Download Evidence of Evolution Lab

EVIDENCES OF EVOLUTION LAB
BACKGROUND: Evidence has been found to indicate that living things have changed gradually during
their natural history. The studies of fossils as well as embryology, biochemistry, anatomy, geographic
distribution and current observations of natural selection provide evidence for evolution.
SECTION 1 : EVIDENCE FROM COMPARATIVE ANATOMY
By comparing anatomical structures, evolutionary links can be established between groups of organisms.
These comparisons include examining Homologous Structures, Analogous Structures and Vestigial
Structures.
a. HOMOLOGOUS STRUCTURES
The structures in FIGURE 1 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.
1. Carefully examine the drawings of the bones in FIGURE 1. Look for similarities among the various
animals. COLOR each part of the human arm a different color. Color all the bones of the wrist another
color and the bones of the phalanges (fingers) yet another color. Then color the corresponding bone in
each of the other animals the same color as those in the human bone.
2. In Table 1, describe the function of the phalanges (fingers) of each set of bones.
FIGURE 1
TABLE 1
ANIMAL
FUNCTION of PHALANGES
Human
Lion
Horse
Whale
1. Explain how homologous structures are evidence of an evolutionary relationship among species?
b. ANALOGOUS STRUCTURES
FIGURE 2
Some apparently unrelated animals have organs
with similar function, yet are very different
in structure and form. These structures are
called analogous structures.
Examine FIGURE 2 of the moth wing and
the bat wing. Answer questions 3-5.
3. What function do the structures in FIGURE 2 share?
4. How do the structures in FIGURE 2 differ internally and externally?
5. Do bats and insects share any structural similarities that would suggest they are closely related?
c. 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. Organs or structures that lost their function in the organism and become reduced in size
(because of efficiency) are called vestigial structures. Human vestigial organs are well documented.
The fish in FIGURE 3 are related, but the
cave fish is blind. Think for a moment about
how this lack of vision would affect the cave
fish, then answer questions 6 - 9.
FIGURE 3
6. Why is eyesight not an important adaptation to life in a cave?
7. Does the appearance of the cave fish and minnow suggest common ancestry? Why?
8. How do you think vestigal structures came about?
9. How do vestigal structures give evidence for evolutin?
Read the list of human vestigial structures in Table 2. Complete Table 2 with suggestions for possible
functions for each structure.
TABLE 2
STRUCTURE
Appendix
Coccyx (tail bones)
Muscles that move ears
Muscles that make hair
stand up (for warmth)
Wisdom Teeth
PROBABLE FUNCTION
Possible raw meat digestion
WHY VESTIGIAL?
FIRE…. Started cooking meat
Not needed for walking or
running upright
Reliance on vision
Clothing
Softer food, diet change, fire
SECTION 2: EVIDENCE FROM COMPARATIVE EMBRYOLOGY
Evolution occurs slowly. In most cases, it is not possible to observe evolution in progress. However,
evidence of evolution can be found by observing the early stages of development in vertebrates. All
vertebrate embryos start out similar in appearance. This similarity has led scientists to think that these
organisms have a common ancestor. The diagrams below illustrate stages in the embryonic development
of a fish, a pig, and a human. Study the diagram below and answer questions 10 and 11.
10. How does comparative embryology provide evidence of evolution?
11. As the embryos grow and develop, what happens to the appearance of the embryos?
Section 3:EVIDENCE FROM COMPARATIVE BIOCHEMISTRY
All living things are based on a universal genetic code of DNA. If organisms’ traits change over
time and traits are determined by genes (made of DNA), then we can only assume that their DNA changes
over time as well. Amino acid sequences of certain proteins can be used to determine how closely related
different species are. If the amino acid sequences for a certain protein are very similar in two species, one
can assume that those two species had a common ancestor. All 104 amino acids in the protein
cytochrome c are identical in humans and chimpanzees.
1. Observe CHART 1 in which it shows how many of the amino acids in cytochrome c in other animals
differ from those in humans and chimps. Answer questions 12 and 13.
Animal
Dog
Dogfish shark
Rattlesnake
Rhesus monkey
CHART 1
# of Amino Acid differences in
Cytochrome C compared to humans
8
24
12
1
12. Which of the organisms would be most biochemically similar to humans: fish or pig? Why?
13. How does the information in CHART 1 support evolutionary theory?
SECTION 4: EVIDENCE IN THE FOSSIL RECORD
According to the geological law of superposition, older layers of sedimentary rock lay beneath younger
layers. Scientists use this law to determine the order in which organisms appeared and disappeared in the
fossil record. The law cannot be used to determine the absolute ages of rock layers. It can be used to
determine the relative ages of rock layers by comparing their fossil records.
Study FIGURE 5 containing diagrams that represent neighboring sedimentary rock formations, answer
questions 14-16.
FIGURE 5
14. In FIGURE 5, which layer is the oldest in each formation?
15. Are the two layers the same age? How could you tell?
16. Suppose fossils from Layer "C" of Formation 2 are the same fossils as those in Layer "D" in
Formation 1. What could you say about the relative ages of all layers in both formations?
