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Activity 7: Variations and Adaptations
Introduction
Remember, an ecosystem has both living and nonliving parts. Even though the sun and rain aren't alive, they affect both plants and animals. All parts of the ecosystem affect the other parts. In this activity, you will discover that the survival of the rabbits depends on the survival of the plants that they eat. And the survival of the plants depends on the weather. Changes in the weather can include changes in the amount of rainfall.

Variations in grass
Plants and animals are adapted to survive best in certain environments. The rabbits in the Virtual Ecosystem love to eat plants. The plants that they eat are grasses. Grass is a common type of plant that can survive in a lot of different environments. Each piece of grass isn't exactly the same. There is variation in grass just like in other plants.
Grass A Grass B Grass C

In the Virtual Ecosystem, there are three variations of grass in the population. Grass A is short. Grass B is medium height. Grass C is a taller grass. They are different sizes and grow best with different amounts of water.

On the next page, you will experiment to see if any of the types of grass can grow well in all levels of water. Think about this: A grass that can live in different levels of water has a better chance of surviving when the environment changes.
Experiment: Rainfall and plant growth
Just like the plants you learned about earlier, the different types of grass in the Virtual Ecosystem need a certain level of water to survive best. There is one type of grass that is adapted to grow well in any level of water. In this experiment, you will grow grass in three rainfall levels: most rain, medium rain, and least rain.

Instructions

1. Click the plant button to add grass to the environment. This will add all three types of grass to the field.

2. Press play . Watch the graph to see how the grass population grows. After 20 seconds, look at the graph. Check the boxes for each type of grass if it grows more than 50 plants.

3. Run the experiment with the next level of rainfall. Click reset . Press play and watch again.

4. Try all three rainfall levels. Make sure to run the model for 20 seconds!

Your challenge: Find the grass that grows more than 50 plants with every rainfall level.

Time:


Amount of rain

Lots of rain

Little rain 		After each experiment, look at the graph below.
Check the boxes for grass that grows more than 50 plants.
Amount of Rainfall Grass A Grass B Grass C
Most rain
Medium rain
Least rain


Environmental connections
By changing the level of rainfall, you affected the number of plants in the Virtual Ecosystem. Some grass can only survive with lots of water, but other grass can survive with less water. If a change in rainfall lasts a very long time, only certain types of grass will survive and have offspring. The other types will die before they can reproduce. Over time, the population will contain a lot more of one variety of grass than the others.
Grass A Grass B Grass C

Here is the data you recorded:

Amount of Rainfall Grass A Grass B Grass C
Most rain
Medium rain
Least rain








1. Which type of grass grew best in all levels of rainfall? Grass A Grass B Grass C 2. Which grass is best adapted to live with the least amount of water? Grass A Grass B Grass C 3. How do you think rainfall might affect rabbits living in the field?
Variation in rabbits
So far, you have seen only one type of rabbit hopping around the Virtual Ecosystem. In the real world, there is variation in the members of an animal population. Adult rabbits are different sizes. Some are smaller and some are larger. Just like the teachers at your school, some are short, some are tall, and some are in between! On the next page, you will run experiments to see if the three types of rabbits all like eating the same type of grass.

Remember, even though these rabbits are different sizes, they are all adult rabbits! They are all part of the rabbit population.

Small Rabbit
Medium Rabbit
Large Rabbit

Experiment: Feeding rabbits
The rabbits in the Virtual Ecosystem are hungry! It is your job to feed the rabbits and to figure out which type of grass each rabbit likes best.

Instructions

1. Plant Grass A by clicking the Grass A button, then clicking in the environment.

2. Press play . Watch the rabbits. Do all the rabbits eat Grass A?

3. Click reset . Plant a different grass. Watch the rabbits again.

4. Run the experiment a few times with different grass.
Your challenge: Find the grass each rabbit likes the best. Record your data in the table below.


Which rabbits eat which grass?
Grass A Grass B Grass C
Large rabbit
Medium rabbit
Small rabbit


Small rabbit Medium rabbit Large rabbit
Rabbit food
Even though the three rabbits in the Virtual Ecosystem are different sizes, they are part of the same population of rabbits. All the rabbits in the population need to eat to survive.

Small Rabbit with Grass A Medium Rabbit with Grass B Large Rabbit with Grass C
Here is the data you recorded:

Grass A Grass B Grass C
Large rabbit
Medium rabbit
Small rabbit








4. Look at the table above. Do all the rabbits like to eat the same type of grass? No Yes 5. What would happen to the rabbit population if Grass C were removed from the ecosystem? There would be no change in the population. The small rabbits would die. The medium rabbits would die. The large rabbits would die. 6. What kind of changes in the environment might cause grass to die?
Conclusion
In the real world, ecosystems are complex and include many types of plants and animals, plus nonliving things like water and sun. Certain variations in plants and animals can be helpful if the environment changes.

In this activity, you learned that changes in the environment, like rainfall level, can affect the types of grass in a population. In the next activity, you will explore how changes in the plant population can affect the rabbit population. Everything in the ecosystem is connected and has an important role to play. Click the X at the top of this window to close the activity and save your work.