Module 4 Intro
1. Module 4 Intro
1.24. Page 4
Module 4—Mechanisms of Population Change
Watch and Listen
Speciation caused by a geographical barrier is sometimes referred to as allopatric speciation. The cichlids (a genus of fish) in Lake Victoria are an example of allopatric speciation. Watch the example of how a geographical barrier can cause allopatric speciation in a population of lizards. Choose "3.71 Allopatric Speciation" from the list.
Try This
TR 2. Leopard Frogs: One Species or Seven?
© Gilles DeCruyenaere/shutterstock
Have you ever considered that not all “ribbits” sound the same? In fact, they can be very different. Read “Thought Lab 4.5” on page 139 of the textbook. Listen to the frog calls provided below. Go to your Lesson 4 Assignment to complete this activity.
Read
You have already looked at the theory of punctuated equilibrium vs. gradualism in Lesson 2. You may wish to refresh your memory and reread pages 140 and 141 of the textbook. If you would like to learn more about punctuated equilibrium, try typing the keywords “punctuated equilibrium” into the pbs.org website. Now that you know more about how new species arise, are you more inclined to follow one theory?
Self-Check
SC 5. Which of the two models, gradualism or punctuated equilibrium, suggests that species undergo most of their changes when they first diverge from the ancestral parent species?
Self-Check Answer
SC 5. Punctuated equilibrium is the correct answer.