Pearson eText Genetic Analysis: An Integrated Approach -- Instant Access (Pearson+)
3rd Edition
ISBN: 9780135564172
Author: Mark Sanders, John Bowman
Publisher: PEARSON+
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Chapter 20, Problem 8P
Catastrophic events such as loss of habitat, famine, or overhunting can push species to the brink of extinction and result in a genetic bottleneck. What happens to allele frequencies in a species that experiences a near
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The loss of genetic variability within populations is an important concern for conservation biologists when trying to conserve a species whose numbers have been greatly reduced due to loss of habitat. This is true for the example of the Bengal Tiger, Clemson’s mascot. This reduction of genetic variability in small populations affects their evolutionary potential. Which of the following are NOT potential consequences of the loss of genetic variability for tiger populations?
A. Increased homozygosity can lead to the expression of deleterious recessive alleles
B. Increases the ability of the population to adapt to changes in the environment
C. Decreases the probability that the population can withstand a disease outbreak
D. Increases the risk of extinction for the population
Galapagos marine iguanas are differentiated by islands. However, the iguanas swim well, suggesting that gene flow can occur. You survey the frequency of allele A in Isla Tortuga and find that it is 0.33. In the next generation, the A allele frequency has gone up to 0.36. Because tiny Isla Tortuga lies close to giant Isla Isabela, you assume all migrants must come from there and follow a continent-island model. Allele frequency in Isla Isabela is 0.6 and stable. What proportion of alleles (m) entered Isla Tortuga from Isabela to explain your observations?
What is an example of how migration causes changes in gene frequencies?
Genetic material can become lost over time due to lack of reproduction when animals migrate.
When animals migrate, their genes mutate on their own, changing the frequency that a gene allele shows up.
When animals migrate, the mating becomes less random, causing inbreeding and, therefore, shifts in the proportion of alleles.
Seeds of plants are carried to different locations and introduced to a new population, adding their own genetic material and, therefore, changing gene frequencies.
Chapter 20 Solutions
Pearson eText Genetic Analysis: An Integrated Approach -- Instant Access (Pearson+)
Ch. 20 - 20.1 Compare and contrast the terms in each of the...Ch. 20 - In a population, what is the consequence of...Ch. 20 - 20.3 Identify and describe the evolutionary forces...Ch. 20 - Describe how natural selection can produce...Ch. 20 - Thinking creatively about evolutionary mechanisms,...Ch. 20 - 20.6 Genetic drift, an evolutionary process...Ch. 20 - Over the course of many generations in a small...Ch. 20 - Catastrophic events such as loss of habitat,...Ch. 20 - 20.9 George Udny Yule was wrong in suggesting that...Ch. 20 - 20.10 The ability to taste the bitter compound...
Ch. 20 - Figure 20.6 illustrates the effect of an ethanol ...Ch. 20 - 20.12 Biologists have proposed that the use of...Ch. 20 - 20.13 Two populations of deer, one of them large...Ch. 20 - 20.14 Directional selection presents an apparent...Ch. 20 - 20.15 What is inbreeding depression? Why is...Ch. 20 - 20.16 Certain animal species, such as the...Ch. 20 - Genetic Analysis 20.1 predicts the number of...Ch. 20 - 20.18 In a population of rabbits, and . The...Ch. 20 - Sickle cell disease (SCD) is found in numerous...Ch. 20 - 20.20 Epidemiologic data on the population in the...Ch. 20 - The frequency of tasters and nontasters of PTC...Ch. 20 - Tay-Sachs disease is an autosomal recessive...Ch. 20 - 20.23 Cystic fibrosis (CF) is the most common...Ch. 20 - 20.24 In the mouse, Mus musculus, survival in...Ch. 20 - 20.25 In a population of flowers growing in a...Ch. 20 - Assume that the flower population described in the...Ch. 20 - 20.27 ABO blood type is examined in a Taiwanese...Ch. 20 - 20.28 A total ofmembers of a Central American...Ch. 20 - 20.29 A sample offield mice contains individuals...Ch. 20 - Prob. 30PCh. 20 - Albinism, an autosomal recessive trait...Ch. 20 - 20.32 The frequency of an autosomal recessive...Ch. 20 - 20.33 Evaluate the following pedigree, and answer...Ch. 20 - Evaluate the following pedigree, and answer the...Ch. 20 - The following is a partial pedigree of the British...Ch. 20 - Draw a separate hypothetical pedigree identifying...Ch. 20 - Prob. 37PCh. 20 - 20.38 Achromatopsia is a rare autosomal recessive...Ch. 20 - 20.39 New allopolyploid plant species can arise by...
