Do not write on this – please return
the day the lab write-up is due.
Birds- Beaks and Evolution- A simulation
Group #1, 5, 7
Wading Bird: Whooping Crane
In this simulation, students gather data to see how beak
mutations can influence natural selection.
Objective
Students learn about the role of mutations in natural
selection and evolution.
Procedure - DAY 1
1. The three to four students in your group represent individual wading birds within a
population of 100 birds. This population of whooping cranes has a wild type beak that
you will simulate.
2. Study the beak of your wading bird. How is it shaped? How thick is it? What types of
food might it eat?
3. Sketch a drawing of your bird’s actual beak on your data collection sheet.
4. With your group, look at the wild-type beak model and construct a similar beak by
wedging a toothpick 2 cm from the tips of the craft stick and using the rubber band to
wrap the ends of the craft sticks, making the beak like tongs. Each person in your group
needs a beak.
5. On your data collection sheet, sketch your beak prototype.
6. With your group, look at the 2 different types of food items: A – crustaceans (pasta) and
B - fish (balloon). Predict the type of food that you think your bird will catch the most
frequently. Write down your prediction on your data collection sheet along with your
reasoning of why you think so using, and be sure to use passive voice (no “I” or
“we”).
7. You and your group will be taking turns trying to capture as much food as possible as in a
15 second period. You will each perform 3 separate trials. Before you being, you and
your group must decide on the best way to set up your data table (Data Table 1). This
needs to include everyone in your group (3 trials a person) as well as how many of
EACH type of food caught during each trial, the total food caught during each trial, and
averages (include an average of the total food caught per trial AND the average of each
individual food type (A, B). One person in your group should sketch a table on scrap
paper then show it to Ms. Cardellini for approval. Do not write down the table on your
collection sheet until she approves it. Round your averages to the nearest tenth.
YOU MAY NOT PROCEED UNTIL YOUR DATA TABLE IS APPROVED BY MRS. C
Warning – the more water that splashes the more you have to clean up!
1. Assign each person a role – timer, cheat monitor, recorder and bird. If you only have 3
people in your group, the timer and recorder will be the same person.
2. Add six pieces of each type of food (A, B) to the estuary (for a total of 12 pieces).
3. The 1st bird will use their constructed beak to capture as much food as possible in 15
seconds and you must follow these rules:
-
Don't use the edge of the aquarium to hold food.
-
Don't put your hand or fingers in the water.
-
Pick up only one food item at a time.
-
Replace food before the next feeding trial.
-
Wipe up any water on the floor in between each trial.
4. The timer will tell the bird when to begin and end. The cheat monitor will make sure all
the rules have been followed. If the bird cheated, they cannot count that food item in
their total.
5. Repeat this 2 more times with the same bird then rotate rolls.
6. After everyone has completed their trial, look for any patterns in your data. Can you
draw any conclusions? Record this on your data sheet.
DAY 2
1. Assume that one to two birds (your team members) in your population will undergo
mutations in the genes that code for beak length. Each student will be given a mutation
handout that will explain the kind of mutation and how it will affect the beak size of your
offspring.
2. Follow the instructions on the mutation sheet. Obtain the proper short or long beak from
Mrs. C if you had a mutation.
3. Create Data Table 2 – it will be the same as data table 1 but will now include each
person’s new offspring (Parent 1/ Offspring 1…). Be sure to label the beak length if
it changed. Finally, add a column called “Generational Results” – this is explained
in step 5. Show Mrs. Cardellini your draft table for approval before anyone writes it on
their data sheet.
YOU MAY NOT PROCEED UNTIL YOUR DATA TABLE IS APPROVED BY MRS. C
4. You will now test your offspring. Only this time, your whole group will be
feeding at the same time and competing for food. You will need another
group to time and monitor you (15 sec/trial). Follow the same rules as you
did when testing the parents. You will feed together for three trials.
5. Determine the survival rate of your offspring by following the directions
below and record results in your data sheet in the Generational results
column.
6. Compare your calculated data with your group so you can complete the
generational results column before you leave class.
Guidelines for determining offspring survival:
• If offspring consumed less than half of the parent's average number of total food
minus 2, they will die.
For example, if offspring consumed 4 pieces of food and the parent's average
number of total food was 14, then they will die. ( 4 is less than [14/2]-2=5
death)
• If offspring consumed between half the parent's average minus 2 to half of the
parent's average, they will survive and reproduce 1 offspring.
• If offspring consumed more than half the parent's average, they will survive and
reproduce 4 offspring
You will be completing a formal lab write-up. Use the handout in your binder or
LabWrite to help you. Mrs. Cardellini will assist you in creating a graph for your
write-up on Excel. You will need to create three separate graphs:
a) Total Food Caught Average- Compare offspring to parent
b) Food A caught average- compare offspring to parent
c) Food B caught average- compare offspring to parent
These must be included in the final draft.
Discussion questions
1. Which beak appeared to have the highest fitness in your population? Explain.
2. If this bird population was studied generations later, what type of natural selection
would you expect to see?
3. What was the significance of having only four individuals within a population of
100 wading birds have a mutation?
4. Why did some mutations lead to a change in beak length and some not?
5. In the parent birds, did the mutations occur in their somatic tissue or gametes?
Explain.
6. What happened when the offspring with changed beaks and the offspring with
wild-type beaks fed together?
7. For each type of beak, which food types were consumed in the highest numbers?
Does it appear that one type of beak is more versatile?
Conclusion questions
1. Does natural selection act upon the genotype or phenotype of an organism?
2. What other factors besides beak length affected feeding in your population?
3. What would you expect to happen to the population if the second generation
(offspring’s babies) were allowed to feed and reproduce under the same
conditions?
4. How did this simulation demonstrate natural selection?
5. What is the role of mutations in natural selection?
6. What is the role of sexual reproduction in natural selection?
7. Explain the significance of the following statement:
Natural selection operates on individuals, but evolution occurs at the level of the
population.
Name
Per.
Date:
Group Members
Sample Lab Write-up: Title
I.
 Scientific concepts/relate relevant facts to lab
 Objectives
 hypothesis
II.
III.
 Cut out beak drawings and paste/tape here
 Data table from day 2 (cut and paste from today or re-do)
 Graphed results on Excel (we’ll do this together in class tomorrow)
IV.
V.