1

Lesson 1 Systematics Based on Evolutionary Relationships:

Tree of Life and Systematics

At the end of this Module, you should be able to:

• Describe the multiple lines of evidence used to infer evolutionary relatedness.
• Create a diagram showing classification is based on evolutionary relatedness.
• Explain the classification of organisms based on the tree of life.
• Analyze the evolutionary relationships of organisms using the concepts of lines of evidences and
phylogenetic tree.

To efficiently study the countless organisms that occupy our biosphere, we can attempt to classify
and describe different organisms into groups that will eventually reflect evolutionary relationships.
How many species are here on Earth? For years, this question keeps on perplexing many biologists.
Speculations, wild guesses, and rough estimations point to as low as half a million and as high as 100 million,
or maybe even more. The Philippines alone which is known to be a mega hotspot for biodiversity has a
significant number of endemic (an ecological state of a species being distinctive to a defined geographic
location) wildlife species which is roughly around 60,000 species of flora and fauna.

Task No. 1: What’s the Difference

Directions: Answer the following questions.
What makes you unique and what makes you similar? To your siblings, mother or father.

Similarities Unique Quality

1.
2.
3.
4.
5.

Conclusion (Task No. 1):

__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________

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 Lecturette No. 1

Lines of evidence to infer evolutionary relationships:

1. Fossil evidence
2. Homologies - Similar characters due to relatedness are known as homologies. Homologies can be revealed
by comparing the anatomies of different living things, looking at cellular similarities and differences, studying
embryological development, and studying vestigial structures within individual organisms.
Each leaf has a very different shape and function, yet all are homologous structures, derived from a
common ancestral form. The pitcher plant and Venus' flytrap use leaves to trap and digest insects. The bright
red leaves of the poinsettia look like flower petals. The cactus leaves are modified into small spines which
reduce water loss and can protect the cactus from herbivory.
Another example of homology is the forelimb of tetrapods (vertebrates with legs). - Frogs, birds, rabbits
and lizards all have different fore limbs, reflecting their different lifestyles. But those different forelimbs all
share the same set of bones - the humerus, the radius, and the ulna. These are the same bones seen in fossils
of the extinct transitional animal, Eusthenopteron, which demonstr ates their common ancestry.
Organisms that are closely related to one another share many anatomical similarities. Sometimes the
similarities are conspicuous, as between crocodiles and alligators, but in other cases considerable study is
needed for a full appreciation of relationships.
Developmental biology - Studying the embryological development of living things provides clues to the
evolution of present -day organisms. During some stages of development, organisms exhibit ancestral features
in whole or i ncomplete form.
3. Biogeography - the geographic distribution of species in time and space as influenced by many factors,
including Continental Drift and long -distance dispersal.
4. Molecular clocks help track evolutionary time - The base sequences of some regions of DNA change
at a rate consistent enough to allow dating of episodes in past evolution. Other genes change in a less
predictable way.

Classification is linked to Phylogeny

Biologists use phylogenetic trees for many purposes, including:
I. Testing hypotheses about evolution
II. Learning about the characteristics of extinct species and ancestral lineages III.
Classifying organisms
The connection between classification and phylogeny is that hierarchical classification is reflected in
the progressively finer branching of phylogenetic trees. The branching patterns in some cases match the
hierarchical classification of groups nested within more inclusive groups. In other situations, however, certain
similarities among organisms may lead taxonomists to place a sp ecies within a group of organisms (for
example genus or family) other than the group to which it is closely related. If systematists conclude that such
mistake has occurred, the organism may be reclassified (that is placed in a different genus or family) to
accurately reflect its evolutionary history.

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 Task No. 2: Let’s Analyze
Directions: Answer the question below. Write your answer on the space provided.

Based on the picture from page 3, What is the connection between classification and phylogeny?

