Chapter 17 Classification
Why is
classification
necessary?
•Are you an organized person?
– Consider – do you organize your room?
Your clothes? Your school work? CDs?
•What would happen if nothing was
organized?
– Would you be able to find anything?
Scientists have identified more than
2 MILLION SPECIES!!!
• Every year, thousands of new species are
discovered.
• There may be millions of undiscovered
species
• especially microbes, plants & insects
• In the Tropical Rain Forest & Oceans
Classification helps scientists understand &
study living things.
I. Biodiversity
• Biodiversity is the variety of
organisms on the earth.
• Considered at all levels from
populations to ecosystems.
A.
Taxonomy
• Taxonomy is the science of describing,
naming, and classifying organisms.
• The branch of biology that names & groups
organisms -according to their
characteristics & evolutionary history.
• A Universal System was designed to Eliminate
the use of Common Names and Confusion in the
Scientific World.
The History of Taxonomy
Aristotle – a Greek philosopher who
lived more than 2,000 years ago
–Classified things- Plant or Animal
• Grouped Animals into Land Dwellers, Water Dwellers,
and Air Dwellers.
• Also grouped Plants into 3 categories, based on
differences in their Stems.
Aristotle’s classification system
was replaced
• As modern science Aristotle's system
was found to be
INADEQUATE.
• Aristotle's categories
did not work for
all organisms.
• his use of common names
was problematic.
Use of Common Names
•
COMMON NAMES, such as “robin” or “fir
tree”, for organisms created some problems
•
common names varied from one locale to
next & did not describe species accurately.
Use of long Latin names
•
Used by scientists before 1700’s,- did not
show relationships between species & were
inconvenient, hard to understand.
Describe a problem with each of
these common names :
-Starfish -Seahorse -Jelly fish
-Peanut -Catfish
-Tiger shark
How are their names misleading?
Discuss problems when 1 organism has 2
common names:
Example- firefly & lightening bug
Carl Linnaeus (1707-1778)
“Father of Modern
Taxonomy”
• He used morphology
(which is the organism’s
structure & form)
• Grouped organisms
into hierarchical
categories
Carl Linnaeus
• Formed “Taxa” (groups of organisms)
• (Used Latin for the Names because it was
the language of educated people)
• Morphology -the STRUCTURAL
SIMILARITIES BETWEEN ORGANISMS
• Series of hierarchical categories
used to show relationships
• He had 2 KINGDOMS: PLANTAE & ANIMALIA.
B. Modern classification system is
based on morphological similarities.
• Hierarchy of eight groups (Taxa)
– Domains- include all six kingdoms
– Kingdom – a taxon of similar phyla or divisions
– Phylum – (phyla-plural)- taxon of similar classes
– Class – taxon of similar orders
– Order – taxon of similar families
– Family – group of similar genera
– Genus – group of similar species
– species – most exclusive, specific group. Members
of this grouping can mate, produce viable offspring
– (varieties) – same species but with slight differences
– (subspecies) – same species, different location
8 Modern Levels of Classification
(From the most general to the most specific)
• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species
Species- is the smallest, most specific groupcontains only 1 kind of organism.
Taxon - A particular group in a taxonomic system
Most specific
Taxon (group)
Most general
taxon
Pneumonic Devices
pick one to help you remember the taxa
• Keep Penguins Cool Or Find
Good Shelter
or
• Kennywood Park Can Open For
Good Summers.
or
• King Phillip Comes Over For Good
Spaghetti
Classification Hierarchy
of
Organisms
3 Domains:
(Most modern level by scientist Carl Woese)
• These are Broad groups above the
kingdom level.
Archaea
Bacteria
Eukarya
Binomial Nomenclature
means
Two Name Naming
• Uses the last 2 categories (the most specific)
to name things. uses the Genus & Species
for the 2 parts of the name
• Always Capitalize the Genus but Not the
Species Identifier.
• Both are either underlined or italicized.
Using Binomial Nomenclature
• Acer rubrum - RED MAPLE TREE
•
•
•
Acer is the Latin name for Maple (genus)
rubrum is the Latin word for Red(species)
Can be Abreviated: A.rubrum.
• Homo sapiens - HUMANS
• Homo -large brain & upright posture.
sapiens for our intelligence & ability
to speak.
