Name:_
_Per: ____
Evidence for Evolution WS
Scientists use a variety of techniques to determine if species are closely related or not. All of these techniques provide
evidence for evolution. If species are closely related, then they must have come from a common ancestor that evolved over
time into two separate species. Today we will be using data to analyze the relationships between different species of whales.
1. Scientists use embryos to study the
evolution of organisms. An embryo is an
unborn organism in the process of
development. This is a picture of a whale
embryo at the right. Look at the embryo
handout given to you and compare the
whale embryo to the embryos of other
animals. Which embryo on the handout do
you think is most closely related to the
whale?
2. Why do you think this animal is most closely related to the whale?
3. Scientists also use vestigial structures to look at how organisms evolved.
Vestigial structures are structures that an organism has but that are no longer
used. For example, humans have a tailbone but we don’t actually have a tail!
This is because we came from a common ancestor a long time ago that had a tail.
Over time, our tail got shorter and shorter because we didn’t need it anymore.
Look at the picture below of a whale showing vestigial structures (pelvis and
femur). Why would a whale have a pelvis (hip bone) and femur (legs) even
though it doesn’t walk?
4. Look at the diagram at the right. The common ancestor is the organism at
the bottom of the “tree”. Would the common ancestor of all these
species have a pelvis and femur?
5. In addition to comparing structures that no longer serve a purpose,
scientists compare structures that still serve a purpose for the organism. These structures are called homologous
structures. Look at the picture to the right. How are the flipper and the human arm similar?
6. How are the whale flipper and the human arm different?
7. Given what you know about humans and whales, do you think they may have shared a common ancestor a long time
ago? Why or why not?
8. Fossils can provide scientists with clues as to how organisms evolved. Look at the fossils below. Place them in order
by numbering them to show how whales evolved over time.
_____
_________
____________
____________
___________
____#6_____
9. Scientists use morphology to look at relationships between species. Morphology is the study of physical structures of
organisms (ex: limbs, body parts, shapes). Look at the Whale Species Handout and compare each species to the Sei
Whale. Which species do you think is most closely related to the Sei Whale?
10. List at least two pieces of evidence from the pictures that led you to believe that the species you chose in #9 was
most closely related to the Sei Whale.
11. Scientists also use DNA sequences to figure out which organisms are most closely related to each other. Compare
the B. borealis (sei whale) DNA sequence to the other species of whales. Circle any differences.
B. borealis (sei whale)
B. bonarensis (mink whale)
B. physalus (fin whale)
B. brydei (bryde’s whale)
AAA
AAG
AAG
AAA
CCG
CAC
CAC
CCC
TAG
TTT
TTG
TTG
GCG
GCA
GCA
GCG
TCA
TCA
TCA
TCA
CGG
CCC
CGG
CGG
TAA ATT
TTT ATT
TTT ATT
TAA ATT
CCC
CCG
CCG
CCG
12. Which species of whale seems to be the most closely related to B. borealis (Sei Whale)?
13. Why do you think this whale is most closely related to the B. borealis (Sei whale)? (Hint: how did you use the DNA to
figure it out?)
14. Once scientists have determined which species seem most closely
related, they create a diagram called a cladogram that shows how
the species are related to each other. Which species of whale
seems to be the most closely related to B. borealis (Sei Whale)?
15. How did you determine which species was most closely related to
B. borealis (Sei Whale)?
16. Does your answer from question #14 match your prediction from
your DNA evidence in #12?
17. Look at the cladogram at the right. Which species do you think
would be least related to B. borealis (Sei Whale)?
RECAP:
18. List five things that you used in this lab to determine how the Sei Whale was related to different species:
Embryo Handout
Whale Species Handout
Minke Whale
Size: 18 feet
Weight: 12,000 pounds
Snout: Sharply pointed
Throat Grooves: 50-70
Dorsal Fin size: 21-23 inches
Sei Whale
Size: 60 feet
Weight: 44,000 pounds
Snout: Sharply pointed
Throat Grooves: 32-60
Dorsal fin size: 12-18
inches
Fin Whale
Size: 68 feet
Weight: 100,000 pounds
Snout: Rounded
Throat Grooves: 56-100
Dorsal fin size: 11 inches
Bryde’s Whale
Size: 40-50 feet
Weight: 50,000 pounds
Snout: Sharply pointed
Throat Grooves: 40-50
Dorsal Fin Size: 12-14 inches
Name:_
_Per: ____
Evidence for Evolution WS - KEY
Scientists use a variety of techniques to determine if species are closely related or not. All of these techniques provide
evidence for evolution. If species are closely related, then they must have come from a common ancestor that evolved over
time into two separate species. Today we will be using data to analyze the relationships between different species of whales.
