Taxonomy: Branch of biology that groups all life according to their characteristics and history All life on earth is placed into 1 of 6 kingdoms: – Eubacteria – Archaea – Protista – Fungi – Plantae – Animalia (we’ll look a bit more closely at each one as time goes on)

Classification is always a work in progress. – Until 1866: only two kingdoms, Animalia and Plantae Animalia Plantae –1866: all single-celled organisms moved to kingdom Protista Protista –1938: prokaryotes moved to kingdom Monera Monera –1959: fungi moved to own kingdom Fungi –1977: kingdom Monera split into kingdoms Bacteria and Archaea Archea Bacteria

The 6 kingdoms are classified into domains. Domains are above the kingdom level. – domain model more clearly shows prokaryotic diversity - The three domains in the tree of life are Bacteria, Archaea, and Eukarya.

Developed classification system based on physical features Many rules still used today – Binomial Nomenclature: System of giving every organism 2 names – 1 st word: Genus (broad) Species in the same genus are said to be closely related – 2 nd word: Species (specific, never written alone) Example: House cat – Genus: Felis (wild cats, mountain cats, jungle cats, domesticated cats, etc…) – Species: catus

When Writing: – Genus capitalized – species lowercase – Underlined entirely Ex: Homo sapiens When Typing: – Same, except use italics Ex: Homo sapiens

Scientific names help scientists to communicate in a common language. Why do scientists need a naming system? –Some species have very similar common names. –Some species have multiple common names.

We focus on 7 of the 8 individual levels used to classify organisms Domain Kingdom (largest) Phylum Class Order Family Genus Species (smallest) Allows relationships to be clearly seen

Each level, or group (taxon), is included in the level above it. Levels get increasingly specific from kingdom to species. One way to help you remember the levels…. (Mnemonic Device) Dominant Kings Play Chess On Fine Glass Surfaces

Main Idea: The Linnaean classification system has limitations. Linnaeus taxonomy doesn’t account for molecular evidence. – The technology didn’t exist during Linneaus’ time. – Linnaean system based only on physical similarities. – Does not account for convergent evolution. Physical similarities are not always the result of close relationships. Genetic similarities more accurately show evolutionary relationships due to common ancestry. Ex: The red panda

Quick Review Taxonomy: Science of grouping life according to traits and history All life is placed into 7 taxa (falls under 1 of 3 domains) Genus + species = Scientific name ex: Homo sapiens