Taxonomy and Classification Why Classify Biologists want to
Taxonomy and Classification
Why Classify • Biologists want to better understand organisms so they organize them. • One tool that they use to do this is classification—the grouping of objects or information based on similarities. • Taxonomy is the branch of biology that groups and names organisms based on studies of their different characteristics. • Biologists who study taxonomy are called taxonomists.
Keeping track of species • The Greek philosopher Aristotle (384 -322 B. C. ) developed the first widely accepted system of biological classification. • He classified all the organisms he knew into two groups: plants and animals. • >1 million species named, up to 15 million more. • Taxonomy is not new; cultures have been naming plants and animals around them for 1000’s of years. • It’s practical to have names.
Which one is easier? “Watch out—there’s a bear behind that rock! OR “Watch out--there is a large, furry, four-legged creature with long claws, a big mouth set in a short, stout muzzle, attached to a round head containing small eyes and short triangular ears behind that rock!”
Q. What is the largest wild felid (cat) in the United States? Mountain Lion Cougar Panther Painter Puma Catamount
All of the above Puma concolor
Who devised a system for classification? • Carolus Linneaus (1707 -1778) a swedish naturalist. • Devised a two part naming system known as binomial nomenclature.
Binomial Nomenclature • Standard two-part system for naming things. • In this system, the first word identifies the genus of the organism. • A genus (genera-plural) consists of a group of similar species. • The second word, which sometimes describes a characteristic of the organism, is called the specific epithet. Linnaeus described and named > 6, 000 animals and >4, 000 plants using Latin Scientific name does not replace, but instead further defines common name
Scientific and common names • Taxonomists are required to use Latin because the language is no longer used in conversation and, therefore, does not change. • Scientific names should be italicized in print and underlined when handwritten. • The first letter of the genus name is uppercase, but the first letter of the specific epithet is lowercase. Passer domesticus
• Even though the genus and species are thorough sometimes more is needed. • Varities are splits of species. Example peaches & nectarines are both from a peach tree. • Subspecies are variations of species that occur in different regions.
May tell you where it was first discovered: – Didelphis virginiana “ 2 wombs from Virginia” – Sylvilagus floridanus “wood-hare of Florida” Or who discovered it: – Lepus townsendii “hare” discovered by “Townsend”
Modern Classification • Expanding on Linnaeus’s work, today’s taxonomists try to identify the underlying evolutionary relationships of organisms and use the information gathered as a basis for classification. • Grouping organisms on the basis of their evolutionary relationships makes it easier to understand biological diversity. • Taxonomists group similar organisms, both living and extinct. Classification provides a framework in which to study the relationships among living and extinct species.
How Living Things Are Classified • In any classification system, items are categorized, making them easier to find and discuss. • Although biologists group organisms, they subdivide the groups on the basis of more specific criteria. • A group of organisms is called a taxon (plural, taxa). • Organisms are ranked in taxa that range from having very broad characteristics to very specific ones. • The broader a taxon, the more general its characteristics, and the more species it contains.
Taxonomic Hierarchy Kingdom Phylum Class Order Family Genus Specific epithet (species) Mnemonic kings play cards on fine green sofas
Taxonomic rankings • The smallest taxon is species. Organisms that look alike and successfully interbreed belong to the same species. • The next largest taxon is a genus—a group of similar species that have similar features and are closely related.
Taxonomic rankings • Compare the appearance of a lynx, Lynx rufus, a bobcat, Lynx canadensis, and a mountain lion, Panthera concolor. Lynx Bobcat Mountain lion
Taxonomic goals Place organisms into logical categories – system must be capable of being used for information retrieval, so anyone can properly identify any organism Place organisms into categories that show ancestor-descendant relationships
Taxonomic hierarchy Kingdom (Animalia) Phylum (Chordata) Class (Mammalia) Order (Carnivora) Family (Canidae) Genus (Canis) Specific epithet (species) (familiaris) Scientific name: Canis familiaris
THIS IS NOT MY DOG!!!!
Phylogenetic Classification: Models • The evolutionary history of a species is called its phylogeny. • A classification system that shows the evolutionary history of species is a phylogenetic classification and reveals the evolutionary relationships of species. • One biological system of classification that is based on phylogeny is cladistics. • Scientists who use cladistics assume that as groups of organisms diverge and evolve from a common ancestral group, they retain some unique inherited characteristics that taxonomists call derived traits.
Six Kingdom System
Kingdom Archaebacteria • Unicellular, Prokaryote • Either autotroph or heterotroph • Cell walls made of peptidoglycan • Reproduces by binary fission • Lives in Harsh environments: salty lakes, hot springs, anaerobic environments • AKA–Kingdom Moneran
Kingdom Eubacteria • • • Unicellular, prokaryote Either autotroph or heterotroph Cell walls made of peptidoglycan Reproduces by binary fission Includes common bacteria: tooth decay, yogurt production, food poisoning • AKA–Kingdom Moneran
Kingdom Protista • • Unicellular or multicellular Eukaryotic Cell walls made of varying materials Autotroph or heterotroph About 50, 000 species Reproduces-asexually Examples include: – Euglena – Amoeba
Kingdom Fungi • • Unicellular or multicellular Eukaryotic Heterotrophic Cells walls made of chitin. Reproduces - asexually 100, 000 species Including: toadstools, mushrooms, puffballs, rusts or smut
Kingdom Plantae • • • Multicellular Eukaryotic Autotrophic Can reproduce both ways. Cell walls made of cellulose. All but a few are land dwellers. 350, 000 species • Including: mosses, ferns, conifers, flower plants
Kingdom Animalia • • • Multicellular Eukaryotic Heterotrophic No cell walls Reproduces sexually by meiosis. • All animals have some type of symmetry
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