Classification of organisms Kingdoms: Eubacteria, Archaebacteria, Protist and Fungi
classification • Grouping objects or organisms based on a set of conditions. • For biologists, doing this with all of the organisms there are on the earth, it makes it easier to study them! • There are many different ways to group organisms.
Early systems of classification • Aristotle: plant or animal • Then animals were further classified based on habitat and physical characteristics. • Plants were further classified by size and structure, trees, shrubs • This system did NOT take into account the changes and evolutionary history of the organisms.
New systems of classification • In the 18th century • Carolus Linnaeus developed • Taxonomy • A branch of biology concerned with naming, identifying and classifying species based on morphological and behavioral similarities and differences. • Linnaeus gave each organism 2 names • A genus and a species name and called this binomial nomenclature.
Taxonomy • A systematic method of classifying plants and animals. • Classification of organisms based on degrees of similarity representing evolutionary (phylogenetic) relatedness.
Scientific Names • Binomial nomenclature (Linnaeus) • A 2 name system so that not two organisms will ever have the same name. • The genus name is combined with a second name to make the species name unique. • For example: humans • GenusHomo • SpeciesHomosapiens
Why 2 names? • The name are Latin ( the language of science) • The first is the genus • The second is the epithet or specific identifying name. They are both needed to identify the organism. • Common names can vary but scientific are universal. • First names are capitalized, second are not. • In books, names are italicized, if hand written they are underlined. • The genus can be abbreviated with the first letter
Human classification • Kingdom Animalia • Phylum (Division for plants) Chordata • Class Mammalia • Order Primates • Family Hominidae • GenusHomo • SpeciesHomo sapiens
Levels of classification • King Philip came over from Germany swimming CLASS KINGDOM ORDER PHYLUM FAMILY GENUS SPECIES SMALLEST LARGEST
Domains • The largest groups • Eukarya • Archaea/ Archaebacteria • Bacteria/Eubacteria
Domain Kingdom Phylum (Division for plants) Class Order Family Genus Species • Each level has more and more similarities!
6 Kingdoms heterotroph autotroph heterotroph autotroph heterotroph autotroph heterotroph
How has classification changed? • Today classification looks at the evolutionary relationships and DNA similarities. • Many organisms have been reclassified from where they were originally classified as new information is learned.
genus • A groups of organisms that are closely related and share a common ancestor.
family • A group of genera that have similar characteristics
species • Organisms so closely related that they can mate and produce fertile offspring in a natural setting. • The “biological species concept” • There are exceptions to this definition but it works for most organisms. • Phylogenetic species: goes with biologic and says the organisms have evolved independently from an ancestral population.
phylogeny • The evolutionary history of a species. • Where did it come from? • When organisms become isolated they become different, this can lead to new species…
characters • Inherited features that vary among species • Used by scientists to help put together the evolutionary history of a species: its phylogeny. • The more shared characters/the more closely related. • Homologous structures show relationships • Analogous structures don’t
Understanding phylogenetic trees • http://www.youtube.com/watch?v=xwuhmMIIspo&feature=youtube_gdata_player
Dinosaurs and birds • Oviraptor and sparrow • Feathers, hollow spaces in bones similar bone structures to birds show more similarities to dinosaurs with birds then to reptiles.
DNA sequences • The more similar the sequences, the closer the relationship between the organisms.
Molecular clocks • Mutations occur randomly and can be used to determine how long the DNA has been mutating or changing from its original form. • A major problem with this includes the fact that the genes don’t mutate at a constant rate! • These are used to try to determine when a divergence from a common ancestor occurred.
cladistics • A way to study evolutionary relationships. • It rebuilds phylogenies and hypothesizes evolutionary relationships using shared characters. • Cladograms show branching diagrams where each species may have originated. • Kind of like a pedigree!
Clades show hypothesized phylogeny based on DNA sequences, morphology all of the current information. • Branches are called nodes. • The closer to the end like species b and c, the more closely related..
Construction a cladogram video • http://www.youtube.com/watch?v=46L_2RI1k3k&feature=youtube_gdata_player
Domains • For now there are 3!
Archaea /Archaebacteria • Prokaryotic • Unicellular • No nucleus • No peptidoglycan on the cell walls • Some similarities to eukaryotes in the cytoplasm • Some Autotroph/ most heterotroph
Archaebacteria • The most primitive group, the archaebacteria, are today restricted to marginal habitats such as hot springs or areas of low oxygen concentration. Three types of Archaebacteria: methanogens, halophiles, and thermacidophiles. They live in extreme habitats like very salty water! prokaryotes
Domain and KingdomBacteria/Eubacteriaprokaryotesunicellularno nucleuscell walls contain peptidoglycansome autotrophs/most heterotrophs
Organisms in this group lack membrane-bound organelles associated with higher forms of life. Such organisms are known as prokaryotes. • Their small size, ability to rapidly reproduce (E. coli can reproduce by binary fission every 15 minutes), and diverse habitats/modes of existence make bacteria the most abundant and diversified kingdom on Earth.
Bacteria occur in almost every environment on Earth, from the bottom of the ocean floor, deep inside solid rock, to the cooling jackets of nuclear reactors.
Rod-Shaped ( Bacillus) Bacterium, hemorrhagic E. coli, strain 0157:H7
Scanning electron micrographs illustrating external features of the rod-shaped bacterium E. coli.
Coccus round-shaped Bacterium (causes skin infections), Enterococcus faecium
Left, a cross-section of a cell illustrating the location of a flagella inside the cell; Center, Borrelia burgdorferi, the organism that causes Lyme disease; and Right, Treponema pallidum, the spirochete that causes the venereal disease syphilis. The image above is from http://www.bact.wisc.edu/Bact303/MajorGroupsOfProkaryotes.
Endospores • are a method of survival, not one of reproduction. Certain bacteria will form a spore within their cell membrane (an endospore) that allows them to wait out deteriorating environmental conditions. • Certain disease causing bacteria (such as the one that causes the disease Anthrax) can be virulent (capable of causing an infection) 1300 years after forming their endospores
All other Kingdoms are made up of Eukaryotic cellsDomain EUKARYAHAVE ORGANELLESA NUCLEUS
Evolution of Eukaryotes • The endosymbiosis hypothesis…
PROTISTS ??eukaryoticunicellular/ some multiheterotrophic and autotrophic
New classification?? • Some plant like some animal like. • This is a great example of how the system is constantly changing based on new information!!!
Classification of Protists • The protists include heterotrophs, autotrophs, and some organisms that can vary their nutritional mode depending on environmental conditions. • Protists occur in freshwater, saltwater, soil, and as symbionts within other organisms. • Due to this tremendous diversity, classification of the Protista is difficult.
Protozoa: Single-Celled, Motile Organisms “animal-like” • This group of protists are single-celled, motile, heterotrophs. • Most digest their food by vacuoles formed by phagocytosing other organisms (bacteria or other single-celled creatures). • Reproduction varies greatly, from a binary fission-like process to true meiosis. • The main distinguishing feature is the method of locomotion: flagella, cilia, or pseudopodia.