variants ultimately arise through

mutation

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?

p = 0.35

Sampling error produced by _______________________ tends to ______________________ of genetic drift in a population.

the founder effect; increase the effect

The field of population genetics studies

the genetic makeup of groups of individuals and how it changes through time

If you can assume that a population is in Hardy-Weinberg equilibrium, the frequency of a recessive allele can be estimated as

the square root of the frequency of the recessive phenotype

If a heterozygote has lower fitness than either homozygote, this is called

underdominance

A certain form of congenital glaucoma is caused by an autosomal recessive allele. Assume that the mutation rate is 10-5 and that persons having this condition produce, on the average, only about 80% of the offspring produced by persons who do not have glaucoma. What will the frequency of the disease be in a randomly mating population that is at equilibrium?

0.00005

A certain form of congenital glaucoma is caused by an autosomal recessive allele. Assume that the mutation rate is 10-5 and that persons having this condition produce, on the average, only about 80% of the offspring produced by persons who do not have glaucoma. At equilibrium between mutation and selection, what will the frequency of the gene for congenital glaucoma be?

0.0071

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?

0.54

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?

0.68

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: Gametes Mutations Forward mutations 260,675 5 Reverse mutations 583,360 2 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?

0.85

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?

0.98

The sum of all genotypic frequencies always equals

1

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?

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?

1%

What is a Mendelian population?

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

The Hardy-Weinberg equation can be extended to describe frequencies for:

A. X-linked alleles. B. multiple alleles.

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.

The genetic effects of migration include all of the following to:

A. counter the effect of genetic drift. C. counter the effects of selection. D. allow new alleles to spread.

As population genetics is studied, all of the following are of interest :

A. genotype frequencies. B. allele frequencies. C. phenotype frequencies. D. mutation rates.

The Hardy-Weinberg equation implies:

A. genotypic frequencies are determined by genotypic frequencies. B. populations that meet the equation are not evolving.

Since random mating is an assumption of the Hardy-Weinberg equilibrium, non-random mating can confound it, as in all of the following cases :

A. inbreeding. B. positive assortative mating. C. negative assortative mating.

A Mendelian population is one that:

A. is a group of interbreeding members of a species. B. evolves through changes in its gene pool.

All of the following describe effects of natural selection :

A. it promotes adaptation. B. it reflects differential survival and reproduction according to phenotype. D. it can lead to unstable equilibria.

The Hardy-Weinberg equation is described by all of the following:

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.

The Hardy-Weinberg equilibrium requires all of the following assumptions :

A. mating is random. C. no selection is taking place. D. there is no immigration or emigration.

Depending on the environment and the genotypes involved, selection can produce all of the following effects:

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.

Testing to see if a population is at Hardy-Weinberg equilibrium requires all of the following :

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.

What determines the allelic frequencies at mutational equilibrium?

Both forward and reverse mutation rates

What proportion of the populations shown in Figure 25.13 reached fixation for either one of the alleles by generations 10, 25, and 30?

G10 = 0.0, G25 = 0.2, G30 = 0.4

Which of the following will not increase genetic variation within a population?

Genetic drift

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?

It will stay the same in the first herd and increase in the second herd. Correct! Migration out of a large population will not affect allelic frequency, but migration into a population increases genetic diversity.

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.

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

How would you respond to someone who said that models are useless in studying population genetics because they represent oversimplifications of the real world?

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

Examine Figure 25.15. Which evolutionary forces cause an increase in genetic variation both within and between populations? in pop. btwn pop. increase gen.var mut,mig,nat.sel. mut,gen.drft, nat sel. decrease gen.var. gen drft,nat.sel. mig, nat sel.

Mutation and some types of natural selection

_____________ can introduce new harmful alleles into a population, while_______________ will decrease their frequency.

Mutation; natural selection

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 Correct! This population is likely affected by mutation.

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.

Only the closely linked disease susceptibility trait will be affected. Correct! Because the disease susceptibility trait is linked to the coat-color trait, these two traits will not independently assort, so nonrandom mating preferences for coat color will also affect disease susceptibility.

What assumptions must be met for a population to be in Hardy-Weinberg equilibrium?

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

What is effective population size?

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 A in population II change after migration?

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

What is random mating?

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

Which of the following is not an assumption of populations exhibiting Hardy-Weinberg equilibrium for a given trait?

The population is undergoing natural selection.

What factors affect the magnitude of change in allelic frequencies due to migration?

The proportion of the population due to migrants and the difference in allelic frequencies between the migrant population and the original resident 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. Genotype Number AA 42 AG 24 GG 21 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.

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

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. TETE TETF TFTF 407 170 17

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

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: Genotype Number M^1M^1 20 M^1M^2 45 M^2M^2 42 M^1M^3 4 M^2M^3 8 M^3M^3 6 ___________ TOTAL 125 Calculate the allelic frequencies for this population.

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

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: Genotype Number M^1M^1 20 M^1M^2 45 M^2M^2 42 M^1M^3 4 M^2M^3 8 M^3M^3 6 ___________ TOTAL 125 What would the expected frequency of genotypes be if the population were in Hardy-Weinberg equilibrium?

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 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?

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 . Genotype Number S1S1 4 S1S2 38 S2S2 134

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

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: XOXOfemales 11 XOX+females 70 X+X+females 94 XOYmales 36 X+Ymales 112 Calculate the frequencies of the XO and X+ alleles for this population.

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

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?

f(q) = 0.17

When an allele has reached a frequency of 1, it is said to have reached

fixation

The influx of genes from other populations is known as

gene flow.

Changes in a population's overall ____________________________ lead to evolution of that population.

gene pool

Population genetics makes use of ______________________, which are simple representations of a process that consists of only a few influential factors.

mathematical models

Occasionally, an allele N1 (frequency = p) mutates to N2 (frequency = q). The rate at which the frequency of N2 changes in the population is a function of the

mutation rate and frequency of N 1 (p)

The tendency for like individuals to mate is known as

positive assortative mating.

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?

q = 0.635