Classification of Living Things
Why do we classify things? Supermarket aisles Libraries Classes Teams/sports Members of a family Roads Cities Money
What is classification? Classification: putting things into orderly groups based on similar characteristics Taxonomy: the science of describing, naming, and classifying organisms according to their characteristics and evolutionary history
Early classification Aristotle grouped everything into simple groups such as animals or plants He then grouped animals according to if they had blood or didn’t have blood, and if they had live young or laid eggs, and so on…
Modern Classification System Developed by Carolus Linnaeus Swedish Biologist 1700’s Grouped organisms into hierarchical categories Starts broad and ends specific
Modern Taxonomy The Evidence used to classify into taxon groups 1) Embryology 2) Chromosomes / DNA 3) Biochemistry 4) Physiology 5) Evolution 6) Behavior
The modern system of classification has 8 levels: Domain Kingdom Phylum Class Order Family Genus Species
Helpful way to remember the 8 levels Dumb kids playing catch on freeways get squashed Or…make up your own… D K P C O F G S
Scientific Names: Binomial Nomenclature An organism’s genus is always written first; the organism’s species is always written second The genus is Capitalized; the species is written in lower case Homo sapiens
Representing Evolutionary Relationships: Phylogenetic Tree: - Family tree showing evolutionary history - shows relationships thought to exist between groups or organisms
Representing Evolutionary Relationships: Cladogram: - Uses shared derived traits - Derived traits indicate divergence from a common ancestor