Unit B

Module 4 Introduction


In this module, you will examine how populations evolve or change over time. You will look at the processes, requirements, and evidence for evolution. This module will use the ecological terms discussed in Module 3 and relate them to population change. Prior knowledge about the role sexual reproduction plays in creating change will be explored.

Looking at ancestry helps us to see where new species branch off from their origins. Knowing how organisms are classified, as you learned in Module 3, can show where new species arise by tracing back through the levels of classification. It is a method for tracing ancestry. In order to hypothesize why organisms diversify as Earth ages, we must look at factors such as genetic mutation, sexual reproduction, and survival of the fittest. There are several theories that serve as the basis for modern ideas of evolutionary change. Researchers and scientists have found evidence that they propose is proof that species have evolved from ancestral forms. As you work through this module, these ideas will help you explore the question "How do populations evolve?" This will lead you to predict how new species can arise.

Big Ideas

This module will investigate changing populations over time.

By the end of this module you should be able to
  • explain the mechanisms involved in the change of populations over time

Key Concepts

Concepts that you should be able to explain by the end of the module are

  • variation occurs in all populations due to inherited traits and selective pressures of the environment
  • theory of natural selection provides an explanation for population change
  • history of evolutionary theories
  • modern evolutionary theories
  • evidence for evolution


Skills that you should be able to do by the end of this unit are

  • explain how speciation occurs
  • apply the theory of natural selection to explain changing populations and hypothesize the adaptive significance of particular variations


There are four graded assessments in Module 4. 

  1. Unit B: Section 3 Assignment
  2. Unit B: Section 4 Assignment
  3. Unit B Summative Part 2
  4. Unit B Test

As you work through this unit and its module, you will find Self-Check questions,  labs, and critical thought questions. There will be lesson goals indicated at the beginning of each lesson and then clearly identified throughout the lesson.