About This Chapter
GRE Biology: Genetic Variability, Evolutionary Processes and Consequences - Chapter Summary
Instructors teaching this chapter's video lessons can walk you through the causes of genetic variability and the types of speciation to prepare you for GRE Biology test questions. Topics of discussion include:
- Evidence for the theory of evolution
- Fossil records and molecular clocks
- The Hardy Weinberg equilibrium
- Natural selection and adaptation
- Allopatric and sympatric speciation
- Prezygotic and postzygotic reproductive barriers
- Genetic variation and random mutation
- Rapid adaptation
- Artificial selection
Review material covered in your undergraduate science courses with lessons designed to help you put your best foot forward on exam day. In addition to entertaining videos, you'll find corresponding transcripts as well as multiple-choice quizzes and a chapter test that can be used to keep your test-prep goals on track.
GRE Biology Objectives
College undergraduates interested in applying to a graduate program in one of the sciences can take the GRE Biology exam in an effort to enhance their application materials. This standardized test consists of around 190 multiple-choice questions divided among three main content domains.
The ecology and evolution content domain contains roughly 33% of exam questions, half of which will test your knowledge of topics ranging from genetic variability and evolutionary processes to evolutionary consequences and the history of life. Whether you could use some extra help in these areas or just want to brush up on the basics, use the lessons in this chapter to prepare for questions on the Hardy-Weinberg equilibrium, the dynamics of natural selection, speciation types, the origins of genetic variability, the fossil record and more.
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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