Conclusion (Task No. 2):

__________________________________________________________________________________
__________________________________________________________________________________

Lecturette No. 2

Reconstructing Phylogenies
A phylogeny is a history of the evolutionary descent of extant (i.e., presently living) or extinct (i.e., no longer
living) taxa from ancestral forms. To date, about 1.4 million species (including 750,000 insects, 250,000 plants
and 41, 000 vertebrates) of the 5 to 50 million on Earth have been scientifically described and classified
(Krempels, 2003).
o Primitive vs. Derived Characters
o Homologous vs. Analogous Characters
o Symplesiomorphies vs. Synapomorphies

Cladistic System
Cladistic or phylogenetic systematics is a method that group organisms based on their shared derived
characters. It is said that only shared derived characters can provide information on the phylogeny of the
organism. This is an important work published in 1966 by Willi Hennig. The grouping mainly focuses on taxa
that share many derived characters as opposed to those that do not have shared derived characters.
Relationships are represented as a branching hierarchical tree called a cladogram.
Constructing the Cladogram
Rule 1. The branches at every node can be rotated.
Rule 2. Two lineages branching from a single ancestral node are known as sister taxa.
Rule 3. There is no such as a “most highly evolved species”.
Rule 4. No extant or extinct taxon is considered ancestral to any other extant or extinct taxon.

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Task No. 3: Let’s Try This!
Let us try to exercise your brain cells. Give certain primitive characters with all members of kingdom
Animalia (adapted from Krempels and Lee, 2013). List four primitive characters all humans share with all
other animals, but not with any other living things.

1.
2.
3.
4.

Do you exhibit all four of the characters listed? (Awesome! Now you should be proud that you are
an animal). The characters you have just listed above-if they are exhibited only by animals and not by
other living organisms—are considered symplesiomorphies only with respect to kingdom Animalia. But if
you are considering all living things, then the very same animal characteristics on your list should be
considered synapomorphies that set animals apart from all other living organisms. This means that any
given character cannot be "primitive" or "derived" on its own, however, it can be described as "primitive"
or "derived" only when compared to characters in other taxa. With this in mind, list three derived
characters that set mammals (Mammalia, of which you are a member) apart from all other animals:

1.
2.
3.

Now since you share those characters you just listed with all your mammalian relatives, the
characters are said to be primitive with respect to all mammals, though they are derived with respect to
all animals other than mammals. Do you now recognize this particular logic? Because you share the three
characters above with all other mammals, those characters won't delineate your relationship with other
mammalian groups. Hence, we must consider synapomorphies at the next level. List three derived
characteristics shared by all primates but not shared by other mammals. (You might have to do some
digging.)

1.
2.
3.

The list that you have made above is the three synapomorphies shared primates that set them
apart from all other mammals. Since all primates share these three characters, they are
symplesiomorphies with respect to primates only. However, these three characters will not help you to
determine which primates are your closest relatives. To do that, we must find more unique derived
characters. List two derived characteristics shared by all great apes (Hominidae, of which you are a
member), but not shared by other primates:

1.
2.

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 Now this might be easier for you. Finally, list as many derived characters as possible that make
Homo sapiens different from all other great apes. Be sure to restrict your list to truly BIOLOGICAL
characters. This is where it gets really challenging, since there is no clear line to draw, especially where
cultural influences ("nurture") interact with a truly genetic and heritable ("nature") character.

1.
2.
3.
4.

As what you have done in the previous pages, it is not a simple task to find biological
characteristics that truly separate Homo sapiens from other species of great apes. This is because we
share more than 99% of our DNA with our closest ape relatives, the common Chimpanzees (Pan
troglodytes) and Bonobos (Pan paniscus). If we take a look back at the several lists you have made, note
how synapomorphies identified at higher and higher resolutions help us to determine most recent
common ancestry among the various taxa.
Lifted from General Biology 2 (Rex Bookstore) page 177-178

Task No. 4: Inquiry and Research Case Presentation and Phylogenies

Directions: Research for the following concepts. Construct a brief essay answering the following questions.
Write your answer on your notebook.
1. Why do biologist care about phylogenies? (at least 100 words)

2. Phylogenetic trees have played a key role in a wide range of other applications. Research on other
cases. (at least 100 words)
Example: Investigation whether food sold as “whale meat” in Japan was illegally harvested from
whale species protected under international law.

Task No. 5: Fill Me Please!

What an exemplar performance! You did a great job in finishing this module. Hopefully, you had
an enjoying moment in this journey. Congratulations!

After accomplishing series of Activities, fill in the blanks to complete the sentences below.
It is necessary to have a knowledge about phylogeny because
_______________________________________________________________________________
_______________________________________________________________________________
_____________________________________________________________________________.

