Investigation: Galapagos Finches

Part I: Measuring Beak Depth Variation

Directions:

  1. Choose a partner
  2. Use the ruler and measure the depth of 6 finch beaks in centimeters; measure at the arrows and estimate to 1 decimal point (ex. 6.8 cm)
  3. Record each measurement in Part I Data Table.
  4. Multiply each measurement by 10 to convert it into millimeters (mm); estimate to 1 decimal point
  5. Each picture is 10x larger than the real bird; therefore divide each measurement by 10 to calculate the real size in millimeters.

Questions: Answer using Qwizdom remotes

  1. What was the size of the largest real beak? A) 8.5 mmB) 9.8 mmC) 10.9 mmD) 11.2 mm
  1. What was the size of the smallestreal beak? A) 7.8 mmB) 6.8 mmC) 8.9 mm D) 8.5 mm
  1. Do you think this small variation in beak size could affect a finch’s survival? YesNo

Part II: Battle of the Beaks

Directions:

  1. Work with your partner from part 1
  2. Retrieve the supplies listed below from the lab bench
  3. 2 red cups = stomachs
  4. large and small seeds (inside red cups)
  5. small and large clothespins = small and large finch beaks
  6. ruler
  7. 1 small paper plate = island
  8. Measure the depth of the small and large beak in millimeters (mm) and record in Part 2 Data Table

Normal Year Simulation

  1. Simulate the availability of seeds for a normal year with average rainfall by adding all of the small and large seeds to the paper plate (the island).
  2. Predict which beak size will be more successful by placing an “X” in Part 2 Data Table
  3. One partner will keep track of time while the other uses the small beak to pick up as many seeds as possible in 30 seconds and place them in your stomach (red cup)
  4. After 30 seconds, record the number of small and large seeds in your stomach (red cup) in Part 2 Data Table, trial 1.
  5. Place the seeds back on the island (plate) and repeat with small beak to collect data for trial 2.
  6. Repeat simulation again, but using the large beak.

Drought year Simulation

  1. Simulate the availability of seeds for a drought year with little rainfall by adding all the large seeds and only 3 small seeds to the paper plate (the island).
  2. Predict which beak size will be more successful by placing an “X” in Part 2 Data Table
  3. Reverse rolls: One partner will keep track of time while the other uses the small beak to pick up as many seeds as possible in 30 seconds and place them in your stomach (red cup)
  4. After 30 seconds, record the number of small and large seeds in your stomach (red cup) in Part 2 Data Table, trial 1.
  5. Place the seeds back on the island (plate) and repeat to collect data for trial 2.
  6. Repeat simulation again, but using the large beak.

Questions: answer using Qwizdom remotes

  1. Which beak size was more successful during a normal year? A) SmallB) Large C) Both did well
  1. Which beak size was more successful during a drought year? A) SmallB) Large C) Both did well
  1. How did a change in the environment affect which beak size collected more food?
  2. The drought left mostly large seeds, which could only be picked up by the small beak
  3. The change in the environment did not affect which beak could pick up more seeds
  4. The drought left mostly small seeds, which could only be picked up by the small beak
  5. The drought left mostly large seeds, which could only be picked up by the large beak
  1. Based on the theory of natural selection, how should the population of medium ground finches change during a drought year?
  2. The population will decrease and those that survive will have small beaks
  3. The population will increase and beak variation will also increase
  4. The population will decrease and those that survive will have large beaks
  5. The population will most likely go extinct

Part III: Survival on Daphne Major

Background Information:

The observers on Daphne Major tracked seed abundance by first measuring a square meter area of ground and then sifting through the soil to count every seed. This was done at many different places to get an accurate count. They repeated the count every six months. Here are their data:

The finches were counted every six months. Here are the data for the same period of time as the seeds were measured. Here are their data:

Directions:

  1. Graph the top data onto the Seed Abundance Graph and bottom data onto the Finch Population graph.

Questions: answer using Qwizdom remotes

  1. During what month and year was the seed abundance the highest?

A)January 1977B) July 1976C) January 1976D) July 1978

  1. During what month and year was the seed abundance the lowest?

A)January 1978B) July 1977C) January 1977D) July 1978

  1. During what month and year was the finch population the highest?

A)January 1977B) July 1976C) January 1976D) July 1978

  1. During what month and year was the finch population the lowest?

A)January 1978B) July 1977C) January 1977D) July 1978

  1. What is the relationship between the finch population and seed abundance?
  2. When more seeds are abundant, there are more finches
  3. When more seeds are abundant, there are less finches
  4. When less seeds are abundant, there are more small beaked finches
  5. When less seeds are abundant, there are more finches

Answer questions 13 and 14 in complete sentences on the next page in your composition book.

  1. When the team returned to Daphne Major, they found only one in seven finches survived the drought. When they measured the survivors, they found that most were finches with big beaks. Why do you think bigger-beaked birds survived better than the smaller-beaked birds?
  1. Explain two reasons why the small beak phenotype has not disappeared from the population over time?