Organizing Life’s Diversity • Classification: the grouping of objects or

organisms based on their similarities

• Biologists use a system of classification to

organize information about the diversity of living

things

• Taxonomy is a branch of Biology that is the

science of classifying/grouping and naming of

organisms

Earth’s Amazing Diversity

Aristotle’s Classification System • Greek philosopher who developed first classification

system

• Divided all organisms into 2 GROUPS:

• Non motile (plants)

• Plants were grouped by:

• Size small, medium, large for things like herbs,

shrubs, and trees

• Motile (animals)

• Animals were grouped by:

• Their Habitat (air, water, land)

• Morphology (form or structure)

• “Red-Blooded” and “Bloodless”

Linnaeus's Classification System • 18th Century Swedish Naturalist who broadened

Aristotle’s classification method

• Created a system of naming organisms by their

structures and their behavior. (He didn’t realize it but he

was also classifying them by evolutionary relationship).

• Linnaeus’s system of naming and grouping organisms is

called “Binominal Nomenclature” and this system is

still valid today.

• Written in Latin

• Gives each species a scientific name

that has two parts:

• First part: Genus

• Second part: Species

Binomial Nomenclature• Genus: CAPITALIZED (noun)

• means beginning

• Species: lowercase (adj.)

• Example:

• Humans: Homo (man) sapien (wise/thinking)

• Whitetail Deer: Odocoileus virginianus

• Italicized if printed, Underlined if written

• Organisms have a scientific name and a

common name.

• Scientific name is the Genus species name

• Common name is what the organism is commonly

called and is not used in the scientific community

Binomial Nomenclature• The common name of an organism is not used by

scientists because one species may have many

different common names depending on where the

animal lives.

• For example, the Mountain Lion, Mountain Cat, Black

Panther, Painter, Catamount, Ghost Cat, Cougar and

the Puma are all the same organism. People that live

in different areas just call it different things.

Can you think of any other

organisms that have multiple

common names?

The “New” Evolutionary Classification

• Categories represent lines of evolutionary descent, not

just physical and behavioral similarities

• This new method is called: Evolutionary

Classification

• Scientists classify organisms based on their

Evolutionary beginnings • Cladograms are useful

diagrams that are used

to show evolutionary

relationships between

organisms (You may also

hear this called a

Phylogenetic Tree).

Cladograms/Phylogenetic Trees• Scientists use these to understand how one lineage branched

from another in the course of evolution

• To place organisms in a Cladogram, scientists consider

ancestry and homologous characteristics not found in other

organisms.

• A small number of characteristics are used to define each

group.

• Claddists assume that each successive group has a more

recent common ancestor that other previously branched

species don’t share.

Cladograms/Phylogenetic Trees• Scientists use these to understand how one lineage branched

from another in the course of evolution

• To place organisms in a Cladogram, scientists consider

ancestry and homologous characteristics not found in other

organisms.

• A small number of characteristics are used to define each

group.

• Claddists assume that each successive group has a more

recent common ancestor that other previously branched

species don’t share.