Kindly share your thoughts and learnings by finishing the sentences below:
I have learned that ___________________________________________________________

I have realized that ___________________________________________________________

I will use my learning to ______________________________________________________

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Recommended Readings:
• https://evolution.berkeley.edu/evolibrary/article/evo_04 •
https://evolution.berkeley.edu/evolibrary/article/evo_05 •
https://evolution.berkeley.edu/evolibrary/article/evo_07
• https://evolution.berkeley.edu/evolibrary/article/evo_08

REFERENCES and CREDITS to:

Earth Science- Grade 12 Alternative Delivery Mode Quarter 1 - Module 1: Genetics First Edition, 2020
Published by the Department of Education – Division of Cagayan de Oro Schools Division Superintendent:
Dr. Cherry Mae L. Limbaco, CESO V

Teaching Guide for Senior High School

GENERAL BIOLOGY 2
SPECIALIZED SUBJECT

General Biology 2 (REX Bookstore pages 162-194) M.A. Rea, N.H. Dagamac

Lesson 2
Systematics Based on Evolutionary Relationships: Taxonomy

At the end of this Module, you should be able to:

• Identify the different classifications of organisms.
• Classify organisms into a hierarchy based on their unique/ distinctive characteristics.
• Describe a dichotomous key and its role in hierarchical classification.
• Construct and use dichotomous key for identification.
• Appreciate the work of Linnaeus regarding identifying the unique/ distinctive characteristics of a
specific taxon relative to other taxa

In a strict definition, systematics is the study of the diversification of life forms, both p ast and
present, and their relationships among other organism through time. Taxonomy, on the other hand, is
the science of arranging and classifying living organisms into groups called taxa.

Task No. 1: Can be Grouped!

Directions: Answer the following.
Early taxonomists (e.g. Emperor Shen Nung of China around 3000BC) have classified plants based
on practical uses—for food, as herbal medicine, for shelter and others.
As a learner how will you classify objects or items commonly encountered or used in everyday life
such as those found in homes, schools and neighborhood/communities. Write at least 10 examples.
Examples:
I. Kitchen utensils (can be classified based on their use--- spoons, forks, ladles, pots, pans)
II. Clothing (skirts, blouses, socks, pants)

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 Conclusion (Task No. 1):
__________________________________________________________________________________
__________________________________________________________________________________

Lecturette No. 1

The taxonomic system was devised by Carolus Linnaeus (1707-1778). It is a hierarchical system since
organisms are grouped into ever more inclusive categories from species up to kingdom. In 1981, a
category higher than a kingdom, called domain, was proposed by Carl Woese. The table below illustrates how
human is classified using the present classification system. (Note that it is standard practice to italicize the genus
and species names).
The Linnaean taxonomy which is hierarchical in nature is the most employed system nowadays. Note: This
system was created long before scientists understood that organisms evolved.
The scientific name of a species is a “binomial name”, which includes two parts: the genus and the species
epithet. Nomenclature refers to the practice of assigning scientific names. Binomial comes from the words “bi”
meaning “two” and “nomen” meaning “name”. A species name consists of two parts: the genus or generic name
and the specific epithet. The first letter of the genus is always capitalized (e.g. Canis) while the specific epithet
is not capitalized (e. g. familiaris). One can distinguish a species name from the way it is written. Species name
can be in bold letters or underlined or italicized.

Example:
Human

Task No. 2: Classify Me!

Directions: Classify organism based on the hierarchy and system of classification.

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 Conclusion (Task No. 2):
__________________________________________________________________________________
__________________________________________________________________________________

Lecturette No. 2

Biological Nomenclature and Some Basic Rules

It is always important that a name would be assigned to any organism and though some species can
have thousands of common names throughout the world, each has only a single scientific name.
Thus, a formal system of naming species of living things was created and which follows a complete
organizational hierarchy, from species through domain, as shown below for our own species, Homo
sapiens. Each domain contains related kingdoms and each kingdom consists of related phyla and so
on. Within each of these ranks, there may be larger and smaller taxa such as subkingdom,
superphylum, subclass, subspecies, etc.
At present, the following nomenclature codes govern the naming of species, as follows:
• Algae, Fungi, and Plants – International Code of Nomenclature for algae, fungi and plants
(ICN)
• Animals – International Code of Zoological Nomenclature (ICZN)
• Bacteria – International Code of Nomenclature of Bacteria (ICNB)
• Cultivated Plants – International Code of Nomenclature for Cultivated Plants (ICNCP)
• Viruses – International Committee on Taxonomy of Viruses (ICTV)

Some of the major rules in nomenclature, as guided by ICBN and ICZN, are the following:
1. Names should be written in Latin.
2. The scientific name of an organism is always written with the genus capitalized and the species
epithet in lower case letters.
3. Because the words are Latinized, they should always be italicized.
4. When scientific names are written by hand, each separate word should be underlined. 5. The first
name to be validly and effectively published gets the priority. This rule has caused numerous
name changes, particularly on fossil organisms.
6. All taxa must have an author when described. For example, Homo sapiens L., the L
stands for Linneaus who first successfully described and named the organism.

