Classification of Organisms and the Kingdoms of Living Things

Classification of Organisms and the Kingdoms of Living

Things

Chapter 14 & 19

Categories of Classification

• Taxonomy- the science of naming organisms• Aristotle- 1st ~2000 years ago- grouped plants

and animals according to structural similarities• Genus- Latin for group -Species- kind• 1700’s descriptive names (polynomials) -

name for a bee- Apis pubescens, thorace subgriseo, abdomine fusco, pedibus prosticis glabis,untrique margine ciliatus- these are large and awkward

A simpler system

• Linnaeus- Swedish botanist that devised the binomial nomenclature system

• Latin- 2 word system that used Genus and species identifier

• Honey bee- Apis mellifera

A brief history of classification

QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.

Scientific Names• Genus- always capitalized-Quercus• Species- never capitalized- Quercus rubra• Genus may be used by itself when describing

a group of species• Species never used alone• After use of full name the scientific name may

be abbreviated Q. rubra• Names are italicized when typed underlined

when handwritten

Scientific names

• Common way of communicating regardless of language

• Latin- dead language- never changes• No two organisms can have same

scientific name• Common names change with location-

robin and garter snake

Why Common names are confusing

Levels of classification

-Domain contains kingdoms

-Kingdoms contain phyla

-Phyla contain classes

-Classes contain orders

-Orders contain families

-Families contain genera

-Genera contain species

Levels of classification


Classification of a honeybee

What is a species?• How do you tell two species apart from each

other?• 1942- Ernst Mayr- proposed the biological

species concept• A group of naturally interbreeding populations

that are reproductively isolated from each other

• Sometimes species can interbreed such as dogs and wolves- these are called hybrids

Hybrids

Dog Wolf Dog-Wolf hybrid

There are many differentKinds of hybrids to look upZorse, mule,liger, etc…

Problems with Biological species concept

• Fails to describe asexually reproducing organisms- bacteria, protists, fungi, plants, some animals

• In practice, scientists still use an organism’s features

Number of Species

• Actual number described is much smaller than total number

• 1.5 million described ~ 1 million are arthropods

• Estimated 10 million in world- rainforests, oceans

• Our knowledge is very limited

Evolutionary history

• Classification based on similarities should reflect an organism’s phylogeny- its evolutionary history- not all features are inherited from a common ancestor- wings in birds and insects

• Convergent evolution- similarities evolve in non-related organisms

• Analogous structures- wings, body shape in fish and dolphins

Cladistics• A method of analysis that

reconstructs phylogenies by inferring relationships based on shared characters

• Ancestral character- a trait that is common to both all groups under consideration- birds and mammals are both vertebrates

• Derived character- a trait that evolved only in one group buth not any others- feathers evolved only in birds

Cladogram of vertebrates

Cladogram of Plants

Vascular tissue

Seeds

Flowers

Cuticle

Cladistics

• Based on the principle that shared derived characters show that two groups are closely related, shared ancestral characters, however, do not

• Strength of cladistics is objectivity- this does not take into account the “strength” of a trait

• According to cladistics birds are grouped with reptiles

Evolutionary systematics

• Taxonomists give varying degree of importance to charaters

• Phylogenetic tree is created• This allows scientists to use full

powers of observations along with biases they may have

• Both cladograms and phylogenetic trees arrive at similar conclusions

Vertebrate phylogenetic tree

6 Kingdoms of Life

• Where do biologists begin when they classify an organism?

• What makes something an animal? A plant?

• Biologists focus on a few fundamental characteristics

Fundamental Characteristics

• Cell type- prokaryotic or eukaryotic

• Cell walls- presence or absence, proteins involved

• Body type-unicellular or multicellular

• Nutrition-autotrophs or heterotrophs

3 Domains• 1977- Carl Woese proposed that

some prokaryotes are so fundamentally different than others that they should be placed separate in their own division

• All eukaryotes are placed together• Bacteria (Eubacteria), Archae

(Archaebacteria), Eukarya (Protists, Fungi, Plants, Animals)

