Ch 17 Evidence of Evolution

Marine Biology
Background
When Charles Darwin first proposed the idea that all new species descend from an ancestor, he
performed an exhaustive amount of research to provide as much evidence as possible. Today, the major
pieces of evidence for this theory can be broken down into the fossil record, embryology, comparative
anatomy, and molecular biology.
Fossils
This is a series of skulls and front leg fossils of
organisms believed to be ancestors of the modern-day
horse.

1. Give two similarities between each of the skulls that might lead to the conclusion that these are all related species.

All of the eyes are in similar places and all of the skulls have 2 different parts of the skull.

2. What is the biggest change in skull anatomy that occurred from the dawn horse to the modern horse?

A good chance

3. What is the biggest change in leg anatomy that occurred from the dawn horse to the modern horse?

A not very good chance because they do not look similar at all.
Embryology
Organisms that are closely related may also have physical similarities before they are even born!

Take a look at the six different embryos below and hypothesize which embryo is from each of the following organisms:

Species Embryo

Human C

Chicken B

Rabbit E

Tortoise A

Salamander F

Fish D
Embryology
These are older, more developed embryos from the same organisms.

Hypothesize which embryo is from each of the following organisms:

Species Embryo

Human E

Chicken F

Rabbit D

Tortoise C

Salamander B

Fish A
 Embryology
These are embryos at their most advanced stage, shortly before birth.

Describe how the embryos changed for each of these organisms from their earliest to latest stages.

Species Anatomical Changes From Early to Late Stages

Human The head and limbs form.

Chicken The beak starts to form and their feet also are coming in.

Rabbit The rabbits nose starts to come in and a tail starts to come in.

Tortoise The shell starts to form and the tail starts to form.

Salamander The salamander starts to get arms and legs also gets eyes.

Fish The fins come in and they get longer in length.

2. Does this suggest an evolutionary relationship? Explain how.these embryos be used as evidence of a common ancestor
between each of these six organisms?
Comparative Anatomy
Shown below are images of the skeletal structure of the front limbs of 6
animals: human, crocodile, whale, cat, bird, and bat.

Each animal has a similar set of bones. Pick a color and create a color
code each of the bones for the key below. Then color each of the 6
animals’ bones accordingly to match the colors.
Comparative Anatomy
For each animal, indicate what type of movement each limb is responsible for.

Animal Primary Functions

Human Using tools, picking up and holding objects

Whale Being able to push the whale through the water

Cat

Bat

Bird

Crocodile
Comparative Anatomy
Compare the skeletal structure of each limb to the human arm.

Relate the differences you see in form to the differences in function.

Animal Comparison to Human Arm in Form Comparison to Human Arm in Function

Whale Whale has a much shorter and thicker humerus, radius, and The whale fin needs to be longer to help in movement through
ulna. Much longer metacarpals. Thumb has been water. Thumbs are not necessary as the fins are not used for
shortened to a stub. grasping.

Cat

Bat

Bird

Crocodile
Comparative Anatomy
Compare the anatomy of the butterfly and bird wing below.

1. What is the function of each of these structures?

2. How are they different in form? Give specific differences.

Compare the overall body structure of the cave fish and the minnow.

1. What is the biggest, most obvious difference between the body structure of these two fish?

2. Assume the two fish came from the same original ancestor. Why might the cave fish have evolved without eyesight?

3. What kind of sensory adaptation would you hypothesize the cave fish has to allow it to navigate in a cave, including
catching and eating food?
Comparative Anatomy
You have now studied three different types of anatomical structures:

1. Homologous structures show individual variations on a common anatomical theme. These are seen in organisms
that are closely related. Give an example of a homologous structure from this activity:

2. Analogous structures have very different anatomies but similar functions. These are seen in organisms that are not
necessarily closely related, but live in similar environments and have similar adaptations. Give an example of an
analogous structure from this activity:

3. Vestigial structures are anatomical remnants that were important in the organism's ancestors, but are no longer
used in the same way. Give an example of a vestigial structure from this activity:
Comparative Anatomy
Below are some vestigial structures found in humans. For each, hypothesize what its function may have been.

Structure Possible function?

Wisdom teeth

Appendix

Muscles for moving ears

Body hair

Little toe

Tailbone

How are vestigial structures an example of evidence of evolution?

1. Which species is the most closely related to the dolfish?

2. Which two species are the most closely related to the frozard?

3. Which species is the least related to the manbryo?

4. Based on your DNA base sequences, which species do you think may have
the closest relationship to the dolfish and the manbryo?

5. Starting with the dragomander, list the species from most related to the
dragomander to least related:
Molecular Biology - DNA Fingerprinting
DNA fingerprinting shows relatedness between species. Examine these fingerprints to determine which species are most
closely related.

Which species is most closely related to the manbryo?

Which species is least related to the manbryo?

Which species is most closely related to the dragomander?

Which species probably has a closer relationship with the parrotop– the frozard or the dragomander? Explain why.

List order of species from most to least closely related in relationship to the dolfish:
Molecular Biology - Amino Acids

The amino acid sequence for metathusal in each species is as follows. Compare the amino acid sequences for each
organism to determine relationships.

Which two species are the least related to the dragomander based on differences in their amino acid sequences?

Which of the species seem to be most closely related to the dragomander, according to the amino acid evidence?

Which species is the most related to the frozard: the dragomander or the manbryo? Explain why.
Conclusion
Charles Darwin published his book On the Origin of Species in 1859. Of the different types of evidence that you have
examined, which do you think he relied upon the most, and why?