CLASSIFICATION

Finding Order in Diversity

OrganismNumber Described

Estimated number to be Discovered

Viruses 5,000 about 500,000

Bacteria 4,000 400,000-300 million

Fungi 70,000 1-1.5 million

Protozoans 40,000 100,000-200,000

Algae 40,000 200,000-10 million

Flowering plants 250,000 300,000-500,000

Roundworms 15,000 500,000-1 million

Mollusks 70,000 200,000

Crustaceans 40,000 150,000

Spiders and mites 75,000 750,000-10 million

Insects 950,000 8-100 million

Vertebrates 45,000 50,000

TAXONOMY•The classifying of organisms and the assigning of a universally accepted name to each.

WHY CLASSIFY?1. To study the diversity of

life, biologists use a classification system to name organisms and group them in a logical manner.

WHY CLASSIFY?2. When taxonomists classify

organisms, they organize them into groups based on similarities.

WHY CLASSIFY?

3. Classification makes life easier. What are some ways we classify?

ASSIGNING SCIENTIFIC NAMES

• Using common names can be confusing because many organisms may have several different common names.

• The cougar is also known as the mountain lion, puma or catamount…thus the need for a scientific name.

Felis concolor

•A Swedish botanist named Carolus Linnaeus developed Binomial Nomenclature, a two-word naming system for naming all species on earth.

What do botanists study?

ASSIGNING SCIENTIFIC NAMES

• The first part of the scientific name is the genus. This word is always written first and the first letter is capitalized. It appears in italics or is underlined.

Homo sapien

Ursus arctos

ASSIGNING SCIENTIFIC NAMES

• The second part of the scientific name is the species name. This word is always written second and the first letter is lower-case. It appears in italics or is underlined.

Homo sapien

Ursus arctos

LINNAEUS’S SYSTEM OF CLASSIFICATION

•Linnaeus’s hierarchical system of classification includes seven levels. They are, from largest to smallest, Kingdom, Phylum, Class, Order, Family, Genus, Species.

LINNAEUS’S SYSTEM OF CLASSIFICATION

•The Kingdom is the largest and most inclusive (includes) of the taxonomic categories.

•Species is the smallest and most specific of the taxonomic categories. It includes one

LINNAEUS’S SYSTEM OF CLASSIFICATION

•The more taxonomic levels that two organisms share, the more closely related they are considered to be.

LINNAEUS’S SYSTEM OF CLASSIFICATION

What do the scientific names of the polar, grizzly and panda bears tell you about their similarity to each other?

Ursus maritimus

Ursus arctos

Ailuropoda melanoleuca

THINKING CRITICALLYOrganis

mCat Wolf Fly

Kingdom

Animalia Animalia Animalia

Phylum

Chordata Chordata Arthropoda

Class Mammalia Mammalia Insecta

Order Carnivora Carnivora Diptera

Family Felidae Canidae Muscidae

Genus Felis Canis Musca

Species

F. domesticus

C. lupus M. domestica

THINKING CRITICALLY1. What type of animal

is Musca domestica?2. From the table, which

2 animals are most closely related?

3. At what classification level does the evolutionary relationship between cats and wolves diverge (become different)?

Animal; insect

Cat and Wolf

Family Level

Human classification:

Kingdom Animalia

PhylumChordata

ClassMammalia

OrderPrimates

FamilyHominidae

GenusHomo

speciessapiens

EVOLUTIONARY CLASSIFICATION

• Organisms aren’t just grouped based on similarities. These evolutionary relationships or lines of descent are also used in classification.

• Phylogeny: The study of evolutionary relationships among organisms.

-

What determines evolutionary relationship?

• Anatomy and physiology– Common structures imply a common ancestor.

• Breeding and behavior patterns

• Geographic distribution

• DNA and biochemistry DNA comparisons between these plants show almost

no difference.

EVOLUTIONARY CLASSIFICATION

A B C D E F

Speciation: formation of two new species from one

Clade or lineage

TIME

CLADOGRAM

Fur & MammaryGlands

Jaws

Lungs

Claws or Nails

Feathers

HagfishFish

FrogLizard

Pigeon

Mouse

Chimp

VENN DIAGRAMS• Venn Diagrams can be used to

make models of hierarchical classification schemes. A Venn diagram is shown below:

A.

B.

C. D.

• Four groups are represented by circular regions• Each region represents different taxonomic levels.• Regions that overlap, share common members.• Regions that do not overlap do not have common

members.

A.

B.

C. D.

Matching:MammalsAnimals with backbonesInsectsAll animals

A.

B.

C. D.

C

BD

A

Dichotomous key:

• A key that is used to identify different organisms based on physical characteristics.

• It is made up of sets of two statements that deal with a single characteristic of an organism, such as leaf shape (toothed or smooth edge) or hair (has hair or doesn’t have hair)

So how are all living things put into these different groups?

• All living things are classified based on several features:– Cell type– Number of cells– Cell structures– Mode of nutrition– Motility

Remember the 2 Cell Types?

• Prokaryotic– Small, simple cells without

membrane-bound organelles; i.e. bacteria

• Eukaryotic– Large, complex cells

containing many specialized organelles, nucleus; i.e. plants, animals, protists & fungi

Domains

• Largest , most inclusive group– Bacteria: Prokaryotic cells

• 1 kingdom: Eubacteria

– Archaea: Prokaryotic cells• 1 kingdom: Archaebacteria

– Eukarya: Eukaryotic cells• 4 kingdoms: Protista, Fungi, Plantae, Animalia

Kingdom Eubacteria• Unicellular• Very strong cell walls

(peptidoglycan)• Autotrophic or

heterotrophic• diverse habitat• Some motile, other

non-motile• Ex: streptococcus,

Escherichia coli

Kingdom Archaebacteria • Most live in extreme

environments– Most do not use oxygen to

respire (anaerobic).– Ancestor to eukaryotes

• Unicellular • Cell walls lack peptidoglycan• Can be heterotrophic or

autotrophic• Some motile, others non-

motile• Examples: Halophiles,

methanogens.

Kingdom Protista• Most are unicellular, few are

multicellular– lacks complex organ systems

• lives in moist environments• diverse metabolism/motility

– Animal-Like

– Plant-Like (cellulose, chloroplasts)

– Fungus-Like

• Ex: paramecia, euglena, algae, slime molds

Kingdom Fungi• Saprobes: decomposes

matter by absorbing materials

• Multicellular (mushrooms) or unicellular (yeast)

• Cell walls (chitin)• Non-motile

Kingdom Plantae• Multicellular• Autotrophic:

Photosynthetic– Cells contain

chloroplasts

• Immobile• Cell walls (cellulose)• Ex: grass, rose,

moss

• Multicellular

• Mobile (at one point during their lifetime)

• Lack cell walls

• Diverse habitats

• Heterotrophic

• Ex: insects, worms,

squirrels, birds

Kingdom Animalia

Bacteria

Protista

AnimaliaPlantae Fungi

EuPro

MultiUni

(Seaweeds)

Nutritional types

Auto(photo) Hetero(absorb) Hetero(ingest)

Evolution and the 6 Kingdoms