Sample mnemonics:
• Kings Play Chess On Fine Glass Sets
• Kings Play Chess On Finely Green Spaces
• Keep Pond Clean Or Froggy Gets Sick
• Kings Play Chess On Fine Grained Sand
• King Philip Came Over For Green Soup
• Kindly Put Candy Out For Good Students

DICHOTOMOUS KEY AS A TOOL IN IDENTIFICATION

A dichotomous key is a tool that helps identify unknown organisms to some taxonomic level (e.g.,
species, genus, family, etc.). The key is constructed in such a way that a series of choices is made that
leads the user to the correct identity of a sample organism. "Dichotomous" means, "divided into two
parts." Therefore, a dichotomous key always offers two choices for each step, each of which
describes key characteristics of a particular organism or group of organisms.

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Here is an example of Dichotomous key. Familiarize and analyze.

Task No. 3: Create Output

Directions: Construct a dichotomous key. Using these fruits below from family Rutaceae, observe the
features or characteristics of each fruit. Identify possible characters that they can use like
presence/absence of a feature or trait, shape, color etc. Use common names at the end of each choice. a.
citron
b. key lime
c. pomelo
d. makrut lime or Mauritius papeda
e. calamondin or calamansi
f. bitter orange
g. mand arin orange
h. Cochin China Atalantia

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After comparing, answer the guide questions below. Write your answer on your notebook.
I. What trait(s) or character(s) did you use to separate the fruits into groups? Give an example to
illustrate this.
II. Notice differences among fruits. These differences set them distinct from the others. Can you
give an example to show this?

Performance Task Task No. 4: The Science of Entitlement

Directions: Write a short essay regarding Carl Linnaeus and his work. Write the importance of using his
theory and discovery. How is it useful to the current millennium? Write your output in a long bond paper.
(at least 200 words)

Task No. 5: Fill Me Please!

What an exemplar performance! You did a great job in finishing this module. Hopefully, you had
an enjoying moment in this journey. Congratulations!

After accomplishing series of Activities, fill in the blanks to complete the sentences below.
As a studen t, it is important to know taxonomy because
___ ____________________________________________________________________________
_______________________________________________________________________________
______________________________________________________ ________ _______________.

Kindly share your th oughts and learnings by finishing the sentences below:
I have learned that ______________ ____________________________________________

I have realized that _______________ ____________________________________________

I will use my learning to __________ ____________________________________________

11
 SUMMATIVE TEST: GENERAL BIOLOGY 2
Module 3

Name of Learner: ____________________________________ Grade Level: _____________________

