reference text: modern biology chapter 18 – classification
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CLASSIFICATIONChapter 18
Reference Text:Modern BiologyChapter 18 – Classification
BIG IDEA
• All Organisms on earthare said to have descended from an ancient common ancestor – the classification of all species reflects their relationship with many related species…
WHAT THINGS DO WE CLASSIFY?WHY DO WE CLASSIFY THEM?
HISTORY OF TAXONOMY
Every Year, thousands of new species are discovered.
HISTORY OF TAXONOMY
To study so many life-forms, biologists organize or classify them into numerous
groups based on their similar characteristics (structures).
HISTORY OF TAXONOMY
Classification: to group things according to similar/different structures that they share.Classification is very useful in Biology…
• Indicates relationships between species
• Accurately & uniformly names organisms; star fish and jelly fish aren't’ really fish
WHAT IS CLASSIFICATION?
TAXONOMY:The branch of biology that classifies organisms
according to their characteristics andevolutionary history
EARLY SYSTEMS OF CLASSIFICATION
TAXONOMISTSTaxonomists are scientists that identify & name
organisms.
EARLY SYSTEMS OF CLASSIFICATION
Taxonomists name things in a way that reflects their classification.
They use the same language (Latin or some Greek) for all names.
Panthera tigris
Panthera onca
EARLY SYSTEMS OF CLASSIFICATION
The first classification system was developed 2000 years ago by Greek Philosopher Aristotle. He was the first taxonomist.•Aristotle divided organisms into plants & animals
•He then subdivided them by their habitat - land, sea, or air dwellers
EARLY SYSTEMS OF CLASSIFICATION
EARLY SYSTEMS OF CLASSIFICATION
As more & more organisms began to be discovered, Aristotle’s system was no longer adequate for naming & organizing all life on earth.
Sea”horse”??
EARLY SYSTEMS OF CLASSIFICATION
In response to the need for better organization, an 18th century Swedish botanist named Carolus Linnaeus offered a solution to the confusion of classifying and naming organisms.
• Created a hierarchical system for classifying organisms
• Developed naming system still used today
Linnaeus’s SystemCarolus Linnaeus
1707 – 1778
The “Father of Taxonomy”
• Linnaeus classified organisms based on similarities in morphology (form & structure), rather than by location.
For example, although Bats can fly, he classified them as mammals, not birds, because they share common traits with other mammals; they have hair, have live births and nurse their offspring with milk.
Linnaeus’s System
•The Linnaeus System of Taxonomy uses a hierarchical system for classifying organisms from broadest to most specific..
•Called Levels of Classification!
Linnaeus’s System
Linnaeus’s Seven-Level Classification System:
Kingdom, Phylum, Class, Order, Family, Genus, species
Each category is called taxa, hence the name
taxonomy!
Linnaeus’s System
Linnaeus’s Seven-LevelClassification System:
KingdomPhylum ClassOrderFamilyGenusSpecies
BROADEST TAXON
MOST SPECIFIC
Linnaeus’s System
KeepPlatesCleanOrFamilyGetsSick
Levels of Classification
Which two animals would be more closely related, two from the same phylum or two from the same genus?
THINK ABOUT IT
Linnaeus also developed the
modern system of naming organisms
known as:
Binomialnomenclature
Linnaeus’s System
Oops! Common names can vary!Example:
______________ ______________ ______________ ______________ . . . are all names for the same animal
mountain lion
puma
catamou
cougar
EARLY SYSTEMS OF CLASSIFICATION
Also, some early scientific names were often long and difficult to remember…
The European bee, for example, carried the name Apis pubescens, thorace subgriseo, abdomine fusco, pedibus posticis glabris utrinque margine ciliatis.
EARLY SYSTEMS OF CLASSIFICATION
Binomial nomenclature is a two-part naming system that identifies a species with 2 names:
Uses Genus & species
Either Latin or Greek
Italicized in print
Capitalize Genus, but NOT species
Underline when writing American Robin
Turdus migratorius
Linnaeus’s System
Binomial Nomenclature
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Which TWO are more closely related?
