About This Chapter
Evolutionary Mechanisms - Chapter Summary
Evolutionary biologists recognize several major forces of evolutionary change, such as gene flow. Once the forces are identified, there are established methods for performing calculations to show expected changes to population genetics. Use these fun lessons to fully understand the concepts related to these evolutionary mechanisms. With quizzes and worksheets accompanying all the lessons, you can easily be sure you're on the right track. Once you've worked through the materials in this chapter, you should be able to:
- Explain the equation and evolutionary agents associated with the Hardy-Weinberg equilibrium
- Discuss how natural selection acts on phenotype and the evolution of novel phenotypes
- Define effective population size
- Give examples of gene flow
- Illustrate how inbreeding reduces genetic diversity
- Discuss how to adapt calculations when genes to do not sort randomly
- Differentiate between quantitative and qualitative traits
1. The Evolution of Novel Phenotypes
In this lesson we'll be reviewing what evolution is, and how changes in master switches of the genetic code can lead to large scale changes in phenotypes. We'll look at two examples specifically, novel beak formation in the Galapagos finches and jaw formation in the cichlid fish.
2. Why Natural Selection Acts on Phenotype, Not Genotype
Evolution works through the mechanism of natural selection. This mechanism influences the genetic make-up of populations, acting on the population's physical traits. In this lesson, we'll explore examples of why this is.
3. Effective Population Size: Definition, Calculation & Example
By understanding effective population sizes, scientists can predict how quickly a population of animals will lose genetic variation, and become at risk for extinction. This lesson will delve into genetic variation, as well as how to calculate effective population size.
4. Gene Flow: Definition & Examples
Chances are you've probably witnessed gene flow today! This lesson will define gene flow and give examples. It will also explain why gene flow creates genetic diversity.
5. 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.
6. 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.
7. 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.
8. Including Gene Flow in Hardy-Weinberg Equilibrium
In this lesson, learn how gene flow is related to the Hardy-Weinberg Equilibrium equation. We will describe the effect of gene flow on the frequencies of genes within a population.
9. Inbreeding & Hardy-Weinberg Equilibrium
The Hardy-Weinberg equilibrium allows scientists to predict the frequency of alleles in a population. We will be discussing inbreeding and how that impacts a population's Hardy-Weinberg equilibrium.
10. Practical Application: Hardy Weinberg Equilibrium
In this lesson, you will practice how to use the Hardy Weinberg equation to evaluate environmental conditions and population dynamics. After reviewing what the Hardy Weinberg equation and equilibrium is, we'll try some practice problems.
11. Genetic Linkage: Problems, Mapping & Studies
In this lesson, we'll discuss what happens when genes don't assort randomly. We'll then discuss how to calculate this non-randomness. It's easier than you might think!
12. Qualitative vs. Quantitative Traits: Definition & Mapping
This lesson will help you navigate the sometimes scary world of equations and terms in genetics. We'll learn about qualitative and quantitative traits, broad and narrow heritability, and response to selection.
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