Download Ch 18: Classification Notes

Classification
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 Evolution
has lead to a large variety of
organisms.
 Biologists
have identified and named about
1.5 million species so far.
 They
estimate anywhere between 2 and 100
million additional species have yet to be
discovered.
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
The science of classifying and naming organisms.

Goal – organize living things into groups that have
biological meaning.

This ensures that everyone is talking about the same
organism.

Uses accepted names and common criteria to group
things.
• “Teacher” or “Mechanic”
• “Biology Teacher” or “Auto Mechanic”
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 18th
century- European scientists recognized
that referring to organisms by common
names was confusing.
 Common
names vary among regions within a
country.
• In UK buzzard refers to a hawk
• In the US buzzard refers to a vulture
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 First
attempts at standard scientific names often
described physical characteristics.
 As
a result, these names could be 20 words long!
 The
English translation of the scientific name of
a particular tree might be “Oak with deeply
divided leaves that have no hairs on their
undersides and no teeth around their edges.”
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Carolus
Linnaeus (18th Century) –
a Swedish botanists.
• Hierarchical system that consists of 7
levels/taxa (taxon).
• Currently there are now 8 levels.
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Domain
Kingdom
Phylum
Class
Order
Family
Genus
species
Largest / Least Specific
Taxon :A group or
level of organization
Smallest / Most Specific
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Domain
Kingdom
Phylum
Class
Order
Family
Genus
species
Did
King
Phillip
Come
Over
For
Good
Soup
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DOMAIN Eukaryota
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Developed by Linnaeus.
Two-word naming system.
Assigns a two-part scientific
name.
• Universally accepted
• Written in Greek and Latin
• Written in italics
• First word is capitalized
• Second word is lowercased
• Composed of a genus and species
• Example:
Canis lupis
C. lupis
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 Organisms
determine who belongs to their
species by choosing with whom they will
mate!
 Taxonomic groups above species are
“invented” by researchers.
 Sometimes, due to Convergent Evolution
organisms that are quite different from each
other evolve similar body structures.
 Example: Crab, limpet, barnacle
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Crabs
Barnacles
Limpets
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 Darwin’s
theory of evolution changed the
entire way that biologists thought about
classification.
 Biologists now group organisms into
categories that represent lines of
evolutionary descent, not just physical
similarities.
• Phylogeny
 Species within a genus are more closely
related then species within another genus.
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 Many
biologists now prefer a method
called cladistic analysis.
 This method of classification identifies
and considers only those new
characteristics that arise as lineages
evolve over time.
 Derived characteristics - Characteristics
that appear in recent parts of a lineage
but not in its older members.
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CLADOGRAM-
a diagram which shows evolutionary
relationships among a group of organisms.
Things to know:
-Location of “circles” represent when a characteristic first
appeared.
-Derived traits determine the grouping of organisms.
-Help scientists understand how one lineage might have
branched from another.
Cladogram
Descendants
A splitting event
– called a node
Derived character
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Cladogram
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 Suppose
you were trying to compare diverse
organisms such as yeast and humans.
 It wouldn’t make sense to try to classify
anatomical similarities.
 The genes of many organisms show
important similarities at the molecular level.
 These similarities can be used as criteria to
help determine classification.
 Example: Myosin in humans & yeast
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 American
storks.
vultures have a behavior similar to
• Urinate on legs when overheated.
 Evaporative cooling
 Scientists analyzed DNA.
• Share more similarities in DNA.
• Common ancestor
• American vulture
shares a common
ancestor with a stork
over the African
vulture.
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 Before
Linnaeus’s time, the only two
Kingdoms that existed were Plants and
Animals.
 As scientists discovered new organisms that
didn’t fit into the plant or animal category,
they made new categories.
 Microorganisms got the kingdom - Protista
 Mushrooms, yeast and mold were separated
from plants – and made into Fungi.
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1. Bacteria
 Kingdom Eubacteria
2. Archaea
 Kingdom Archaebacteria
3. Eukarya
 Kingdom Protists, fungi, plantae,
animalia
(Everything with a nucleus)
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•Unicellular
•Prokaryotic
•Live in Extreme environments
•Volcanic Hot springs
•Some need oxygen (Aerobic), others
live in oxygen deprived (Anaerobic)
environments
•Cell walls lack peptidoglycan
•Autotroph or Heterotroph
•Asexual reproduction- binary fission
 Unicellular
 Prokaryotic
- no nucleus, no membrane
bound organelles.
 Cell walls with peptidoglycan.
 Some autotrophic/some heterotrophic.
 Important decomposers.
 Asexual reproduction.
 Found in soil, water, on / inside humans.
 Some cause disease, others help make chemicals
to help humans fight disease causing bacteria.
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Consists
of all organisms that
have a nucleus.
The four kingdoms include:
• Protista
• Fungi
• Plantae
• Anamalia
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1.
2.
3.
4.
5.
Monera - Bacteria
Protist
Fungi
Plants
Animals
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 Recently, biologists
come to recognize that the
Monera (bacteria) were composed of two distinct
groups
• Eubacteria and Archaebacteria
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