Download evidence of evolution-comparative anatomy

EVIDENCE OF EVOLUTION-COMPARATIVE ANATOMY
INTRODUCTION: Evidence has been found to indicate that living things have changed gradually
during their natural history. The study of fossils as well as embryology, biochemistry, and
comparative anatomy provides evidence for evolution.
OBJECTIVE: In this lab activity you will learn about homologous, analogous, vestigial structures,
fossils, embryology and biochemistry and their significance in evolution theory.
MATERIALS: Map Pencils
PROCEDURES:
HOMOLOGOUS STRUCTURES
1. Carefully examine the drawings of the bones. Look for similarities among the various
animals.
2. Color the homologous bones according to the color scheme below:

Green = humerus

Red = radius

Blue = ulna

Yellow = metacarpals

Purple = phlanges
3. Then color the corresponding bone in each of the other animals the same color as the human
bone.
humerus
radius
ulna
metacarpals
phalanges
Human
Horse
Cat
Bat
Bird
Whale
2. Describe the function of each set of bones below:
ANIMAL
FUNCTION
Human
Horse
Cat
Bat
Bird
Whale
3. Are the bones arranged in a similar way in each animal? _________________________
These structures are formed in similar ways during embryonic development and share like
arrangements: however, they have somewhat different forms and functions. They are called
homologous structures.
ANALOGOUS STRUCTURES
Examine the butterfly wing and the bat wing.
butterfly
bat
4. What function do these structures share? ____________________________________________
5. How do the structures differ?_______________________________________________________
6. Do bats and insects share any structural similarities that would suggest they are closely related?
Some apparently unrelated animals have organs with similar function, yet are very different in
structure and form. These structures are called analogous structures.
VESTIGIAL STRUCTURES
Gradual changes have occurred through time that have in some cases reduced or removed
the function of some body structures and organs. The penguin’s wings and the leg bones of
snakes are examples of this phenomenon. The term "vestigial" is used in the sense of an organ no
longer or not being used as it is in most other animals. Whales have a pelvis and a femur. In most
animals the pelvic bones are needed in order to be able to move the lower or rear set of limbs for the
purpose of locomotion.
7. Explain why the presence of a pelvis is not an important adaptation to life in the ocean.
8. Does the appearance a pelvis in a whale suggest common ancestry to land animals? Explain.
9. Read the list of human vestigial structures in Table 2 Suggest a possible function for each
structure and explain why it became vestigial. Remember, these organs would have been functional
in our ancestors. Think about why our ancestors would have needed this organ and then think about
why modern humans (through evolution) would no longer need this organ. Other animals still have
these organs. Think about why they have them/how they use them…this might help understand why
our ancestors needed them.
STRUCTURE
Appendix
PROBABLE FUNCTION
Possible raw meat digestion
WHY VESTIGIAL?
FIRE…. Started cooking meat
Coccyx (tail bones)
Muscles that move ears
Muscles that make hair stand up
Little toe
Wisdom Teeth
Embryology
Can you tell a chicken from a fish? How about a human from a pig? Sure you can, you say. Chickens
have wings, fish have fins, humans have arms and pigs have hoofs. But what about when they are
just starting to form?
10. Look at the embryology cards. They represent three developmental stages of five different
animals. They have been all mixed up -- see if you can tell what's what.
11. Arrange the squares and see if you can correctly match the embryos with the animals, placing
them in order from earliest to latest stages of development.
12. Fill in the chart with the number that is on the card.
FISH
Stage 1
Stage 2
Stage 3
CHICK
PIG
CALF
HUMAN
13. Write an explanation of why you ordered the drawings the way you did.
14. What are some similarities among the drawings?
15. What are some differences among the drawings?
16. What patterns (among all 5 species) do you see as you go from stage 1 to stage 3?
Amino Acid Sequencing
PURPOSE: To analyze amino acid sequences as a guide for relationships and common ancestry.
Scientists can examine the amino acid sequences of particular protein molecules found in vertebrates to
determine the degree of similarity between vertebrate species. Even organisms that appear to have few
physical similarities may have similar sequences of amino acids in their proteins and be closely related
through evolution. Scientists believe that the greater the similarity in the amino acid sequences of two
organisms, the more closely related they are in an evolutionary sense.
Part A: Cytochrome-c is a protein found in the mitochondria that is used in cellular respiration. This protein
consists of a chain of 104 amino acids. The chart below shows the amino acid sequence of nine vertebrates. The
letters identify the name of the amino acid.
Animal
Horse
Chicken
Tuna
Frog
Human
Shark
Turtle
Monkey
Rabbit
A
B
C
D
E
F
G
Amino Acid Sequences in Cytochrome-c
