CLASSIFICATION

Finding Order

in Diversity

WHAT IS TAXONOMY?

Discipline of classifying organisms and assigning each organism a universally accepted name.

WHY CLASSIFY?

To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner.

WHY CLASSIFY? When taxonomists classify organisms, they organize them into groups that have biological significance.

Examples of biological significance

physical features DNA sequence

behaviors

WHY SCIENTIFIC NAMES?

Using common names is confusing because many organisms may have several different common names. The cougar is also known as the mountain lion, puma or catamount…thus the need for a scientific name. Photo courtesy Texas Parks and Wildlife Department © 2004

Felis concolor

What is a SCIENTIFIC NAME?

The first part of the scientific name is the genus. This word is always written first and the first letter is capitalized. It appears in italics or is underlined.

Homo sapien

Ursus arctos Grizzly bear picture is reproduced with permission from WWF. © 2004 WWF- World

Wide Fund For Nature (Formerly World Wildlife Fund). All Rights Reserved.

www.panda.org.

The second part of the scientific name is the species name. This word is always written second and the first letter is lower-case.

It appears in italics or is underlined.

Homo sapien

Ursus arctos

What is a SCIENTIFIC NAME?

A Swedish botanist named Carolus Linnaeus developed Binomial Nomenclature, a two-word naming system for naming all species on earth.

What is BINOMIAL NOMENCLATURE?

What is the LINNAEUS SYSTEM of CLASSIFICATION?

Linnaeus’s hierarchical system of classification includes seven levels. They are, from largest to smallest, Kingdom, Phylum, Class, Order, Family, Genus, Species.

The Kingdom is the largest and most inclusive (includes) of the taxonomic categories.

Species is the smallest and least inclusive of the taxonomic categories.

What is the LINNAEUS SYSTEM of CLASSIFICATION?

The more taxonomic levels that two organisms share, the more closely related they are considered to be.

What is the LINNAEUS SYSTEM of CLASSIFICATION?

What do the scientific names of the polar, grizzly and panda bears tell you about their similarity to each other?

Common name: Polar bear Scientific name:

Ursus maritimus

Common name: Grizzly bear Scientific name:

Ursus arctos

Common name: Panda bear Scientific name:

Ailuropoda melanoleuca

What is the LINNAEUS SYSTEM of CLASSIFICATION?

THINKING CRITICALLY Organism Cat Wolf Fly

Kingdom Animalia Animalia Animalia

Phylum Chordata Chordata Arthropoda

Class Mammalia Mammalia Insecta

Order Carnivora Carnivora Diptera

Family Felidae Canidae Muscidae

Genus Felis Canis Musca

Species F. domesticus C. lupus M. domestica

THINKING CRITICALLY 1. What type of animal is

Musca domestica? 2. From the table, which

2 animals are most closely related?

3. At what classification level does the evolutionary relationship between cats and wolves diverge (become different)?

Animal; insect

Cat and Wolf

Family Level

What is EVOLUTIONARY CLASSIFICATION?

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

What is EVOLUTIONARY CLASSIFICATION?

What is PHYLOGENY? The study of evolutionary relationships

among organisms. What is a CLADE? A group of organisms, such as a species,

whose members share homologous features derived from a common ancestor.

What is a CLADOGRAM?

A B C D E F

Speciation: formation of two

new species from one

Clade or

lineage T

I

M

E

CLADOGRAM of vertebrates

Fur &

Mammary

Glands

Jaws

Lungs

Claws

or Nails

Feathers

Hagfish Fish

Frog

Lizard

Pigeon

Mouse

Chimp

How are CLADOGRAMS used in EVOLUTIONARY CLASSIFICATION?

The characteristics listed below the line are called derived characters (traits).

When the derived character appears above an organism, the organism lacks that derived character.

When the derived character appears below the organism, the organism possesses that derived character.

LIMITATIONS to Linnaen classification

Not all organisms fit neatly into a category

Classification is a work in progress, and subject to change

As new discoveries are made, classification is re-evaluated and revised