Scientific Classification

Why Classify?

• Biologists must organize living things into groups that have biological meaning.

• Use classification system to name organisms and group them in a logical manner.

Taxonomy

• Discipline in which scientists classify organisms and assign each organism a universally accepted name.

• Organize them into groups that have biological significance.

• Why might we need universally accepted name?

Write first bird that pops into your head

Write the first Hawk that comes into your head

Common Names

• Not good for biologists due to different languages and different regions containing the same animals.

• Shared common names leads to confusion– i.e. Buzzard

Describe this…

First attempts

• Scientists described the physical characteristics – Up to 20 words long!

• Very confusing, no template existed– Scientists describe different things

Binomial Nomenclature• Developed by Carolus Linnaeus

• Each species is assigned two-part scientific name.

• Always written in italics– First word capitalized, second lowercased– First word=genus Second word=unique characteristic• Escherichia coli (E. coli)

Linnaeus’s System of Classification

• Consists of levels (hierarchical)

• Seven levels

• Each level called a taxon (taxonomic category)

Kingdom

• Highest taxonomical rank made up of similar phylum– 6 present kingdoms• Anamalia, Plantae, Fungi, Protista, Archaea, and

Bacteria

Phylum

• Includes many different organisms that share important characteristics

• i.e. Chordata – Share features in their body plan and internal

functions

Class

• Taxon containing similar orders

• i.e. Mammalia – Animals that are warm-blooded, have body hair,

and produce milk for their young

Order

• Taxon containing similar families

• i.e. Carnivora– Ursidae, Canidae, Felidae, etc.

Family

• Taxon containing similar genera

• i.e. Ursidae– Ursus and Ailuropoda

Genus

• Group of closely related species

• i.e. Ursus– Ursus maritimus, Ursus arctos, Ursus americanus,

Ursus thibetanus

Species

• Group of similar organisms that can breed and produce fertile offspring

• i.e. Ursus maritimus

A bit of an example for ya

Kingdom

• Communication Device

Phylum

• Communicates Voice

Class

• Telephone

Order

• Cell Phone

Family

• Smart Phone

Genus

• Droid

Species

• Razr

KingsPlayChess OnFiberGlassStools

Make an anagram

KPCOFGS

SGFOCPK

• Who selects the members of a species?– Nature depends who can mate

• Who selects members of other levels?– We do

• How do we select the characteristics on which to base grouping?

Phylogeny• The study of evolutionary relationships among

organisms.

• Groupings now represent lines of evolutionary descent—not just physical similarities!– Dolphins, whales versus sharks

OR?

Evolutionary relationships

• Species in a genus are more closely related to one another than in another genus. – Share a recent, common ancestor

• All genera in a family share a common ancestor.

Evolutionary Relationships

• The higher the level of the taxon, the further back in time the common ancestor of all the organisms in the taxon.

• Organisms may not appear similar, but are.

Similarities in DNA & RNA

• Even organisms with very different anatomies have common traits.

• Every organism uses DNA & RNA to– Pass information– Control growth and development

• Allow for comparison of organisms at most basic level

Similar Genes

• Starkly different organisms show surprising similarities– i.e. humans and yeast both code for myosin

• Similarities between genes prove common ancestor

Similar Genes

• Starkly different organisms show surprising similarities– i.e. humans and yeast both code for myosin

• Similarities between genes prove common ancestor