Module 4 Intro
1. Module 4 Intro
1.23. Page 3
Module 4—Mechanisms of Population Change
Watch and Listen
What are the requirements for evolution and the creation of a new species? The following animation provides the answer to this question.
Read
A population must be isolated in some way for speciation to occur. Read “Keeping Populations Separate” on pages 137 and 138 of the textbook to find out how this isolation can occur. The animation also covers this topic.
Self-Check
SC 1. What two types of barriers can prevent interbreeding?
SC 2. A bird’s call can be a barrier to speciation. How?
Self-Check Answers
SC 1. A geographical barrier keeps populations physically separated from one another. Examples include canyons, mountain ranges, water between islands, large lava flows, and glaciers.
With a biological barrier, organism ranges may overlap but biological barriers prevent reproduction. Courtship/mating rituals, pheromones, behaviour, niche/habitat preferences, and reproductive anatomy differences are examples of biological barriers.
SC 2. Bird calls play a large role in mate selection. Variations in calls may affect the ability of males to attract female mates. Intraspecific variations in calls can lead to reproductive isolation.
Watch and Listen
Read more about speciation and adaptive radiation on pages 139 and 140 of the textbook.
Self-Check
SC 3. Give an example of adaptive radiation.
SC 4. Why is this species an example of adaptive radiation?
Self-Check Answers
SC 3. Darwin’s finches or the Drosphila fly of the Hawaiian Islands are examples of adaptive radiation.
SC 4. Both species had an original isolated population on one island. The species proliferated on the first island and then began to disperse to other islands. They adapted to the different conditions on each separate island. Various selective pressures resulted in different feeding and mating habits.
Try This
TR 1. Biological Barriers
Print or save a copy of the “Biological Barriers” handout. Read and answer the questions. Save this data in your course folder. Compare your answers with the answer key. This will be a helpful review and may be used in your Module Project.