Transcript Taxonomy
Taxonomy BIOL 1407 What is taxonomy? • Naming and classification of organisms • Traditionally based on system developed by Carolus Linnaeus Two Components to Linnaean System • Idea of binomial nomenclature – naming organisms • Idea of hierarchy – classifying organisms into groups Binomial Nomenclature • Idea is that each species is assigned a unique name • Name has two parts: a genus name and a specific epithet • Together, the two words make up the scientific name of the species Binomial Nomenclature • Allows clear communication between different researchers • Prevents confusion that can occur from use of common names Example • Scientific Name: Yucca filamentosa • Common Names: Bear grass, Adam’s needle, Weak-leaf yucca • Picture Credit: Larry Allain @ USDANRCS PLANTS Database Scientific Names: General Guidelines • Scientific names are based on Latin. • Scientific names are always italicized (when printed) or underlined (when hand-written) • Modern scientific names follow international guidelines Scientific Names: General Guidelines • Different species with the same genus name are considered to be more closely related to each other than to other species. • Genus name is always capitalized; specific epithet is always lower-case. Example • • • • • Panthera leo – lion Panthera onca – jaguar Panthera pardus – leopard Uncia uncia – snow leopard Lions, jaguars and leopards are more closely related to each other than to snow leopards. Scientific Names: General Guidelines • Some scientific names, especially older ones, include the name of the person who discovered or described the species. • Example: The Tibetan antelope Pantholops hodgsonii was named for the 19th century British naturalist who discovered it, Brian Houghton Hodgson. • Picture Credit: Rhett A. Butler, mongabay.com General Naming Guidelines • Other scientific names refer to a region, such as Didelphis virginiana (Virginia opossum) • Picture Credit: Alden M. Johnson @ California Academy of Sciences General Naming Guidelines • Scientific names often include some feature or trait of the species. The specific epithet for the hairy bush clover, Lespedeza hirta, refers to its “hairy” stem. • Picture Credit: Tom Barnes, University of Kentucky Scientific Names Poison Arrow Frog Dendrobates azureus “Blue Tree-Walker” • Picture Credit: Jessie Cohen, Courtesy of Smithsonian National Zoo @ nationalzoo.si.edu Scientific Names Giant Anteater Myrmecophaga tridactyla “Eater of ants, with three fingers” Picture Credit: Courtesy of Smithsonian National Zoo @ nationalzoo.si.edu Taxonomic Hierarchy • Linnaeus classified organisms into groups, based on shared characteristics. • There were different levels of groups. • Each level nests within the group above. • In his system, the Kingdom was the most inclusive. Successive groups contain fewer and fewer organisms. Linnaean Hierarchy • Kingdom (most general) • Phylum • Class • Order • Family • Genus • Species (unique) Two Kingdom System • Linnaeus classified organisms into two kingdoms: Plantae and Animalia • Plants, fungi, photosynthetic protists were all included into Plantae • Animals, heterotrophic protists (such as Amoeba) were included into Animalia • This system was revised several times. Five Kingdom System • Proposed by Whittaker in 1968 • Kingdom Monera – prokaryotes • Kingdom Protista – protists (eukaryotes that were not plants or animals or fungi) • Kingdom Plantae – plants • Kingdom Fungi – fungi • Kingdom Animalia – animals Five Kingdom Classification Scheme Research by Carl Woese • Research done by Carl Woese in the 1980s with rRNA comparisons showed that all prokaryotes are not closely related. • Prokaryotes are divided into two groups: true bacteria and archaeans (formerly called archaebacteria) rRNA Comparisons • Based on rRNA, plants, animals and fungi share more similarities with each other than with bacteria or archaeans • All eukaryotes share more similarities with each other than with prokaryotes • Archaeans share more similarities with eukaryotes than with bacteria Domains • Based on rRNA studies, Woese proposed a Three Domain System • Domain Bacteria – “true” bacteria (prokaryotes) • Domain Archaea – archaeans (prokaryotes) • Domain Eukarya – eukaryotes Modern Taxonomic Hierarchy • Domains are the highest level (most inclusive), above Kingdoms. • Kingdom Monera is no longer used. • Kingdom Protista is no longer used. • Kingdoms Plantae, Fungi and Animalia are still in use. Modern Taxonomy • Modern taxonomy is in a state of flux. • As genomes are sequenced for different organisms, evolutionary relationships often become more clear. Taxonomy should reflect those relationships. • Expect major changes in taxonomy over the next several years. Three Domains Three Domains Modern Taxonomic Hierarchy Modern Taxonomic Hierarchy Example: Giant Anteater Myrmecophaga tridactyla Domain: Eukarya Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Xenarthra Family: Myrmecophagidae Genus: Myrmecophaga Species: Myrmecophaga tridactyla Categories and Taxa • In this hierarch of classification, the different levels are categories. • A named group at a level is called a taxon (plural = taxa). • The giant anteater is in Class Mammalia. Class is the category; Mammalia is the taxon. • The giant anteater is in Family Myrmecophagidae. Family is the category; Myrmecophagidae is the taxon. The End Unless otherwise specified, all images in this presentation came from: Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.