reference text: modern biology chapter 18 – classification

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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