Section: _________________________________________ Date: ____________________

I. MULTIPLE CHOICE
DIRECTIONS: Encircle the letter that corresponds to the correct answer. Avoid ERASURES.

1. Which is the correct order of taxa to classify organisms?

a. class, order, domain, species, kingdom, family, phylum, class
b. phylum, kingdom, domain, species, genus, family, order, class
c. genus, domain, order, class, species, family, phylum, kingdom
d. domain, kingdom, phylum, class, order, family, genus, species
2. The study of biological diversity based on evolutionary relationships is
a. classification b. natural selection c. systematics d. taxonomy
3. Organisms are classified based on their ___________.
a. eating habits
b. physical, molecular, and behavioral characteristics
c. reproductive cycles
d. niches
4. Which of the following is the taxa larger than order but smaller than phylum?
a. Classes b. families c. phyla d. species
5. What is used to determine phylogeny?
a. mutation b. DNA c. evolutionary history d. organism on Earth
6. What do scientist in the field of systematics accomplish?
a. discover new fossil sites
b. organize and classify organism
c. name new species
d. communicate among field biologists
7. Which statement about the taxonomic classification is correct?
a. There are more domains than kingdom.
b. Kingdoms are the top category of classification
c. Classes are division of orders
d. Subspecies are the most specific category of classification
8. On a phylogenetic tree, which term refers to lineages that diverged from the same place?
a. sister taxa b. basal taxa c. rooted taxa d. dichotomous taxa
9. Which statement about analogies is correct?
a. They occur only as errors
b. They are synonymous with homologous traits
c. They are derived by similar environmental constraints
d. They are a form of mutation.
10. What does the trunk of the classic phylogenetic tree represent?
a. single common ancestor
b. pool of ancestral organisms
c. new species
d. old species
11. Which phylogenetic model proposes that all the three domains of life evolved from a pool of primitive
prokaryotes?
a. tree of life b. web of life c. ring of life d. network model
12. Which of the following situation is NOT a part of a taxonomist role?
a. Assigning the scientific name to various mosses surveyed in a pristine forest.
b. Constructing a comprehensive compendium of birds in a reserved national park.
c. Provide an in-depth annotation about the morphology of parasitic insects
d. Explain the relatedness of endemic plants found in two different populations
e. Identify an unknown flowering plant found in a herbarium.
13. Which of the following statements is incorrect about the rules in biological nomenclature?
a. Order is a higher rank than family
b. Linnean nomenclature is composed of genus and specific epithet

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 c. A taxon is composed of a name, rank and content
d. It is not a standard rule for all organisms to have a latinized scientific name
e. When writing a scientific name of plants by hand in paper, it must be always italicized.
14. Which of the following best explains the morphological species concept?
a. Sexual reproduction among only similar kinds of species is likely to occur.
b. Different clones with variations in its genetic composition is considered a separate species.
c. Speciation genes among species caused variation in individuals.
d. Mating among different breeds is impossible.
e. A clear difference in appearance makes one a separate species.
15. Which of the following terms is related to cladistics.
a. branching tree
b. synaphomorphic characters
c. primitive domain
d. nested hierarchy
e. paraphyly
16. Birds have wings, as do butterflies and mosquitoes. However, they do not share a recent, common ancestor.
Therefore, the possession of wing in this scenario is called as:
a. homology
b. homoplasy
c. apomorphy
d. polyphyly
e. ancestry
17. Two different monophyletic groups that share common ancestry with each other more recently than either
does with other taxa are known as:
a. subspecies
b. syplesiomorphy
c. synapomorphy
d. sister group
e. polyphyletic
18. While there are many criteria to describe the difference between two species, the biological definition of a
species is based on being part of:
a. a population of animals living in one place
b. a group of animals that behave similarly
c. an interbreeding population of animals
d. a population of animals capable of hybridizing
e. animals that look alike
19. In lake Taal, a species of Sardinella is found to be existing only in that place and nowhere else. This is an
example of ____________________.
a. cosmopolitan species
b. endemic species
c. insipient species
d. phylogenetic species
e. outgroup
20. Molecular phylogenetics can compare the sequence of amino acids in proteins as well as __________________
to identify the characters used to construct cladogram.
a. triglyceride sequence
b. nucleotide sequence
c. carbohydrates chain
d. ribosomes
e. fatty acids

II. IDENTIFICATION
Directions: Identify what is being described in each number. Write your answer in a clean sheet of paper.
1. He devised the present-day taxonomic system.
2. A system of organizing groups into ranks according to status; putting groups at various levels.
3. The theory and practice of classifying organisms.
4. A yardstick for measuring the absolute time of evolutionary change based on the observation that some
genes and other regions of genomes appear to evolve at constant rates.
5. The evolutionary history of a species or group of species.

13
 6. The study of the kinds and diversity of organisms and of any and all relationships among them.
7. Similarity due to shared ancestry.
8. Studying the embryological development of living things provides clues to the evolution of present-day
organisms.
9. Refers to the practice of assigning scientific names.
10. Is a tool that helps identify unknown organisms to some taxonomic level (e.g., species, genus, family, etc.).
11. A principal taxonomic category that ranks above class and below kingdom.
12. Often defined as the largest group of organisms in which any two individuals of the appropriate sexes or
mating types can produce fertile offspring, typically by sexual reproduction.
13. A taxonomic rank in the classification of organisms between genus and order.
14. This is a taxonomic category ranking used in biological classification that is below family and above
species.
15. The highest taxonomic rank in the hierarchical biological classification system, above the kingdom level.

