Ch 3: Population Genetics and Evolution

About This Chapter

Watch online population genetics video lessons and learn the theory of evolution, natural selection, speciation, and more. Determine how well you understand the subject matter with the quizzes that accompany each lesson.

Population Genetics and Evolution - Chapter Summary and Learning Objectives

With millions of known species on Earth, evolution may seem like an amazing and complicated phenomenon. In this chapter, professional instructors will explain how evolution works, from the original theory that Darwin posited to the way we understand it today. You'll look at the equation biologists use to determine how genes are inherited within certain populations and how traits can appear in subsequent generations. We'll also go over the ways in which different species can be formed and the biological barriers to interspecies breeding. This chapter is designed to teach you:

  • How to use the Hardy-Weinberg equation
  • The process of natural selection
  • Why some traits are inherited
  • How two species can form from one

Theory of EvolutionLearn about how traits evolve and the difference between the theories of Lamarck and Darwin.
Hardy-Weinberg Equilibrium I: OverviewExplore the genetic makeup of populations and how the Hardy-Weinberg equilibrium can be used.
Hardy-Weinberg Equilibrium II: The EquationTake a look at the equation used to calculate the frequency of certain genes within a large, stable population.
Hardy-Weinberg Equilibrium III: Evolutionary AgentsUnderstand how the Hardy-Weinberg equation can be used to identify populations that are not in equilibrium.
Inbreeding: Definition, Coefficient, and EffectsReview the effects of breeding between organisms with very similar genetic makeup.
Natural Selection and AdaptationExamine the ways in which new traits can appear in different species over time.
Types of Natural SelectionDiscover the four main ways in which natural selection can occur based on fitness.
Genetic Fitness: SelectionUnderstand how selection occurs at the phenotype level and in the presence of non-genetic factors.
Speciation I: Gene Pool IsolationLearn how to define a species and what makes species split into new groups or organisms.
Speciation II: Prezygotic BarriersExplore the biological barriers to reproduction that prevent similar species from interbreeding.
Speciation III: Postzygotic IsolationTake a look at the ways in which interspecies breeding can be disrupted after fertilization.

12 Lessons in Chapter 3: Population Genetics and Evolution
Theory of Evolution

1. Theory of Evolution

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.

Hardy Weinberg Equilibrium I: Overview

2. 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

3. 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

4. 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.

Inbreeding: Definition and Effects

5. Inbreeding: Definition and Effects

You know you're not supposed to marry your sister or even your cousin. But why? In this lesson, learn why inbreeding can be harmful, but on the other hand, why it's sometimes done on purpose.

How to Calculate the Coefficient of Inbreeding

6. How to Calculate the Coefficient of Inbreeding

So, you know what inbreeding is and what effects it can have on a population. In this lesson, we'll walk you through the next step: how to calculate just how inbred an individual is.

Natural Selection and Adaptation

7. Natural Selection and Adaptation

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.

Types of Natural Selection

8. Types of Natural Selection

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.

Genetic Fitness: Selection

9. Genetic Fitness: Selection

We have all heard the expression 'survival of the fittest.' Natural selection of organisms is based upon their fitness. But what exactly does 'fitness' entail? Here, we will explore how selection occurs at the physical and genetic levels.

Speciation I: Allopatric and Sympatric Speciation

10. Speciation I: 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.

Speciation II: Prezygotic Barriers

11. Speciation II: Prezygotic Barriers

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.

Speciation III: Postzygotic Barriers

12. Speciation III: Postzygotic Barriers

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.

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