Ch 43: Biological Evolution & Natural Selection

About This Chapter

Watch these video lessons to refresh your knowledge of the theory of evolution, natural selection and adaptation. Learn about the equation for the Hardy Weinberg equilibrium, and explore how the peppered moth has adapted to changes in the environment.

Biological Evolution & Natural Selection - Chapter Summary

The video lessons in this chapter explore the theory of evolution and various types of evidence for evolution. Our instructors look at several hypotheses for rates of evolution and examine the Hardy Weinburg equilibrium in detail. Other lessons examine adaptation and natural selection.

You will review information on speciation, genetic variability and random mutation, and explore an example of rapid adaptation in animals. By the time you've watched these lessons, you should be prepared to:

  • Describe evolutionary theory
  • Show evidence for evolution found in paleontology, biogeography, embryology, comparative anatomy and molecular biology
  • Explain punctuated equilibrium and the molecular clock hypothesis
  • State the equation for the Hardy Weinberg equilibrium
  • Describe natural selection and adaptation, including rapid adaptation; also describe artificial selection
  • Name types of natural selection
  • Talk about allopatric and sympatric speciation, as well as prezygotic and postzygotic barriers
  • Explore genetic variability and random mutation

Our instructors have developed brief, engaging lessons, filled with real world examples that will aid you in your studies. You may re-discover material that you last studied in high school, and some of the information will probably be brand new to you. The quizzes that are included with the lessons offer a chance to assess your knowledge and see if you need to devote more study time to any particular area.

14 Lessons in Chapter 43: Biological Evolution & Natural Selection
Test your knowledge with a 30-question chapter practice test
Theories of Evolution: Lamarck vs. Darwin

1. Theories of Evolution: Lamarck vs. Darwin

We'll look at the interplay between population genetics and environment. Are traits individually acquired or do entire populations evolve? The flying hamsters and a few other notable experiments will provide the answers.

Evidence for Evolution: Paleontology, Biogeography, Embryology, Comparative Anatomy & Molecular Biology

2. Evidence for Evolution: Paleontology, Biogeography, Embryology, Comparative Anatomy & Molecular Biology

There is much support for the theory of evolution. This evidence comes from a variety of scientific fields and provides information that helps us trace changes in species over time. In this lesson, we'll look at this evidence and explore how it supports the theory of evolution.

Rates of Evolution: Punctuated Equilibrium & Molecular Clock Hypothesis

3. Rates of Evolution: Punctuated Equilibrium & Molecular Clock Hypothesis

In general, evolution is a very long process. But rates of evolution can be different for different organisms. In this video lesson, you will identify how scientists study rates of evolution and fill in some of the missing 'steps' in the fossil record.

Hardy-Weinberg Equilibrium I: Overview

4. Hardy-Weinberg Equilibrium I: Overview

In this lesson, we'll examine population genetics in greater detail. We'll also explore notions of Hardy-Weinberg equilibrium for large, stable populations. Is the genetic makeup of our flying hamster population changing? The Hardy-Weinberg equilibrium can serve as a reference point as we try to answer population genetics questions.

Hardy-Weinberg Equilibrium II: The Equation

5. Hardy-Weinberg Equilibrium II: The Equation

The Hardy-Weinberg equilibrium equation is represented by a polynomial, so we'll have to do some calculations. Don't be intimidated; a few coin tosses can help us make sense of allelic frequencies in a given gene pool.

Hardy-Weinberg Equilibrium III: Evolutionary Agents

6. Hardy-Weinberg Equilibrium III: Evolutionary Agents

In this lesson, you'll learn how the Hardy-Weinberg equation relates to different evolutionary agents and population changes. Discover how the equation may be used to discover populations that are not in equilibrium.

Natural Selection & Adaptation: Definition, Theory & Examples

7. Natural Selection & Adaptation: Definition, Theory & Examples

How does natural selection help shape the amazing types of animals we witness around us? In this lesson, we'll explore adaptations and what they can tell us about a species' past evolution.

Natural Selection: Definition, Types & Examples

8. Natural Selection: Definition, Types & Examples

We'll take a look at the types of natural selection that can occur. From flying hamsters to moths, you'll start to grasp the different paths organisms can take as they respond to their changing environments over time.

Speciation: Allopatric and Sympatric Speciation

9. Speciation: Allopatric and Sympatric Speciation

Discover the definition of a species and learn more about how species split. Find out common terms related to the splitting of species and study what role polyploidy plays in the development of a species.

Prezygotic Reproductive Barriers & Speciation: Definition & Examples

10. Prezygotic Reproductive Barriers & Speciation: Definition & Examples

We may take for granted why animals choose to mate with other animals of similar appearance, but it's not that simple. There are actually biological barriers to reproduction that can prevent even seemingly closely related species from reproducing. This lesson looks at one such category of hindrances, prezygotic barriers, which make fertilization impossible.

Postzygotic Reproductive Barriers: Definition & Examples

11. Postzygotic Reproductive Barriers: Definition & Examples

Do flying hamsters represent a separate species from your run-of-the-mill hamsters? We'll get to the bottom of this by performing crosses between the two hamster types. You'll explore postzygotic reproductive barriers and their possibly tragic consequences.

Genetic Variability and Random Mutation

12. Genetic Variability and Random Mutation

Evolution is driven by variation among populations. The amount of variability determines how well a population can adapt to environmental changes, while random mutations can provide new variations that help a population adapt to unexpected changes.

An Example of Rapid Adaptation: The Peppered Moths

13. An Example of Rapid Adaptation: The Peppered Moths

Normally, adaptations occur over thousands or millions of years. However, drastic changes in the environment can shorten the time period in which a change comes about. In such cases, we can learn a lot about the evolutionary process and how natural selection drives it forward.

Artificial Selection in Evolution

14. Artificial Selection in Evolution

Humans have been selectively breeding for desirable traits in plants and animals for a long time. This artificial selection allows for a lot of control in the breeding process but can also lead to unintended mutations within a population of organisms.

Chapter Practice Exam
Test your knowledge of this chapter with a 30 question practice chapter exam.
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Practice Final Exam
Test your knowledge of the entire course with a 50 question practice final exam.
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