The pictures show a tundra environment and a desert environment. The tundra is the coldest biome, and the ground is permanently frozen. The tundra has a short growing season because it is cold most of the year. Most desert regions, like the one in the image on the right, are hot most of the year and receive very little rainfall.

An adaptation is a trait or characteristic that helps an organism survive in its environment. Because the tundra and desert environments each experience extreme conditions, organisms in these environments have special adaptations that enhance survival.

Each box in the interactive activity below describes a plant or animal trait that is an adaptation in the tundra or desert. Drag and drop each adaptation to the environment where it would be most helpful. If you need more information, view the tundra and desert videos in the View Related Resources section at the bottom of the page. (NOTE: The activities in this resource are flash-based and will play best in Internet Explorer.)

To retake the quiz, reload the page and then select "no" when the "Resume Quiz" dialog box appears.

Natural Selection

Individual organisms are born with a particular set of genetic traits, including color, leg length, and size, that are inherited from their parents. Organisms are not able to change their genetic traits based on the environment.

Individual organisms do not change, but the traits of species do change over time. Recall from the Engage activity that adaptations are traits that help organisms survive.  Whether or not a trait is an adaptation depends on the environment. Genetic traits that are beneficial in one environment may no longer help an organism survive if the environment changes.

Organisms that are born with favorable traits, or adaptations, are more likely to survive, reproduce, and pass on beneficial traits to their offspring. Over time, more and more organisms in the population are born with adaptations that help them survive. This process of change over many generations is called natural selection.

Charles Darwin

 

Birds from the original finch population in South America lived on each island. Each island has a its own unique environment, including different plants and sources of food. Birds that were born with a beak shape that helped them get more food were more likely to survive, reproduce, and pass on the beak shape to their offspring. Over time, bird populations on each island developed different beak shapes based on available food sources.

Click the image below to learn more about the Galapagos finches.

Sources: Charles Darwin, ca. 1870 downloaded from Library of Congress. No known restrictions on publication. Satellite image of Galapagos Islands Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC. Darwin's bird observations downloaded from PBS Learning Media, //www.pbslearningmedia.org. Rights to use this asset expire on 12/31/2099. Asset Copyright: This work is out of copyright, with photographic rights held by the Bridgeman Art Library.

Let's Review

Let’s review the main elements of natural selection. Match each term with its description. Once you have completed the activity, add these terms to your handout or notebook.

It is important to remember that individual organisms cannot change their own genetic traits to adapt to an environment. Natural selection is a process that occurs over time within a population of organisms.

The process of selective breeding (or artificial selection) occurs when humans breed organisms to create offspring with a specific set of traits.

Click the "Artificial vs. Natural Selection" box to view an interactive presentation. As you view the presentation, think about the following questions, and record your ideas in your science notebook or on the Selective Breeding Notes handout found in the View Related Resources section at the bottom of the page.

• What is selective breeding (or artificial selection)?
• How is selective breeding similar to natural selection?
• How is selective breeding different from natural selection?
• Describe at least two examples of the selective breeding of animal species.
• Describe at least two examples of the selective breeding of plant species.

In your notebook or on the Selective Breeding Notes handout, compare and contrast the processes of natural selection and selective breeding.

To retake the quiz, reload the page and then select "No" when the "Resume Quiz" dialog box appears.

This resource is a compilation of text, videos, and other elements to create a scaffolded 5E learning experience for students. This is meant for Tier I instruction under the Response to Intervention (RtI) model for science TEKS 7(11)(C). In this lesson, students will identify some changes in genetic traits that have occurred over several generations through natural selection and selective breeding.

Be sure to check for prerequisite knowledge and skills as well as differentiation needs by reviewing the entire resource and the related items before assigning it to or working through it with your students.
This resource can be used for instruction in a variety of ways.

• Use with a single computer and projector; this resource can be delivered in a traditional classroom.
• Use with a combination of individual student computers and teacher computer and projector (in either a computer lab or other 1:1 environment).
• Assign the resource to students as work to do outside of the school day as part of a flipped lesson to allow application, practice, and additional support during the school day.
• Use with students as tutorials.
• Share with parents to inform them about what their child is learning in school.
• Use with students who are unable to participate in the traditional classroom environment.

Lesson Part	Description
Engage	Students will identify plant and animal adaptations to the tundra and desert ecosystems.
Explain 1	There is a reading passage about natural selection and a short interactive activity that outlines four major elements of natural selection: variation, inheritance, selection, and adaptation. A common misconception is that individual organisms change their traits to adapt to their environment. Organisms are born with a particular set of  inherited traits that do not change based on environment. These inherited traits may or may not help an organism survive. Organisms with beneficial traits are more likely to survive long enough to reproduce and pass on beneficial traits to their offspring. Over many generations, the beneficial trait may become a common characteristic found in the population—an adaptation.
Explain 2	Students view an interactive presentation about selective breeding (or artificial selection) versus natural selection. Students are asked to respond to a number of questions in their notebook or on a handout provided in the View Related Resources section at the bottom of the page.
Elaborate	Students compare and contrast natural selection and selective breeding. Student responses may vary. A sample Venn diagram is provided below.
Evaluate	Students will complete a short quiz on natural selection and selective breeding.