TAXONOMY, PHYLOGENY, AND CLADOGRAMS
Objectives:
Become acquainted with the relationship between evolution the taxonomy
Become familiar with the taxonomic categories
Acquire a basic understanding of phylogeny
Determine how cladograms can be used to evaluate the relationships
between organisms
Introduction
Humans have an insatiable need to categorize objects, whether they are living or
otherwise. Taxonomy is the branch of biology that is concerned with identifying,
naming, and classifying living organisms.
EXERCISE 1
Understanding Taxonomy
All living organisms can be placed into three broad categories or domains. They
are the Domain Eukarya, Domain Bacteria and Domain Archaea. Bacteria and
Archaea are examples of prokaryotes and have a unique cell structure compared
to other living organisms. All living organisms in Domain Eukarya are eukaryotes.
The difference between eukaryotes and prokaryotes centers on the fact that
prokaryotes do not have a nucleus but eukaryotes do.
Below is an example of the categories used in the standard taxonomic system.
1. Domain all inclusive category
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species very restricted category
As previously mentioned, most of the above categories can be subdivided. For
example, class may be subdivided into super class, class, and subclass or there
may be an addition of a super family or subfamily.
Created by Dr. Jennifer Knapp and Revised by Dr. Kevin Ragland Page 1 of 8
, There are six kingdoms to which all organisms can be classified. The kingdoms
that make up the living world include, but aren’t limited to, Animalia, Plantae,
and Fungi.
On the surface, the members of the Domains and Kingdoms appear to be
extremely diverse in shape, size, color and function but, in fact, they share many
common characteristics. These characteristics include cellular organization,
biochemistry, and molecular biology. These common characteristics are what
unify the living world.
The most restrictive categories, genus and species, are used for identifying an
organism. For example, Homo sapiens identifies human beings. The genus and
species names are also referred to as an organism's scientific name. An
organism’s scientific name is two words or a binomial, the genus and species.
The names are either Greek or Latin. The genus and species are written in
italics. The genus is always capitalized and the species is always written with the
genus. The genus may be abbreviated (for example H. sapiens for humans) if it
is written out completely the first time it is used.
Who names an organism? The first person to describe it gets to name it. How
and what they name it is totally up to them. By rule, if two individuals happen to
discover and name the same species, whichever name was used first has
priority and the second one will be discarded.
Answer the following questions by writing the answers in the blanks
provided.
1. What are eukaryotic cells?
Cells that contain a nucleus and organelles, and are enclosed by a
plasma membrane.
2. Which taxon level is considered to be the most inclusive?
Domain has the most individuals in a group.
3. Which taxon level is the most restricted?
Species.
EXERCISE 2
Understanding Evolution
Phylogeny is the origin and evolution of a set of organisms. Phylogenetic
taxonomy is a way to classify groups of organisms by their evolutionary
relatedness.
Objectives:
Become acquainted with the relationship between evolution the taxonomy
Become familiar with the taxonomic categories
Acquire a basic understanding of phylogeny
Determine how cladograms can be used to evaluate the relationships
between organisms
Introduction
Humans have an insatiable need to categorize objects, whether they are living or
otherwise. Taxonomy is the branch of biology that is concerned with identifying,
naming, and classifying living organisms.
EXERCISE 1
Understanding Taxonomy
All living organisms can be placed into three broad categories or domains. They
are the Domain Eukarya, Domain Bacteria and Domain Archaea. Bacteria and
Archaea are examples of prokaryotes and have a unique cell structure compared
to other living organisms. All living organisms in Domain Eukarya are eukaryotes.
The difference between eukaryotes and prokaryotes centers on the fact that
prokaryotes do not have a nucleus but eukaryotes do.
Below is an example of the categories used in the standard taxonomic system.
1. Domain all inclusive category
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species very restricted category
As previously mentioned, most of the above categories can be subdivided. For
example, class may be subdivided into super class, class, and subclass or there
may be an addition of a super family or subfamily.
Created by Dr. Jennifer Knapp and Revised by Dr. Kevin Ragland Page 1 of 8
, There are six kingdoms to which all organisms can be classified. The kingdoms
that make up the living world include, but aren’t limited to, Animalia, Plantae,
and Fungi.
On the surface, the members of the Domains and Kingdoms appear to be
extremely diverse in shape, size, color and function but, in fact, they share many
common characteristics. These characteristics include cellular organization,
biochemistry, and molecular biology. These common characteristics are what
unify the living world.
The most restrictive categories, genus and species, are used for identifying an
organism. For example, Homo sapiens identifies human beings. The genus and
species names are also referred to as an organism's scientific name. An
organism’s scientific name is two words or a binomial, the genus and species.
The names are either Greek or Latin. The genus and species are written in
italics. The genus is always capitalized and the species is always written with the
genus. The genus may be abbreviated (for example H. sapiens for humans) if it
is written out completely the first time it is used.
Who names an organism? The first person to describe it gets to name it. How
and what they name it is totally up to them. By rule, if two individuals happen to
discover and name the same species, whichever name was used first has
priority and the second one will be discarded.
Answer the following questions by writing the answers in the blanks
provided.
1. What are eukaryotic cells?
Cells that contain a nucleus and organelles, and are enclosed by a
plasma membrane.
2. Which taxon level is considered to be the most inclusive?
Domain has the most individuals in a group.
3. Which taxon level is the most restricted?
Species.
EXERCISE 2
Understanding Evolution
Phylogeny is the origin and evolution of a set of organisms. Phylogenetic
taxonomy is a way to classify groups of organisms by their evolutionary
relatedness.
