Classification

• Classification – grouping of objects or information based on similarities

• Taxonomy – branch of biology that groups and names organisms based on their characteristics

History of Classification Systems• The way we classify organisms changes as we

gather information about: – DNA/protein analysis– Embryology – study of an organism’s early stage

of life

– Anatomy (body parts)/morphology (form)– Phylogeny – evolutionary history of an organism

1. Aristotle (384-322 BC)

- Classified all organisms into 2 groups (kingdoms)

Plants & Animals

herbs shrubs trees air land water

2.Carolus Linnaeus (1707-1778)

• Developed two-word naming system called binomial nomenclature

Ex. Homo sapiensMost names are in Latin – 1st word = genus (capitalized)– 2nd word = species (lowercase) – usually descriptive– Both words must be italicized or underlined

Examples of Scientific Names

• Felis catus

• Panthera leo

• Homo neanderthalensis

3.Current system (with human classification):• Domain (3) – group of similar kingdoms (Eukarya)• Kingdom (7) – group of similar phyla (Animalia)• Phylum – group of similar classes (Chordata)• Class – group of similar orders (Mammalia)• Order – group of similar families (Primates)• Family – group of similar genera (Hominidae)• Genus – group of similar species (Homo)• Species – a group of organisms that can interbreed and

produce fertile offspring in nature (H. sapiens)

Dumb King Phillip Cried Out “For Goodness Sake!”

Examples of Offspring between Two Non-Species

• Horse x donkey = mule

• Lion x tiger = liger

• Zebra x donkey = zonkey

• Camel and llama = cama

• Dog x cat = catdog…just kidding!

Same Species…Different Subspecies

• Canis lupus – gray wolf

• Canis lupus familiaris – domestic dog

subspecies

Which two of these organisms are most closely related?

Ursus americanus, Lepus americanus, Ursus arctos

Phylogenetic tree – diagram that shows an organism’s evolutionary history

Q: Which 2 organisms are most related?

A&B or A&C?A&C or C&D?

Dichotomous Key – identification key that contains pairs of contrasting descriptions