Loading video...
Natural Selection
- While studying species during his voyage on the HMS Beagle, Darwin observed that:
- Individuals within a population vary in the traits that they possess.
- Species produce more offspring than can be supported by the environment and the offspring must compete for survival.
- Offspring inherit traits from their parents.
- Darwin concluded that the offspring who possess favorable traits will have a higher probability of surviving and producing more offspring. Over many generations, these favorable traits will increase in the population.
- Stabilizing selection selects for intermediate phenotypes and decreases the frequency of extreme phenotypes.
- Directional selection results in an increase in the frequency of a phenotype at one extreme of a spectrum.
- Disruptive selection results in an increase in the frequency of phenotypes at both extremes.
Natural Selection
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
- Intro
- Background
- Work of Other Scientists
- Aristotle
- Carl Linnaeus
- George Cuvier
- James Hutton
- Thomas Malthus
- Jean-Baptiste Lamark
- Darwin's Theory of Natural Selection
- Genetic Variation
- Natural Selection and the Peppered Moth
- Types of Natural Selection
- Sexual Selection
- Evidence for Evolution
- Homologous and Analogous Structure
- Example 1: Genetic Variation & Natural Selection
- Example 2: Types of Natural Selection
- Example 3: Mechanisms By Which Genetic Variation is Maintained Within a Population
- Example 4: Difference Between Homologous and Analogous Structures


































Start Learning Now
Our free lessons will get you started (Flash® 10 required).
Sign up for Educator.comGet immediate access to our entire library.
Features Overview