SECTION 5: GEOGRAPHIC EVIDENCE OF EVOLUTION
All organisms are adapted to their environment to a greater or lesser extent. If the abiotic (not living) and
biotic (living) factors within a habitat are capable of supporting a particular species in one geographic area, then
one might assume that the same species would be found in a similar habitat in a similar geographic area, as for
instance in Africa and South America. This is not the case. Plant and animal species are distributed irregularly
throughout the world. For example:
Old World monkeys, which resemble humans and the great apes in anatomy and body functions, are found
mostly in parts of Africa and Asia. Many spend as much or more time on the ground as they do in trees. New
World monkeys, found in the Americas, are all tree dwellers, and many of them use their prehensile tails in
traveling through forests.
Examine the similarities & differences between the Old World and New World organisms shown below.
Answer questions 17 and 18.
Old World
Africa: Old World Monkeys, apes,
elephants, leopards, giraffes, hornbills,
camels, Euphorbs (succlents)
New World
The Americas: New World Monkeys,
cougars (aka Mountain Lions), jaguars,
sloths, llamas, toucans, cacti
17. Compare and contrast one Old World orgnanism with a similar New World organism. What
characteristics do they have in common? What are the differences? Why may that be?
18. How does their geographic location provide evidence for evolution?
SECTION 6: EVIDENCE FROM OBSERVED NATURAL SELECTION
Examples for the evidence for evolution often stems from direct observation of Natural Selection
in the field and the laboratory. Scientists have observed and documented a multitude of events where
Natural Selection can be seen in action. The most well known examples are antibiotic resistance in the
medical field and the spread of pesticide resistant forms of plants and insects.
One classic example of adaptation in response to selection pressure is the case of the peppered
moth. The color of the moth has gone from light to dark to light again over the course of a few hundred
years due to the appearance and later disappearance of pollution from the Industrial Revolution in
England. Originally, the vast majority of peppered moths had light coloration, which effectively
camouflaged them against the light-coloured trees and lichens which they rested upon. However,
because of widespread pollution during the Industrial Revolution in England, many of the lichens died
out, and the trees that peppered moths rested on became blackened by soot, causing most of the lightcolored moths to die from predation. At the same time, the dark-colored moths flourished because of
their ability to hide on the darkened trees. With improved pollution laws, the soot has been controlled,
and the light colored moths are once again dominant.
Peppered Moths prior to
the Industrial Revolution
Peppered Moths during the
Industrial Revolution
19. How does the Peppered Moth observation of natural selection support the theory of evolution?
TABLE 3: EVIDENCES OF EVOLUTION
COMPLETE THE CHART by checking the kind of evidence described.
KIND OF EVIDENCE
Evidence
COMPARATIVE…
STURCTURAL ANATOMY
Embryology
Homologous
E
20. A modified
structure seen among
different groups of
descendants
21. In the earliest
stages of
development, a tail
and gill slits can be
seen in fish, birds,
rabbits, and mammals.
22. The continuous
discovery new
antibiotic resistant
bacteria
23. The forelimbs of
flightless birds
24. Changes in the
coloration of insects
within only a few
generations
25. Similarities
between the Old
World Monkeys and
the apes.
26. A body structure
reduced in function
but may have been
used in an ancestor
27. The beaks on the
finches of the various
Galapagos Islands
28. DNA and RNA
comparisons may lead
to evolutionary trees
29. Bird and
butterfly wings have
same function but
different structures.
30. Examples of
forelimbs of bats,
penguins, lizards, and
monkeys
31. Give your own
example of how the
Fossil Record can be
an evidence of
evolution
Analogous
Vestigial
Biochemistry
Geographic
Distribution
Observed
Natural
Selection
TABLE 3: EVIDENCES OF EVOLUTION
COMPLETE THE CHART by checking the kind of evidence described.
KIND OF EVIDENCE
Evidence
COMPARATIVE…
STURCTURAL ANATOMY
Embryology
Homologous
E
20. A modified
structure seen among
different groups of
descendants
21. In the earliest
stages of
development, a tail
and gill slits can be
seen in fish, birds,
rabbits, and mammals.
22. The continuous
discovery new
antibiotic resistant
bacteria
23. The forelimbs of
flightless birds
24. Changes in the
coloration of insects
within only a few
generations
25. Similarities
between the Old
World Monkeys and
the apes.
26. A body structure
reduced in function
but may have been
used in an ancestor
27. The beaks on the
finches of the various
Galapagos Islands
28. DNA and RNA
comparisons may lead
to evolutionary trees
29. Bird and
butterfly wings have
same function but
different structures.
30. Examples of
forelimbs of bats,
penguins, lizards, and
monkeys
31. Give your own
example of how the
Fossil Record can be
an evidence of
evolution
Analogous
Vestigial
Biochemistry
Geographic
Distribution
Observed
Natural
Selection