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Ch 22: Evolution: Theories and Principles

About This Chapter

Watch video lessons and learn about theories, findings, research and more related to evolution. Take quizzes to gauge your understanding of evolution.

In these lessons, our instructors will teach you about various topics related to evolution in order to help you understand the process and the research behind it. You will have the chance to study different evolution theories and the evolution of different species. By the end of the lessons, you will know about:

  • The Lamarckism and Darwinism evolution theories
  • An overview of and equation used in the Hardy-Weinberg Equilibrium
  • How natural selection, adaptation and speciation relate to evolution
  • How living organisms are classified
  • The evolution of plants, animals and humans
  • The history of life on earth throughout the different geologic eras

VideoObjectives
Theory of Evolution Explore some basic theories on evolution, such as Lamarckism and Darwinism.
Hardy-Weinberg Equilibrium I: Overview Learn the basic ideas of this theory, including random mating, migration, mutation and natural selection.
Hardy-Weinberg Equilibrium II: The Equation Discover the equation used in the theory and related terms, such as genotype, phenotype, allele and genotypic frequency.
Natural Selection and Adaptation Explore the ideas of natural selection and adaptation, learning more about fitness, homology, analogy and convergence.
Types of Natural Selection Find out about concepts like stabilizing, directional and disruptive selection.
Speciation I: Allopatric and Sympatric Speciation Explore geographic, sympatric and allopatric speciation.
Speciation II: Prezygotic Barriers Discover problems that can occur in the prezygotic stage of development, such as spatial, temporal, mechanical, gametic and behavior isolation.
Speciation III: Postzygotic Barriers Examine problems that could occur in the postzygotic stage, such as a hybrid zygote, abnormalities, hybrid infertility and low hybrid viability.
Classification of Living Organisms Study the different classifications, such as taxonomy, morphological, binomial nomenclature, species, genus, family, order, class, phylum and kingdom.
The Endosymbiosis Theory Explore the ideas of this theory, including chloroplast, mitochondria, cyanobacteria, eukaryote and prokaryote.
Evolution of Plants Discover the different concepts associated with the evolutionary process of plants, such as multicellular, heterotroph, autotroph and motile.
History of Life on Earth Take a tour through the different geographic eras to study the evolution of life.
Evolution of Humans Study concepts related to human evolution, such as primate, hominids, bipedalism and culture.

8 Lessons in Chapter 22: Evolution: Theories and Principles
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 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.

Natural Selection & Adaptation: Definition, Theory & Examples

4. 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

5. 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

6. 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

7. 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

8. 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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