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Classification

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CLASSIFICATION Why do you think scientists like to put organisms into groups, like mammals or insects? WHAT IS CLASSIFICATION? Classification is the arrangement of ... – PowerPoint PPT presentation

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Title: Classification


1
Classification
  • Why do you think scientists like to put organisms
    into groups, like mammals or insects?

2
What is Classification?
  • Classification is the arrangement of organisms
    into orderly groups based on their similarities
  • Classification is also known as taxonomy
  • Taxonomists are scientists that identify name
    organisms
  • Taxonomists classify organisms into groups called
    taxon

3
Why Classify?
  • Scientists have classified about 2 million
    species
  • However, there are many more organisms than we
    have found.
  • Estimates usually range from 3-10 million, but go
    as high as 50 million
  • That shows Earth has a tremendous amount of
    biodiversity(variety of organisms)
  • This is only 1-5 of all organisms that have ever
    lived!!!!!

4
Why Classify?
  • Accurately uniformly names organisms
  • Prevents misnomers such as starfish jellyfish
    that aren't really fish
  • Uses same language (Latin or some Greek) for all
    names

Sea horse??
5
Confusion in Using Different Languages for Names
6
Latin Names are Understood by all Taxonomists
7
Early Taxonomists
  • 2000 years ago, Aristotle was the first
    taxonomist
  • Aristotle divided organisms into plants animals
  • He subdivided them by their habitat ---land, sea,
    or air dwellers

8
Carolus Linnaeus 1707 1778
  • 18th century taxonomist
  • Classified organisms by their structure
  • Developed naming system still used today

9
Carolus Linnaeus
  • Called the Father of Taxonomy
  • Developed the modern system of naming known as
    binomial nomenclature
  • Two-word naming system

10
Binomial nomenclature
  • Genus species
  • Latin or Greek
  • Capitalize genus, but NOT species
  • Underline when writing
  • Italicized in print
  • American Robin

11
Binomial nomenclature
  • The International Code for Binomial Nomenclature
    contains the rules for naming organisms
  • All names must be approved by International
    Naming Congresses (International Zoological
    Congress)
  • This prevents duplicated names
  • Organisms are often named using descriptive
    words, like habitat or a physical characteristic
    OR sometimes using the person whom discovered
    them

12
Levels of Classification
  • The levels of classification are a hierarchy of
    groups (taxa) from broadest (domain) to most
    specific (species)

13
Levels of Classification
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
  • Sometimes subspecies is added to the bottom of
    the list
  • Subspecies are the same species, but they live in
    different areas

14
  • King
  • Phillip
  • Came
  • Over
  • For
  • Good
  • Soup!

15
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16
Systematics
  • Systematics is a science whose goal is to
    classify organisms in terms of their natural
    relationships
  • Phylogenetics is a type of systematics

17
Phylogenetics
  • The analysis of the evolutionary or ancestral
    relationships among taxa.
  • Classification is based on evolutionary
    relationships
  • Found by studying RNA, DNA, amino acids,
    homologous structures, and embryos
  • These relationships are often shown in a
    cladogram

18
Cladistics
  • Cladisticsis a type of phylogenetics
  • A cladogram is a type of phylogenetic diagram

19
Cladistics
  • Cladogram-A diagram showing how organisms are
    related based on shared, derived characteristics
    such as feathers, hair, or scales
  • Shared characters are features that ALL members
    of a group have in common.
  • For example, all organisms in the Domain Eukarya
    domain have true nuclei
  • Derived characters are features that evolved only
    in the group under consideration.
  • Feathers for example, are believed to have
    evolved only in the birds, not from a common
    ancestor that they have with reptiles.

20
Cladistics
  • Cladograms are organized into clades, which is an
    ancestor and all of its descendants.
  • Cladograms are not only based on physical
    features, they are also based on biomolecular
    similarities (like DNA, chromosomes and proteins)
  • Outgroups-have no shared characteristics with the
    other organisms in the diagram and are only
    distantly related

21
Cladogram
  • Feathers are a derived characteristic in the
    birds
  • Hagfish are the outgroup
  • Jaws are a shared characteristic between all
    organisms except the hagfish

22
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23
Cladogram
  • Hair is a derived characteristic in leopards (on
    this cladogram, only leopards have hair)
  • NOTE-hair is a shared characteristic in the
    previous cladogram, so these characteristics can
    change based on the cladogram
  • Character tables may help you make cladograms

24
Dichotomous Keys
  • Used to identify organisms
  • "Dichotomous" means "divided into two parts".
  • Characteristics given in pairs
  • Read both characteristics and either go to
    another set of characteristics OR identify the
    organism

25
Dichotomous Keys
  • Always read both choices, even if the first seems
    to be the logical one at first.
  • Be sure you understand the meaning of the terms
    involved. Do Not Guess.
  • When measurements are given, use a calibrated
    scale. Do Not Guess.
  • Since living things are always somewhat variable,
    do not base your conclusion on a single
    observation. Study several specimens to be sure
    your specimen is typical.
  • If the choice is not clear, for whatever reason,
    try both divisions. If you end up with two
    possible answers, read descriptions of the two
    choices to help you decide

26
Dichotomous Keys
  • 1. a. Bean round..Garbanzo bean
  • b. Bean elliptical or oblong..Go to 2
  • 2. a. Bean whiteWhite northern
  • b. Bean has dark pigmentsGo to 3
  • 3. a. Bean solid in color.Go to 4
  • b. Bean is spotted...Pinto bean
  • 4. a. Bean black........Black bean
  • b. Bean reddish-brown.Kidney bean

27
Making Dichotomous Keys
  • Eliminate an organism in every step (one part
    leads to a name, the other part leads to another
    step)
  • Use measurements rather than terms like "large"
    and "small".
  • Try to make the choice a positive one -something
    "is" instead of "is not".

28
Making Dichotomous Keys - Continued
  • If possible, start both choices of a pair with
    the same word.
  • If possible, start different pairs of choices
    with different words.
  • Precede the descriptive terms with the name of
    the part to which they apply.(like legs are red
    instead of red legs)

29
DICHOTOMOUS KEY ASSIGNMENT
  • You will be creating your own dichotomous key
  • The subjects of the key will be all the people in
    your row of desks
  • Criteria must be high school appropriate and
    non-insulting
  • Everyone should have between 7 10 people
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