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- ADJUST Negative assortative mating means that organisms choose mates that are different from themselves. If negative assortive mating occurs in a population, what would expect to happen to genotype frequency over generations? O a) Frequency of the heterozygous genotype will increase. b) Frequency of the homozygous genotypes will decrease. O c) Frequency of the homozygous genotypes will increase. O d) Both A and B AUTO ||||||||| Cancel Revertarrow_forwardConsider the following hypothetical scenario involving giraffes. A population of giraffes is composed of individuals of varying neck lengths, i.e., some giraffes have long necks, others have short necks, and some are in-between. Neck length in giraffes is a heritable trait, i.e., offspring have necks similar to their parents due to them inheriting genes from their parents. Within this population, there is competition for resources (leaves to eat). Long-necked giraffes are able to consume more leaves than short or medium-necked giraffes because they can reach leaves that are higher up in the canopy. Therefore, long-necked giraffes, in the current generation, have begun to survive and reproduce more often than giraffes with short or medium necks. https://www.globalchange.umich.edu/globalchange1/current/lectures/selection/selection.html (you can also search “natural selection Michigan” to find this helpful website) If you read between the lines…the above paragraph tells…arrow_forwardDescribe what happens to allele frequencies as a result of the bottleneck effect. Discuss the relevance of this effect with regard to species that are approaching extinction.arrow_forward
- Negative assortative mating means that organisms choose mates that are different from themselves. If negative assortive mating occurs in a population, what would expect to happen to genotype frequency over generations? a) Frequency of the heterozygous genotype will increase. b) Frequency of the homozygous genotypes will decrease. c) Frequency of the homozygous genotypes will increase. O d) Both A and Barrow_forwardIf (positive) assortative mating increases in a population, what would expect to happen to genotype frequency over generations? O a) Frequency of the heterozygous genotype will increase. b) Frequency of the homozygous genotypes will decrease. O c) Frequency of the homozygous genotypes will increase. O d) There will be no change in genotype frequency.arrow_forwardWithin a population of butterflies, the color brown (B) is dominant over the color white (b) and 40% of all butterflies are white. Given this information and HWE calculate the following: a) The percentage of butterflies in the population that are heterozygous. b) The frequency of homozygous dominant individuals.arrow_forward
- The red wolf (Canis rufus) was once widespread in the southeastern United States but was declared to be extinct in the wild. Biologists bred captive red wolf individuals and reintroduced them into areas of eastern North Carolina, where they are federally protected as endangered species. The current wild population is estimated to be about 100 individuals. However, a new threat to red wolves has arisen: hybridization with coyotes (Canis latrans), which have become more numerous in the areas inhabited by red wolves. Although red wolves and coyotes differ in morphology and DNA, they are capable of interbreeding and producing fertile offspring. Social behavior is the main reproductive barrier between the species and is more easily overcome when same-species mates are rare. For this reason, some people think that the endangered status of the red wolf should be withdrawn and resources should not be spent to protect what is not a “pure” species. Do you agree? Why or why not?arrow_forwardIn a real habitat, new squirrels often come into the habitat (immigrate) and others leave the area (emigrate). How might emigration of squirrels with gray fur from this population affect the gene frequency of G and g in this population of squirrels? How might immigration of leucistic squirrels into this population affect the gene frequency of G and g in this population of squirrels? How might you simulate the effect of each of these scenarios if you were to repeat this simulation activity?arrow_forwardWhich of the following is not true for a critically endangered species? Expression of deleterious alleles and increased homozygosity increases mortality of young, and inbreeding depression leads to reduced offspring fitness The individuals of the species which have declined to low numbers are still a genetically open system Loss of some allele from the species causing loss of genetic diversity with consequent inability to respond rapidly to selection Reduction of population breeding ability due to increased relatedness through the action of incompatibility mechanisms in plants or behavioural difficulties in animalsarrow_forward
- When male lions reach sexual maturity, they leave their pride in search of a new pride. Mating with females in the new pride can change the allele frequencies in the population through which of the following mechanisms?arrow_forwardIn Manx cats, the recessive allele for tail length can be lethal. A heterozygous dominant genotype results in a shortened tail, while a homozygous dominant genotype results in a normal tail. A homozygous recessive genotype is lethal. In an ideal Manx cat population exhibiting Hardy-Weinberg equilibrium, if the lethal allele has a frequency of 0.22, what percentage of the Manx cat population retains a shortened or normal tail length? Express your answer using three significant digits.arrow_forwardWhat is inbreeding depression and why is it particularly a concern for conservation biology? A) It is a chemical imbalance in the brain of animals forced into close quarters, such as those rescued from the wild and placed in zoos. B) It is a situation where the frequency of an allele over time depends greatly upon its initial frequency, as such if populations are too small, the present alleles are at risk of being lost. C) It is a situation where offspring of genetic relatives have increased fitness, this occurs when populations of animals are large and they mate freely. D) It is a situation where offspring of genetic relatives have reduced fitness, this occurs when populations of animals become too small and they are thus likely to mate with closely related individuals.arrow_forward
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