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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