GOAL:

To develop an understanding of the interdependence of all organisms and the need for conserving natural resources

The earth's biosphere is variously subdivided according to specific characteristics.

Ecology L5.00 To understand that dispersal of populations between biomes and biogeographical regions are limited by certain physical barriers

5.01 describe the nature of physical barriers.

5.02 explain the major vehicles of dispersal.

5.03 identify the role of humans in dispersal of organisms between regions.

I. Dispersal is the movement of organisms from one habitat to another.
II. Dispersal can be broken down into two categories based on how it occurs.
A. Active dispersal: organisms move by their own energy.
B. Passive dispersal: organisms are moved by water, wind, or animals.
III. Animals and plants do not move freely because of barriers.
A. Geographical barriers: mountains, deserts, oceans, rivers, and lakes.
B. Ecological barriers: food, shelter, climate, and type of soil.

TN COMPONENT OF SCIENCE: Science in Society

GOAL:

To enable students to demonstrate positive attitudes toward science in solving problems and making personal decisions about issues affecting the individual, society and the environment.

4.1 ATTITUDES - The progress of science and the attitudes of society influence one another.

4.1c - The perceived value of any technology may vary for different groups of people and at different times.

BENCHMARK: Individual and collective needs and the influence of societal pressures have motivated technological advances throughout our history.

TIME REQUIRED:

45 minutes

Maps that show the physical structure of Earth

Geographical barrier, ecological barrier, behavioral barrier, habitat.

There has been a lot of talk in recent years about keeping illegal aliens out of the U.S. What are some of the things we use to keep illegal aliens out? (Students should say the border and the border patrol.) Just as people have political boundary that keep them from traveling freely from country to country (without a passport), plants and other animals have things that keep them from living all over the world. Things that prevent plants and animals from moving to new locations are called barriers. Today we will discuss two kinds of barriers.

The place where an organism lives is called its habitat. A habitat for an animal must contain food and shelter. Plants must have from one habitat to another is called dispersal.
Dispersal can be either active or passive. When organisms move by their own energy, we call this active dispersal. What kind of organism would be more likely to exhibit active dispersal? (Animal.) In passive dispersal, organisms are carried into new habitats by water, wind, or animals. What kind of organism would be most likely to move by passive dispersal?(Plant.)
Plants and animals do not move freely from one habitat to another because of barriers. The three types of barriers to dispersal are geographical, ecological, and behavioral.
Geographical barriers include physical features of the earth's surface that might block an organism from traveling from place to place. Can anyone name geographical barriers that might restrict the movement of an organism? (Answers should include mountains, deserts, oceans, rivers, and lakes.)
Ecological barriers include the lack of suitable food, shelter, climate, and soil type. What are some of the things that might prevent a polar bear from living in the Mojave. (Mojave is a desert.)
The human desire to obtain and raise plants and animals have overcome some of natures most important barriers, and in some cases have had disastrous results. The introduction of rabbits to Australia is an example.

Have students write a report on the disastrous consequences of importing and exporting illegal plants and animals.

Plants and animals have a tendency to move from one habitat to another. The movement of organisms into locations is called dispersal. Animals do not move freely because of barriers. The disastrous consequences of bringing exotic species of plants and animals into the U.S. have prompted authorities to band such shipments without prior approval.

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