AP Biology

Lecture #44Classification

• Organisms classified from most general group, domain, down to most specific, species– domain, kingdom,

phylum, class, order, family, genus, species

Finding commonality in variety

use the mnemonic!

Solar System

Earth

No. America

U. S.

WI

So. WI

Green Co.

New Glarus

Devil Cat

Ghost Cat

Mountain Lion

Screaming Cat

Puma

Florida Panther

Cougar

•There are at least 50 common names for the animal shown on the previous 7 slides.

•Common names vary according to region.

•Soooo……why use a scientific name?

• Why are some kinds similar and others NOT similar?

• Question to be answered later?

• How can we make sense of (explain) this diversity?

• How can we organize what we know about these organisms?

Early Efforts at Naming Organisms

• The first attempts at standard scientific names often described the physical characteristics of a species in great detail.

• Results in long names

• Difficult to standardize the names of organisms

• Different scientists described different characteristics.

Answer: CLASSIFY!

• Similar “types” (species) grouped together, separated from other species.

• Then, group similar groups together, etc.

•The science of classifying organisms is called taxonomy.

•The “father of modern taxonomy” was Carolus Linnaeus (Carl von Linné).

Why Do We Classify Organisms?• Biologists group organisms to

represent similarities and proposed relationships.

• Classification systems change with expanding knowledge about new and well-known organisms.

Tacitus bellus

• Classification system organizes biological knowledge.

• Classification itself is HYPOTHESIS about relationships, similarity because of common ancestry.

Leucaena leucocephala Lead tree

Classification• Binomial Nomenclature

– Two part name (Genus, species)

• Hierarchical Classification– Seven Taxonomic Catagroies

• Systematics– Study of the evolution of biological

diversity

CLASSIFICATION

Archaebacteria&Bacteria

Classification• Old 5 Kingdom system

• Monera, Protists, Plants, Fungi, Animals

• New 3 Domain system– reflects a greater

understanding of evolution & molecular evidence• Prokaryote: Bacteria• Prokaryote: Archaebacteria• Eukaryotes

– Protists– Plants– Fungi– Animals

Prokaryote

Eukaryote

KingdomProtist

KingdomFungi

KingdomPlant

KingdomAnimal

KingdomArchaebacteria

KingdomBacteria

Kingdoms

Single-celled ancestor

prokaryotes

eukaryotes

Eubacteria

Archaebacteria

Protista

multicellular

uni- tomulticellular

autotrophs

heterotrophs

Plantae

Fungi

Animalia

absorptivenutrition

ingestivenutrition

Hierarchical Classification• Taxonomic categories

– Kingdom King– Phylum Philip– Class Came– Order Over– Family For– Genus Green– Species Soup

CLASSIFICATION = Sequence of levels. Linnaean system, from Carolus Linnaeus, 1740's

Kingdom Phylum Class Order Family Genus Species

King Phil called old fat George stupid.

CLASSIFICATION = Linnaean system

The 7 taxonomic categories• Species - a group of organisms that breed with one another

and produce fertile offspring.

• Genus - a group of closely related species.

• Family - genera that share many characteristics.

• Order - is a broad taxonomic category composed of similar families.

• Class - is composed of similar orders.

• Phylum- several different classes that share important characteristics.

• Kingdom - largest taxonomic group, consisting of closely related phyla

CLASSIFICATIONWhittaker’s Five Kingdoms, 1965

• Kingdom Monera (Bacteria)

• Kingdom Protista• Kingdom Fungi• Kingdom Plantae• Kingdom Animalia

Woese, 1985• Prokaryotic organisms are far more

diverse than thought previously.• Domain Eubacteria (prokaryotic “true bacteria”)

• Domain Archaea (prokaryotic “archaeans”)

• Domain Eukarya (eukaryotic organisms)

Bacteria Archaea Eukarya

Bacteria Archaea Protista Plantae Fungi Animalia

Monera Protista Plantae Fungi Animalia

The three-domain system

The six-kingdom system

The traditional five-kingdom system

• Prokaryotic organisms are far more diverse than thought previously.

• Domain Eubacteria (prokaryotic “true bacteria”)

– Kingdom Gram-positive bacteria– Kingdom Gram-negative bacteria– Kingdom Mycoplasmas– Kingdom Rickettsias– Kingdom purple-sulfur bacteria– and more

• Domain Archaea (prokaryotic “archaeans”)

• Domain Eukarya (eukaryotic organisms)

Domain Eubacteria

• Prokaryotic organisms are far more diverse than thought previously.

• Domain Eubacteria (prokaryotic “true bacteria”)• Domain Archaea (prokaryotic “archaeans”)– Kingdom Thermophiles– Kingdom Halophiles– Kingdom Methanogens– Kingdom ARMANS

• (“Archeal Richmond Mine Acidophilic Nanoorganism” Science vol 314, 22 Dec. 2006.)

• Domain Eukarya (eukaryotic organisms)

Domain Archaea

• Prokaryotic organisms are far more diverse than thought previously.

