Concepts of Genetics (12th Edition)
12th Edition
ISBN: 9780134604718
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino, Darrell Killian
Publisher: PEARSON
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Chapter 26, Problem 31ESP
Recent reconstructions of evolutionary history are often dependent on assigning divergence in terms of changes in amino acid or
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Recent reconstructions of evolutionary history are often dependenton assigning divergence in terms of changes in amino acid ornucleotide sequences. For example, a comparison of cytochromec shows 10 amino acid differences between humans and dogs,24 differences between humans and moths, and 38 differencesbetween humans and yeast. Such data provide no information asto the absolute times of divergence for humans, dogs, moths, andyeast. How might one calibrate the molecular clock to an absolutetime clock? What problems might one encounter in such acalibration?
The second step to calculate the evolutionary rate is based on the values of p obtained
above. The relationship between the evolutionary rate, 1 (i.e., changes in sequence per number of
years), the proportion of different sites, p, and divergence time in years between the two species,
t, is approximately:
21t=p
6. We are assuming that the average value of l applies to all lineages and that each pair of
species shares a common ancestor. Given that, why does the formula have a factor of 2 on
the left hand side? Hint: think about what happens at a divergence.
Briefly discuss the differences in how a selectionist (one that believes that Natural Selection is a strong evolutionary force) and a neutralist (one that believes that genetic drift is a strong evolutionary force) views the following: molecular clock, evolution of coding sequences, evolution of "pseudogenes".
Chapter 26 Solutions
Concepts of Genetics (12th Edition)
Ch. 26 - The ability to taste the compound...Ch. 26 - Determine whether the following two sets of data...Ch. 26 - If the albino phenotype occurs in 1/10,000...Ch. 26 - A prospective groom, who is unaffected, has a...Ch. 26 - In a region of Quebec, Canada, 1 in 22 people are...Ch. 26 - Critics argue that a uniform panel of disorders...Ch. 26 - Others argue that the current testing system...Ch. 26 - HOW DO WE KNOW? Population geneticists study...Ch. 26 - CONCEPT QUESTION Read the Chapter Concepts list on...Ch. 26 - Price et al. [(1999).J. Bacteriol181:2358-2362)...
Ch. 26 - The genetic difference between two Drosophila...Ch. 26 - The use of nucleotide sequence data to measure...Ch. 26 - Prob. 6PDQCh. 26 - What must be assumed in order to validate the...Ch. 26 - In a population where only the total number of...Ch. 26 - If 4 percent of a population in equilibrium...Ch. 26 - Consider a population in which the frequency of...Ch. 26 - If the initial allele frequencies are p = 0.5 and...Ch. 26 - Under what circumstances might a lethal dominant...Ch. 26 - Assume that a recessive autosomal disorder occurs...Ch. 26 - One of the first Mendelian traits identified in...Ch. 26 - Describe how populations with substantial genetic...Ch. 26 - Achondroplasia is a dominant trait that causes a...Ch. 26 - Prob. 17PDQCh. 26 - Prob. 18PDQCh. 26 - A botanist studying water lilies in an isolated...Ch. 26 - A farmer plants transgenic Bt corn that is...Ch. 26 - In an isolated population of 50 desert bighorn...Ch. 26 - To increase genetic diversity in the bighorn sheep...Ch. 26 - What genetic changes take place during speciation?Ch. 26 - Some critics have warned that the use of gene...Ch. 26 - Prob. 25PDQCh. 26 - What are the two groups of reproductive isolating...Ch. 26 - A form of dwarfism known as Ellisvan Creveld...Ch. 26 - The original source of new alleles, upon which...Ch. 26 - A number of comparisons of nucleotide sequences...Ch. 26 - Shown below are two homologous lengths of the...Ch. 26 - Recent reconstructions of evolutionary history are...
