Taxonomy

The science of naming organisms.

Aristotle

Plant or animal? If an animal, does it

– Fly– Swim– Crawl

Simple classifications Used common names

Carolus Linnaeus

Described organisms with two word names, instead of polynomials

Developed binomial nomenclature First word = genus name Second word = species name

Why binomial nomenclature?

Much easier than a 10+ word name under old “polynomial system”

Same name no matter where you go Less confusion Binomial = SCIENTIFIC NAME

Scientific Names You Need to Know Homo sapiens Canis lupus Felis domesticus Pan pan

Taxonomic hierarchy

Names organisms and their relationships from very broad to very specific

All organisms classified in a hierarchy Kingdom (broadest) Phylum Class Order Family Genus Species (most specific)

Notes assignment:

Look up the classification for humans for all seven hierarchies and write them below.

What is a species anyway?

Biological species concept– A group of actually or potentially breeding

natural groups that are reproductively isolated from other groups.

» Ernst Mayr, 1924

BSC’s problems– Hybrids

• Sterile offspring of two different species

– Asexual organisms

How many are out there?

Scientists currently estimate that– There are 10 million species worldwide– Over 5 million live in the tropics– Most unnamed species are small or

microscopic

Why is taxonomy useful?

Helps prevent confusion among scientists

Helps to show how organisms are related

Can be used to reconstruct phylogenies – evolutionary histories – of an organism or group

A note on cladograms

Graph showing when different groups diverged from a common ancestral line

Points where they diverge are often noted with a feature that was different between ancestral group and a “new” feature in the group that split off.

Bird Cladogram

The 6 kingdoms

Prokaryotes (Used to be 1 kingdom, Monera)– Archaebacteria– Eubacteria

Eukaryotes– Fungi– Protista– Animal– Plantae

Overview of the 6 kingdoms

Archaebacteria– Unicellular– Live in extreme environments– Prokaryotic

Eubacteria– Unicellular– Prokaryotic– “Common bacteria”

Overview of the 6 kingdoms

Protista– Eukaryotic– Unicellular or colonial– Lots of different life styles

Fungi– Cell walls made of chitin– Eukaryotic– Multicellular– External heterotrophs

Overview of the 6 kingdoms

Plantae– Eukaryotic & Multicellular– Cell walls made of cellulose– Autotrophic

Animalia– Eukaryotic & Multicellular– No cell walls– Internal heterotrophs