TUTORIAL:
Differences Between Organisms
What makes a frog a frog? Is it a frog’s bulging eyes, its long hind legs, its croak, or the color of its skin? Once you start to think about frogs, you realize that frogs differ in many ways. These differences set one kind of frog apart from another. The frogs in the figure below look different from each other, yet they may live in the same area.
A characteristic that helps an organism survive and reproduce in its environment is called an adaptation. Some adaptations, such as a long neck or striped fur, are physical (physiological). Other adaptations are behaviors (behavioral) that help an organism find food, protect itself, or reproduce.
Living things that have the same characteristics may be members of the same species. A species is a group of organisms that can mate with one another to produce fertile offspring. A group of individuals of the same species living in the same place is a population.
Do Species Change Over Time?
Scientists think that Earth has changed a great deal in its history and that living things have changed, too. They estimate that the planet is 4.6 billion years old. Since life first appeared on Earth, many species have died out, and many new species have appeared.
Scientists observe that species have changed over time and the inherited characteristics in populations have changed, too. Scientists think that as populations change over time, new species may form. Thus, newer species descend from older species. The process in which populations change over time is called evolution.
Darwin’s Theory of Natural Selection
In 1859, Darwin published a famous book called On the Origin of Species by Means of Natural Selection. In his book, Darwin proposed the theory that evolution happens by natural selection. Natural selection is the mechanism, or process, by which organisms that are better adapted to their environment survive ad reproduce more successfully than less well-adapted organisms do.The process of natural selection has four steps: overproduction, inherited variation, struggle to survive, and successful reproduction.
PROCEDURE:
1. Choose Environment 1, 2, or 3 as a background to simulate the environment in which the beetles live.
2.Sample A will appear in the background that you have chosen. Examine the beetles.
3.Click Hide Leaves to see the beetles without the background. Click Show Leaves to show the background.
4.Record the number of brown beetles and the number of tan beetles for the sample in the given fields. Color in the pie chart and visually represent your data.
5.Repeat steps 2 - 3 to analyze Samples B and C.
6.When you have answered all of the questions, try the simulation again with another background.
Use the procedure as given and fill in all data and answer below. COLOR IN THE FOLLOWING PIE CHARTS TO REPRESENT THE COLLECTED DATA FOR EACH SAMPLE IN THE ENVIRONMENT. LABEL AS NEEDED.
ENVIRONMENT ____ / SAMPLE A / SAMPLE B / SAMPLE CBROWN BEETLES
TAN BEETLES
TOTAL NUMBER OF BEETLES
1)In this environment (Sample A), which color beetle is more likely to be found and eaten by birds.
- Brown beetles are more likely to be eaten than tan beetles.
- Tan beetles are more likely to be eaten than brown beetles.
- Brown beetles and tan beetles are equally likely to be eaten.
- None of the beetles is likely to survive.
DEFEND YOUR ANSWER: ______
______
2)Think about the environment (Sample B) in which the beetles live. Which beetle is more likely to survive and reproduce, brown beetles or tan beetles?
- Brown beetles are more likely than tan beetles to survive and reproduce.
- Tan beetles are more likely than brown beetles to survive and reproduce.
- Brown beetles and tan beetles are equally likely to survive and reproduce.
- None of the beetles is likely to survive.
DEFEND YOUR ANSWER: ______
______
3)As time passes (Sample C), did the proportion of brown beetles to tan beetles change significantly, or did it remain about the same?
- The proportion of brown beetles to tan beetles remained about the same.
- The proportion changed significantly. One type of beetle coloration became more common than the other type of coloration.
DEFEND YOUR ANSWER: ______
______
ENVIRONMENT ____ / SAMPLE A / SAMPLE B / SAMPLE C
BROWN BEETLES
TAN BEETLES
TOTAL NUMBER OF BEETLES
4)In this environment (Sample A), which color beetle is more likely to be found and eaten by birds.
- Brown beetles are more likely to be eaten than tan beetles.
- Tan beetles are more likely to be eaten than brown beetles.
- Brown beetles and tan beetles are equally likely to be eaten.
- None of the beetles is likely to survive.
DEFEND YOUR ANSWER: ______
______
5)Think about the environment (Sample B) in which the beetles live. Which beetle is more likely to survive and reproduce, brown beetles or tan beetles?
- Brown beetles are more likely than tan beetles to survive and reproduce.
- Tan beetles are more likely than brown beetles to survive and reproduce.
- Brown beetles and tan beetles are equally likely to survive and reproduce.
- None of the beetles is likely to survive.
DEFEND YOUR ANSWER: ______
______
6)As time passes (Sample C), did the proportion of brown beetles to tan beetles change significantly, or did it remain about the same?
- The proportion of brown beetles to tan beetles remained about the same.
- The proportion changed significantly. One type of beetle coloration became more common than the other type of coloration.
DEFEND YOUR ANSWER: ______
______
ENVIRONMENT ____ / SAMPLE A / SAMPLE B / SAMPLE CBROWN BEETLES
TAN BEETLES
TOTAL NUMBER OF BEETLES
7)In this environment (Sample A), which color beetle is more likely to be found and eaten by birds.
- Brown beetles are more likely to be eaten than tan beetles.
- Tan beetles are more likely to be eaten than brown beetles.
- Brown beetles and tan beetles are equally likely to be eaten.
- None of the beetles is likely to survive.
DEFEND YOUR ANSWER: ______
______
8)Think about the environment (Sample B) in which the beetles live. Which beetle is more likely to survive and reproduce, brown beetles or tan beetles?
- Brown beetles are more likely than tan beetles to survive and reproduce.
- Tan beetles are more likely than brown beetles to survive and reproduce.
- Brown beetles and tan beetles are equally likely to survive and reproduce.
- None of the beetles is likely to survive.
DEFEND YOUR ANSWER: ______
______
9)As time passes (Sample C), did the proportion of brown beetles to tan beetles change significantly, or did it remain about the same?
- The proportion of brown beetles to tan beetles remained about the same.
- The proportion changed significantly. One type of beetle coloration became more common than the other type of coloration.
DEFEND YOUR ANSWER: ______
______
10) In the environments you examined, was one of the traits more favorable than other traits?
- Larger beetles are more likely to survive and reproduce.
- Beetles with coloration similar to their environment are more likely to survive and reproduce.
- Beetles with coloration that is less similar to their environment are more likely to survive and reproduce.
- Faster beetles are more likely to survive and reproduce.
11) Using the claim that you stated above, in the space below, cite the evidence from your data to support this claim.