About This Chapter
Mechanisms of Biological Evolution - Chapter Summary
Our professional instructors and video lessons in this chapter help you review the mechanisms of biological evolution. Refresh your memory of evolutionary theory and the principles of Darwinian evolution. You will study Hardy-Weinberg equilibrium and speciation as well as genetic variability, adaptation and natural selection.
In addition, you may even learn something new about the benefits and drawbacks of artificial selection. Once you've finished the lessons, you should feel comfortable with:
- Discussing multi-field evidence for evolution
- Explaining how scientists determine rates of evolution
- Defining Hardy-Weinberg equilibrium
- Identifying types of natural selection
- Distinguishing between allopatric and sympatric speciation
- Listing prezygotic and postzygotic reproductive barriers
- Recognizing the significance of genetic variability
- Providing examples of adaptation
- Describing the effects of artificial selection
Our short and entertaining video lessons offer a number of examples and graphics to help you understand these biological evolution concepts. Use video tags to rewatch major points during study sessions, and be sure to take a look at the lesson transcripts. The latter may contain links to other text lessons with more information about key concepts or terms. After reviewing the material, you can take multiple-choice lesson quizzes to see how well you grasp the covered topics.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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Other chapters within the NES Biology (305): Practice & Study Guide course
- About the NES Test
- Safety Procedures and Hazards in Scientific Research
- Overview of Chemical Bonds and Reactions
- Structure and Function of Macromolecules
- How Enzymes Work
- Basics of Metabolic Biochemistry
- Overview of Cell Division
- Process of DNA Replication
- The Transcription and Translation Process
- Basics of Gene Mutations
- Plant Biology
- Plant Reproduction and Growth
- Requirements of Biological Systems
- Animal Reproduction and Development
- Male Reproductive System
- Female Reproductive System
- Physiology I: The Circulatory, Respiratory, Digestive, Excretory, and Musculoskeletal Systems
- Physiology II: The Nervous, Immune, and Endocrine Systems
- Biology: Diseases & Prevention
- Cardiovascular Disorders
- Neurological Disorders
- Common Human Disorders
- Populations and Biological Communities
- Overview of Animal Behavior
- Ecosystems and Biomes
- Biochemical Cycles
- Human Activity and the Biosphere
- NES Biology Flashcards