Taxonomy The science of naming organisms. Aristotle Plant or animal?  If an animal, does it  – Fly – Swim – Crawl Simple classifications  Used common names  Carolus Linnaeus Described organisms with two word names, instead of polynomials  Developed binomial nomenclature  First word = genus name  Second word = species name  Why binomial nomenclature? Much easier than a 10+ word name under old “polynomial system”  Same name no matter where you go  Less confusion  Binomial = SCIENTIFIC NAME  Scientific Names You Need to Know Homo sapiens  Canis lupus  Felis domesticus  Pan pan  Taxonomic hierarchy  Names organisms and their relationships from very broad to very specific All organisms classified in a hierarchy Kingdom (broadest)  Phylum  Class  Order  Family  Genus  Species (most specific)  Notes assignment:  Look up the classification for humans for all seven hierarchies and write them below. What is a species anyway?  Biological species concept – A group of actually or potentially breeding natural groups that are reproductively isolated from other groups. » Ernst Mayr, 1924  BSC’s problems – Hybrids • Sterile offspring of two different species – Asexual organisms How many are out there?  Scientists currently estimate that – There are 10 million species worldwide – Over 5 million live in the tropics – Most unnamed species are small or microscopic Why is taxonomy useful? Helps prevent confusion among scientists  Helps to show how organisms are related  Can be used to reconstruct phylogenies – evolutionary histories – of an organism or group  A note on cladograms Graph showing when different groups diverged from a common ancestral line  Points where they diverge are often noted with a feature that was different between ancestral group and a “new” feature in the group that split off.  Bird Cladogram The 6 kingdoms  Prokaryotes (Used to be 1 kingdom, Monera) – Archaebacteria – Eubacteria  Eukaryotes – Fungi – Protista – Animal – Plantae Overview of the 6 kingdoms  Archaebacteria – Unicellular – Live in extreme environments – Prokaryotic  Eubacteria – Unicellular – Prokaryotic – “Common bacteria” Overview of the 6 kingdoms  Protista – Eukaryotic – Unicellular or colonial – Lots of different life styles  Fungi – Cell walls made of chitin – Eukaryotic – Multicellular – External heterotrophs Overview of the 6 kingdoms  Plantae – Eukaryotic & Multicellular – Cell walls made of cellulose – Autotrophic  Animalia – Eukaryotic & Multicellular – No cell walls – Internal heterotrophs