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Chapter 18: Classification

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Chapter 18: Classification * * 18 1 Finding Order in Diversity Life on Earth has been changing for more than 3.5 billion years 1.5 million species named between 2 ... – PowerPoint PPT presentation

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Title: Chapter 18: Classification


1
Chapter 18 Classification
2
181 Finding Order in Diversity
  • Life on Earth has been changing for more than 3.5
    billion years
  • 1.5 million species named
  • between 2 and 100 million additional species have
    yet to be discovered

3
Why Classify?
  • organize living things into groups that have
    biological meaning
  • Taxonomy discipline of classifying organisms
    and assigning each organism a universally
    accepted name

4
Assigning Scientific Names
  • Common names are confusing and vary among
    languages or even regions
  • Ex cougar, mountain lion, panther, puma
  • different species sometimes share a single common
    name
  • Ex buzzard hawk? Vulture?
  • Scientists have agreed to a single name for each
    species
  • Use Latin Greek

5
Binomial Nomenclature
  • Carolus Linnaeus,
  • a Swedish botanist, 1700s
  • binomial nomenclature classification system in
    which each species is assigned a two-part
    scientific name
  • written in italics
  • first word is capitalized, the second word is
    lower case

6
Scientific Names
  • grizzly bear is called Ursus arctos
  • Ursus is the genus
  • Genus group of closely related species
  • arctos is the species
  • unique to each species within the genus
  • Often a Latinized description of some important
    trait of the organism or an indication of where
    the organism lives
  • Ursus maritimus, the polar bear
  • maritimus, referring to the sea

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8
Linnaeus's System of Classification
  • Hierarchical - it consists of levels
  • includes seven levels
  • from smallest to largestspecies, genus, family,
    order, class, phylum, and kingdom.
  • Each level is called a taxon or taxonomic
    category

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10
Ursus arctos (Grizzly Bear)
  • Kingdom Animalia
  • Phylum Chordata
  • Class Mammalia
  • Order Carnivora
  • Family Ursidae
  • Genus Ursus
  • species - arctos

11
Humans
  • Kingdom Animalia
  • Phylum (Division for plants) Chordata
  • Class Mammalia
  • Order Primates
  • Family Hominidae
  • Genus Homo
  • species sapiens

12
  • Taxonomic groups above the level of species are
    invented by researchers who decide how to
    distinguish between one genus, family, or phylum,
    and another.

13
  • Phylogeny the study of evolutionary
    relationships among organisms
  • Biologists now group organisms into categories
    that represent lines of evolutionary descent, or
    phylogeny, not just physical similarities.

14
  • evolutionary classification method of grouping
    organisms together according to their
    evolutionary history

15
  • The higher the level of the taxon, the farther
    back in time is the common ancestor of all the
    organisms in the taxon.

16
  • Cladogram diagram that shows the evolutionary
    relationships among a group of organisms

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20
  • The genes of many organisms show important
    similarities at the molecular level.
  • Similarities in DNA can be used to help determine
    classification and evolutionary relationships.
  • The more similar the DNA sequences of two
    species, the more recently they shared a common
    ancestor, and the more closely they are related
    in evolutionary terms.

21
Dichotomous Key
  • A dichotomous key is a tool that allows the user
    to determine the identity of items in the natural
    world, such as trees, wildflowers, mammals,
    reptiles, rocks, and fish.
  • Keys consist of a series of choices that lead the
    user to the correct name of a given item.
  • "Dichotomous" means "divided into two parts".
    Therefore, dichotomous keys always give two
    choices in each step.

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23
183 Kingdoms and Domains
  • There are now 6 Kingdoms listed below.

24
  • Domain most inclusive taxonomic category
    larger than a kingdom

25
Eubacteria
  • Unicellular
  • Prokaryotic
  • Autotroph or heterotroph
  • Cell walls with peptidoglycan
  • Examples E. coli, Streptococcus, Staph

26
Archaebacteria
  • unicellular
  • prokaryotic
  • extreme environments
  • volcanic hot springs, brine pools, and black
    organic mud totally devoid of oxygen
  • Auto or heterotroph
  • cell walls lack
  • peptidoglycan

27
Protista 
  • eukaryotic
  • greatest variety
  • Most single-celled, some multi
  • photosynthetic or heterotrophic
  • Ex kelp, amoebas, slime mold, paramecium, euglena

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Fungi 
  • heterotrophs
  • feed on dead or decaying
  • organic matter
  • Eukaryotic
  • Most multicellular, some uni
  • Cell walls of chitin
  • EX mushroom, yeast

30
Plantae 
  • multicellular
  • photosynthetic autotrophs
  • Eukaryotic
  • Cells walls of cellulose

31
Animalia 
  • multicellular
  • heterotrophic
  • Eukaryotic
  • No cell walls
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