Biology: Life on Earth
10th Edition
ISBN: 9780321729712
Author: Gerald Audesirk, Teresa Audesirk, Bruce E. Byers
Publisher: Benjamin Cummings
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Textbook Question
Chapter 15, 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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Students have asked these similar questions
Average human height has changed over the past few centuries. The current
generation's average height is 168 centimeters (i.e. 5 foot 10 in). The selection
coefficient for height is ß = 0.08, phenotypic variation is Vp = 1.5, and heritability is h² =
0.45.
=
a. What is the response to selection (R) for height?
b. What is the average height expected to be for the next generation?
c. Would you say this is strong or weak selection?
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 15 Solutions
Biology: Life on Earth
Ch. 15 - The ________ provides a simple mathematical model...Ch. 15 - 2. Different versions of the same gene are called...Ch. 15 - An organism's ________ refers to the specific...Ch. 15 - 4. A random form of evolution is called _________....Ch. 15 - Competition is most intense between members of...Ch. 15 - 6. The evolutionary fitness of an organism is...Ch. 15 - 1. What is a gene pool? How would you determine...Ch. 15 - 2. Define equilibrium population. Outline the...Ch. 15 - How does population size affect the likelihood of...Ch. 15 - If you measured the allele frequencies of a gene...
Ch. 15 - 5. People like to say that “you can’t prove a...Ch. 15 - 6. Describe the three ways in which natural...Ch. 15 - What is sexual selection? How is sexual selection...Ch. 15 - In North America, the average height of adult...Ch. 15 - Malaria is rare in North America. In populations...Ch. 15 - By the 1940s, the whooping crane population had...Ch. 15 - Prob. 4ACCh. 15 - A preview question for Chapter 16: A species is...
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- 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_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 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_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 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_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
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