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Classification of Organisms Chapter 17 Biodiversity The variety of organisms considered at all levels of populations to ecosystems. Biologists have classified almost 2 million species More remain unidentified QuickTime™ and a decompressor are needed to see this picture. www2.warwick.ac.uk/ about/environment/faqs/ Taxonomy The science of describing, QuickTime™ and a decompressor are needed to see this picture. www.schenectady.k12.ny.us/.../ naming, and classifying organisms A particular group within a taxonomic system is called a taxon Taxonomy continued Aristotle classified organisms into 2 groups – plants or animals. This was inadequate because more and more organisms are found and described. QuickTi me™ and a decompressor are needed to see thi s pi ctur e. The Linnaean System The system of grouping organisms into hierarchical categories according to their form and structure. Each category represents a level or grouping from larger, more general categories to smaller, more specific categories. Levels of Classification Modern version of Linnaeus’s system uses 8 levels: (see page 338) 1. Domain 2. Kingdom 3. Phylum 4. Class 5. Order 6. Family 7. Genus 8. Species QuickTime™ and a decompressor are needed to see this picture. Binomial Nomenclature System of two-part names. The genus name followed by the species identifier. The species name is written in Italics with the genus name capitalized Species names generally come from Latin roots Subspecies – variations of a species that live in different geographic areas Binomial Nomenclature (examples) Homo sapiens Chaos chaos The species name or scientific name is written in italics with the genus name capitalized Systematics Modern biologists use this to classify organisms not only by visible similarities, but also similarities in embryos, chromosomes, proteins, and DNA. The goal is to classify organisms in terms of their natural relationships Phylogenetics The analysis of the evolutionary or ancestral relationships among taxa. Systematists usually use several types of evidence to hypothesize about polygenetics. Use phylogenetic diagram Cladistics A system of phylogenetic analysis that used shared and derived characters as the only criteria for grouping taxa Three Domains of Life QuickTime™ and a decompressor are needed to see this picture. Three Domains of Life Domain Bacteria Domain Archaea Domain Eukarya Small, single-celled prokaryotic organisms Prokaryotes, live in harsh places, has distinctive cell membranes Eukaryotic organisms, large cells with true nucleus and complex organelles Ex. Cyanobacteria & Hetrotrophic bacteria Ex. Halophiles and Thermophiles Ex. Everything else: plants, animals, etc. Six Kingdoms Eubacteria Arachaebacteria Protista Fungi Plantae Animalia See page 349