Module 9S1 Ecological Interactions

4.9.2S1 page 2

Explore

Although venom is a commonly used defense in reptiles and insects, producers have also evolved chemical defenses against consumers. Some plants produce chemical toxins that simply taste bad or can poison consumers who eat them. The roots of some plants secrete toxins that inhibit growth of their neighbors, reducing inter or intraspecific competition. Behavioral defenses are fascinating: the arched back of a cat produces the same large, threatening silhouette as a bear standing on its hind legs or a dog with its hair standing on end. Markings and coloration usually provide a distinct selective advantage. Cryptic coloration allows prey organisms to evade predators, and allows predators to sneak up on prey. Protective coloration is ensured when bright colors signal clear warnings to would-be predators. Looking dangerous is one strategy, but mimicry of dangerous species may be just as effective. Your text offers good examples.

  

Read

Read pages 722-724 in the textbook.

 

Try This

TR 1. Read the following 2 statements. Although both of these indicate chemical defenses, what is the difference between them?

1. Some species of plants produce toxins that prevent them from being eaten by herbivores.
2. Some species of plants secrete chemicals into the ground that prevent other plants of its own species from growing near it.

 

Self-Check

SR 1. Describe the following as being either: (a) chemical defense, (b) cryptic coloration, (c) protective coloration, (d) mimicry

1. When elephants begin to eat the leaves of the Thorn tree, the tree releases a bitter tasting substance into the leaves that prevents elephants from consuming the whole tree.
2. The beautiful red, blue, and yellow tree frogs of Costa Rica produce some of the poisonous venoms of the natural world.
3. The dusty, golden-brown coyote is difficult to spot against the dry grasses of the prairie.
4. A harmless sea snake has almost the identical bright markings as the highly venous coral snake.

 

Guppy Predator Simulation

Scientists have found that the number and type of predators in a stream influence the natural selection of guppies. Conduct online research about evolution in guppy populations.

Retrieve your copy of Module 9: Section 1—Lesson 2 Assignment that you saved to your computer earlier in this lesson. Complete the assignment. Save your completed assignment in your course folder. You will receive instructions later in this lesson on when to submit your assignment to your teacher.

 

Watch and Listen

Watch the following video that shows the use of thermal defenses in bees.

 

Module 9: Section 1—Lesson 2 Assignment

Submit your completed Module 9: Section 1—Lesson 2 Assignment to your teacher for assessment.