Concepts of Genetics (11th Edition)
11th Edition
ISBN: 9780321948915
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino
Publisher: PEARSON
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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.
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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
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A, A, A, A, A2
A2 A2 A2 A2 A2
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(b) Effect of extreme
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A, A,
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The arrows represent
A, p= 0.5 offspring genotypes
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The frequencies
of…
White throated sparrows have been called 'the bird with four sexes'
because of their supergene. Within white throated sparrows there
is 'disassortative mating' for alleles at this super gene - every
breeding pair has one individual who has a tan throat, and one
individual with a white throat (Tuttle et al. 2016, Current Biology,
http://dx.doi.org/10.1016/j.cub.2015.11.069). Tan striped sparrows
are homozygous whereas white striped sparrows are heterozygous.
From this, we conclude which of the following about the super
gene:
White throat homozygotes could be inviable
Tan alleles are haploinsufficent
White alleles are 'poisonous'
Multiple genes in the super gene are interacting
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...
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