Biology
12th Edition
ISBN: 9780134813448
Author: Audesirk, Teresa, Gerald, Byers, Bruce E.
Publisher: Pearson,
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Textbook Question
Chapter 16, Problem 1AC
In North America, the average height of adult humans has been increasing steadily for decades. Is directional selection occurring? What data would justify your answer?
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You are asked to assess whether a population of endangered salamanders can adapt to warming climate in their preferred habitat. The salamanders vary at a locus that determines adaptation to temperature, and the warming climate creates selection favoring one of two alleles at that locus. Drawing on what you know about natural selection and genetic drift, what information would you need to know about the salamanders to determine whether the allele that improves their adaptation to warmer climates will become fixed in the population?
Strictly no plagiarism.
A species of hummingbird feeds on nectar of a particular plant whose flowers
form a long, skinny cup. Beak length is a heritable trait that varies among
individual hummingbirds. The birds' beaks must be long enough to reach the
nectar, but longer beaks are also heavier and make flying more costly in terms of
energy.
a. Which mode of selection is this hummingbird species experiencing?
b. How does this mode of selection affect the mean and standard deviation
over time?
There are five generations of complete selection against recessive individuals (a) , migration (b), and random genetic drift (c). that affect the gene (A, a) and genotypic (AA, Aa, aa) frequencies of the population. Afterward, answer the question that follows.
Based on the figures, what are the effect of complete selection, migration, and random genetic drift on the gene and genotypic frequencies of the population? Describe the trend for each scenario and provide a brief explanation.
a. complete selection against recessive individuals
b. migration
c. random genetic drift (random mating in a very small population)
Chapter 16 Solutions
Biology
Ch. 16.1 - define evolution in terms of concepts from...Ch. 16.1 - define equilibrium population and describe the...Ch. 16.2 - If it were true that mutations do occur in...Ch. 16.2 - Explain how the distribution of genotypes in...Ch. 16.2 - A flu vaccination stimulates your immune system to...Ch. 16.2 - Prob. 3TCCh. 16.2 - If a population grows large again after a...Ch. 16.2 - Prob. 5TCCh. 16.2 - Evolution of a Menace The mutant alleles that...Ch. 16.2 - describe how mutation, gene flow, genetic drift,...
Ch. 16.3 - A team of phys clans treated four patients with...Ch. 16.3 - If we studied a population of bighorn sheep and...Ch. 16.3 - When selection is directional, is there any limit...Ch. 16.3 - describe why selection of phenotypes can affect...Ch. 16.3 - explain how competition and predation influence...Ch. 16.3 - Prob. 3CYLCh. 16.3 - compare and contrast directional selection,...Ch. 16.3 - Microbiologists have discovered that alleles...Ch. 16 - The alleles responsible for antibiotic resistance...Ch. 16 - Stabilizing selection on a trait tends to a. make...Ch. 16 - An adaptation is a. any trait that arises from a...Ch. 16 - Which of the following statements about mutations...Ch. 16 - Genetic drift occurs a. when different phenotypes...Ch. 16 - The ______ provides a simple mathematical model...Ch. 16 - Different versions of the same gene are called...Ch. 16 - An organisms ______ refers to the specific alleles...Ch. 16 - A random form of evolution is called ________....Ch. 16 - Competition is most Intense between members of...Ch. 16 - The evolutionary fitness of an organism is...Ch. 16 - What is a gene pool? How would you determine the...Ch. 16 - Define equilibrium population. Outline the...Ch. 16 - How does population size affect the likelihood of...Ch. 16 - If you measured the allele frequencies of a gene...Ch. 16 - People like to say that you cant prove a negative....Ch. 16 - Describe the three ways in which natural selection...Ch. 16 - What is sexual selection? How is sexual selection...Ch. 16 - In North America, the average height of adult...Ch. 16 - By the 1940s, the whooping crane population had...
