+ Taxonomy

+ Biologist have identified and named 1.5 million species so far 2 – 100 million additional species have yet to be discovered

+ Taxonomy: discipline where scientist classify organisms and assign each organism a universally accepted name Organisms placed in the same group are more similar than organisms in a different group

+ Assigning Scientific Names Common names: vary among regions and are confusing Ex. Buzzard refers to hawk in some parts but in the US it refers to vultures Scientific names were assigned in Latin and Greek in the 18 th century Latin is a dead language, so if you were to travel to Japan, Latin would still be the same there.

+ Binomial Nomenclature Early efforts (Traditional Classification) Scientific names described physical characteristics Very long names and difficult to standardize Binomial Nomenclature: Carolus Linnaeus Each species assigned 2-part name Scientific name written and underlined First word is capitalized and second word is lowercased First word: Genus Second word: species

+ Classification Based on work from Linnaeus 8 levels of classification or taxa from largest to smallest Domain Kingdom Phylum Class Order Family Genus Species

+ Species are grouped according to which organisms individuals will mate Linnaeus grouped species into larger taxa according to visible similarities and differences But which characteristics are most important?

+ Evolutionary relationships Now use evolutionary descent and not just physical similarities Members of a genus share a recent common ancestor Organisms that appear very similar may not share a recent common ancestor

+ Cladograms Cladistic analysis considers only new characteristics that arrive over time Characteristics that appear in recent parts of a lineage but not in older members are called derived characteristics Cladogram: diagram that shows the evolutionary relationships among a group of organism

+ Cladograms