ANTHROPOLOGY.... "Natural Selection"

Name:__________________________________

Student Sheet—Natural Selection: for the Birds

Each of you is a member of a bird population with a wide variety of genetic variations with respect to beak type. Each group of 5 or 6 students represents one of the beak types found in the population.

Procedure

1. Your teacher will ring a bell to initiate the start of feeding.

2. All the groups collectively, using only their beaks, will be given one minute to obtain food from a common feeding area and place the food into the “mouth” (test tube).

3. Your teacher will ring a bell to terminate the feeding period.

4. The pieces of food “eaten” by each “bird” will be counted, a group total calculated and recorded in the appropriate column on Table 1.

5. The total “eaten” by the group will be reported to the teacher to obtain a class total. This figure is needed to determine the number of survivors (parents and offspring).

6. Calculate the number of birds your group has earned by using the following formula: Survivors= total pieces eaten by your group/total pieces eaten by the population X total # of birds in the population

7. If your group ate relatively little food and thus earned fewer “birds” than you started with, some “birds” will die, turn in their beaks, and become offspring for other groups. If your group ate a lot of food, it will earn more “birds”. These “birds” will be drawn from the group of extras and get a beak that is the same as the group they will be joining.

8. Steps 1 through 6 will be repeated 4 more times, thus accumulating five generations of data.

9. Record data in Table 2.

10. Graph all results, showing how the percentages of beak type in the total population changed over time.

11. Write a summary of your observations.

12. Submit report including written summary, data, and graph.

Table 1: Total Seeds Eaten Per Generation in Simulation

Generation 1	Generation 2	Generation 3	Generation 4	Generation 5
Beak 1
Beak 2
Beak 3
Beak 4
Beak 5

Identify each of your “beak” types.

Beak 1___________

Beak 2___________

Beak 3___________

Beak 4___________

Beak 5___________

Generation 1	Generation 2	Generation 3	Generation 4	Generation 5
# Beaks	% Beaks	# Beaks	% Beaks	# Beaks	% Beaks	# Beaks	% Beaks	# Beaks	% Beaks
Beak 1
Beak 2
Beak 3
Beak 4
Beak 5
total

Table 2: Percentage “Beak” Type in Total Population

Survivors= total pieces eaten by your group/total pieces eaten by the population X total # of birds in the population

Analysis

1. How does genetic variation allow a population to survive during environmental changes?

2. How does natural selection control the genetic diversity found in populations?

3. Using your knowledge of natural selection, explain how extinction occurs.

Adapted from a Discovery Institute CUNY lesson (http://discovery.csi.cuny.edu/pdf/lessonplandraft.pdf)