• Domain Eubacteria (prokaryotic “true bacteria”)• Domain Archaea (prokaryotic “archaeans”)• Domain Eukarya (eukaryotic organisms)– Kingdom Protista– Kingdom Fungi– Kingdom Plantae– Kingdom Animalia

Domain Eukarya

Kingdom Protista

Amoeba Paramecium Giardia

Water Mold Slime Mold

Euglena DinoflagellatesDiatomBrown AlgaeGreen Algae

Kingdom Fungi

Kingdom Plantae

Bryophyte (Moss)

Pteridophyte(Fern)

Pteridophyte(Fern)

Coniferophytes (Pine Trees) Angiosperm;

DicotAngiosperm;

Monocot

Kingdom Animalia

DOMAIN

KINGDOM

CELL TYPE

CELL STRUCTURES

NUMBER OF CELLS

MODE OF NUTRITION

EXAMPLES

Bacteria

Eubacteria

Prokaryote

Cell walls with peptidoglycan

Unicellular

Autotroph or heterotroph

Streptococcus, Escherichia coli

Archaea

Archaebacteria

Prokaryote

Cell walls without

peptidoglycan

Unicellular

Autotroph or heterotroph

Methanogens, halophiles

Protista

Eukaryote

Cell walls of cellulose in some; some have chloroplasts

Most unicellular; some colonial; some multicellular

Autotroph or heterotroph

Amoeba, Paramecium, slime molds, giant kelp

Fungi

Eukaryote

Cell walls of chitin

Most multicellular; some unicellular

Heterotroph

Mushrooms, yeasts

Plantae

Eukaryote

Cell walls of cellulose; chloroplasts

Multicellular

Autotroph

Mosses, ferns, flowering plants

Animalia

Eukaryote

No cell walls or chloroplasts

Multicellular

Heterotroph

Sponges, worms, insects, fishes, mammals

EukaryaClassification of Living Things

Key Characteristics of Kingdoms and Domains

Go to Section:

Section 18-3

are characterized by

such as

and differing which place them in

which coincides withwhich coincides with

which place them in which is subdivided into

Living Things

Kingdom Eubacteria

Kingdom Archaebacteria

Eukaryotic cellsProkaryotic cells

Important characteristics

Cell wall structures

Domain Eukarya

Domain Bacteria

Domain Archaea

Kingdom Plantae

Kingdom Protista

Kingdom Fungi

Kingdom Animalia

Go to Section:

EubacteriaArchaebacteriaProtistaPlantaeFungiAnimalia

Kingdoms

Domain Kingdom Phylum Class Order Family Genus SpeciesDid King Phil call old fat George stupid ?

Carolus von Linnaeus(1707-1778)

Swedish scientist who laid the foundation for

modern taxonomy

Binomial Nomenclature• Carolus von Linnaeus • Two-word naming system

– Genus• Noun, Capitalized,

Underlined or Italicized– Species

• Descriptive, Lower Case, Underlined or Italicized

Ursus americanus

American Black Bear

Binomial Nomenclature: “a two-name system”

First part of name: genus first letter always capitalized

Second part of name: species first letter always lowercase

Entire name is underlined and italicized

Names must be submitted for acceptance by original discoverer, and are generally Latin or Latinized

Canis domesticus Canis lupus

Names are generally closely related organisms are often in the same genus, also giving clues about their names.

Some names are given for the discoverer, or the discovery location, or even a Latinized descriptive term in English.

Often Latin names contain clues about the type of organism being described.

Systematics:Evolutionary Classification of

Organisms

• Systematics is the study of the evolution of biological diversity, and combines data from the following areas.– Fossil record– Comparative homologies– Cladistics– Comparative sequencing of DNA/RNA among

organisms– Molecular clocks

Mammals Turtles Lizards and Snakes

Crocodiles Birds Mammals Turtles Lizards and Snakes

Crocodiles Birds

CladogramPhylogeneticTree

Taxonomic Diagrams

A phylogenetic tree is a family tree that shows a hypothesis about the evolutionary relationships thought to exist among groups of organisms. It does not show the actual evolutionary history of organisms.

Why a hypothesis?

Phylogenetic trees are usually based on a combination of these lines of evidence:

    Fossil record

    Morphology

    Embryological patterns of development

    Chromosomes and DNA

Taxa show unique combinations of characteristics.

For example, birds have feathers, beaks, and wings, and lay eggs, while mammals have hair, teeth, and give live birth.

Cladistics - is a relatively new system of phylogenetics classification that uses shared derived characters to establish evolutionary relationships. A derived character is a feature that apparently evolved only within the group under consideration.

Diagrams called cladograms are used to represent the phylogeny of organisms.

A phylogenetic tree based on a cladistic analysis is called a cladogram.

What derived character is shared by all the animals on the cladogram on the next slide?

There are three basic assumptions in cladistics:

1.Organisms within a group are descended from a common ancestor.

2.There is a bifurcating pattern of cladogenesis.

3.Change in characteristics occurs in lineages over time.

Cats are more similar to dogs than they are to frogs, because they share a more recent common ancestor with dogs

TRADITIONAL CLASSIFICATION

CLADOGRAM

Appendages Conical Shells

Crab Barnacle Limpet Crab Barnacle Limpet

Crustaceans Gastropod

Molted exoskeleton

Segmentation

Tiny free-swimming larva

Traditional Classification Versus Cladogram

Birds MammalsReptile

AmphibianFish

Four LimbsAmniotic Egg

EndothermicFur

Feathers

Vertebrae

Fish

Amphibians

Reptiles

Birds Mammals

Possible evolution of the Kingdom Animalia

Modern Evolutionary Classification

• Molecular Clocks– Comparisons of DNA can

also be used to mark the passage of evolutionary time.

– A model known as a molecular clock uses DNA comparisons to estimate the length of time that two species have been evolving independently.

• Comparison reveals more DNA in common, the more recent the common ancestor

Dichotomous Keys Identify Organisms • Dichotomous keys versus evolutionary classification• Dichotomous keys contain pairs of contrasting

descriptions.• After each description, the key directs the user to another

pair of descriptions or identifies the organism.

Example: 1. a) Is the leaf simple? Go to 2

b) Is the leaf compound? Go to 3

2. a) Are margins of the leaf jagged? Go to 4b) Are margins of the leaf smooth? Go to 5