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Chapter 18--Classification

Chapter 18--Classification. Linnaeus developed the scientific naming system still used today. White oak: Quercus alba. A taxon is a group of organisms in a classification system. Taxonomy is the science of naming and classifying organisms. . uses Latin words

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Chapter 18--Classification

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  1. Chapter 18--Classification

  2. Linnaeus developed the scientific naming system still used today. White oak:Quercus alba • A taxon is a group of organisms in a classification system. Taxonomy is the science of naming and classifying organisms.

  3. uses Latin words • scientific names always written in italics • two parts are the genus name and species descriptor Binomial nomenclature is a two-part scientific naming system.

  4. A genus includes one or more physically similar species. • Species in the same genus are thought to be closely related. • Genus name is always capitalized. • A species descriptor is the second part of a scientific name. • always lowercase • always follows genusname; never written alone Tyto alba

  5. Scientific names help scientists to communicate. • Some species have very similar common names. • Some species have many common names.

  6. Linnaeus’ classification system has seven levels. • Levels get increasingly specific from kingdom to species. Each level is included in the level above it.

  7. King • Phillip • Came • Over • For • Gooseberry • Soup!

  8. The Linnaean classification system has limitations. • Linnaeus taxonomy doesn’t account for molecular evidence. • The technology didn’t exist during Linneaus’ time. • Linnaean system based only on physical similarities.

  9. Physical similarities are not always the result of close relationships. • Genetic similarities more accurately show evolutionary relationships.

  10. Molecular evidence reveals species’ relatedness. • DNA is usually given the last word by scientists. Molecular data may confirm classification based on physical similarities. Molecular data may lead scientists to propose a new classification.

  11. cladograms – diagram used to show evolutionary relationship among a group of organisms Appendages Conical Shells Crustaceans Gastropod Crab Barnacle Limpet Crab Barnacle Limpet Molted exoskeleton Segmentation Tiny free-swimming larva CLADOGRAM CLASSIFICATION BASED ON VISIBLE SIMILARITIES

  12. Mutations add up at a fairly constant rate in the DNA of species that evolved from a common ancestor. Ten million years later— one mutation in each lineage Another ten million years later— one more mutation in each lineage Molecular clocks use mutations to estimate evolutionary time. The DNA sequences from two descendant species show mutations that have accumulated (black). The mutation rate of this sequence equals one mutation per ten million years. DNA sequence from a hypothetical ancestor • Mutations add up at a constant rate in related species. • This rate is the ticking of the molecular clock. • As more time passes, there will be more mutations.

  13. an event known to separate species • the first appearance of a species in fossil record Scientists estimate mutation rates by linking molecular data and real time.

  14. Mitochondrial DNA and ribosomal RNA provide two types of molecular clocks. • Different molecules have different mutation rates. • higher rate, better for studying closely related species • lower rate, better for studying distantly related species

  15. grandparents mitochondrial DNA nuclear DNA parents Mitochondrial DNA is passed down only from the mother of each generation,so it is not subject to recombination. child Nuclear DNA is inherited from both parents, making it more difficult to trace back through generations. • Mitochondrial DNA is used to study closely related species. • mutation rate ten times faster than nuclear DNA • passed down unshuffled from mother to offspring

  16. Ribosomal RNA is used to study distantly related species. • many conservative regions • lower mutation rate than most DNA

  17. Plantae Animalia Classification is always a work in progress. • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms,Animalia and Plantae

  18. Protista Classification is always a work in progress. Plantae Animalia • 1866: all single-celled organisms moved to kingdom Protista • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms,Animalia and Plantae

  19. Plantae Animalia Protista Monera Classification is always a work in progress. • 1866: all single-celled organisms moved to kingdom Protista • 1938: prokaryotes moved to kingdom Monera • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms,Animalia and Plantae

  20. Plantae Animalia Protista Fungi Classification is always a work in progress. • 1866: all single-celled organisms moved to kingdom Protista • 1938: prokaryotes moved to kingdom Monera • 1959: fungi moved to own kingdom Monera • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms,Animalia and Plantae

  21. Plantae Animalia Protista Archea Bacteria Fungi Classification is always a work in progress. • 1866: all single-celled organisms moved to kingdom Protista • 1938: prokaryotes moved to kingdom Monera • 1959: fungi moved to own kingdom • 1977: kingdom Monerasplit into kingdoms Bacteria and Archaea • The tree of life shows our most current understanding. • New discoveries can lead to changes in classification. • Until 1866: only two kingdoms,Animalia and Plantae

  22. The three domains in the tree of life are Bacteria, Archaea, and Eukarya. • Domains are above the kingdom level. • proposed by Carl Woese based on rRNA studies of prokaryotes • domain model more clearly shows prokaryotic diversity

  23. Domain Bacteria includes prokaryotes in the kingdom Bacteria. • one of largest groups on Earth • classified by shape, need for oxygen, and diseases caused

  24. Domain Archaea includes prokaryotes in the kingdom Archaea. • cell walls chemically different from bacteria • differences discovered by studying RNA • known for living in extreme environments

  25. Domain Eukarya includes all eukaryotes. • kingdom Protista

  26. Domain Eukarya includes all eukaryotes. • kingdom Protista • kingdom Plantae

  27. Domain Eukarya includes all eukaryotes. • kingdom Protista • kingdom Plantae • kingdom Fungi

  28. Domain Eukarya includes all eukaryotes. • kingdom Protista • kingdom Plantae • kingdom Fungi • kingdom Animalia

  29. Kingdom Protista eukaryotic organisms that cannot be classified as animals, plants, or fungi unicellular or multicellular autotrophic or heterotrophic can be plant-like, fungi-like, or animal-like

  30. Kingdom Fungi eukaryotic heterotrophs cell walls made of chitin decomposers mostly multicellular (mushrooms) but a few are unicellular (yeasts)

  31. Kingdom Plantae • eukaryotic & multicellular • photosynthetic autotrophs • nonmotile • cell walls contain cellulose • plant kingdom includes cone-bearing and flowering plants as well as mosses and ferns

  32. Kingdom Animalia eukaryotic & multicellular heterotrophic cells don’t have cell walls most can move = locomotion great diversity

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