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Classification. Vocabulary. Prokaryote – unicellular organisms without a nucleus Eukaryote – unicellular or multicellular organisms with a nucleus. Vocabulary. Autotrophs – “self feeder” organisms that can make their own food through photosynthesis
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Vocabulary • Prokaryote – unicellular organisms without a nucleus • Eukaryote – unicellular or multicellular organisms with a nucleus
Vocabulary • Autotrophs – “self feeder” organisms that can make their own food through photosynthesis • Heterotrophs – “other feeder” organisms that must ingest (eat) their food
Why Do We Classify Things? • Placing items in categories is natural for humans. • Wild animals: domesticated animals • Edible plants: poisonous plants • Fresh water fish:salt water fish • There are numerous examples of classification systems.
The First Classification System • The first classification system developed 2,500 years ago by Aristotle. • Organisms were separated into two groups, Plants and Animals. A statue of Aristotle, 384 – 322 BC
Aristotle • He further placed animals into three groups, those that fly, those that walk, and those that swim.
Aristotle • Plants were classified as trees, shrubs or herbs depending on size and structure.
Linnaeus • But, more divisions were needed, and scientists would name organisms whatever they wanted. • A better system was needed that everyone could use. • In 1760 Carolus von Linnaeus published his book on classification.
Binomial Nomenclature • Binomial “two names” • Nomenclature is a system of naming • Carolus von Linnaeus • Two-word naming system • Genus • Noun, Capitalized, Underlined or Italicized • Species • Descriptive, Lower Case, Underlined or Italicized Carolus von Linnaeus(1707-1778) Swedish scientist who laid the foundation for modern taxonomy
Why Do We Classify Organisms? • Biologists group organisms to represent similarities and proposed relationships. • Classification systems change with expanding knowledge about new and well-known organisms. Tacitus bellus
Why a Scientific Classification System? • Ambiguity of terms • All scientists use the same system. • Latin “dead language” • The Latin terms will not change over time • Categorization of relationships: • Evolutionary • Structural • Biochemical
Classification • Classification starts at the largest division that includes the most organisms. • Classification consists of three domains and six kingdoms. The Three Domains Archaea Bacteria Eukarya
The Six Kingdoms The six-kingdom system Archaea Eubacteria Protista Fungi Plantae Animalia • How are organisms placed in kingdoms? • Cell type, prokaryotic or eukaryotic • The number of cells in their body, unicellular or multicellular • Their ability to make food, autotrophs or heterotrophs
Kingdom Phylum Class Order Family Genus Species King Phillip Came Over For Good Soup Classification
The farther you go down the classification system the more specific the name becomes for that particular organism. • What is classification based on?
Biochemistry Genetic System, DNA and RNA Evolutionary History Nutrition Molecular Make-up A Dichotomous Key is used to classify organisms Classification Criteria
Classification System for Lynx and Bobcat • Kingdom: Animalia • Phylum: Chordata • Class: Mammalia • Order: Carnivora • Family: Felidae • Genus: Lynx • Species: Lynx canadensis Lynx rufus lynx bobcat The same to this point, the animals share the same characteristics
Family: Less closely related Larger group Genus: More closely related Precedes species= interbreeding Family:Felidae Lions, tigers, leopards house cats,cheetahs, ocelots Genus: Panthera Leopards (pardus) Lion (leo) Tigers (tigris) Family or Genus Relations?
The First Cat • Most authorities agree that the domestic cat descended from the Caffre cat, a small breed of African wildcat. The Caffre cat was domesticated in ancient Egypt, possibly as early as 2500 BC.
Evolutionary History • The evolutionary history of a species is called its phylogeny. • Cladistics is a system of taxonomy that reconstructs phylogenies by inferring relationships based on similarities.
Taxonomic Diagrams • Biologists group organisms into categories that represent common ancestries, not just physical similarities. • Early naturalists used physical characteristics and later, fossil data, attempting to represent evolutionary relationships among organisms.
Taxonomic Diagrams • Today, modern classification systems use fossil data, physical characteristics and DNA/RNA information to draw increasingly more accurate branching diagrams. • Two types of diagrams are Cladistic and Phylogenic diagrams
Cladistics • Cladograms are based only on characteristics observable in existing species. • The branching patterns in a cladogram are defined by the presence of unique, characteristics shared by all members of the group.
Cladistics • A branching diagram to show an evolutionary family tree is known as a cladogram. • Cladisticshypothesize that every phylum originated from a single group of organisms that has branched into today’s species.
Cladograms • Each branch point or fork in the cladogram, shows a point in evolution where a unique characteristic developed to separate one group from another. • Cladograms are concerned with the order structural differences happened.
Taxonomic Diagrams • Phylogenetic trees, or phylogenies, represent hypothesized evolutionary relationships among organisms and may include extinct as well as modern species.
