Transcript Chapter 18 Classification

Chapter 17
Classification
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Chapter 17 – The Tree of Life
DAY 1
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Taxonomy
•What is taxonomy?
•The science of classification
•Why should we classify
organisms?
•Provides a way to organize
unfamiliar organisms
•Provides a way to name
organisms
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Aristotle
• 2000 years ago,
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Aristotle was the first
taxonomist
Aristotle divided
organisms into plants
and animals.
He subdivided them by
their habitat (land, sea,
or air dwellers)
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Early Taxonomists
• John Ray, a
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botanist, was the
first to use Latin
for naming
His names were
very long
descriptions telling
everything about
the plant
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Carolus Linnaeus
• Father of Taxonomy
(classification)
• Divided organisms on the
basis of structure
• Created the 2-part
system for naming and
classifying organisms
called binomial
nomenclature.
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Binomial Nomenclature
• Two words
• Language
of Latin (it’s universal;
whereas common names may be
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different)
Genus species (capitalize the Genus,
not the species)
Must be underlined or italicized
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Homo sapiens or Homo sapiens
• Look at the example above
• Notice the first word, Homo, is capitalized. The
second is not.
• When writing a scientific name, always capitalize
the genus only.
• Use italics or underlining to let others know it is
a scientific name.
• By the way, Homo sapiens is a human!
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More on Linnaeus
•Linnaeus also came up with a
system for organizing different
types of organisms.
Linnaeus’s system of
classification uses eight taxonomic
categories…
Each group or level of
organization is called a taxonomic
category or a taxon.
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Classification Timeline
• 2 Kingdom system accepted until 1866 when
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Haeckel proposed moving all single-celled
organisms to the kingdom Protista
1938 – Copeland argued that the prokaryotes
deserved their own kingdom called Monera
1959 – Whittaker proposed that because of how
they feed, fungi should be placed into their own
kingdom
1977 – Woese revealed two genetically different
groups of prokaryotes splitting Monera into two
kingdoms, Bacteria and Archaea
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Hierarchy-Taxonomic Groups
BROADEST TAXON
Domain
Kingdom
Phylum (Division – used for plants)
Class
Order
Family
Genus
Most
Species
Specific
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D K P C O F G S
• It helps to come up with a sentence using
the first letter of each taxon to help you
remember them. For example,
Did King Phillip Come Over For Good
Spaghetti?
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3 Domain System
Some scientists use a 3 domain system. Domains
are BIGGER than kingdoms.
These 2
kingdoms
used to
be
combined
into one
called
“Monera”
Domains
Kingdoms
Bacteria
Eubacteria
Archaea
Archaebacteria
Eukarya
Protista
Fungi
Plantae
Animalia
Domains
• Broadest, most inclusive taxon
• Three domains
• Archaea and Eubacteria are
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unicellular prokaryotes (no nucleus or
membrane-bound organelles)
Eukarya are more complex and have a
nucleus and membrane-bound
organelles
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THE 6 KINGDOMS
EUBACTERIA
ARCHAEBACTERIA
PROTISTA
FUNGI
PLANTAE
ANIMALIA
ARCHAEA
• Probably the 1 cells to evolve
• Live in HARSH environments
• Found in:
st
–Sewage Treatment Plants
–Thermal or Volcanic Vents
–Hot Springs or Geysers that are
acid
–Very salty water (Dead Sea; Great
Salt Lake)
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ARCHAEAN
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EUBACTERIA
• Some may cause DISEASE
• Found in ALL HABITATS except
harsh ones
• Important decomposers for
environment
• Commercially important in making
cottage cheese, yogurt,
buttermilk, etc.