III. CONSTRUCT YOUR OWN

Directions: Construct your own mnemonics on the hierarchy of taxonomy. (example: Kindly Put Candy Out For Good
Students) After that, make a 3 sentence explanation about your mnemonics. Make it as comprehensive as you can.
(10 points)

IV. ESSAY
Directions: Answer the following questions. Write your answer on your notebook. (At least 3 to 5 sentences) (5
points each)
1. Why are protist, plants, fungi and animals classified into the same domain but into different kingdoms?
2. If you start conversing with a friend who is not familiar with scientific names, how would you describe why it is
important and how scientist name species.
3. Why are viruses, viroids, and prions not included in the biological classification system?

References/Lifted from:
 General Biology 2 (REX Bookstore pages 196-198) M.A. Rea, N.H. Dagamac
 Exploring Life Through Science General Biology 2 (Phoenix Publishing House page 328-329) A.C.
MoralesRamos, J.D. Ramos
 Teaching Guide for Senior High School GENERAL BIOLOGY 2 Specialized Subject (pages 109-128)

Lesson 3
Systematics Based on Evolutionary Relationships:
Cladistics and Phylogeny

At the end of this Module, you should be able to:

• Explain how shared derived characters can be used to reveal degrees of relationship through the
concept of phylogeny
• Create a phylogenetic tree showing evolutionary relationships and relatedness of different
organisms
• Describe cladistics and how it can be used to show evolutionary relationship between organisms.
• Create a cladogram showing shared characteristics of a set of organisms.
• Infer the importance of species diversity and cladistics in evolutionary relationships.

14
 Basically, a family picture represents a family tree. Family trees show how people are related to each other.
Similarly, scientists use phylogenetic trees like cladograms to study the relationships among organisms.
Sometimes, family trees are used to show relationships between individuals. Those who are closely related
are located closer tog ether than those who are only distantly related. For instance, in a family tree, we can
see that the siblings are close together, indicating a close genetic relationship. But the siblings are far from
their great aunt, indicating a more distant genetic relationship. Family trees can also be used to see ancestral
connections. That is, we can see that all the people in the last generation have the same great great-
grandparents in common.

Task No. 1: Pre-Activity

Directions: Answer the following questions. Write your answer on a separate sheet of paper.
1. Do you remember the last time you had a family reunion? A summer vacation or a family barbecue
and the latest family picture taken together? Can you describe your family members? What makes
you similar to them and what makes you unique?”
2. List characters or features that served as evidences (e.g. morphological, genetic, etc.) that indeed
they belong to the same family. Note as many as they can think of.

Conclusion (Task No. 1):

__________________________________________________________________________________
__________________________________________________________________________________

Lecturette No. 1

The Cladistic System

Cladistics or Phylogenetic Systematics is a method that group organisms based on their shared derived
characters. It is said that only shared derived characters can provide information on the phylogeny of the
organism. This is an important work published in 1966 by Willi Hennig. The groupings mainly fo cus on taxa
that share many derived characters as opposed to those that do not have shared derived characters.
Relationships are represented as a branching hierarchical tree called a cladogram. The cladogram is
constructed such that the number of changes from one character state to the next are minimized. In the
cladistic system, organisms are classified exclusively on the basis of how recent are the descendants from their
common ancestor. Therefore, always remember that the synapomorphies are the main bas es for the
determination of taxonomic/phylogenetic relationships. The presence of many shared derived characters
among taxa is considered strong evidence of their common descent. Differences in the degree of rate of
change among branches of organisms are i rrelevant to their classification.

Reconstructing Phylogenies

A phylogeny is a history of the evolutionary descent of extant or extinct taxa from ancestral forms.

1. Primitive vs. Derived Characters

Species found at present evolved from previously existing species that we call as ancestral species. Any
character that shows little or no change from ancestral trait is said to be primitive and those that undergo
modification in terms of appearance and/or function in relation to its ancestral trait is said to be derived
character. A primitive character is known as plesiomorphy; a shared primitive character between two or more

15
taxa is symplesiomorphy; a derived character is apomorphy; a shared derived character between two or more
taxa is known as a synapomorphy.

