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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 Some Common Scientific Names What are the Common Names? Homo sapiens Canis lupus Felis domesticus Homo Sapiens Canis Lupus Grey Wolf Felis domesticus or catus Domestic Cat 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. – – – – – – – Kingdom Phylum Class Order Family Genus Species Check Your Answers Kingdom – Animalia Phylum – Chordata Class – Mammalia Order – Primate Family – Hominidae Genus – Homo Species – H. Sapiens 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 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) 1. Archaebacteria 2. Eubacteria Eukaryotes 1. 2. 3. 4. 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 Any Questions? Let’s Classify the Domestic Cat and The Grey Wolf Grey Wolf Kingdom - Animalia Phylum - Chordata Class - Mammalia Order - Carnivora Family - Canidae Genus - Canis Species - C. Lupus Domestic Cat Kingdom - Animalia Phylum - Chordata Class - Mammalia Order - Carnivora Family - Felidae Genus - Felis Species - F. Catus Dichotomous Key A Dichotomous Key is a tool used in plant or animal identification. The dichotomous key is a series of questions, and each question is a choice between two characteristics. The identity of an organism is determined through the process of eliminating characteristics that do not apply to it. A Simplified Version of a Dichotomous Key Another Simplified Dichotomous Key Example of a Dichotomous Key used for Determining Land Cover Credits step.nn.k12.va.us/science/Bio/biology_p pt/taxonomy.ppt