1. Scientists use embryos to study the
evolution of organisms. An embryo is an
unborn organism in the process of
development. This is a picture of a whale
embryo at the right. Look at the embryo
handout given to you and compare the
whale embryo to the embryos of other
animals. Which embryo on the handout do
you think is most closely related to the
whale?
Pig or Bat
2. Why do you think this animal is most closely related to the whale?
The embryo of the pig or bat looks most similar to the embryo of the whale.
3. Scientists also use vestigial structures to look at how organisms evolved.
Vestigial structures are structures that an organism has but that are no longer
used. For example, humans have a tailbone but we don’t actually have a tail!
This is because we came from a common ancestor a long time ago that had a tail.
Over time, our tail got shorter and shorter because we didn’t need it anymore.
Look at the picture below of a whale showing vestigial structures (pelvis and
femur). Why would a whale have a pelvis (hip bone) and femur (legs) even
though it doesn’t walk?
The whale evolved from a common ancestor that used to have legs
and be able to walk.
4. Look at the diagram at the right. The common ancestor is the organism at
the bottom of the “tree”. Would the common ancestor of all these
species have a pelvis and femur?
Yes because it shows the common ancestor with legs so it would be able
to walk.
5. In addition to comparing structures that no longer serve a purpose,
scientists compare structures that still serve a purpose for the organism.
These structures are called homologous structures. Look at the picture to
the right. How are the flipper and the human arm similar?
They both have five “finger” bones. They both have the same pattern of
one big bone, two small bones, and many little bones.
6. How are the whale flipper and the human arm different?
The human arm is longer than the whale flipper. The whale flipper has
two very long middle finger bones while the human has finger bones that
are all roughly the same size. The “arm bone” of the human is longer than
that of a whale.
7. Given what you know about humans and whales, do you think they may have shared a common ancestor a long time
ago? Why or why not?
Yes because they are both mammals and they both have similar bones in the arms and flippers. They also both have
pelvic bones.
8. Fossils can provide scientists with clues as to how organisms evolved. Look at the fossils below. Place them in order
by numbering them to show how whales evolved over time.
____4_
____2_____
______5______
___1_________
_____3______
____#6_____
9. Scientists use morphology to look at relationships between species. Morphology is the study of physical structures of
organisms (ex: limbs, body parts, shapes). Look at the Whale Species Handout and compare each species to the Sei
Whale. Which species do you think is most closely related to the Sei Whale?
Answers will vary here, but as long as students justify their answer, I mark it correct.
10. List at least two pieces of evidence from the pictures that led you to believe that the species you chose in #9 was
most closely related to the Sei Whale.
Answers will vary. Common answers include: Similar length, similar weight, similar snout, similar dorsal fin, similar
throat grooves.
11. Scientists also use DNA sequences to figure out which organisms are most closely related to each other. Compare
the B. borealis (sei whale) DNA sequence to the other species of whales. Circle any differences.
B. borealis (sei whale)
B. bonarensis (mink whale)
B. physalus (fin whale)
B. brydei (bryde’s whale)
AAA
AAG
AAG
AAA
CCG
CAC
CAC
CCC
TAG
TTT
TTG
TTG
GCG
GCA
GCA
GCG
TCA
TCA
TCA
TCA
CGG
CCC
CGG
CGG
TAA ATT
TTT ATT
TTT ATT
TAA ATT
CCC
CCG
CCG
CCG
12. Which species of whale seems to be the most closely related to B. borealis (Sei Whale)?
B. brydei because it has the fewest DNA differences
13. Why do you think this whale is most closely related to the B. borealis (Sei whale)? (Hint: how did you use the DNA to
figure it out?)
It has the fewest differences in DNA (or the DNA is most similar to the Sei Whale)
14. Once scientists have determined which species seem most closely
related, they create a diagram called a cladogram that shows how
the species are related to each other. Which species of whale
seems to be the most closely related to B. borealis (Sei Whale)?
B. Borealis
15. How did you determine which species was most closely related to
B. borealis (Sei Whale)?
B. Borealis is closest to the Sei Whale on the cladogram
16. Does your answer from question #14 match your prediction from
your DNA evidence in #12?
Yes
17. Look at the cladogram at the right. Which species do you think
would be least related to B. borealis (Sei Whale)?
B. bonaerensis because it is furthest away from B. borealis
RECAP:
18. List five things that you used in this lab to determine how the Sei Whale was related to different species:
DNA, morphology, fossils, homologous structures, vestigial structures