3 Domains

3 Domains


Domain Bacteria• Contains Kingdom Eubacteria• All range from 0.1 to 15 um• Found almost everywhere• Bacteria that we are used to• Cell wall made of peptidoglycan• Unique amino acid sequences in

ribosomes and RNA polymerases• 3 shapes- round, rod, spiral• Obtain energy from organic

compounds, inorganic compoounds, heterotrophic, autotrophic, anaerobic, aerobic, decomposers

Eubacteria


Domain Archae• Contains Kingdom Archaebacteria• More closely related to Eukaryotes• Cell wall that lacks peptidoglycan• Unique lipids in cell wall• Genes that are interupted by introns like

eukaryotes• Methanogens- form methane gas found in

swamps, sewage, mammal intestines• Thermophiles- found in very hot conditions• Halophiles- found in highly salty areas• Acidophiles- highly acidic areas• Nonextremes- found in same as eubacteria

Archaebacteria


Domain Eukarya• Contains Protists, Fungi, Plants,

Animals

• Highlyt organized cells- contain nucleus and other organelles

• Multicellularity- cells are coordinated

• Sexual reproduction- haploid gametes fuse to create variation

Kingdom Protista

• Most diverse- more of what they “are not” than what they are

• Pseudopods- protists that use cytoplasmic lobes to move- amoebas- Forams make a shell and project pseudopods through shell

• Flagellates- use flagella to move- Euglena• Ciliates - use cilia- Paramecium

Kingdom Protista• Double shells- diatoms- photosynthetic-

double shells made of silica- part of plankton• Photosynthetic algae- green algae that you

see in lakes and ponds, brown algae, red algae- all the seaweeds

• Fungus-like protists- slime molds and water molds- produce spores and act like a fungus

• Spore-forming protists- nonmotile as adults- parasitic spores produced, complex life cycles- malaria and other diseases

Kingdom Protista


Kingdom Fungi• Almost all unicellular• Yeasts are unicellular group• Cell walls that contain chitin• Cells interconnected and share cytoplasm• Slender strands called hyphae• Lack chlorophyll, roots, movement, leaves• Heterotrophs- decomposers that secrete

enzymes then absorb the nutrients• Saprophytes- live on dead organsisms- some

are parasitic

Kingdom Fungi

• 3 kinds based on reproductive structures

• Zygomycetes- zygosporangia- common bread mold

• Basidiomycetes- mushrooms- produce basidiomycetes

• Ascomycetes- asci- sac-like structures

Kingdom Plantae

• Multicellular autotrophs• Most have vascular tissue for transporting

water and organic molecules• Cannot move from place to place• Most have roots, leaves, stems• All do photosynthesis• Cell walls made of cellulose• Seeds or spores

Kingdom Plantae• 4 basic kinds of plants• Nonvascular- lack vascular tissues- mosses-

has cuticle• Seedless vascular- ferns- roots, stems,

leaves, no seeds but spores• Nonflowering seed plants- vascular tissue,

seeds, no flowers- pine trees• Flowering plants- vascular tissue, seeds,

flowers- rose bush, apple tree

Kingdom Plantae


Kingdom Animalia• Complex, multicellular heterotrophs- all must

eat something else• No cell wall• Mostly diploid cells• Only group tp have muscles for movement• Most are invertebrates- 99%• Most animals live in the oceans• Can be very large-blue whale 100 ft- or small

0.02 inches- microscopic mites

Kingdom Animalia


Major animal phyla• Sponges- Porifera• Jellyfish- Cnidaria• Flatworms-

Platyhelminthes• Roundworms-

Nematoda• Worms- Annelida• Mollusks- Molluska• Arthropods-

Arthropoda

• Starfish- Echinodermata• Invertebrate chordates• Vertebrates

– Hagfish– Sharks– Fish– Amphibians– Reptiles– Birds– Mammals

Multicellularity

• Colonial organisms- unicellular organisms begin to cluster together- they cannot communicate and still exist by themselves

• Aggregations- a temporary collection of organisms that come together temoprarily and then separate- slime molds

• True Multicellularity- cells are permanently associated with each other- only found in eukaryotes- cells become specialized for specific functions- differentiation

Complex multicellularity

• Specialized cells and structures mad of these cells

• Tissue (group of cells performing the same function) --> Organ( groups of tissues performing the same function) --> Organ System (groups of organs performing together) --> Organism (multiple organ systems working together)

Viruses


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Classification of Organisms and the Kingdoms of Living Things