Lab # _____: Variation through Time
Lab skills: 13, 27, 28
Background: Evolution means change. Almost all natural systems change. Through time, life has
evolved from simple forms into the present vast array of organisms. Evolution explains the ways in
which organisms are both similar and different.
In this laboratory investigation, you will model what scientists do when they organize a collection of
fossils to reflect evolutionary change. The drawings show a fossil collection of fictional vertebrates.
You will sequence these pictures through time to depict a tree showing the gradual evolution of all
the organisms from a single ancestor.
Hypothesis: If organisms have evolved from a common ancestor, then… (tell me if they will or will
not share similar features.)
Procedure:
1. Examine the illustrations of the fictitious vertebrates. With your lab partner discuss the similarities and differences
amongst organisms. Record at least 3 similarities and 3 differences among the creatures on a T-chart similar to
the one below on a blank sheet of paper.
Similarities
Differences
2. Construct an evolutionary tree out of the illustrations.
a. You will first have to decide from which one of the 19 organisms all of the others evolved.
b. Cut out and arrange the pictures in a sequence that shows gradual evolutionary change from one
generation to the next.
i. You should examine the traits that are present in each organism and remember that evolution
does not result in drastic changes in short amounts of time. It takes extended amounts of time for
variations to accumulate.
c.
Once you have decided on an evolutionary order, glue the creatures down. Make sure to spread the
pictures out.
3. Draw arrows between the pictures to show the direction in which evolution is occurring.
4. Circle the organism from which all others evolved with a brightly colored marker or colored pencil. Please do not
use red.
5. Label the end of each branch of your evolutionary tree with a number. Please write neatly and large!
6. Give your arrangement a descriptive title and staple it to the last page of your lab report.
7. If time permits, you may color the pictures of organisms. Make sure that colors make sense, though.
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Analysis:
A. Take a moment to examine the traits of the original creature on your evolutionary tree. Based on the features
that the original creature possessed, what type of environment do you think it inhabited?
B. How many branches exist on the evolutionary tree you created?
C. List the shared characteristics that you used to determine each of the branches of your evolutionary tree.
D. Describe the environment you think that the last creature in each branch inhabited and provide one reason for your
feeling this way.
E. Select a creature that you placed at the end of a branch
and draw a picture of what you think the creature might
look like if it were to evolve any further in a box about the
same size as the one to the right.
From which branch on your evolutionary tree did the
organism drawn evolve?
F. What trait(s) that you included on the new organism make it different from the one it evolved from?
G. What caused that creature to evolve as it has?
H. What represents a greater amount of time and thus evolutionary change – the distance between organisms
that are far apart on an evolutionary tree or the distance between organisms that are close together?
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