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Ch. 22 - Evolution by Natural Selection
Freeman - Biological Science 8th Edition
Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook
Chapter 22, Problem 7

Why don't the biggest and strongest individuals in a population always produce the most offspring?
a. The biggest and strongest individuals always have higher fitness.
b. In some environments, being big and strong lowers fitness.
c. Sometimes the biggest and strongest individuals may choose to have fewer offspring.
d. Sometimes the number of offspring is not related to fitness.

Verified step by step guidance
1
Understand the concept of 'fitness' in biology: Fitness refers to an organism's ability to survive and reproduce in its environment. It is not solely determined by size or strength.
Consider environmental factors: In some environments, being big and strong might require more resources, which could be scarce, thus lowering the individual's overall fitness.
Evaluate reproductive strategies: Some individuals may invest more in fewer offspring to ensure their survival, while others may produce many offspring with less investment in each.
Recognize that fitness is multifaceted: Fitness includes survival, reproduction, and the ability to pass on genes to the next generation, which may not always correlate with size or strength.
Analyze the relationship between offspring number and fitness: The number of offspring produced is one aspect of fitness, but it is not the only factor. Other factors like offspring survival and reproductive success also play a role.

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Key Concepts

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

Fitness in Evolutionary Biology

In evolutionary biology, fitness refers to an organism's ability to survive and reproduce in its environment. It is not solely determined by physical strength or size but by how well an organism's traits enable it to adapt to its environment and successfully pass on its genes to the next generation. Thus, fitness can vary depending on environmental conditions and other factors.
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Trade-offs in Reproductive Strategies

Organisms often face trade-offs in their reproductive strategies, balancing between the number and quality of offspring. Producing many offspring may spread resources thin, reducing individual offspring survival chances, while fewer, well-cared-for offspring might have higher survival rates. These trade-offs can influence reproductive success and are shaped by environmental pressures and resource availability.
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Environmental Influence on Fitness

The environment plays a crucial role in determining which traits are advantageous, affecting an organism's fitness. In some environments, being large and strong may be beneficial, while in others, it could be a disadvantage due to factors like resource scarcity or predation. Thus, the relationship between physical traits and reproductive success is complex and context-dependent.
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Related Practice
Textbook Question

How can evolutionary fitness be measured? Select True or False for each statement.

T/F Document how long individuals survive.

T/F Count the number of healthy, fertile offspring produced.

T/F Determine which individuals are strongest.

T/F Determine which phenotype is the most common.

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Textbook Question

According to data presented in this chapter, which of the following are correct? Select True or False for each statement. T/F When individuals change in response to challenges from the environment, their altered traits are passed on to offspring. T/F Species are created independently of each other and do not change over time. T/F Populations—not individuals—change when natural selection occurs. T/F The traits of populations become more perfect over time.

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Textbook Question

Some biologists summarize evolution by natural selection with the phrase "mutation proposes, selection disposes." Mutation is a process that creates heritable variation. Explain what the phrase means.

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Textbook Question

The global “One Health” movement fosters collaborations at the intersection of human health, veterinary health, and environmental health. Explain why “One Health” seeks to reduce the use of antibiotics in farm animals to improve human health.

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Textbook Question

Coral reefs are biodiverse ecosystems that provide food, income, coastal protection, and many other services to millions of people. Yet coral reefs are under threat from human impacts such as climate change—many corals cannot tolerate the warming ocean water and have suffered massive 'bleaching' events, which can be fatal. Researchers have discovered that some corals have the capacity to acclimatize to warmer water, while other corals do not. The researchers fear that because corals are long-lived colonial animals and thus evolve slowly, they may not be able to adapt to global warming fast enough to avoid extinction. Explain how the difference between acclimatize and adapt is important to the fate of corals.

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Textbook Question

The geneticist James Crow wrote that successful scientific theories have the following characteristics: (1) They explain otherwise puzzling observations; (2) they provide connections between otherwise disparate observations; (3) they make predictions that can be tested; and (4) they are heuristic, meaning that they open up new avenues of theory and experimentation. Crow added two other elements of scientific theories that he considered important on a personal, emotional level: (5) They should be elegant, in the sense of being simple and powerful; and (6) they should have an element of surprise. How well does the theory of evolution by natural selection fulfill these six criteria?

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