Natural Selection Lab (Wormeaters)

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Biology

Jones

Name:

Period: Date:

Natural Selection Lab

Background: There is a strange species of organisms found in the deep rain forests of Borneo called the Wormeaters. They eat worms,…big, fat, juicy worms.

Now, as in any population, there are slight differences between each Wormeater.

Some have beaks that are long and pointy, some have beaks that are shorter and rounder. Wormeater beaks come in all shapes and sizes, and all the Wormeaters are doing pretty well for themselves on their island home.

But the environment is disrupted, and a succession of rainstorms and floods kill off many of the worms. This results in the starvation of many of the

Wormeters and the stage is set for natural selection to drive the evolution of their population.

 Here is a list of the different variation in beak shape and size that can be found in the Wormeater population:

Beak variation name

“Tubie” beak

“Spooner” beak

“Forcepie” beak

“Chopper” beak

“Strawie” beak

“Pinner” beak

Represented by

Test tube holders

Spoons

Forceps

Chopsticks

Straws

Clothespins

Procedure: Twelve Wormaters (two students for each beak variation) will collect worms (rubber bands) for thirty seconds (one generation). They may only use their beaks (NO HANDS ALLOWED!) to gather food for their offspring. At the end of the thirty seconds, each Wormeater and their partner(s) will count the number of worms that were collected and tell the teacher your numbers to record the data.

Because there are only so many worms to go around, the Wormeaters that collect the LEAST amount of worms will not be able to support themselves or their offspring and one will (gulp) die. The Wormeaters that gathered the MOST food will be able to reproduce and add another of their same variation to feed during the next generation.

Beak Variation

1 2

Generations

3 4 5 6

“Tubie”

“Spooner”

“Forcepie”

“Chopper”

“Strawie”

“Pinner”

# of worms eaten

# of birds left

# of worms eaten

# of birds left

# of worms eaten

# of birds left

# of worms eaten

# of birds left

# of worms eaten

# of birds left

# of worms eaten

# of birds left

Post-Lab

1.

2.

3.

Create a graph of # of Worms eaten vs. Time (Generations). Use a different color to represent each type of Wormeater beak.

Create a graph of # of Birds vs. Time (Generations). Again, use a different color to represent each type of Wormeater beak.

Read through the background and procedure again. Use Darwin’s theory of Natural

Selection and explain how the population of Wormeaters changed over time.

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State each component of Natural Selection.

Describe each component of Natural Selection as discussed in lecture.

Support each component of Natural Selection with a specific example from the lab.

The speciation component was not specifically demonstrated in this activity. If the Wormeaters were to continue to evolve over the next million years, discuss, briefly, how speciation could take place if their food supply doesn’t increase and competition for their food stays fierce.

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