H
I
J
K
L
M
N
O
gln
gln
gln
gln
gln
gln
gln
gln
gln
pro
glu
glu
ala
pro
gln
glu
pro
val
phe
phe
phe
phe
tyr
phe
phe
tyr
phe
thr
ser
ser
ser
ser
ser
ser
ser
ser
thr
thr
thr
thr
thr
thr
thr
thr
thr
ala
asp
asp
asp
ala
asp
glu
ala
asp
lys
lys
lys
lys
lys
lys
lys
lys
lys
asn
asn
ser
asn
asn
ser
asn
asn
asn
lys
lys
lys
lys
lys
lys
lys
lys
lys
thr
thr
val
thr
ile
thr
thr
thr
thr
lys
gly
asn
gly
gly
gln
gly
gly
gly
glu
glu
asn
glu
glu
gln
glu
glu
glu
glu
asp
asp
asp
asp
glu
asp
asp
asp
thr
thr
thr
thr
thr
thr
thr
thr
thr
leu
leu
leu
leu
leu
leu
leu
leu
leu
P
Q
R
S
T
U
V
met
met
met
met
met
arg
met
met
met
glu
glu
glu
glu
glu
ile
glu
glu
glu
lys
lys
ser
ser
lys
lys
asp
lys
lys
ala
ala
ala
ala
ala
thr
ala
ala
ala
thr
thr
thr
cys
thr
ala
thr
thr
thr
asn
ser
ser
ser
asn
ala
ser
asn
asn
glu
lys
-lys
glu
ser
lys
glu
glu
DATA
Compare the amino acid sequence of
human cytochrome-c with that of the
other eight vertebrates. For each
vertebrate, count the number of
amino acids that differ from those in
the human and write the number in
the chart to the right.
TABLE 1
Number of Amino Acid Differences
from Human Cytochrome-c
Number
Species
Differences
Human
0
Horse
Chicken
Tuna
Frog
Shark
Turtle
Monkey
Rabbit
DATA ANALYSIS
1. Based on the data, list the order
in which these vertebrates are
related to humans. Place the
vertebrates more similar to
humans in sequence at from the
top.
TABLE 2
Similarity Ranking
Animal
AA Difference
Human
0
2. Using the amino acid differences, which organism is most closely related to humans? _____________
3. Using the amino acid differences, which organism is least closely related to humans? _____________
4. A cladogram is a tree-like diagram showing evolutionary relationships. Use the data from Table 2 and fill in
the cladogram to show the relationship of these animals compared to the human. Label the location on the
cladogram where you would place the common ancestor to all of these animals.
0
5
10
15
Number of amino acid differences from
human Cytochrome-c
5. In the table you completed above, the number listed for the chicken and horse as compared to the human
differs by only one. Compare the differences in amino acid sequences between the horse and the chicken.
The difference is ____ . Considering both sets of data, can you conclude from this that the horse and the
chicken are closely related? _______ Why or why not? _____________________________________
_________________________________________________________________________________
CONCLUSION:
Summarize the concept of amino acid comparisons as they would indicate the possibility/closeness of a
common ancestor.
_________________________________________________________________________________
Fossil Evidence :
The fossil record contains many well-documented examples of the transition from one species into
another, as well as the origin of new physical features. Evidence from the fossil record is unique,
because it provides a time perspective for understanding the evolution of life on Earth. This
perspective is not available from other branches of science or in the other databases that support the
study of evolution.
During the 1990s our understanding of whale evolution made a quantum jump. In 1997, Gingerich
and Uhen noted that whales (cetaceans) "... have a fossil record that provides remarkably complete
evidence of one of life's great evolutionary adaptive radiations: transformation of a land mammal
ancestor into a diversity of descendant sea creatures."
The trail of whale evolution begins in Paleocene time, about 55 mya, with a group of even-toed,
hoofed, trotting, scavenging carnivorous mammals called mesonychians. The first whales (pakicetids)
are known from lower Eocene rocks, that formed about 50 mya; the pakicetids are so similar to
mesonychians that some were misidentified as belonging to that group. However, the teeth of
pakicetids are more like those of whales from middle Eocene rocks, about 45 mya, than they are like
the teeth of mesonychians. Pakicetids are found in nonmarine rocks and it is not clear how aquatic
they were.
In 1994, Ambulocetus natans, whose name means "walking whale that swims," was described from
middle Eocene rocks of Pakistan. This species provides fossil evidence of the origin of aquatic
locomotion in whales. Ambulocetus preserves large forelimbs and hind limbs with large hands and
feet, and the toes have hooves as in mesonychians. Ambulocetus is regarded as having webbing
between the toes and it could walk on land as well as swim; thus, it lived both in and out of the water.
From late Eocene time onward, evolution in whales shows reduction of the hind-limbs, modification of
the forelimbs and hands into flippers for steering, development of a massive tail, etc.; all of these
changes are modifications for the powerful swimming of modern whales. The fossil Rodhocetus from
the upper Eocene rocks, about 46 mya, of Pakistan already shows some of these modifications.
1. Cut out the strips of “whales in the making” and arrange them in the correct order
showing the evolution of the modern whale. Glue them onto the back of this lab in the
correct order (oldest at the top of the page and youngest at the bottom of the page).