2. Homologous vs. Analogous Characters

If the similarity between two characters in two separate taxa is attributable to their presence in a
common ancestor, then these two characters are said to be homologous. For example, the forelimb bones of
all tetrapod (four-legged) vertebrates are homologous to one another because they all evolved from the same
bones in a common tetrapod ancestor.
When two species have a similar characteristic because of convergent evolution, the feature is called an
analogous feature. For example, a shark and a dolphin both share a fusiform shape that is well adapted for
rapid swimming. However, while the shark’s body evolved from a fishlike ancestor with a somewhat fusiform
shape, the dolphin’s fishlike form is secondarily derived from that of a terrestrial, four legged mammalian
ancestor.

Task No. 2: True or False

Directions: Read the following statement. Write T if the statement is TRUE and F if the statement is FALSE.
Write your answer on the space provided before each number.

______1. Constructing a phylogenetic tree is one way to visualize evolutionary relatedness.

______2. Phylogenetic systematics emphasize descent and common ancestry in order to determine the
evolutionary history of groups of organisms as a determining factor in classification.
______3. Phylogeny is based on the phylogenetic theories that all living organisms share a common
ancestry.
______4. The main goal of phylogenetic tree is to create a diagram that represents evolutionary
relationships among organisms.
______5. Shared derived characters can reveal all the degrees of relationships between different
living and nonliving organisms.

Conclusion (Task No. 2):

__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________

16
 Lecturette No. 2

Relationships are represented as a branching hierarchical tree called a cladogram.

Constructing the Cladogram
Rule 1. The branches at every node can be rotated.
Rule 2. Two lineages branching from a single ancestral node are known as sister taxa.
Rule 3. There is no such as a “most highly evolved species”.
Rule 4. No extant or extinct taxon is considered ancestral to any other extant or extinct taxon.

Task No. 3: Build That Tree

Directions: Answer the following activity. Write your output in a separate sheet of paper.
1. For this activity, you should familiarize the diverse group of vertebrates and make a phylogenetic tree
showing their evolutionary relationships. This tree should be primarily based on physical characteristics,
such as:
I. Presence or absence of a backbone
II. Ability to breathe in air or water
III. Cold or warm blooded
IV. Carnivore, herbivore, or omnivore
V. Presence or absence of hair/fur
VI. Any other external structure such as horns
2. Cut the pictures of each animal including the name. (Refer to the last page)
3. Lay all the animals on their desks and separate them into two groups using the presence or absence of a
backbone as the first character.
4. On a separate sheet of paper, start constructing the phylogenetic tree like the one shown below.

5. Continue separating the animals into smaller groups using the characters in number one.
6. When an animal reaches the tip of the branch, glue it. Repeat for all other animals in the collection.

Task No. 4 Building a Cladogram: Performance Task

Directions: Answer the following activity. Write your output in a separate sheet of paper.
1. Go online. Choose a group of organisms you are interested to work with (e.g. invertebrates,
vertebrates);
2. Download pictures of different species.
3. Print the pictures. In tabular form, list all the characters. Evaluate the characters (whether
primitive or derived).
4. Remember that in building your cladogram, use only shared derived characters.
5. Construct your own cladogram.

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 Task No. 5: Fill Me Please!
What an exemplary performance! You did a great job in finishing this module. Hopefully, you had
an enjoying moment in this journey. Congratulations!

After accomplishing series of Activities, fill in the blanks to complete the sentences below.
By using cladograms and tracing phylogeny of an organisms we can be able to
_______________________________________________________________________________
_______________________________________________________________________________
_____________________________________________________________________________.
Kindly share your thoughts and learnings by finishing the sentences below:
I have learned that ___________________________________________________________

I have realized that ___________________________________________________________

I will use my learning to ______________________________________________________

REFERENCES and CREDITS to:

Earth Science- Grade 12 Alternative Delivery Mode Quarter 1 - Module 1: Genetics First Edition, 2020
Published by the Department of Education – Division of Cagayan de Oro Schools Division Superintendent:
Dr. Cherry Mae L. Limbaco, CESO V

Teaching Guide for Senior High School

GENERAL BIOLOGY 2
SPECIALIZED SUBJECT

General Biology 2 (REX Bookstore pages 162-194) M.A. Rea, N.H. Dagamac

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 SUMMATIVE TEST: GENERAL BIOLOGY 2
Module 4

Name of Learner: ____________________________________ Grade Level: _____________________

