Name:_____________________________________ Date: ____________________ Period: _____
Darwin’s process of natural selection has four
components.
Beaks of Finches
1. Variation. Organisms (within populations)
exhibit individual variation in appearance and
behavior. These variations may involve body
size, hair color, facial markings, voice
Charles Darwin
properties, or number of offspring. On the
HMS Beagle
other hand, some traits show little to no
variation among individuals—for example,
number of eyes in vertebrates.
2. Inheritance. Some traits are consistently
Natural Selection
passed on from parent to offspring. Such
traits are heritable, whereas other traits are
strongly influenced by environmental conditions and show weak heritability.
3. High rate of population growth. Most populations have more offspring each year than local
resources can support leading to a struggle for resources. Each generation experiences
substantial mortality.
4. Differential survival and reproduction. Individuals possessing traits well suited for the
struggle for local resources will contribute more offspring to the next generation.
From one generation to the next, the struggle for resources will favor individuals with some variations
over others and thereby change the frequency of traits within the population. This process is natural
selection.
Adaptations are the traits that are advantageous to those individuals who leave more offspring.
Blunt Tip
Tweezers
Galapagos Islands
Pointed Tip
Tweezers
Pliers
Clothes Pin
Small Seed Island
Lab Tongs
Serving Tongs
Needle-nose Pliers
Barbeque Tongs
Test Tube
Tongs
Pre-Investigation
Bag Clip
Binder Clip
Ice Tongs
Large Seed Island
Pre-Lab Questions: Answer in complete sentences.
1. Examine the different tools (“Beaks”) and seeds provided. Predict which “beak” will be the most
successful at picking up small seeds. Give the reason for your choice.
2. Predict which ‘beak” will be the least successful at picking up seeds. Give the reasons for your
choice.
3. From this point on, you and your partner will model a finch feeding. The tool you were assigned
will be your “beak”. Describe what characteristics it has that make it beneficial or non-beneficial
for picking up small seeds.
4. In the space below draw an outline of your “beak”.
Now both you and your partner should practice using your “beak” to transfer the small seeds
1 at a time from Island (plate) to mouth (cup). You may not “scoop/shovel” into your mouth. We
eat with manners here. 
Round One: Feeding With No Competition
Number of Seeds
Collected
Round
One: Feeding with no Competition
Partner #1
# seeds
collected
Partner #2
Partner #1
Partner #1&2 Average
Trial #1
Trial #2
Partner #2
Original Island-Small Seeds
Trial #1
Trial #2
Partner Average fewer than 13 seeds/ 30 seconds move to New – Large Seed Island for Round Two
Partner# 1&2 Average
Partner Average greater than 13 seeds/ 30 seconds stay on Original – Small Seed Island for Round Two
Partner average fewer than 13 seeds/30 sec. move to New- Large
Seed Island for Round Two: Feeding with Competition.
Round Two: Feeding With Partner
Competition
average greater than 13 seeds/30 sec. stay on Original- Small
Round
Two:
Feeding
with Competition
Seed
Island
for Round
Two: Feeding with Competition.
Number of Seeds
Collected
Partner #1
Partner #1
# seeds
collected
Trial #1
Original Island-Small Seeds
Trial #2
Partner #2
Partner #2
Partner #1&2 Average
Trial #1
Trial #2
Partner# 1&2 Average
New Island-Large Seeds
Partner Average fewer than 13 seeds/ 30 seconds you are now extinct
Partner average fewer than 13 seeds/30 sec. you are now extinct.
Partner Average greater than 13 seeds/ 30 seconds move onto Round Three
Partner average greater than 13 seeds/30 sec. move onto Round
Three: Feeding with Increased Competition.
Round Three: Feeding With Increased Competition
Round Two: Feeding with Competition
Number of Seeds
Collected
Partner #1
Partner #1
Trial #1
# seeds
collected
Original Island-Small Seeds
Trial #2
Partner #2
Partner #2
Partner #1&2 Average
Trial #1
Trial #2
Partner# 1&2 Average
New Island-Large Seeds
Partner average fewer than 13 seeds/30 sec. you are now extinct.
Fill in Data Table for the Class Results, and complete the analysis questions
Partner average greater than 13 seeds/30 sec. move onto Round
Three: Feeding with Increased Competition.
Data Table: Class Results
Beaks That Were
Number of
Beak Types
Types of Beaks (Name of Tool)
Present at the beginning of
activity
Successful at feeding in
Round One: Original Island
– Small Seeds.
Not Successful in Round
One: Had to move to New
Island - Large Seeds
Successful at feeding in
Round Two: Original
Island – Small Seeds
Successful at feeding in
Round Two: New Island –
Large Seeds
Data Table: Class Results Continued
Not Successful in Round
Two on either Island –
became extinct.
Successful at feeding in
Round Three: Original
Island – Small Seeds.
Successful at feeding in
Round Three: New Island –
Large Seeds
Not Successful in Round
Three on either Island–
became extinct
Post Analysis Questions: To be answered in complete sentences on a word document with
grammar and spell checked.
ANALYSIS OF INDIVIDUAL & CLASS DATA:
1. What characteristic(s) of your “beak” contributed or interfered with feeding success on the
original island – small seeds?
2. Name three traits other than beak characteristic that could contribute to the ability of a finch to
compete successfully?
3. It is very unlikely that all the beaks within a species of a finch are exactly alike. Random mutations
and new gene combinations resulting from sexual reproduction are the source of beak variations.
Describe three beak variations that could randomly appear and further improve your species’
chances of survival when feeding on small seeds.
4. Looking at Data Table Class Results, did those who were successful in Round One survive equally
well when others were competing for food at the same dish during Round Two? Support your
answer with an explanation.
5. Explain how this activity simulates the following concepts of natural selection. Describe specific
examples from the activity.
a. Variation:
b. Competition for resources:
c. Adaptation:
d. Selecting agent:
Base your answers to questions 6-10 on the Diagram below.
6. Predict which species of finch would most likely survive if the weather on the Galapagos Islands
gradually changed and the seeds available to the finches became larger with heavier coverings.
Support your answer with an explanation.
7. One Island is populated by two species – Ground Finches and Small Tree Finches. What two types
of food would you expect to be available on this island? Support your answer with an explanation.
8. Would you expect the two species - Ground Finches and Small Tree Finches to compete for food on
this island? Support your answer with an explanation.
9. Which finch species is least likely to survive a severe drought that reduces the insect population
on the island? Explain your answer.
10. How could finches have such different beaks yet come from the same ancestor?
11. What Is the Point
In a few short sentences, explain the link between this activity and the unit that we are covering in
class. How does this simulation relate to what we are currently learning?