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- A scientist is attempting to build a cladogram that shows the evolutionary closeness of three organisms in relation to humans. After doing DNA analysis, they determine that the organisms share the following percentages of DNA: Organism A and humans share 85% of their DNA. Organism B and humans share 80% of their DNA. Organism C and humans share 90% of their DNA. Based on this information, which order should they go on the cladogram (from least related to most related)?arrow_forwardCrickets have colonized each island in the Hawaiian Archipelago. Geological data indicates that Kauai is the oldest island in the chain and Hawaii is the youngest. Researchers hypothesized that crickets sequentially colonized islands as they rose out of the ocean and created a cladogram based on molecular relationships to test this idea. 1) Mark & label (as “MRCA”) the most recent common ancestor for all crickets on the island of Kauai. 2) Molokai is roughly equally distant from Oahu as Maui, but not equally related. Are Molokai crickets more closely related to those on Oahu or Maui?_________arrow_forwardThe Amish community in Eastern Pennsylvania stemmed from a small closed population of around 200 individuals from Eastern Europe. Certain mutant alleles have been found at higher frequencies in the Amish relative to the general population, including a rare form of dwarfism called Ellis-Van Creveld syndrome, in which the short stature is accompanied by polydactyly. Evaluate the factors driving evolution in the Amish population. Is this form of evolution adaptive? Explain.arrow_forward
- The Galapagos Islands are inhabited by organisms that are similar to the organisms on the mainland of South America but they have specific characteristics that set them apart. One of the most famous groups of organisms that has been studied has been the finches. There are at least 13 different species of ground finches found throughout the Galapagos, most likely all coming from a common ancestor that arrived from the mainland of South America in the distant past. Which of the following explanation accurately explains the variation of finches on the Galapagos Islands? Question options: Divergent evolution has occurred because the finches all share characteristics that are similar to the common ancestor but differ because each species occupies different niches that require different characteristics to survive. Convergent evolution has occurred because the finches do not share characteristics that are similar to the common ancestor and differ because each species occupies…arrow_forwardImagine that you have the DNA sequences from the intron of a gene in three species called A, B, and C. Species A and B are most closely related, while C is more distantly related. The sequences of A and B differ by 18 base pairs, A and C differ by 26 base pairs, and B and C differ by 28 base pairs. Fossils show that species A and B diverged about 1.2 Mya, but there is no fossil evidence as to when the most recent common ancestor of all three species lived. (Draw a simple tree to help you think about the problem) Use the genetic data to estimate that date (most recent common ancestor). HINT = use Eqn 7.1, several times- first to estimate mutation rate. Then to estimate the unknown time since divergencearrow_forwardImagine that you have the DNA sequences from the intron of a gene in three species called A, B, and C. Species A and B are most closely related, while C is more distantly related. The sequences of A and B differ by 18 base pairs, A and C differ by 26 base pairs, and B and C differ by 28 base pairs. Fossils show that species A and B diverged about 1.2 Mya, but there is no fossil evidence as to when the most recent common ancestor of all three species lived. (Draw a simple tree to help you think about the problem) Use the genetic data to estimate that date (most recent common ancestor). What assumptions are you making to get this estimate?arrow_forward
- Scientists conducted research to examine the evolutionary relationship between 10 bird species and an alligator species. They isolated the amounts of the dinucleotides cytosine and guanine found in the genomic DNA of each species. The graph shows the traditional taxonomic groups of the bird species used and the average percentage of dinucleotides in their DNA. Which of the following statements is best supported by the DNA evidence? A - Gamebirds likely evolved after non-perching birds. B - A bird’s ability to fly may be linked to its dinucleotide percentage. C - The dinucleotide percentages demonstrate coevolution of all species. D - Non-perching birds are more similar genetically to alligators than flightless birds.arrow_forwardA cladogram shows the evolutionary relationship between humans, chimpanzees, and gorillas. The cladogram currently shows humans and chimpanzees with a more recent common ancestor compared to gorillas. Which piece of evidence, if true, would most likely weaken this hypothesis? Amino acid analysis of the cytochrome shows significant differences in the sequence of amino acids between humans and goriffas. DNA sequence analysis of the hemoglobin alpha gene shows that humans and chimpanzees have a more similar sequence to each other than they do to the gorilla's DNA sequence. The cells of the eye in embryos of gorillas and humans follow a similar pattern of development chimpanzee embryos are different Fossils of humans appear in deeper sedimentary rock layers compared to fossils of chimpanzees.arrow_forwardWhat is the 50-500 rule? What does each of these numbers represent? With what mechanism of evolutionary change (of the five Hardy-Weinberg assumptions) does this rule primarily deal? What other major field of study uses this rule and why?arrow_forward
- identify and define the four forces of evolution. provide an actual or possible real-world example of each.arrow_forwardMatch the terms to their descriptors. NOTE: If you want to change your selection, you'll need to delete the one you already chose. After you delete it, the list of choices will pop back up and you can make a different choice. Two species evolve in different directions from a common starting point Divergent evolution Two species independently evolve similar structures Homologous structures Traits that look similar but were not inherited from a common Convergent evolution ancestor Analogous structures Traits that are similar because they were inherited from a common ancestorarrow_forwardIn the past, the evolutionary history of whales was represented by cladogram A, shown below. As you can see, whales were believed to be closely related to mesonychids, an extinct group of mammals that looked similar to wolves. Today, that cladogram has been revised, as shown in cladogram B. Which of the following statements best describes the reason for this change? A - Cladograms A and B are hypotheses that changed as new evidence became available.B - Cladogram B was revised to show a water-to-land pattern of evolution in groups of organisms.C - Cladogram B was altered to better include similarities in habitat as new information became available.D - Cladograms are organized today to show a much more simplified pattern like the one shown in cladogram B.arrow_forward
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