Section: _________________________________________ Date: ____________________

I. MULTIPLE CHOICE
DIRECTIONS: Encircle the letter that corresponds to the correct answer. Avoid ERASURES.

1. A primitive character is known as ________________.

a. plesiomorphy b. apomorphy c. synapomorphy d. amorphy
2. What characteristic is observed in the organism such as the flippers of whales (mammals) or fins of
sharks (fish) that share a trait but is different in morphological ancestry.
a. analogous b. homologous c. vestigial d. divergent
3. If the similarity between two characters in two separate taxa is attributable to their presence in a
common ancestor, then these two characters are said to be ______________.
a. analogous b. homologous c. vestigial d. divergent
4. His works mainly focus on taxa that share many derived characters as opposed to those that do not
have shared derived characters.
a. William Hen b. Willi Hennig c. Willi Hen d. William Hennig
5. Which of the following is NOT true about cladogram?
a. The branches at every node can be rotated.
b. Two lineages branching from a single ancestral node are known as sister taxa.
c. The organism in the base of the cladogram is the highly evolved one.
d. No extant or extinct taxon is considered ancestral to any other extant or extinct taxon.
6. This shows the putative evolutionary relationship. It also shows the taxa that is represented as
branches that bifurcate from nodes.
a. phylogenetic roots b. phylogenetic map c. phylogenetic tree d. phylogenetic forest
7. Is an approach to biological classification in which organisms are grouped together based on whether
or not they have one or more shared unique characteristics which are derived from the group’s last
common ancestor and are not present in more distant ancestors.
a. Phylogeny b. Cladistics c. Systematics d. Taxonomy
8. Birds have wings, as do mosquitoes and flies. However, they do not share a recent, common ancestor.
This is known as _____________.
a. homology b. homoplasy c. apomorphy d. polyphyly
9. The evolutionary history of a certain species is referred to as its ______________
a. domain b. classification c. inheritance d. phylogeny
10. In a phylogenetic tree, what do you call the point which a split has occur, which shows a single lineage
evolving to two different branches.
a. trunk split b. branch point c. interval d. node
11. In a cladogram, this represents how organisms diverge into two or more species.
a. trunk split b. branch point c. interval d. node
12. What do you call certain organisms that are found to not possess shared derived traits with other
groups are classified in a cladistic study?
a. ingroup b. outgroup c. inward d. outward
13. These are the traits inherited from the common ancestors of the group.
a. ancestral characters b. derived characters c. normal characters d. common characters
14. The resulting diagram of reconstructing phylogenetic relationship is called ___________________,
which depicts patterns of shared derived traits among groups of organisms.
a. Phylogenetic Tree b. Cladogram c. Clade d. Taxon
15. In a phylogenetic tree, when two lineages stem from the same branch point, they are called
_________________.
a. mother taxa b. father taxa c. sister taxa d. offspring taxa

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 16. Which part of the phylogenetic tree indicates that an ancestral lineage gave rise to all organisms in the
tree?
a. branch point b. sister taxa c. root d. basal taxon
17. Which of the following is used to determine phylogeny?
a. DNA b. life cycle c. species mutation d. evolutionary history
18. What do scientists use to apply cladistics?
a. homoplasy b. homologous traits c. monophyletic trait d. analogous trait
19. What does the word “phyletic” mean?
a. evolutionary development b. heredity c. organismal change d. shared characteristics
20. According to the assumption of cladistics which of the following is TRUE?
a. Groups of related species descended from a common ancestor.
b. Characteristics change over time
c. Branching patterns symbolizes relationships among groups, with new evolutionary groups arising
from a common ancestor.
d. d. All of the above.

II. ESSAY
Directions: Answer the following questions. Write your answer on a separate sheet of paper. (At least 3 to
5 sentences) (5 points each)
1. How does a phylogenetic tree relate to the passing of time?
2. Some organisms that appear very closely related on a phylogenetic tree may not actually be closely
related. Why is this?
3. Why is it important for scientist to distinguish between homologous and homologous characteristics
before building phylogenetic trees?

References/Lifted from:
 General Biology 2 (REX Bookstore pages 196-198) M.A. Rea, N.H. Dagamac
 Exploring Life Through Science General Biology 2 (Phoenix Publishing House page 293-296) A.C.
Morales-Ramos, J.D. Ramos
 General Biology 2 Textbook Department of Education (page 123-129, 141)

CONGRATULATIONS FOR COMPLETING MODULE 1,2 and 3.

Completed the First Quarter of General Biology 2.

~~~

________________________________________
Parent/Guardian’s Signature over Printed Name

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For Task No. 3

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