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Live in the intestines of animals
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Domain Eukarya is Divided
into Kingdoms
•Protista (protozoans, algae…)
•Fungi (mushrooms, yeasts …)
•Plantae (multicellular plants)
•Animalia (multicellular
animals)
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•Most are
unicellular
•Some are
multicellular
•Some are
Protista
autotrophic, while
others are
heterotrophic
Aquatic
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Fungi
• Multicellular,
except yeast
• Absorptive
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heterotrophs
(digest food
outside their
body & then
absorb it)
Cell walls made
of chitin
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Plantae
•Multicellular
•Autotrophic
•Absorb sunlight to
make glucose –
Photosynthesis
Cell walls made of
cellulose
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• Multicellular
• Ingestive
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Animalia
heterotrophs
(consume food
& digest it
inside their
bodies)
Feed on plants
or animals
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Dichotomous Keying
• Used to identify
organisms
• Characteristics given
in pairs
• Read both
characteristics and
either go to another
set of characteristics
OR identify the
organism
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Example of Dichotomous Key
1a Tentacles present – Go to 2
1b Tentacles absent – Go to 3
2a Eight Tentacles – Octopus
2b More than 8 tentacles – 3
3a Tentacles hang down – go to 4
3b Tentacles upright–Sea Anemone
4a Balloon-shaped body–Jellyfish
4b Body NOT balloon-shaped - 5
This does not mean they need to
be classified in the same group.
Maybe they only evolved similar
body structures!
These situations make it very
difficult for scientists to classify!
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Things
Section 18-3
Classification of Living Things
Go to Section:
Chapter 17 – The Tree of Life
DAY 2
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Problems with Traditional Classification
• During Linnaeus’s time, scientists
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classified organisms based on their
physical appearance, but today we know
that doesn’t always work!
Example: dolphins -> fish or mammals?
Remember, convergent evolution ->
sometimes organisms that are different
from each other evolve similar body
structures, due to the change in the
environment.
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Evolutionary Classification
• Biologists now group
organisms into
categories that
represent lines of
evolutionary descent,
not just physical
features.
• Evolutionary
classification – is the
strategy of grouping
organisms together
based on their
evolutionary history.
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Traditional v/s Evolutionary Classification
Appendages
Crab
Conical
Shells
Barnacle
Crustaceans
Limpet
Crab
Gastropod
Limpet
Barnacle
Molted exoskeleton
Segmentation
Tiny free-swimming larva
TRADITIONAL
CLASSIFICATION
EVOLUTIONARY
CLASSIFICATION
Evolutionary relationships
• These provide clues and information
about how species evolved.
• They are determined on basis of:
•Similarities in structure
•Breeding behavior
•Geographical distribution
•Chromosomes
•Biochemistry
• I. Structural Similarities:
• Imply that species are closely related
and may have evolved from same
ancestor
Examples:
Dandelions/Sunflowers
Bobcat/Lynx
II. Breeding Behavior:
Patterns of reproduction and mating
Examples:
Frogs
III. Geographical Distribution:
Genetic similarities despite
geographic isolation
Examples:
Galapagos Island Finches
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• IV. Chromosomal Comparisons:
• Species may look different
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but have chromosomes that
are almost identical in
structure
Example: Cauliflower,
Cabbage, Broccoli
V. Biochemistry:
Studying DNA sequences,
proteins, nucleotides in
different organisms
If their DNA sequences and
proteins are more alike, then
probably the organisms are
closely related.
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Classification using Cladograms
• To refine evolutionary
classification, biologists now
prefer a method called
cladistics.
Cladogram – a diagram that
shows the evolutionary
relationships among a group
of organisms; includes new
characteristics that arise
as lineages evolve.
Characteristics that appear
in recent parts of a lineage
but not in its older members
are called derived
characters
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Here is an example…
Derived
Characters
Now let’s see what you can do…
Use the following derived characters
to fill in the cladogram, above:
-Wings
- 6 Legs
-Segmented Body - Dbl set of wings
-Jumping legs
- Crushing Mouth parts
-Legs
- Curly Antennae
Did you get it?
Crushing
Mouthparts
Jumping
Legs
Wings
6 Legs
Crushing Mouthparts
Segmented Body
Curly
Antennae
Double Set
of Wings
Now create your own Cladogram…
First, look at the animals we are studying and establish
which characteristics that they share & which are
unique to each individual species.
CELLS
Slug
Catfish
Frog
Tiger
Human
BACKBONE
LEGS
HAIR
OPPOSABLE
THUMB
Now you try drawing your own
cladogram using the information
in the chart….
How’d you do?