General Biology 2
Quarter 3: Evidence of
Evolution
Target
In this lesson, it explicitly discusses the various concepts on pieces of evidence in evolution on
how changes in organisms occurred starting from the simple origin of life to the wide variety of plants,
animals and microorganisms existing today which are intended for you to enjoy learning in biology.
Through diverse fun-filled activities, you will explore and describe the different evidence used in biology
to show that evolution did take place.
You will also learn to infer the evolutionary relationship between organisms using the evidence
of evolution.
After accomplishing this lessom, you are expected to:
1. Explain evidence of evolution (e.g., biogeography, fossil record, DNA/protein sequences,
homology, and embryology) (STEM_BIO11/12- IIIc-g-12)
2. Infer evolutionary relationships among organisms using the evidence of evolution
(STEM_BIO11/12-IIIc-g-13)
Before going on, check how much you know about the lesson. Do the next activity on a
separate sheet of paper.
Jumpstart
In the next activity you will appreciate a body structure that is present in us and in some
organisms related to humans.
Activity: What a Thumb Can Do For You
Do you understand how important your thumbs are? Only primates have hands capable of
grasping objects. The grasp is created possible by the opposable thumbs. Are you aware that you simply
perform plenty of tasks using your thumb and fingers? have you ever experienced doing a series of tasks
without the help of your thumb?
Ask a companion to tape your thumbs to the palms of each hand with masking tape. Be cautious
not to wrap the tape too tightly because it will cut off the blood circulation to your hand. Then do the
following:
a. pick up your pen
b. write your name on a paper
c. turn the doorknob
d. pick up any plastic container
e. unbutton or rebutton a shirt
Question:
How has having an opposable thumb helped primates, especially humans to adapt to their
environment and survive better than other animals?
Sounds interesting! Let us go to another scientific journey.
Lesson
Pieces of Evidence for
Evolution
1
In the previous lessons, it is said that evolution is the process of change in species over time.
Some changes are easily visible. Other changes occur so gradually through time and are not easily
observed.
Darwin’s theory of evolution was eventually recognized when scientists were able to supply
verifications that Darwin himself had been unable to specify. Natural selection gives us with an outline
in understanding the ideologies of evolution. Darwin’s idea of evolution has been improved by new
evidence that have been gathered by modern scientists. Moreover still, modern scientists are at an
interminable expansion on collecting data and evidence that may verify or invalidate the information
about evolution of life that we have now. And these pieces of evidence are significant in the field of
biology.
Discover
Previously, you have studied the patterns of descent with modification from our common
ancestor to the present organismal diversity. As well as you also have traced the development of
evolutionary thoughts from a few notable individuals in the field of evolution.
Before we begin, try some more activity to boost your vocabulary.
Activity: Word Parts
Directions: Below are words that have been divided into halves. Find the pieces that fit
together and write them in your answer sheets.
spe
igin
riod
adap
or
inhert
sils fos
em
homo
gans
lohous
cies
ry
theo
igial
tation
tance
evo its
bryology
vest lution
pe
tra
CONCRETE EVIDENCE OF EVOLUTION AND HOW TO INFER USING ITS
EVOLUTIONARY RELATIONSHIP
A. Fossils
Fossils are preserved remnants of once living organisms trapped in rocks, tar pits, frozen in ice
or embedded in amber. The most common fossils are bones, shells and seeds or pollen grains. Most
fossils are formed in sedimentary rock. Paleontologists (a specialist in the study of the forms of life
existing in prehistoric or geologic times), use the fossils found in rocks to track the evolutionary history
of many organisms.
(a)
(b)
Figure 1. (a) Fossilized shrimp. (b) Mammalian (peccary) fossil
Source: http://www.citruscollege.edu/lc/archive/biology/Pages/Chapter17-Rabitoy.aspx
By identifying the age of rocks in which fossils appear, we can obtain an accurate idea of how
old the fossils are. Geologists use Relative dating rocks were dated by their position with respect to one
another; rocks in deeper strata are generally older. On the other hand, in absolute dating rocks are dated
by measuring the degree of decay of certain radioisotopes contained in the rock; the older the rock, the
more its isotopes have decayed. Since radioactive isotopes decay at a constant rate unchanged by
temperature or pressure, the isotopes in a rock act as an internal clock, determining the time after the rock
was formed. Hence, the records found in the rocks show a gradual evolutionary descent from simpler
to more complex life forms. Furthermore, the fossil record provides a clear record of the major
evolutionary transitions that have occurred through time.
