Transcript Natural Selection Lab - Mrs. Basepayne's Science Spot

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
Generation 2
Generation 3
Generation 4
Generation 5
Spoon
Fork
Knife
Clothespin
Offspring Per Generation
Generation 1
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
6
Number of Offspring per Generation
Spoons
Offspring
5
4
Forks
3
Spoons
2
1
0
1
2
3
Generations
4
5
1.
2.
3.
4.
5.
6.
7.
Analysis Questions
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?
Which beak was best adapted to the food? Which beak was least
adapted to the available food?
What do you think will happen in 20 generations?
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?
If the paper clips were high-protein beetles that were 4 times more
nutritious than the beans, how would your feeding strategy change?
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?
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?