Classification and Kingdoms

Classification Scientists have identified more than 2 million species of organisms on earth, but estimate that there are a total of 40 million that actually inhabit the earth. So, how do we classify new species that are discovered?

Purpose of a Classification System Assign a single universal name to each organism Place organisms into groups that have real biological meaning

Taxonomy Field of biology that studies the classification of organisms Names and groups organisms according to their characteristics and evolutionary history A universal system is necessary to have clear communication among scientists Eliminates the use of common names and confusion

Classification History Aristotle – 2,000 years ago Grouped animals into Land Dwellers, Water Dwellers, and Air Dwellers What about caterpillars  butterflies? Where should they be classified? What about frogs? Grouped plants into 3 categories, based on differences in their stems.

Classification History Carl Linnaeus – mid-1700’s “Father of Modern Taxonomy” Developed a hierarchy that is the basis of Modern Taxonomy Hierarchy goes from broad to narrow Used morphology (form and structure) to classify organisms Developed a system of groups called TAXA Categories in which related organisms are placed First divided all organisms into 2 groups (kingdoms) Plantae Animalia What about bacteria? Fungi? Where do they fit?

Binomial Nomenclature Seven levels of modern classification (Linnaeus had five – K, C, O, G, S) Kingdom Phylum Class Order Family Genus Species Broadest – most inclusive Narrowest – most exclusive King Phillip Came Over For Grandma’s Soup

Binomial Nomenclature Kingdom level is the largest/most general group. It is the most INCLUSIVE group (includes the most organisms). Species level is the smallest/most specific level. It identifies the specific organism. It is the most EXCLUSIVE group (includes the fewest organisms).

Binomial Nomenclature “Two-word naming” Use the genus and species for scientific naming (genus is written 1st, species written 2nd) ie, for humans: Homo sapiens (italics when typing, underline when writing; always capitalize the genus name, but never the species name)

Classification of the Grizzly Bear Kingdom - Animalia Phylum - Chordata Class - Mammalia Order - Carnivora Family - Ursidae Genus - Ursus Species – Horribilis The scientific name… Ursus horribilis

Binomial Nomenclature Why do we have Binomial Nomenclature? England – robin North America – robin Erithacus rubicula E. rubicula Turdus migratorius T. migratorius B.N. avoids confusion - different animals with same name

Binomial Nomenclature Sand dollar Seahorse B.N. avoids confusion - Confusing names

Binomial Nomenclature Puma, cougar, or mountain lion? Felis concolor B.N. avoids confusion - one animal with many names

Binomial Nomenclature Species Two organisms are the same species if they can breed and produce fertile offspring. Felis domesticus Felis domesticus Felis concolor Which two are the same species?

Modern Phylogenetic Taxonomy Phylogeny – the study of evolutionary relatedness among various groups of organisms

Modern Phylogenetic Taxonomy Considerations Modern Taxonomists Take to Yield Reliable Information About and Organism’s Phylogeny Morphology Chromosomal Characteristics Nucleotide and Amino Acid Sequences – Molecular Biology Embryological Development Fossil Record

Modern Phylogenetic Taxonomy Systematic Phylogenetic Tree Shows relationships thought to exist among groups of organisms ??

Modern Phylogenetic Taxonomy

Modern Phylogenetic Taxonomy Cladistic Cladograms New system of phylogenetic classification, uses certain features of organisms – DERIVED CHARACTERISTICS

Modern Phylogenetic Taxonomy

Six-Kingdom System Modern taxonomists recognize that many organisms are neither plant nor animals, so they use the six - kingdom system. Kingdoms group organisms together that have similarities in such fundamental characteristics Major cellular structure Methods of obtaining nutrients Metabolism

Six Kingdoms Archaebacteria (“archae” – ancient) May be directly descended from and very similar to the first organisms on earth Unicellular prokaryotes with distinctive cell walls without peptidoglycan Some are autotrophic, producing food by chemosynthesis, while others are heterotrophic Lives in harsh environments such as sulfurous hot springs, very salty lakes, and in anaerobic environments Include chemosynthetic bacteria

Six Kingdoms Eubacteria (“eu” – true) Unicellular prokaryotes Have cell walls made of peptidoglycan Both autotrophs and heterotrophs Include disease-causing bacteria that cause ailments like tooth decay.

Six Kingdoms Monerans – original name of both Archaebacteria and Eubacteria. These combined kingdoms have the greatest number of organisms on earth. Both reproduce by binary fissions, but do have some ways of recombining genetic information  allowing for evolution

Six Kingdoms Protista (“ash and trash” kingdom) All eukaryotes that are NOT plant, animal, or fungi Have cell walls; some have chloroplasts Unicellular, and some Multicellular Include Euglena and amoebas

Six Kingdoms Fungi Multicellular eukaryotes Have cell walls that contain chitin Heterotrophic and obtain their nutrients by releasing digestive enzymes into a food source Act either as decomposers or as parasites in nature. Includes molds, mildews, mushrooms, and yeast.

Six Kingdoms Plantae Multicellular eukaryotes Most are autotrophic Have cell walls that contain cellulose. Cells are specialized for specific functions, such as photosynthesis, transport of materials, and support. Includes mosses, ferns, cone-bearing plants (gymosperms) and flowering plants (angiosperms)

Six Kingdoms Animalia Multicellular eukaryotes Heterotrophic No cell walls Are mobile, but some are permanently attached to surfaces (sponges and barnacles) Includes fish, birds, reptiles, amphibians, mammals, sponges, jellyfish, worms, sea stars, insects

Six Kingdoms

Domains Used to group kingdoms together 3 Domains Bacteria Archae Composed of prokaryotic celled organisms Archae Eukarya Composed of eukaryotic celled organisms

Domains

Domains