Concepts of Genetics (11th Edition)
11th Edition
ISBN: 9780321948915
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Textbook Question
Chapter 23, Problem 29ESP
In 1988, Horst Wilkens investigated blind cavefish, comparing them with members of a sibling species with normal vision that are found in a lake [Wilkens, H. (1988). Evol. Biol. 25:271–367]. We will call them cavefish and lakefish. Wilkens found that cavefish eyes are about seven times smaller than lakefish eyes. F1 hybrids have eyes of intermediate size. These data, as well as the F1 × F1 cross and those from backcrosses (F1 × cavefish and F1 × lakefish), are depicted below. Examine Wilkens’s results and respond to the following questions:
- (a) Based strictly on the F1 and F2 results of Wilkens’s initial crosses, what possible explanation concerning the inheritance of eye size seems most feasible?
- (b) Based on the results of the F1 backcross with cavefish, is your explanation supported? Explain.
- (c) Based on the results of the F1 backcross with lakefish, is your explanation supported? Explain.
- (d) Wilkens examined about 1000 F2 progeny and estimated that 6–7 genes are involved in determining eye size. Is the
sample size adequate to justify this conclusion? Propose an experimental protocol to test the hypothesis. - (e) A comparison of the embryonic eye in cavefish and lakefish revealed that both reach approximately 4 mm in diameter. However, lakefish eyes continue to grow, while cavefish eye size is greatly reduced. Speculate on the role of the genes involved in this problem.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
Consider the following statement: ‘female, w+w flies have red eyes’. In this example:
Group of answer choices
1) w+w is the genotype, and red eyes is the phenotype
2) female is the genotype, and red eyes is the phenotype
3) not enough information provided to determine genotype or phenotype
4) red eyes is the genotype, and w+w is the phenotype
Read in your textbook about positive assortative mating. In this example, from your text, positive
assortative mating is 100% (i.e. there is no random mating). Note that the frequency of
heterozygotes is cut in half each generation. Does this match your answers above? Look at the
actual values make sure you understand why positive assortative mating leads to an increase in
homozygosity.
(a) Only heterozygotes
produce heterozygote
offspring, but only 50%
of the time
Homozygote
parent for A,
Heterozygote
parent
Homozygote
parent for A,
Eggs
A,
A,
Eggs
A2
A,
Eggs
A2
A2
A, A, A, A, A,
A, A, A, A, A2
A2 A2 A2 A2 A2
A, A, A, A, A,
A, A, A2 A2 A2
A2 A2 Az A2 A2
(b) Effect of extreme
inbreeding (self-
fertilization)
over time
A, A,
Homozygote
A, A2
Heterozygote
A2 A2
Homozygote
The arrows represent
A, p= 0.5 offspring genotypes
that are produced
by each parental
genotype
Generation 1
Az q = 0.5
100%
25%
50%
25%
100%
A, p= 0.5
Az q= 0.5
Generation 2
100%
25%
50%
25%
100%
The frequencies
of…
One of the findings from Strickland et al. 2019, was that certain color morphs among Chelymorpha alternans beetles are more common at some field sites than they are at other sites. Strickland and colleagues used cross breeding experiments to investigate these patterns and found evidence that color variation was mainly due to Mendelian inheritance. In other species, geographic variation in coloration might not be due to Mendelian genetics.
(a) What is another possible explanation for geographic variation in coloration?
(b) What sort of experiment could you use to test this alternative explanation?
Chapter 23 Solutions
Concepts of Genetics (11th Edition)
Ch. 23 - A homozygous plant with 20-cm-diameter flowers is...Ch. 23 - The following table shows measurements for fiber...Ch. 23 - The following cable gives the percentage of twin...Ch. 23 - Prob. 1CSCh. 23 - Prob. 2CSCh. 23 - Prob. 3CSCh. 23 - HOW DO WE KNOW? In this chapter, we focused on a...Ch. 23 - CONCEPT QUESTION Review the Chapter Concepts list...Ch. 23 - Define the following: (a) polygenic, (b) additive...Ch. 23 - A dark-red strain and a white strain of wheat are...
Ch. 23 - Height in humans depends on the additive action of...Ch. 23 - An inbred strain of plants has a mean height of 24...Ch. 23 - Erma and Harvey were a compatible barnyard pair,...Ch. 23 - In the following table, average differences of...Ch. 23 - What kind of heritability estimates (broad sense...Ch. 23 - List as many human traits as you can that are...Ch. 23 - Corn plants from a test plot are measured, and the...Ch. 23 - The following variances were calculated for two...Ch. 23 - The mean and variance of plant height of two...Ch. 23 - Prob. 14PDQCh. 23 - Prob. 15PDQCh. 23 - In an assessment of learning in Drosophila, flies...Ch. 23 - Prob. 17PDQCh. 23 - Prob. 18PDQCh. 23 - In a population of 100 inbred, genotypically...Ch. 23 - Many traits of economic or medical significance...Ch. 23 - A 3-inch plant was crossed with a 15-inch plant,...Ch. 23 - In a cross between a strain of large guinea pigs...Ch. 23 - Type A1B brachydactyly (short middle phalanges) is...Ch. 23 - In a series of crosses between two true-breeding...Ch. 23 - Students in a genetics laboratory began an...Ch. 23 - Prob. 26ESPCh. 23 - Canine hip dysplasia is a quantitative trait that...Ch. 23 - Floral traits in plants often play key roles in...Ch. 23 - In 1988, Horst Wilkens investigated blind...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- What is the relative fitness of the F1 hybrids relative to both parental populations according to this model?arrow_forwardThe Soay sheep of St. Kilda Island near Scotland have changed coat color over the past 20 years, with dark colored sheep declining in frequency and light colored sheep increasing. Coat color is determined by the TYRP1 gene. The TYRP1-T homozygote is light colored, while TYRP1-G homozygotes and heterozygotes are dark. Discuss the hypothesis that assortative mating between sheep with similar coat color is the cause of the increase in light coat color over this period.arrow_forwardHibiscus plants have different varieties of flowers. In an instance, both the red and white flowers showed that they are incompletely dominant with each other. What is the percentage that the color of the resulting flower in the 2nd experiment will be red? Explain A) 50% B) 25% C) 100% D) 75%arrow_forward
- 8% of XY individuals are color blind in a population. Assume Hardy-Weinberg conditions. Submit your answer as it is. a) What is the percentage of color-blind XX individuals? b) What is the percentage of XX individuals who are carriers? c) If this population has 1000 individuals with 50% of male and 50% of female, how many carriers are present in this population? Submit your answer as it is. Do not round up.arrow_forwardConsider bats, where the folded ear allele (e) is recessive to the upright ear allele (E). If, in a colony of 100 bats, 64 of the bats have upright ears (assuming the colony is at Hardy-Weinberg equilibrium) how many do you expect to be:a) Homozygous Dominant? b) Homozygous Recessive? c) Heterozygous?arrow_forwardTwo pea plants that are true-breeding for recessive white flowers are mated and their offspring analyzed. Which of the following statements about this situation is true? Group of answer choices A)The offspring represent the P generation. B)The gametes produced by the offspring will carry only one allele for this gene. C)Both parents are referred to as heterozygotes. D)Half of the offspring will be true-breeding for white flowers.arrow_forward
- 1) Plumage colour in mallard ducks is controlled by a number of alleles at one locus. MR is the allele for restricted mallard pattern, M for mallard and m for dusky mallard. The dominance hierarchy is MR>M>m. Determine the genetotypic and phenotypic ratios for the following crosses a) MRMR X MRM b) MRMR X MⓇm c) MⓇM x MⓇm d) MⓇm x Mm e) Mm x mmarrow_forwardIn cardinals, a dominant allele R is required for red feathers (r = colorless). In addition, the dominant allele I (of an unlinked gene. is an inhibitor of color (birds with an I allele are colorless; I overrides the effects of R). If a true breeding red cardinal mates with a colorless female (genotype = r/r; I/I): a) What would be the genotype of the F1 progeny? b) What would be the phenotype of the F1 progeny? c) If the F1 progeny are selfed, what is the expected colorless:red ratio among the progeny?arrow_forwardA) A corgì was born with short fur, which is recessive to longer fur. This corgi eventually had puppies of its own with a homozygous long haired corgi. What percentage of the offspring will have long fur? 2 B) Based off the above information, what percentage of the offspring will be heterozygous?arrow_forward
- The agouti gene determines coat colour in mice. Heterozygous mice have yellow coats, while homozygous dominant mice have black coats. However, having two copies of the recessive alleles is lethal. In a population of 2 000 mice, 1 082 mice have black coats. a) Calculate the frequency of each allele. Show all your work and express your answer as a value between 0 and 1 rounded to two decimal places. b) What percentage of the mouse population is expected to be carriers of the lethal allele? Show all your work and express your answer rounded to one decimal place. c) How many mice will die during fetal development? Show all your work and round your answer to the closest whole number.arrow_forwardCardigan Corgi tail length is determined by 5 genes. The genotype DDEEFFGGHH produces a tail length of 44cm, while the genotype ddeeffgghh produces a tail length of 4cm. a) Each additive allele adds how many centimeters to the tail length? b) Predict the tail length for the following genotype: DDEEFfGgHh Group of answer choices 8cm, 56cm 4cm, 12cm 8cm, 24cm 4cm, 32cmarrow_forwardIn humans, the ability to smell hydrocyanic acid (HCN) is inherited as a recessive trait (h = can smell HCN, H = cannot smell HCN). A woman, a man, and their biological child are all standing in a room. The child can smell the HCN but the parents cannot. 1.) What is the genotype of the child? 2.) What are the possible phenotypes of the parents?arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education
Human Anatomy & Physiology (11th Edition)
Biology
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:PEARSON
Biology 2e
Biology
ISBN:9781947172517
Author:Matthew Douglas, Jung Choi, Mary Ann Clark
Publisher:OpenStax
Anatomy & Physiology
Biology
ISBN:9781259398629
Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa Stouter
Publisher:Mcgraw Hill Education,
Molecular Biology of the Cell (Sixth Edition)
Biology
ISBN:9780815344322
Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter
Publisher:W. W. Norton & Company
Laboratory Manual For Human Anatomy & Physiology
Biology
ISBN:9781260159363
Author:Martin, Terry R., Prentice-craver, Cynthia
Publisher:McGraw-Hill Publishing Co.
Inquiry Into Life (16th Edition)
Biology
ISBN:9781260231700
Author:Sylvia S. Mader, Michael Windelspecht
Publisher:McGraw Hill Education
How do Plants Handle Stress?; Author: Alex Dainis;https://www.youtube.com/watch?v=TYsnveEHqec;License: Standard Youtube License