Classification/Taxonomy

Unit III

Why Classify?To study the diversity of life, biologists use a

classification system to name organisms &

group them in a logical manner.

TaxonomyDefined:

Discipline of classifying organisms and assigning each

organism a universally accepted name.

In other words, naming things based on their characteristics.

Why common names don’t workCommon names vary among languages.

Example:

United Kingdom – Buzzard refers to a hawk

United States – Buzzard refers to a vulture

Red-tailed Hawk Honey Buzzard Turkey Vulture

Carolus Linnaeus

(1707 – 1778)

Created the system of naming we use today.

In taxonomy, a group or level of organization is called a taxonomic category or taxon.

Binomial Nomenclature“Bi” means 2

“nomial” means naming

Nomenclature means “the system of”

Defined:

In binomial nomenclature, each species is assigned a two-part

scientific name.

Example of Binomial NomenclaturePolar Bear is Ursus maritimus Ursus: genus

Ursus contains 5 other kinds of bears

maritimus: species

The Latin word, maritimus, refers to the sea.

Polar bears often live on pack ice that floats in the sea.

Definitions to know

Genus: is a group of closely related species

Species: Group of similar organisms that can breed and produce fertile offspring

Family: Group of genera that share many characteristics

Order: Group of similar families

Class: Group of similar orders

Phylum: Group of closely related classes

Kingdom: Largest taxonomic group, consisting of closely related phyla.

Here We Go…Polar Bear

Species: maritimusGenus: Ursus

Family: UrsidaeOrder: CarnivoraClass: MammaliaPhylum: ChordataKingdom: Animilia

What do these mean?...lets see

What they mean

Species: maritimus (lives in marine environment)

Genus: Ursus (kind of bear)

Family: Ursidae (larger category of bears)

Order: Carnivora (meat-eating animals)

Class: Mammalia (warm-blooded, hair, & milk)

Phylum: Chordata (vertebrates)

Kingdom: Animilia (there are 6 kingdoms)

How to remember:

King Phillip Came Over From Great Spain

Kingdom Phylum Class Order Family Genus Species

Rules of the GameUniqueness: Every name has to be unique.

Universality: Zoologists have adopted, by international agreement, a single language to be used on a worldwide basis. All animals are given a generic (common name) and specific name in Latin (scientific name).

These names are in italics or are underlined separately (i.e. Homo sapiens).

(Homo sapiens)

Visuals

Phylum

Chordata

Class

Mammalia

Order

Carnivora

Family

Ursidae

Genus Ursus

Speciesmaritimus

Taxonomy Video

If these three species belong to the same genus, they are descended from a common ancestor.

Genus species

Felis

domestica

leo

margarita Sand cat`

Lion

Domestic Cat

Felis domestica

Felis leo

Felis margarita

A Problem with Traditional Classification

Traditional classification systems relied on body structure comparisons only

Due to convergent evolution, organisms that are quite different from each other evolve similar body structures.

Convergent Evolution: Process by which unrelated organisms independently evolve similarities when adapting to similar environments.

A Problem with Traditional ClassificationExample: The Crab, The barnacle, & The limpet

• The barnacle and the limpet have similarly shaped shells & look alike

• The crab has a very different body form

• Based on anatomy, the barnacle & limpet could be classified together and the crab in a different group.

Related

This incorrect because crabs and barnacles are actually related

Crustaceans

Even though they do not look a like, crabs & barnacles are actually

related

Gastropods

Molted Exoskeleton

Segmentation

Free swimming Larva

Evolutionary Classification

Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities

Evolution Classification: Is the strategy of grouping organisms together based on their evolutionary history.

Classification Using Cladograms

Cladogram: A diagram that shows the evolutionary relationships among a group of organisms.

Crustaceans

Using Cladograms, you can see that crabs and barnacles share similar characteristics

because they both molt & are segmented

Gastropods

Molted Exoskeleton

Segmentation

Free swimming Larva

Crustaceans

You can also see that ALL have a free

swimming larva stage

Gastropods

Molted Exoskeleton

Segmentation

Free swimming Larva

Classification History

1700s Plantae Animalia

1800s Protista Plantae Animalia

1950s Monera Protista Fungi Plantae Animalia

1990s Eubacteria Archaebacteria Protista Fungi Plantae Animalia

The 6 kingdom paradigm Recently, as evidence about microorganisms

continue to accumulate, biologists came to realize that the Kingdom Monera were composed of 2 distinct groups.

The 6-Kingdom system of classification includes kingdoms:

1. Eubacteria 2. Archaebacteria 3. Protista4. Fungi 5. Plantae 6. Animalia

For our purposes, we will use the 5-Kingdom paradigm and group both types of bacteria together in the Kingdom Monera.

6 KingdomsEubacteria Archaebacteria Protista Fungi Plantae Animalia

E. ecoli Paramecium Fern frodH. coccinea Homo sapiensPyrococcus furiosus

ProkaryoteProkaryote Eukaryote Eukaryote Eukaryote Eukaryote

Autotroph or

heterotrophAutotroph orheterotroph

Autotroph/heterotroph

Heterotroph HeterotrophAutotroph

Most common bacteria

Live in very hot places

Includes Algae

Don’t belong in other euk

Cell walls &

Chloroplasts

Release enzymes to digest

food

No cell wall

No chloroplasts

Multicellular

“Ancient Bacteria”

Where do viruses go?Viruses: Are particles of nucleic acid, protein,

and in some cases lipids that can reproduce ONLY by infecting living cells.

Viruses are made of a core of either DNA or RNA surrounded by a protein coat.

These are T4 Bacteriophage

A bacteriophage is a virus which infects

bacteria

Where do viruses go? (continued)Viruses are not considered alive because they

don’t have ALL the characteristics of life.

Example: They can’t reproduce independently

These are the Influenza Viruses

Influenza or "flu" is an infection of the respiratory

tract that can affect millions of people every year.

The End.