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CLASSIFICATION Sections 17.1 , 17.2, 17.4 THE LINNAEAN SYSTEM OF CLASSIFICATION 17.1 pg. 518 TAXONOMY Taxonomy – science of naming and classifying organisms. Gives scientists a standard way to refer to species and organize the diversity of living things. Group of organisms = taxon SCIENTIFIC NAMES Binomial Nomenclature: SCIENTIFIC NAMES 1 st name: Genus – includes one or more physically similar species that are thought to be closely related. Italicized and Capitalized 2 nd name: Species descriptor – refers to a trait of the species, scientist who discovered it, or its native location. Italicized and lower case SCIENTIFIC NAMES Examples: Quercus alba =scientific name for white oak Tyto alba = scientific name for barn owls These two organisms share the species name alba. Does this mean they are closely related? SCIENTIFIC NAMES Advantages over common names: 1. many common names for organisms are similar; scientific names help scientists talk about particular species without confusion. 2. one organisms can have multiple common names; one scientific name leads to less confusion. 3. Different languages in different countries. ADVANTAGES OVER COMMON NAMES LINNAEAN CLASSIFICATION How its organized: Seven levels, or taxa Most general to most specific 1. Kingdom 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species Lets make a pneumonic! LINNAEAN CLASSIFICATION Limitations: Focuses on physical similarities alone; no molecular biology (DNA) to back it up. Are physically similar looking species always closely related? Why/why not? LINNAEAN CLASSIFICATION Limitations Example: Panda and raccoon have similar coloring, so Linnaean grouped them together in the same family. DNA evidence shows us that a panda is more closely related to bears than raccoons. Red pandas are more closely related to raccoons than to giant pandas. CLASSIFICATIONS BASED ON EVOLUTIONARY RELATIONSHIPS 17.2 pg. 524 PHYLOGENIES 1. Defined as: evolutionary history for a group of species. PHYLOGENIES 2. Can be shown using diagrams called: cladograms 3. Which are constructed by identifying: common ancestors Cladistics – classification on common ancestry PHYLOGENIES 4. Can be determined using evidence such as: Molecular evidence – DNA a cladogram before and after molecular evidence CLADOGRAM Derived Characters – how groups of species are placed in order shown as hash marks between branches of cladogram Node: represent the most recent common ancestor shared by a clade each place where a branch splits Clade: “snip rule” – when you snip a branch off under a node, a clade falls off. CLADOGRAM DOMAINS AND KINGDOMS 17.4 pg. 533 WOESE’S DISCOVERY Woese discovered two genetically different groups of prokaryotes This discovery split Monera into Bacteria and Archaea. Each group has different cell walls RESULT: life is now divided into three domains THREE DOMAINS 2. Bacteria – which includes kingdom Bacteria One of the largest groups of organisms on Earth. THREE DOMAINS 4. Archaea – which includes kingdom Archaea Known for their ability to live in extreme environments. THREE DOMAINS 6. Eukarya – which includes the kingdoms Protista, Plantae, Fungi, and Animalia. All organisms in Eukarya are eukaryotic with a nucleus and membrane bound organelles. They can be single cellular, colonial, or multicellular. THREE DOMAINS