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Unit 6: Classification and Diversity KEY CONCEPT Organisms can be classified based on physical similarities. Unit 6: Classification and Diversity Linnaeus developed the scientific naming system still used today. • Taxonomy is the science of naming and classifying organisms. White oak: Quercus alba • We always write names in the Genus and species. Unit 6: Classification and Diversity • Binomial nomenclature is a two-part scientific naming system. – uses Latin words – scientific names always written in italics – two parts are the genus name and species descriptor Unit 6: Classification and Diversity • A genus includes one or more physically similar species. – Species in the same genus are thought to be closely related. – Genus name is always capitalized. • A species descriptor is the second part of a scientific name. – always lowercase – always follows genus name; never written alone Tyto alba Unit 6: Classification and Diversity • Scientific names help scientists to communicate. – Some species have very similar common names. – Some species have many common names. Unit 6: Classification and Diversity Linnaeus’ classification system has seven levels. • Each level is included in the level above it. • Levels get increasingly specific from kingdom to species. Unit 6: Classification and Diversity 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. Unit 6: Classification and Diversity • Physical similarities are not always the result of close relationships. • Genetic similarities more accurately show evolutionary relationships. Unit 6: Classification and Diversity Racoon Kingdom: Phylum: Class: Order: Family: Genus: Species: Red Panda Animalia Chordata Mammalia Carnivora Procyonidae Procyon P. lotor Kingdom: Phylum: Class: Order: Family: Genus: Species: Animalia Chordata Mammalia Carnivora Ailuridae Ailurus A. fulgens Unit 6: Classification and Diversity KEY CONCEPT Modern classification is based on evolutionary relationships. DNA!!! De-oxy Ribo Nucleic Acid Unit 6: Classification and Diversity Cladistics is classification based on common ancestry. • Phylogeny is the evolutionary history for a group of species. • evidence from living species, fossil record, and molecular data • shown with branching tree diagrams Unit 6: Classification and Diversity • Evolutionary trees. – classification based on common ancestry – species placed in order that they descended from common ancestor Unit 6: Classification and Diversity Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms, Animalia and Plantae Animalia Plantae Unit 6: Classification and Diversity Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms, Animalia and Plantae Animalia – 1866: all single-celled organisms moved to kingdom Protista Plantae Protista Unit 6: Classification and Diversity Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms, Animalia and Plantae Animalia – 1866: all single-celled organisms moved to kingdom Protista Plantae Protista – 1938: prokaryotes moved to kingdom Monera Monera Unit 6: Classification and Diversity Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms, Animalia and Plantae Animalia – 1866: all single-celled organisms moved to kingdom Protista Plantae Protista – 1938: prokaryotes moved to kingdom Monera – 1959: fungi moved to own kingdom Monera Fungi Unit 6: Classification and Diversity Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms, Animalia and Plantae Animalia – 1866: all single-celled organisms moved to kingdom Protista Plantae Protista – 1938: prokaryotes moved to kingdom Monera – 1959: fungi moved to own kingdom Archea Fungi Bacteria – 1977: kingdom Monera split into kingdoms Bacteria and Archaea Unit 6: Classification and Diversity • Kingdom eubacteria. – one of largest groups on Earth – classified by shape, need for oxygen, and diseases caused Unit 6: Classification and Diversity • Kingdom Archaebacteria . – cell walls chemically different from bacteria – differences discovered by studying RNA – known for living in extreme environments Unit 6: Classification and Diversity – Kingdom Protista Unit 6: Classification and Diversity Kingdom Plantae Unit 6: Classification and Diversity Kingdom Fungi Unit 6: Classification and Diversity Kingdom Animalia Unit 6: Classification and Diversity • Bacteria and archaea can be difficult to classify. – transfer genes among themselves outside of reproduction bridge to transfer DNA – blurs the line between “species” – more research needed to understand prokaryotes