B. Embryology
An embryo is an organism in its initial phases of development. While embryology is the study
of the development of the anatomy of an organism to its adult form also gives evidence of relatedness
between now widely different groups of organisms. Scientists observed that at some point during the
development process, embryos of many different animals appeared so similar that it was difficult to tell
them apart. During development, at some time all vertebrates have a supporting dorsal rod, called a
notochord, and demonstrate paired pharyngeal pouches. This could indicate that an organism passes
through some of the embryonic stages that its ancestors passed through. Then numerous variations occur
in ways appropriate to an organism’s final form.
However, the similarities in the early stages of embryo development are further evidence
that living organisms have evolved from earlier living things and that they do share a common
ancestry.
Figure 2. Vertebrate embryonic development
Source: http://www.geo.arizona.edu/Antevs/nats104/00lect12.html
C. Anatomical Evidence
In comparing the anatomy and the development of organisms, it shows a unity of plan among
those that are closely related. The more body structures that two species have in common, the more
closely they are related. It adopts the idea of “descent from a common ancestor”.
Similar structures in different species irrespective of their functions are called homologous
structures. Homology seems to indicate descent from common ancestor. The limb skeletons of
vertebrates are homologous structures.
Figure 3. The limb skeletons of vertebrates are homologous structures.
Source: http://www.geo.arizona.edu/Antevs/nats104/00lect12.html
Analogous structures are structures which are different in appearance but have the similar
function. Analogy does not indicate common ancestry. Examples of are the limbs of insects and
mammals, and wings of butterflies and birds.
Figure 4. Analogy of bat & bird wings
Source: http://www.mun.ca/biology/scarr/ Analogy_of_forelimbs.htm
Vestigial structures seem like to give more evidence for evolutionary change. Vestigial
structures are anatomical features that are usually reduced and have no function in many organisms.
These are organs that were previously functional in the ancestors of the species but are only remnants
in the present-day species. For example, skeletal extremities discovered in certain snakes have no
known use to these animals. In humans, appendix is thought to have no use, but in other mammals it
aids in the digestion of cellulose.
Table 1. Some Vestigial Organs in Man
Coccyx (tail bone)
Appendix
Ear muscles for wiggling
Wisdom teeth
D. Biochemical
Living organisms shared numerous related biochemical molecules, such as DNA, ATP, amino
acids, and enzymes. This finding supports descent from a common ancestor. The more closely linked
organisms are the more related is their biochemical genetic makeup.
1. DNA/Nucleic acids
Genes are located in the chromosomes, which are made of DNA or deoxyribonucleic acid.
The more closely related two living organisms are, the more similar the sequence of their
DNA molecules will be.
Figure 5. The phylogenetic tree of the hemogobin gene (with its branches) shows the number
of nucleotide changes that have occurred.
Source: https://evidenceforevolution13bio.weebly.com/biogeography.html
2. Proteins
Proteins are molecules that are used to
build up and repair body parts. Scientists
believe that the more similar the structure
of protein molecules of different
organisms is, the more related they are
and the more recent the existence of their
common ancestor. Unrelated species
have different amino acids.
E. Biogeography
Table 2. Cytochrome c
Biogeography is the study of the geographic distributions of organisms. Darwin’s trip around
South America allowed him to observe the diversity of organisms in different areas and the resemblance
of such species of birds and tortoises in an island to nearby mainland. Darwin believed that the group
of organisms in each island is adapted to a distinct way of life. The common ancestors of these organisms
had come from one place, expanding out into other accessible regions.
Figure 6. Pangolins share similar characteristics with anteaters and armadillos
Need another activity! Try the next activity on the next page.
Explore
Activity 1: Complete the Map!
Direction: Complete the concept map. Use a separate piece of paper.
Evidence for Evolution
Activity 2: Practice Test
Directions: Fill in the puzzle. The puzzle contains terms used in the lesson. Use the letter
clues below to complete the spelling of each word.
1. _ _ _ _ E _ _ _
2.
V________
______
3.
_O_____
4.
____L_____
5. _ _ _ _ _ _ _ _ _ _U _ _ _ _ _
____
6.
___T____
7.
_I__________
8.
_____O____
9.
_N_______
Clues:
a.
b.
c.
d.
A proof or testimony
Non-functional or partly functional organs
Preserved remains of an ancient organisms
Similar structures from the same ancestral body parts but have different
functions
e. The major constituent of genes
f. Made up of amino acids
g. The study of the geographic distributions of organisms
h. The study of the development of the anatomy of an organism to its adult form
i. Have similar functions but different anatomical structures
Deepen
Activity: Self -Test
Directions: Write a short explanation on each question below. Write your answer on a
separate sheet of paper.
1. Can you describe why certain extinct plants and animals were not fossilized?
2. A friend informs you, “man came from apes” since many structural and biochemical
similarities are observed between them. How would you respond to this?
3. On the left are the structural palms of various organisms
or species of primates.