Abbreviated H. sapiens
Additional Categories
• Zoologists
– use term “SUBSPECIES” for variations that
may occur in species from different geographical
locations- ie, timber wolf and the northern timber
wolf- ex Canis Lupus ssp occidentalis
• Botanists
– May use the term “division” instead of phylum
– sometimes split species into Subsets known as
VARIETIES. Example: peaches &
nectarines are varieties of Prunus persica var.
Additional Categories
• Microbiologists- Bacteria are also
broken into subsets called STRAINS.
Example: Escherichia Coli – some strains are
harmless, even helpful;- live in our intestines,
but strain E. coli 157 is responsible for food
poisoning deaths.
According to the CDC there are an
estimated 73,000 cases of E. Coli
infection every year in the United States.
The typical symptoms are bloody diarrhea
and (if severe) kidney failure. These
symptoms most commonly appear when a
person has eaten undercooked or
contaminated ground beef.
Testbook Assignment:
• Read chapter 17, section 2
• do end of section questions
• & Define:
– Systematics
– Phylogeny
– Phylogenic Trees
– Embryology, -blastula, -gastrula
– Cladistics
– derived characters,
– cladogram
II. Systematics
• The way we group organisms
continues to change
Today these methods reflect the
evolutionary history of organisms
(What’s in their genes).
This is called Phylogeny.
A. Phylogeny
• organizes the diversity of living
organisms in the context of evolution.
• are based on several types of
evidence:
1. Fossil Record
2. Morphology
3. Embryology
4. Chromosomes & Macromolecules
Phylogenic Trees
• A family tree that shows
evolutionary relationships thought
to exist among organisms.
• Is a hypothesis about the
relationships.
• Is subject to change - as more
evidence is learned.
II. Evidences for Evolutionary Relationships
1. Fossil Record
• a useful tool for ancient organisms.
• Record is incomplete
– Some organisms overrepresented
– Some organisms may be missing
• Need other evidences to verify
phylogenic relationships
Fossils Types:
actual preservation, petrification,
imprints, molds, casts, footprints
• Dated by radioactive
isotopes in fossil or
geological formation in
which fossils are found
• Requires long periods
of time and unusual
conditions for fossil
preservation
II. Evidences for Evolutionary Relationships
2. Morphology
• Examine structure & function
• Homologous structures- similar
features that originated from similar ancestors.
(forelimbs on bat, human, penguin)
• Analogous structures- features that
serve similar functions & look alike but
originated from different embryonic tissues.
(wings- on butterfly, bat, hummingbird)
• Vestigial structures -serve no useful
function any longer in the organism
Homologous structures
Comparing the structural features found in different
organisms reveals a basic similarity.
example is the forelimb of mammals - Although function
is quite different, they are similar structurally.
Analogous structures
• We must look at
structures that look &
function the same but
are not derived from
the same embryonic
tissue.
• These features do not
show recent, related
ancestory.
Vestigial structures
• Features which serve no useful function any
longer in the organism.
• Examples: the pelvis bone in the whale,
tailbone & appendix in humans, pelvis & leg
bones in some snakes, etc
II. Evidences for Evolutionary Relationships
3. Embryology
• SIMILARITIES IN
EARLY
EMBRYOLOGICAL
DEVELOPEMNT OF
VERTEBRATES
• CAN BE TAKEN AS
ANOTHER INDICATION
THAT VERTEBRATES
MAY SHARE A
COMMON ANCESTOR.
At the blastula stage, scientists
begin to look for differences in the
ways organisms develop.
Blastula - An early embryonic form produced by
cleavage of a fertilized ovum - a spherical layer of cells
surrounding a fluid-filled cavity.(think of a basketball)
Gastrula -
double-walled stage of the embryo
succeeding the blastula; the outer layer of cells is the
ectoderm and the inner layer differentiates into the
mesoderm and endoderm
Embryology exampleAt the blastula stage- what happens if a scientist
separates a cell from the ball?
• In Vertebrates (animals with a backbone) &
Echinoderms animals like starfish & sand
dollars)- any cell separated can produce a “twin”.
• But blastula cells in a fruit fly cannot- the separated
cells are already specialized to form a part & will die.
• Conclusion- we are more closely
related to starfish than insects
II. Evidences for Evolutionary Relationships
4. Chromosomes &
Macromolecules
• Taxonomists compare Macromolecules like DNA,
RNA & Proteins.
• Example- the number of differences in amino acids
is a clue to how long ago 2 species “Diverged”
• Divergent Evolution- 2 species become
more and more dissimilar.
• Convergent Evolution- Species which
have different ancestors, but have become more
similar
Proteins indicate degree of relatedness.
