ClassificationClassification

Why Classify?Why Classify?

– To study the great diversity of organisms, biologists must give each organism a name.

– Biologists must also attempt to organize living things into groups that have biological meaning.

Assigning Scientific NamesAssigning Scientific Names

– History• 18th century scientists recognized problem with

naming organisms by their common names– cougar, puma, panther, mountain lion– UK: buzzard hawk, US: buzzard vulture

Why all the weird names?Why all the weird names?

• 18th century scientists understood Latin and Greek

Early efforts at naming organismsEarly efforts at naming organisms

• 1st attempts at naming organisms often described physical characteristics– PROBLEMS

• some names were 20 words long• Different scientists described different

characteristics

Binomial NomenclatureBinomial Nomenclature

– (Carolus Linnaeus ~ Swedish botanist)• Two word naming system

– 1st word is capitalized, 2nd is lowercased and italicized– 1st part GENUS / 2nd part special character or

location

Linnaeus’s System of Linnaeus’s System of ClassificationClassification

– Taxonomy taxonomic levels or taxon (taxa: plural)

• Seven levels: • Kingdom• Phylum• Class• Order• Family• Genus• Species

• Kingdom ~ King

• Phylum ~ Phillip

• Class ~ Came

• Order ~ Over

• Family ~ For

• Genus ~ Great

• Species ~ Soup

Grizzly bear (Ursus Grizzly bear (Ursus arctosarctos))

• Genus: Ursus group of closely related species• Contains 5 other kinds of bear including Ursus

maritimus.• 2nd part: arctos / maritimus is unique to species

within genus (important trait or indication of where the organism lives ~ maritimus: sea)

– Giant Panda differs enough to be placed in its own genus• Ailuropoda

Grizzly bear (Ursus Grizzly bear (Ursus arctosarctos))

• Genera that share many characteristics, such as Ursus & Ailuropoda, are grouped into families ~ (Ursidae)

• These bears together with 6 other families of meat-eating animals, (dogs: canidae and cats: felidae are in order Carnivora.

• Carnivora is grouped into class mammalian (worm-blooded, body hair, milk) which also includes order primates (humans, apes, monkeys, prosimians)

• Class mammalian is grouped with birds (aves), reptiles, amphibians, and all fish into a phylum: Chordata.

TaxonomyTaxonomy

Linnaeus only named two kingdoms Linnaeus only named two kingdoms (plants & animals)(plants & animals)

Modern Evolutionary ClassificationModern Evolutionary Classification

– Problems with traditional classification• Dolphins fish or mammals• Barnacle, limpet, crab

– Because of convergent evolution, sometimes organisms that are very different evolve similar body structures

Evolutionary ClassificationEvolutionary Classification

• Darwin’s theory of evolution changed the entire way that biologist thought about classification

• scientists began to understand that organisms share certain traits because of their evolutionary history

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