Ch. 23 - Evolutionary Processes

Freeman - Biological Science 7th Edition

Freeman7th EditionBiological ScienceISBN: 9783584863285Not the one you use?Change textbook

Freeman 7th Edition

Ch. 23 - Evolutionary Processes

Problem 8

Chapter 23, Problem 8

Draw a small concept map showing how selection, genetic drift, gene flow, and mutation relate to genetic variation.

Verified step by step guidance

Step 1: Start by drawing a circle in the center of your paper and label it 'Genetic Variation'. This will be the main concept that all other concepts connect to.

Step 2: Draw four lines radiating out from the 'Genetic Variation' circle. At the end of each line, draw a circle and label them 'Selection', 'Genetic Drift', 'Gene Flow', and 'Mutation'. These are the four factors that contribute to genetic variation.

Step 3: Connect 'Selection' to 'Genetic Variation' with a line. Write on the line 'Natural selection can increase or decrease genetic variation in a population by favoring certain alleles over others'.

Step 4: Connect 'Genetic Drift' to 'Genetic Variation' with a line. Write on the line 'Genetic drift can cause random changes in allele frequencies, leading to genetic variation'.

Step 5: Connect 'Gene Flow' and 'Mutation' to 'Genetic Variation' with lines. Write on the 'Gene Flow' line 'Gene flow introduces new alleles into a population, increasing genetic variation'. Write on the 'Mutation' line 'Mutation creates new alleles, contributing to genetic variation'.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Natural Selection

Natural selection is the process by which certain traits become more common in a population due to their advantageous effects on survival and reproduction. Organisms with favorable traits are more likely to survive and reproduce, leading to an increase in those traits in subsequent generations. This mechanism plays a crucial role in shaping genetic variation by favoring alleles that enhance fitness.

Genetic Drift

Genetic drift refers to random changes in allele frequencies within a population, particularly in small populations. These changes can lead to the loss of genetic variation over time, as certain alleles may become fixed or lost purely by chance. Genetic drift can significantly impact the evolutionary trajectory of a population, especially when combined with other mechanisms like selection.

Gene Flow

Gene flow, or gene migration, is the transfer of genetic material between populations through the movement of individuals or their gametes. This process can introduce new alleles into a population, increasing genetic variation and potentially altering allele frequencies. Gene flow acts as a counterbalance to the effects of genetic drift and selection, promoting genetic diversity within and between populations.

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Related Practice

Textbook Question

In the 1700s and 1800s, royalty in Europe often married their close relatives; furthermore, recessive genetic diseases such as hemophilia showed up much more often among royals than in the general population. Explain the likely connection.

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Textbook Question

Determine what is incorrect in the following statement: Red deer mutated their genes so that they could have larger antlers to compete for mates.

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Textbook Question

Determine what is incorrect in the following statement: Deer mice living on beaches mutated their genes so that they could have white fur color, providing better camouflage to survive on beaches.

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Textbook Question

In humans, albinism is caused by loss-of-function mutations in genes involved in the synthesis of melanin, the dark pigment in skin. Only people homozygous for a loss-of-function allele (genotype aa) have the albino phenotype. In Americans of northern European ancestry, albino individuals are present at a frequency of about 1 in 10,000 (or 0.0001). Assuming that genotypes are in Hardy–Weinberg equilibrium, what is the predicted frequency of Caucasians in the United States who carry a single allele for albinism?

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Textbook Question

Suppose you were studying several species of monkeys. In one, males never helped females raise offspring. In another, males provided just as much parental care as females except for actually carrying the fetus during pregnancy. How does the fundamental asymmetry of sex compare in the two species? How would you expect sexual dimorphism to compare between the two species?

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Textbook Question

Human activities are causing the fragmentation of the Brazilian Atlantic rain forest. One result is that toucans have become extinct or nearly extinct in some of the forest fragments. Does the absence of toucans affect the forest?

Toucans disperse seeds of key forest species such as juçara palms by eating the fruit and defecating the seeds in new locations, sometimes more than a kilometer away. If there are no toucans, is the genetic diversity of palms likely to increase or decrease within forest fragments? Why?

a. Increase (due to increased genetic drift)

b. Decrease (due to decreased gene flow)

c. Decrease (due to decreased mutation rate)

d. Decrease (due to decreased natural selection)

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