Differences - Amino Acids in Protein Cytochrome C
Number of different amino acids found in human cytochrome C as opposed to selected organisms
Organism
# of amino acids different
compared to humans
Human
0
Self (Family Hominidae, Order Primates)
Monkey
1
Different family (Pongidae), same order (Primates)
Pig, bovine, sheep
10
Horse
12
Dog
11
Rabbit
9
Chicken, Turkey
13
Duck
11
Rattlesnake
14
Turtle
15
Tuna
21
Different class (Ostheichthys), same phylum (Chordata) poikilothermic
Moth
31
Different phylum (Arthropoda), same Kingdom (Animalia)
Candida fungus
51
Different Kingdom (Fungi)
•
Different order (Carnivora), same class (Mammalia)
Different class (Aves), same phylum (Chordata) homeothermic
Different class (Reptilia), same phylum (Chordata) poikilothermic
(From Atlas of Protein Sequence and Structure, 1967-68 by Margaret O. Dayhoff
Chromosome comparisons
• For example, cauliflower, cabbage, kale, and
broccoli look different but have chromosomes
that are almost identical in structure.
Martin (1993).
B. Cladistics
• uses shared, derived characters as
the only criterion for grouping taxa.
• Shared character - A feature that all
members of a group have in common
• Derived character - A feature that
evolved only within the group under
consideration
• is a newer way to display relationships
• Derived Characters- are special features that
apparently have only developed in that group.
Examples:
– feathers in birds
– larger brains. Homosapiens
have larger brains than the
'outgroup' (monkeys). The larger brain of
homosapiens is a derived characteristic.
• Clade – A Group of organisms that includes an
ancestor plus all of its descendants
Cladogram
• Diagrams which show derived characters
• Shared & derived characters are strong
indicators of common ancestry.
• Cladograms can show non-traditional
conclusions about
which organisms
are “close cousins”.
Cladogram
From this cladogram, we can figure out that
brown bears have more derived characters in
common with sun bears than with dogs &
lesser pandas are more closely related to
racoons than giant pandas.
Linnaean Taxonomy - compared to
Phylogenetic Nomenclature:
• Linnaean Taxonomy - Primary goal
is to group species based on morphological
similarities (who has 6 legs)
• Phylogeny- Primary goal is to reflect the
process of evolution (who’s close cousins)
Dichotomous Key
• graphically organizes data.
• You start with a main idea, split that
into two major pieces.
• Those pieces are then split again into two
major pieces. You continue splitting until you
reach only one possible answer.
• Each set of questions is called a couplet, &
contains instructions for which couplet to go
to next.
Example of Dichotomous Key
Dichotomous Key Use
• Can be used by any one to classify anything.
• Are used by taxonomists to classify organisms.
III. Taxonomic Groups
3 domains, 6 kingdoms
1. Domain Archaea
– aligns with Kingdom Archaebacteria, are
single-celled prokaryotic cells that have distinctive
cell walls & are “ancient bacteria”
2. Domain Bacteria
– aligns with Kingdom Eubacteria, are singlecelled prokaryotic cells that are “true bacteria”.
3. Domain Eukarya
– Domain Eukarya includes the kingdoms Protista,
Fungi, Plantae, & Animalia.
– All members of this domain have eukaryotic cells.
•
SIX KINGDOMS GROUP ORGANISMS TOGETHER THAT
HAVE SIMILARITIES SUCH AS MAJOR CELLULAR
STRUCTURE, METHODS OF OBTAINING NUTRIENTS,
AND METABOLISM.
A closer look at
each of the 6
kingdoms:
Domain: Archaea, kingdom
Archaea
vs.
Domain: Bacteria, Kingdom
Eubacteria
• Organisms in the Kingdoms Eubacteria
& Archaea are very different from each
other, both genetically &
biochemically!
• Archaea have been found in temperatures
above the boiling point and in cold that
would freeze your blood.
• Eubacteria are the “regular” bacteria.
Domain:
Archaea,
Kingdom
Archaea
1. Archaea
• “archae”- from the Greek for "ANCIENT".Scientists
think these are similar to Earth’s First Organisms
• “Extremophiles” – Many types of
Archaeans live in HARSH ENVIRONMENTS
Some types are
• Methanogens
• Themoacidophiles
• Extreme Halophiles
Methanogens
Live in ANAEROBIC
Environments,
• Produce Methane
Gas, a byproduct of
metabolism in conditions of very low oxygen
• Includes Chemosynthetic Bacteria.
