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
Test your knowledge with a 30-question chapter practice test
Theories of Evolution: Lamarck vs. Darwin

1. Theories of Evolution: Lamarck vs. Darwin

Evolution is possible because of the vast genetic variation that exists and is inherited within a population. Learn more about the theories of evolution such as Lamarck versus Darwin through reviewing examples.

Hardy-Weinberg Equilibrium I: Overview

2. Hardy-Weinberg Equilibrium I: Overview

The Hardy-Weinberg equilibrium equation is regularly used to describe genotypic frequency in a population. Learn more on Hardy-Weinberg Equilibrium I, the five criteria and it's usage in the genetics of a population.

Hardy-Weinberg Equilibrium II: The Equation

3. Hardy-Weinberg Equilibrium II: The Equation

The Hardy-Weinberg equilibrium equation helps in analyzing and understanding the gene pool of a population. Learn about this equation, including the variables it represents and where to find these variables, understand alleles and genotypes, and explore the significance of allelic and genotypic frequencies.

Hardy-Weinberg Equilibrium III: Evolutionary Agents

4. Hardy-Weinberg Equilibrium III: Evolutionary Agents

The Hardy-Weinberg equilibrium equation has been developed to be used to test the evolutionary status of a population. Learn more about evolutionary agents, non-random mating, natural selection, genetic drift, population bottleneck and the founder effect.

Inbreeding: Definition and Effects

5. Inbreeding: Definition and Effects

Inbreeding may produce genetic disorders such as hemophilia and cystic fibrosis, but it can also be used to exhibit desirable traits in animals or produce. Learn about it and outbreeding through definitions and understand their different effects.

How to Calculate the Coefficient of Inbreeding

6. How to Calculate the Coefficient of Inbreeding

Calculating the inbreeding coefficient helps geneticists calculate the probability that an individual has two identical alleles for a particular gene. Explore how to use pedigrees, or family trees, to determine the inbreeding paths for an individual and the inbreeding coefficient.

Natural Selection & Adaptation: Definition, Theory & Examples

7. Natural Selection & Adaptation: Definition, Theory & Examples

Evolutionary fitness is a trait's ability to change the contribution of offspring by an individual for the next generation. Explore natural selection, adaption, and the different traits that determine fitness in this lesson.

Natural Selection: Definition, Types & Examples

8. Natural Selection: Definition, Types & Examples

Natural selection is a process in the evolution and adaptation of organisms to increase primary characteristics. Learn about the process of natural selection, the different types of natural selection, and the concept of polymorphism.

Genetic Fitness: Selection

9. Genetic Fitness: Selection

The genetic makeup of an organism is an important factor that determines its fitness. Learn about the fitness of an organism, the role of genes in determining fitness, the gene buddy system, and understand natural selection at work.

Speciation: Allopatric and Sympatric Speciation

10. Speciation: Allopatric and Sympatric Speciation

A species is a particular group of organisms. Speciation is the process of a species splitting into new species. Discover the two different types of speciation - allopatric or geographic speciation, and sympatric speciation.

Prezygotic Reproductive Barriers & Speciation: Definition & Examples

11. Prezygotic Reproductive Barriers & Speciation: Definition & Examples

Prezygotic barriers prevent the fertilization of an egg cell. Explore the types of prezygotic barriers - spatial isolation, temporal isolation, mechanical isolation, gametic isolation, and behavioral isolation.

Postzygotic Reproductive Barriers: Definition & Examples

12. Postzygotic Reproductive Barriers: Definition & Examples

Postzygotic reproductive barriers reduce the reproductive capacity of hybrid offspring. Discover the three types of postzygotic barriers - hybrid zygote abnormality, hybrid infertility, and low hybrid viability.

Chapter Practice Exam
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Practice Final Exam
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