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Ch 18: Evolutionary Principles & Natural Selection

About This Chapter

Watch evolution video lessons and learn about Darwin, the Hardy-Weinberg equilibrium, gene pool isolation, adaptation and more. Each lesson is accompanied by a short multiple-choice quiz you can use to check your understanding of these science topics.

Charles Darwin is widely known for his significant work on evolution. If he were around today, what do you think he might say if he saw a flying hamster? Based on our knowledge of Darwin, we can guess that he would probably look for its evolutionary advantages. Why did certain hamsters develop wings when others didn't? Are flying hamsters more likely to survive than their wingless counterparts? Why or why not? As you watch these lessons on the principles of evolution, you'll begin to understand what influential evolutionary theorists, like Charles Darwin, can teach us.

You'll delve deeper while studying the various ways in which certain species survive or fail to survive and what factors influence those outcomes. For example, you've probably heard of natural selection. Now you can learn about how species are affected by natural selection, as well as genetic drift, mutation, migration and extinction. Additionally, you'll watch lessons on the Hardy-Weinberg equilibrium, a concept that helps us to understand if evolutionary agents are present and affecting a population we want to study.

Evolution isn't only about species changing or dying out. It's also about the emergence of new species, like those flying hamsters. There are many ways that a species that previously didn't exist can come to be. Among the topics you'll learn about related to speciation are geographic speciation, temporal isolation and gametic isolation. But since new species don't always thrive, you'll also learn about hybrid infertility and other topics that prevent new species from succeeding.

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7 Lessons in Chapter 18: Evolutionary Principles & Natural Selection
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.

Hardy Weinberg Equilibrium: Definition, Equation & Evolutionary Agents

2. Hardy Weinberg Equilibrium: Definition, Equation & Evolutionary Agents

In this lesson we will define Hardy-Weinberg equilibrium and break down the Hardy-Weinberg equation to figure out if a population of hypothetical beetles is evolving.

Natural Selection & Adaptation: Definition, Theory & Examples

3. 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

4. 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

5. 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

6. 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

7. 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.

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