• Lives in the Intestines of Mammals.
• Methanobrevibacter smithii is the prominent
methanogen in the human gut, where it
helps digest polysaccharides (sugars).
http://www.nature.com/nrgastro/journal/v8/n10/full/nrgastro.2011.159.html
Thermoacidophiles
- living in Sulfurous Hot Springs & Volcanic Vents
They “love”“acid” & “heat”
Extreme Halophiles
Live in Very Salty Places
(like the great Salt lake & the Dead Sea)
(Halite is the mineral name for NaCl)
Domain: Bacteria, Kingdom Eubacteria
2. “true” or
Eubacteria
• The first thing you probably think of
when you say this word is “disease”something like strep. throat or maybe an
infection in a cut.
• Most of the bacteria that are disease
causing are Eubacteria.
• NOTE: Only about 1% of bacteria
are disease causing.
Domain: Bacteria, Kingdom Eubacteria
• Many bacteria are very helpful organisms.
• Actinomycetes, produce antibiotics such as
streptomycin and nocardicin;
• others live symbiotically in the guts of animals
(including humans) or elsewhere in their bodies,
or on the roots of certain plants, converting
nitrogen into a usable form.
• Bacteria put the tang in yogurt and the sour in
sourdough bread;
• help to break down dead organic matter; & make
up the base of the food web in many
environments.
Domain: Bacteria, Kingdom Eubacteria
“True” Bacteria:
So remember- Most bacteria are beneficial
• Benign (benign = good, friendly, kind)
• Pathogens (means disease causing -only a
few are “bad guys”)
• Bacteria occur in 3 basic shapes: cocci,
bacilli & spiral. Many are named by
their shape.
biology.clc.uc.edu
Examples of common bacteria
Lactobacillus
acidophilus
Streptococcus
pneumoniae
Escherichia
coli
answersingenesis.org
http://www.oley.org/lifeline/Probiotics.html
genome.microbio.uab.edu
Domain: Eukarya, Kingdom Protista
3. Protists
• Made of a variety of organisms that don’t “fit”
anywhere else. (Some are not very much like
the others in this group.)
• EUKARYOTIC (has a true nucleus)
• 50,000 species- many unicellular, some are
like fungi, some like plants or animals.
• Includes protozoans, unicellular algae, slime
molds & water molds
Examples of Protists includes slime
molds & protozoans like Euglena,
Paramecium, Ameoba
Domain: Eukarya, Kingdom Fungi
4. Fungi
• Can be Unicellular or multicellular
• HETEROTROPHIC (eats something else)
–NOT like plants (photosyntheic) (this is why
they were kicked out of the plant kingdom)
100,000 species of mushrooms,
puffballs, rusts, mildew & molds
Agaricus bisporus:
The Button Mushroom
Fungi Examples:
Stink horn
Candida albicanscan cause yeast
Infections- like this
mouth thrush
fcps.edu
reference.medscape.com
http://www.mushroomexpert.com/agaricus_bisporus.html
Domain: Eukarya, Kingdom Plantae
5. Plantae
• Multicellular &
• Photosynthetic (Autotrophs)
(They make their own food & are the chief
food producers of the world.)
• Found in all the types of environments:
aquatic algae, amphibian mosses, and
terrestrial ferns and seed-bearing plants.
• 350,000 species identified.
http://plantspages.com/typesofplants.htm
Cladogram of the plant kingdom
Domain: Eukarya, Kingdom Animalia
6. Animalia
• Eukaryotic,
• Multicellular
• Heterotrophic
• Most animals are symmetrical
• Movement at some time in
their life cycle.
Examples of animals
biology.kenyon.edu
What is on the ch 17 test?
• 1-6 Matching the 6 kingdoms or 3 domains
with the correct description.
• 7-40. Multiple choice. Review you notes.
*Know the classification groups, the
correct way to write binomial nomenclature
& the morphology terms (homologous,
analogous, vestigial structures) &
phylogenic tree info.
• 41-50. True/ False
• 10-55. short answer.
Practice these short answer
questions for the test:
• Write a pneumatic devise to remember the
classification categories, in order (this can
be one we used in class or your own):
• What are the 6 kingdoms recognized
today?
• What do plants & fungi have in common
with animals?
*You can do online flash cards
for the vocab in this chapter at:
• http://quizlet.com/2096160/chapter-17classification-flash-cards/