Tarsiers are one of the small species of primates generally
found at tropical islands like Bohol, Philippines. Gibbons are
small apes usually found in the forests of Southeast Asian
regions, Chimpanzees are few of the assumed “smart” animals
and humans are considered to be the highest form of “thinking
organisms” on Earth.
One of the assertions of the theory of Evolution is these
organisms evolved from the related ancestor.
By examining at the picture how will you support or reject the
said claim?
4. In the book, Jurassic Park, by Michael Crichton, scientists are able to reconstruct dinosaurs
by getting dinosaur DNA from a mosquito that had been well-preserved in amber since the era
of dinosaurs. Do you believe this can actually happen in real life? Why?
Well done! Now get ready to measure your mastery on the next page.
ASSESSMENT
Directions: Choose the letter of the best answer. Write the chosen letter on a separate sheet of
paper.
1. DNA of the life-forms on Earth are almost universal and seem to be templated from one original
source, this line of inferring can be based from what evidence of evolution?
A. Fossil record
B. Comparative Anatomy
C. Molecular Biology
D. Embryology
2. Exactly different organisms such fish and humans may have resemblances during the early stage
of their development and will lose some key likenesses as they grow in later stage of
development, which among the following is the line of evidence and field of study that underlie
the said concept for evolution?
A. Fossil record
B. Comparative Anatomy
C Molecular Biology
D. Embryology
3. Preserved bodies of cave dwelling man from cold and icy places suggested that humans look
different in the past, what evidence of evolution is used?
A. Fossil record
B. Comparative Anatomy
C. Molecular Biology
D. Embryology
4. Identify what evidence of evolution is used: vertebrate animals such as humans, chickens and fish
have gill slits and tails during their embryonic stage.
A. Fossil record
B. Comparative Anatomy
C. Molecular Biology
D. Embryology
5. Boa constrictors, a kind of snake has a remnant of what appears to be rudimentary
hind legs, what type of body structure are these?
A. Analogous structures
B. Homologous structures
C. Embryonic structures
D. Vestigial structure
6. These body structures indicate that organisms descended from a close common ancestor.
A. Analogous structures
B. Homologous structures
C. Embryonic structures
D. Vestigial structures
7. Fox and polar bears which are distant relatives both developed white colored fur to adapt to the
snowy environment where they habituate. These body structures are identified as:
A. Analogous structures
B. Homologous structures
C. Embryonic structures
D. Vestigial structures
8. This is the study of body structures of organisms to compare and infer evolutionary
links.
A. Fossil record
B. Comparative Anatomy
C. Embryology
D. Biogeography
9. Which among the following best explains the fossil records as an evidence
of evolution?
A. Recorded events from the past indicates that the Earth was once
filled with water.
B. Fossils suggest that the Earth is not the same as it is today, for
instance there were once a huge massive interconnected land termed
as Pangaea.
C. Fossils recorded the history of life on Earth and indicates that ancient
life forms were different from modern day species.
D. Recorded activities of animals from prehistoric times suggest that
people came from monkeys.
10. How will you differentiate analogous structures from homologous structures as
evidence of evolution?
A. Analogous structures indicate common ancestry while
homologous structures suggest evolution because of same
environmental factors.
B. Analogous structures are structures which indicates that organisms
might developed structures with same function as needs arise while
homologous structures showed pattern of common descent from
different body structures of closely related specie.
C. Both analogous and homologous structures are body structures used by
researchers to study the evolutionary development of organisms
while vestigial organisms showed different result.
D. B and C
11. What evidence of evolution is portrayed by the unique species on islands which
are usually isolated from another mainland?
A. Fossil record
B. Comparative Anatomy
C. Embryology
D. Biogeography
12. Mapping of DNA allows scientist to compare the genes of organisms from the past
and organisms present today, the evidence of evolution used is:
A. Fossil record
B. Molecular Biology
C. Analogous structures
D. Comparative Anatomy
13. Which is NOT true about fossils?
A. They suggest that life has a history.
B. They are proofs of life in the past.
C. The older the fossil, the less it looks like modern day species.
D. They seem precisely like modern-day species, regardless of their age
14. How will you use biogeography as an evidence to infer evolutionary relationship?
A. Organisms living closer at each other and sharing the same niche are
also closely related to each other.
B. The unique characteristics of the organisms living on a secluded area
is indicative of their ancestry and speciation.
C. Biogeography revealed that organisms with similar developmental
pattern even if found at different places might once live together before
they were separated due to natural events or forces.
D. All of the above
15. The following are the pieces of evidence of evolution that may be used to infer the
evolutionary relationship between organisms, EXCEPT
.
A. Comparative Anatomy
C. Molecular Bonds
B. Fossil record
D. Embryology