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Classification/Taxonomy. Chapter 18. Why Classify?. To study the diversity of life, biologists use a classification system to name organisms & group them in a logical manner. Taxonomy. Defined :
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Classification/Taxonomy Chapter 18
Why Classify? To study the diversity of life, biologists use a classification system to name organisms & group them in a logical manner.
Taxonomy Defined: Discipline of classifying organisms and assigning each organism a universally accepted name. In other words, naming things.
Why common names don’t work Common names vary among languages. Example: United Kingdom – Buzzard refers to a hawk United States – Buzzard refers to a vulture Red-tailed Hawk Honey Buzzard Turkey Vulture
Early Taxonomists • 2000 years ago, Aristotle (384 BC-322 BC) was the first taxonomist • Aristotle divided organisms into plants & animals • He subdivided them by their habitat ---land, sea, or air dwellers
Carolus Linnaeus • (1707 – 1778) • Classified organisms by their structure • Created the system of naming we use today. • His classification system includes 7 levels. • In taxonomy, a group or level of organization is called a taxonomic category or taxon.
Binomial Nomenclature • “Bi” means 2 • “nomial” means naming • Nomenclature means “the system of” Defined: In binomial nomenclature, each species is assigned a two-part scientific name.
Example of Binomial Nomenclature • Polar Bear is Ursusmaritimus • Ursus: genus Ursus contains 5 other kinds of bears • maritimus: species The Latin word, maritimus, refers to the sea. Polar bears often live on pack ice that floats in the sea.
Definitions to know • Genus: is a group of closely related species • Species: Group of similar organisms that can breed and produce fertile offspring
Kingdom: Largest taxonomic group, consisting of closely related phyla. • Phylum: Group of closely related classes • Class: Group of similar orders • Order: Group of similar families • Family: Group of genera that share many characteristics
Here We Go…Polar Bear Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Ursidae Genus: Ursus Species: maritimus What do these mean?...lets see
What they mean Species: maritimus(lives in marine environment) Genus: Ursus(kind of bear) Family: Ursidae (larger category of bears) Order: Carnivora (meat-eating animals) Class: Mammalia (warm-blooded, hair, & milk) Phylum: Chordata (vertebrates) Kingdom: Animalia (there are 6 kingdoms)
How to remember: King Phillip Came Over For Green Salad Kingdom Phylum Class Order Family Genus Species
Rules of the Game Uniqueness: Every name has to be unique. Universality: Zoologists have adopted, by international agreement, a single language to be used on a worldwide basis. All animals are given a generic (common name) and specific name in Latin (scientific name). These names are in italics or are underlined (i.e. Homo sapiens).
Phylum Chordata Class Mammalia Order Carnivora Family Ursidae Genus Ursus Species maritimus
Genus species If these three species belong to the same genus, they are descended from a common ancestor. Felis domestica domestica Domestic Cat Felis Felis leo leo Lion Felis margarita margarita Sand cat`
A Problem with Traditional Classification • Traditional classification systems relied on body structure comparisons only • Due to convergent evolution, organisms that are quite different from each other evolve similar body structures. Convergent Evolution: Process by which unrelated organisms independently evolve similarities when adapting to similar environments.
A Problem with Traditional Classification Example: The Crab, The barnacle, & The limpet • The barnacle and the limpet have similarly shaped shells & look alike • The crab has a very different body form • Based on anatomy, the barnacle & limpet could be classified together and the crab in a different group.
Related This incorrect because crabs and barnacles are actually related
Crustaceans Gastropods Molted Exoskeleton Even though they do not look a like, crabs & barnacles are actually related Segmentation Free swimming Larva
Evolutionary Classification • Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities Evolutionary Classification: Is the strategy of grouping organisms together based on their evolutionary history.
Classification Using Cladograms Cladogram: A diagram that shows the evolutionary relationships among a group of organisms.
Crustaceans Gastropods Molted Exoskeleton Using Cladograms, you can see that crabs and barnacles share similar characteristics because they both molt & are segmented Segmentation Free swimming Larva
Crustaceans Gastropods Molted Exoskeleton You can also see that ALL have a free swimming larva stage Segmentation Free swimming Larva
Classification History 1700sPlantae Animalia 1800s Protista Plantae Animalia 1950s Monera Protista Fungi Plantae Animalia 1990s Eubacteria Archaebacteria Protista Fungi Plantae Animalia
The Three-Domain System • Recently, as evidence about microorganisms continue to accumulate, biologists came to realize that the Kingdom Monera were composed of 2 distinct groups. • The 6-Kingdom system of classification includes kingdoms: 1. Eubacteria 2. Archaebacteria 3. Protista 4. Fungi 5. Plantae 6. Animalia
6 Kingdoms Prokaryote Prokaryote Eukaryote Eukaryote Eukaryote Eukaryote Eubacteria Archaebacteria Protista Fungi Plantae Animalia Autotroph or heterotroph Autotroph or heterotroph Autotroph/ heterotroph Heterotroph Autotroph Heterotroph Includes Algae Don’t belong in other euk No cell wall No chloroplasts Multicellular “Ancient Bacteria” Release enzymes to digest food Most common bacteria Cell walls & Chloroplasts Live in very hot places E. ecoli Pyrococcus furiosus Paramecium H. coccinea Fern frod Homo sapiens
Where do viruses go? Viruses: Are particles of nucleic acid, protein, and in some cases lipids that can reproduce ONLY by infecting living cells. Viruses are made of a core of either DNA or RNA surrounded by a protein coat. These are T4 Bacteriophage A bacteriophage is a virus which infects bacteria
Where do viruses go? (continued) Viruses are not considered alive because they don’t have ALL the characteristics of life. Example: They can’t reproduce independently These are the Influenza Viruses Influenza or "flu" is an infection of the respiratory tract that can affect millions of people every year.