Taxonomic Group: tiger grey wolfKingdom: Animal Animal Phylum: ChordatesChordates Class: Mammals Mammals Order: Carnivores Carnivores Family: Felines Canines Genus: Panthera Canis Species: tigris lupus
Taxonomic Classification
Name: Genus & species
REMEMBER:Organisms are classified together because they are similar; they are similar because they stem from a
common ancestor. Woodchuc
kSquirrel
MODERN PHYLOGENETIC TAXONOMY
Linnaeus focused on morphology or features of an organism when classifying
it.
Today we know that those features are largely influenced by genes, which are
inherited, or passed down from our ancestors.
MODERN PHYLOGENETIC TAXONOMY
Modern taxonomists classify the tremendous diversity of organisms
based on how close their evolutionary relationships are with other living
and once-living things.
MODERN PHYLOGENETIC TAXONOMY
They all agree that the classification of an organisms should reflect their
PHYLOGENEY
•Phylogeney: The evolutionary relationships between all groups of organisms based on ancestor/descendant relationships.
MODERN PHYLOGENETIC TAXONOMY
The morphology Linnaeus followed holds true to phylogeny or
evolutionary relationships in most cases….
Modern taxonomists construct a Phylogenetic tree, or family tree to show these relationships.The phylogenetictree shows theevolutionaryrelationshipsbetweendifferent groupsof organisms.
MODERN PHYLOGENETIC TAXONOMY
Pangolin
Armadillo
Modern Taxonomist consider several lines of evidence when classifying
organisms according to their evolutionary history:
Four Types of evidence include:
• Morphology (homologous structures)
• Embryological development
• DNA, RNA, Amino acid sequences
• Fossil records
MODERN PHYLOGENETIC TAXONOMY
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Homologous Structures (BONES in the FORELIMBS) shows Similarities in the morphology of mammals.
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Similarities in Vertebrate Embryos
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Similarities in DNA
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Evidence found in the Fossil Record
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A relatively new system of phylogenetic classification is called cladistics.
• Based on Derived characteristics:
• Certain features that evolved only within the group being studied
•Example: if the group being studied is birds, having feathers is the derived character.
CLADISTICS
In this approach, ancestry diagrams are made through derived characters
analysis.
These diagrams called CLADOGRAMS
CLADISTICS
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Primate Cladogram
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Aristotle classified organisms as either plants or animals..
Linnaeus took it a step furtherand classified organisms intomore specific groups such asclass, order, family, genus and species.
TWO MODERN SYSTEMS OF CLASSIFICATION
http://science.discovery.com/videos/100-greatest-discoveries-shorts-classification-of-species.html
…some organisms don't quite fit into the plant or animal group.
As a result, several other kingdoms of organisms are now used.
Today's scientists look at cell structure, how the organism moves, gets food,
and reproduces to place it in the correct kingdom.
TWO MODERN SYSTEMS OF CLASSIFICATION
Two Current Classification Systems
•Six Kingdom System
•Three Domain System
TWO MODERN SYSTEMS OF CLASSIFICATION
Old Five Kingdom System:
Monera include all prokaryotic organisms, which are all unicellular life forms that lack a true nucleus.Protista, Fungi, Plantae,Animalia include all eukaryotic organisms, which are all life forms that do contain a true nucleus and various organelles.
MODERN SYSTEMS OF CLASSIFICATION
The NEW Six Kingdom System:
Archaebacteria & Eubacteria include all prokaryotic organisms, which are all unicellular life forms that lack a true nucleus.Protista, Fungi, Plantae,Animalia include all eukaryotic organisms, which are all life forms that do contain a true nucleus and various organelles.
MODERN SYSTEMS OF CLASSIFICATION
PROTISTS
PLANTAE
EUBACTERIA
ARCHAEBACTERIA
ANIMALIAFUNGI
THE SIX KINGDOMS
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Broadest, most inclusive taxons are the Three Domains
Archaea, Bacteria, and Eukaryota
THE THREE DOMAIN SYSTEM
Six-Kingdom System
Three-Domain System
The main criteria of grouping here is Eukaryotic vs. Prokaryotic
REMEMBER: These systems are not etched in stone!They have been revised over the years, and will continue
to be revised when new evidence is discovered.
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Domain – ArchaeaKingdom - ARCHAEBACTERIA• Probably the 1st cells to evolve
• Live in HARSH environments
• Found in:
–Sewage Treatment Plants (Methanogens)
–Thermal or Volcanic Vents (Thermophiles)
–Hot Springs or Geysers that are acid
–Very salty water (Dead Sea; Great Salt Lake) – Halophiles
• Chemosynthesis: use inorganic compounds to make food.
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THE THREE DOMAIN SYSTEM
Kingdom - ARCHAEBACTERIA
Acid mine drainage
Hot Springs
Sulfur SpringsThe Dead Sea
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Domain - BacteriaKingdom - 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. (Acidophilus).
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THE THREE DOMAIN SYSTEM
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Kingdom - EUBACTERIA
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Live in the intestines of animals
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Domain Eukarya is Divided into 4 Kingdoms:
•Protista (protozoans, algae…)
•Fungi (mushrooms, yeasts …)
•Plantae (multicellular plants)
•Animalia (multicellular animals)
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THE THREE DOMAIN SYSTEM
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Domain: EukaryaKingdom: Protista•Most are unicellular•Some are multi-cellular•Some are autotrophic, while others are heterotrophic•Aquatic
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THE THREE DOMAIN SYSTEM
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Domain: EukaryaKingdom: Protista
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THE THREE DOMAIN SYSTEM
Animal Like – move around and eat other organisms
Plant Like – contain chlorophyll for photosynthesis
Fungus Like – made of threadlike fibers
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Domain: EukaryaKingdom: Fungi• Multicellular, except
yeast
• Absorptive heterotrophs (digest food outside their body & then absorb it)
• Cell walls made of chitin
THE THREE DOMAIN SYSTEM
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Domain: EukaryaKingdom: Plantae•Multicellular
•Autotrophic (except for carnivorous plants)
•Absorb sunlight to make glucose – Photosynthesis
•Cell walls made of cellulose
THE THREE DOMAIN SYSTEM
http://www.youtube.com/watch?v=ph7Ex8rQ-IA
Mosses
Angiosperms
Ferns
Liverworts
Gymnosperms
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Domain: EukaryaKingdom: Animalia•Multicellular
•Ingestive heterotrophs (consume food & digest it inside their bodies)
•Feed on plants or animals
THE THREE DOMAIN SYSTEM
Domain Kingdom Cell Type Cell Type Nutrition
Archaea Archaebacteria
Prokaryote Unicellular Both autotroph
and heterotroph
Bacteria Eubacteria Prokaryote Unicellular Both
Eukarya Protists Eukaryote Both Both
Eukarya Fungi Eukaryote Both Heterotroph
Eukarya Plantae Eukaryote Multicellular Autotrophic (mostly)
Eukarya Animalia Eukaryote Multicellular Heterotroph
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THE THREE DOMAIN SYSTEM
Methanogens, Thermophiles,
Acidophilles
THE SIX KINGDOMS
Characteristics Cell Virus
Growth yes No
Homeostasis Yes No
Metabolism Yes No
Mutation Yes Yes; necessary for its survival
Genetic Material Yes DNA, RNA
Reproduction Yes by mitosis*Yes; but only possible when
inside a host cell
StructureCytoplasm, membrane bound
organelles, nucleus
THE VIRUS – IS IT ALIVE?
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Biologists have developed a precise method to help them classify and identify unknown organisms.The classification tool called a dichotomous key
DICHOTOMOUS KEY
•Used to identify organisms•Characteristics given in pairs•Read both characteristics and either go to another set of characteristics OR identify the organism
1a Tentacles present – Go to 21b Tentacles absent – Go to 32a Eight Tentacles – Octopus2b More than 8 tentacles – 33a Tentacles hang down – go to 43b Tentacles upright–Sea Anemone4a Balloon-shaped body–Jellyfish4b Body NOT balloon-shaped - 5
DICHOTOMOUS KEY
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