Classification Classification A Grouping objects organisms or information
Classification
Classification A. Grouping objects, organisms, or information based on similarities B. Taxonomy - science of classifying organisms.
C. Why Study Taxonomy? • Helps us organize living things to see relationships • To find relatedness between organisms Ex. How related are two species of poisonous snakes?
• Useful tool to quickly identify organisms. Ex. You see a snake or mushroom want to find its name and if it is poisonous. Ex. Identify a bird that you see on a nature hike.
• taxonomists often discover new sources of lumber, medicine, and energy
D. Carolus Linnaeus (1707 -1778) developed the binomial system of naming organisms. - Avoids confusion by common or regional names - Includes 7 categories
• Binomial system - uses two words in which each organism is named by genus and species. • Ex. Ursus maritimus (polar bear Felis domesticus (house cat) Homo sapiens (human) • 1 st word = Genus (Capital letter) • 2 nd word = species (lower case)
• 7 taxonomic categories or taxa.
Problems with traditional classification • Often organisms were classified by the way they looked/anatomy, moved, or reproduced. • Sometimes organisms that are very different evolve similar body structures.
Classification Now • Organisms are grouped into categories representing lines of evolutionary descent, not just physical characteristics • Cladograms - Tool that helps show evolutionary relationships among organisms
• Cladistics groups organisms based on new characteristics that evolve over time. • “evolutionary innovations” • Look for derived characteristics - ones that appear in recent parts of lineage but not in older members.
• similarities in DNA and RNA of organisms can be used in classification. Ex. Organisms that share more DNA sequences in common are more related
Changes in Classification • We now use a 6 kingdom system of classification • Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia • DNA and RNA analysis has given rise to a new category: Domain • Bacteria, Archaea, Eukarya
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