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Classification. Biology 11 A. Allen. Classification. There are many everyday situations in which you need to find objects or information; Books in a library. An organized dresser drawer. How do you organize your hard drive? Grouping and naming items is called “classification”.
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Classification Biology 11 A. Allen
Classification There are many everyday situations in which you need to find objects or information; Books in a library. An organized dresser drawer. How do you organize your hard drive? Grouping and naming items is called “classification”. Why classify? Developed by scientists to bring order to the great diversity of life forms. Provides a logical naming system. Newly discovered organisms may be grouped. Identify organisms represent relationships among organisms.
Early Classification Systems • Aristotle, a Greek philosopher (384-322 BC.) observed and grouped over 500 different animals. He grouped them according to where they lived; Animals... Land dwellers air dwellers water dwellers • What are some problems with this system? • (Bats, birds and dragonflies are both ‘air dwellers’, yet they are not related. They are mammals, avians and insects respectively.) • Today, we know that hawks, ostriches and penguins are all birds, but Aristotle classified them as land, water and air dwellers.
...Early Classification Systems • Theophrastus (also from the 4th century BC.) grouped over 500 plants: Plants... herbs shrubs trees • The invention of the microscope and increased world travel led to the need for a more effective classification system.
Classify the following! • Hawk • Earthworm • Whale • Leech • Fire ant • Black widow spider • