Natural Selection Lab

Bird Beak Adaptation

Background• Hopefully, you recall that Darwin was amazed by the variation in the

characteristics of plants and animals he encountered on his journey. In any habitat, food is limited and the type of food available may vary. Animals that have variations that enable them to take advantage of available foods will be more likely to survive. We call beneficial inherited variations adaptations. Adaptations are inherited characteristics that increase an organism’s chance of survival. Those with the most helpful adaptations will be the most likely to live long enough to pass on their genes to the next generation. This process ensures that beneficial adaptations will continue in future generations, while disadvantageous characteristics will not. Understanding the concept of adaptive advantage is absolutely required for an understanding of how populations exist in ecosystems as well as the process of evolution.

Purpose

• To learn about the advantages and disadvantages of phenotype variation, by simulating birds with different types of beaks competing for various foods.

Pre-Lab Questions

1. Define Evolution.2. Define Natural Selection.3. What are the four principles of Natural

Selection?

Procedures

• Each student will be given a beak “adaptation”– Spoon– Fork– Knife– Clothespin

• Each student will also get a “stomach”– Plastic cup

• At the teachers directions you will collect your food until the teacher says stop

• You will then count your food and record in the data table.

Hypothesis

• Write your hypothesis.• Your hypothesis should state which adaptation

will be the best type of beak and why.

Data• Draw 3 tables like the one on the board. Label one

Group Data, and one CLASS data and one offspring per generation.

• After each round record your qualitative observations of this activity.

Class Data

Generation 1 Generation 2 Generation 3 Generation 4 Generation 5

Spoon

Fork

Knife

Clothespin

Offspring Per Generation

Generation 1 Generation 2 Generation 3 Generation 4 Generation 5

Spoon

Fork

Knife

Clothespin

Feeding• Choose your “beak” (spoon, fork, knife, clothespin)• For 5 rounds you will eat for 20 seconds each round. During

that 20 seconds you will collect your food and place it in your stomach.– Stomach must remain on the table!!– Any food you drop gets “away” and goes back into the

food supply.• After 20 seconds count your food and record in the data

tables• Calculate how many offspring you have by dividing the

number of beans you ate by 10. Record this in the data table.– If you ate less than 10 beans record that you had NO

offspring that round.

Graphing the Data

1. What is the dependent variable? What is the independent variable?

2. Why is it better to use the class averages from the results for creating a graph and answering the questions, rather than only using your own data?

3. For this experiment, is it better to use a bar graph or a line graph to display the data?

4. Create an appropriate graph for the class data for this experiment.

Example graph

1 2 3 4 50

1

2

3

4

5

6

Number of Offspring per Generation

Spoons

Forks

Spoons

Generations

Offs

prin

g

Analysis Questions1. What did you notice about your behavior and the behavior of the

other “birds”? Was the behavior of the birds analogous to the behavior of real birds in the wild?

2. Which beak was best adapted to the food? Which beak was least adapted to the available food?

3. What do you think will happen in 20 generations?4. Obviously, most habitats have more than one food type available.

How would your strategy differ if there were only paper clips available as food? If both paper clips and beans were available?

5. If the paper clips were high-protein beetles that were 4 times more nutritious than the beans, how would your feeding strategy change?

6. What would happen if all the bird types in this activity flew to an island where no birds had been before and the only food available was macaroni. Which birds would be most successful? Which birds would be least successful?

7. If we came back to the island in question 5 in 50 years, what should we expect to see? (What type of birds will live on the island?)

Conclusion

• How does this lab simulation provide support for the theory of evolution? What did you learn from this lab? Was your hypothesis right or wrong? If it was wrong explain why your think the other “beak” was a better adaptation?