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- would the heritability of human height in native Hawaiians different from the height of Lithuanians? 1) no since both of them are in different racial groups 2) yes since the genetic diversity and the environment influences are different in both groups 3) yes, the sample size in the study is not the same 4) no because heritability is homogenous across all subpopulations.arrow_forwardA scientist measures the circumference of acorns in a population of oak trees and discovers that the most common circumference is 2 cm. What would you expect the most common circumference(s) to be after 10 generations of diversifying selection?arrow_forwardIn New Zealand you begin to study the relationship between snails and their trematode parasites. You found that the parasites cause cyclical patterns of selection on the snail populations, and vice a versa, such that snails with rare genotypes typically survive better compared to those that have more common genotypes. In the ten years you’ve been sampling, you notice that the two alleles cycle between being rare and common from year to year. What pattern of selection did you observe? a. selection against the dominant allele b. selection against the recessive allele c. frequency-dependent selection d. overdominancearrow_forward
- Storage of excess carbohydrates in the diet in the form of fat would have helped human populations survive famine. However, this process is also a risk factor for obesity and type 2 diabetes in modern populations. Modern populations vary greatly in the prevalence of type 2 diabetes, but there is no evidence that alleles increasing type 2 diabetes susceptibility have been under positive selection in human populations. Which of the following is the best inference we can draw from these findings. Selected answer will be automatically saved. For keyboard navigation, press up/down arrow keys to select an answer. b C d Past selection for alleles increasing fat storage probably does not explain differences in type 2 diabetes prevalence in modern populations. Storage of excess carbohydrates probably does not contribute to type 2 diabetes. There is no genetic basis for differences between populations in type 2 diabetes. Fat storage has always been a deleterious trait for humans.arrow_forwardif a population of jumping spiders consists of 40 females and 40 males, what is the effective population size? Give the appropriate equation and show your work. Will genetic drift be an important evolutionary force in this population? Why or why not? If your answer is "yes", what does genetic drift do to allele frequencies? If your answer is "no", name two forces other than genetic drift that might be important in determining allele frequencies. asaparrow_forwardIn the 1900s, the Florida panther population declined drastically due to hunting and habitat loss, and, by the mid-1990s, there were fewer than 30 Florida panthers left in the wild. What were the most likely consequences of this decline in population size on the frequency of genetic abnormalities, such as malformed testicles, in the remaining population? A. The frequency of genetic abnormalities decreased due to the weakest panthers being eliminated through natural selection. B. The frequency of genetic abnormalities increased due to an increased rate of migration of other panthers into the population. C. The frequency of genetic abnormalities increased due to the random loss of genetic diversity and increased inbreeding in small populations. D. The frequency of genetic abnormalities decreased because the concentration of adaptive alleles in the small population decreased as the population declined.arrow_forward
- In a population of sociable weavers (small birds that live in the African savanna), body weight was recorded for 977 birds and graphed. Identify and describe the type of selection that is occurring in the population of sociable weavers. (b) A group of fire ants from North America were accidentally brought to African savanna by an American tourist in their luggage. The fire ants bite and cause harm to all organisms and their food supply in the savanna. Explain how the fire ants will impact the ecosystem dynamics.arrow_forwardIn the garden shed belonging to one of this text’s authors, stabilizing selection has occurred over the past 10 years in the house mouse, Mus musculus. Which of the following scenarios is an example of stabilizing selection? (a) Small and medium-sized mice cannot reach the seed shelf in the shed and therefore are at a disadvantage for finding food, so they do not survive and reproduce as well as large mice do.(b) Small mice cannot reach the seed shelf, and large mice are easily seen by hawks circling above. Medium-sized mice therefore survive and reproduce better than both small and large mice. (c) Small mice can easily cross the yard to the vegetable garden, and large mice can easily reach the seed shelf. Medium-sized mice have trouble with the seed shelf and are seen by hawks in the yard. Small and large mice survive and reproduce much better than medium-sized mice. (d) All of these are examples of stabilizing selection. (e) None of these are examples of stabilizing selection.arrow_forwardWhich of the following is a case of directional selection? Question 70 options: During a drought, individual leopard frogs of intermediate body size are less likely to survive than large and small individuals. During a drought, individual house finches with intermediate beak size are more likely to survive than individuals with large or small beaks. During a drought, individual cattails that are heterozygous at a particular locus are more likely to die than homozygous individuals. During a drought, the larger individuals in a population of lizards are less likely to survive than the smaller ones.arrow_forward
- In a population of sociable weavers (small birds that live in the African savanna), body weight was recorded for 977 birds and graphed. (n) Identify and describe the type of selection that is occurring in the population of sociable weavers. (o) A group of fire ants from North America were accidently brought to African savanna by an American tourist in their luggage. The fire ants bite and cause harm to all organisms and their food supply in the savanna. Explain how the fire ants will impact the ecosystem dynamicsarrow_forwardOn many remote islands in the Pacific, there are endemic species of wingless insects that apparently have evolved from winged ancestral species that colonized the island in the distant past. For this example, describe the conditions which must have been met in order for winglessness to have evolved, the means by which winglessness was able to increase in frequency in the population, and the mode of selection that must have taken place within this population. Your answer to this question must define and use terminology appropriate to a discussion of evolution.arrow_forwardWhich of the following traits would you expect to be under weakest selection? Explain your answer. 1. The development of prostate cancer in older male humans 2. The development of digits in frogs 3. The silver hair color on silver back male gorillas 4. The dance choreography in peacock spidersarrow_forward
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