C LASSIFICATION Ms. Moore 1/14/12

W HY CLASSIFY ? To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner. Taxonomy : the discipline where scientists classify organisms and assign each organism a universally accepted name

E ARLY C LASSIFICATION S YSTEMS 350 B.C. Aristole set up 2 kingdoms: Animal Plant 1600s John Ray recognized 2 kingdoms: Animal Plant Classified by : Land Sea Air Classified by : Similarities in body structure

C OMMON N AMES M ISLEADING John Ray noticed that common names were misleading So, he chose to name them in Latin because all scientists knew Latin and it is not spoken so translation is not a problem. Drawback: names were too long! Example: Carnation = dianthus floribus solitoriis squamis calycinis subovatis brevissimis corollis crenatis

L INNAEUS TO THE R ESCUE ! 1700s Carolus Linnaeus developed a two kingdom system Animal Plant Agreed with Ray and used Latin, but gave every organism a two-part scientific name Genus – Species Ex. Homo sapiens This system of classification is known as binomial nomenclature.

B INOMINAL N OMENCLATURE Genus : group of closely related species Species : unique to each species within the genus Ursus arctos Ursus maritimusAiluropoda melanoleuca

L INNAEUS ’ S S YSTEM OF C LASSIFICATION Heirarchial system includes 7 levels/ taxons : Species Genus Family Order Class Phylum Kingdom

G ENUS SPECIES Two smallest categories Examples: Homo sapien Canis lupus Heterocephalus glaber Sus scrofa

F AMILY /O RDER /C LASS /P HYLUM /K INGDOM Family : groups of genera Ursidae family of bears Order : broad taxonomic category composed of similar features Canidae (dogs) and Felidae (cats) Class : composed of similar orders Mammalia: warm-blooded, have body hair, produce milk Phylum : includes many different organisms that nevertheless share important characteristics Mammals groups with birds, reptiles, etc in the phylum Chordata (backbone) Kingdom : largest and most inclusive of Linnaeus’s taxonomic categories Animals and Plants

S IMILARITIES Species were grouped together in larger taxa according to visible similarities and differences. How would you have classified dolphins? Evolutionary relationships are important in classification.

E VOLUTIONARY C LASSIFICATION Phylogeny is the study of evolutionary relationships among organisms. Organisms are now grouped into categories that represent lines of evolutionary descent. Grouping organisms together based on their evolutionary history is called evolutionary classification. Species within a genus are more closely related to one another than to species in another genus. This is because all members of a genus share a recent common ancestor.

U SING C LADOGRAMS Cladograms are diagrams used to show the relationship among organisms with evolutionary innovations—new characteristics that arise as lineages evolve. Characteristics that appear in recent parts of a lineage, but not in its older members are called derived characters. Just like a family tree shows the relationships among different lineages within a family, cladograms represent a type of evolutionary tree.

S HOWING R ELATIONSHIPS

DNA AND RNA IN C LASSIFICATION How can DNA and RNA be used in classification? The genes of many organisms show important similarities at the molecular level. Similarities in DNA can be used to help determine classification and evolutionary relationships. Humans and yeast related? Myosin The more similar the DNA of two species, the more recently they shared a common ancestor. The more two species have diverged from each other, the less similar their DNA will be.

T HE T REE OF L IFE E VOLVES As biologists learn more about he natural world, they realize that Linnaeus's two kingdoms Plantae and Animalia did not represent the full diversity of life. Changing Number of Kingdoms First IntroducedNames of Kingdoms 1700sPlantaeAnimali a Late 1800sProtistaPlantaeAnimali a 1950sMoneraProtistaFungiPlantaeAnimali a 1990sEubacteriaArchaebacteriaProtistaFungiPlantaeAnimali a

T HREE -D OMAIN S YSTEM Eukarya (eukaryote = nucleus) Protista include organisms that cannot be classified as animals, plants, or fungi. Amoeba, Paramecium, slime molds, giant kelp, algae Fungi members are heterotrophs who usually feed on dead or decaying matter. Mushrooms, yeasts Plantae members are photosynthetic autotrophs and immobile. Mosses, fens, flowering plants Animalia includes multicellular and heterotrophic organisms who have no cell wall. Sponges, worms, insects, fishes, mammals Bacteria (prokaryote = no nucleus) Bacteria are unicellular and prokaryotic. Cell walls contain peptidoglycan. Archaea (prokaryote = no nucleus) Archaea are also unicellular and prokaryotic. Cell walls do not contain peptidoglycan. Members of this domain live in some of the most extreme environments you can imagine—volcanic hot springs, brine pools, etc.

Working in lab groups, complete the cladogram worksheets.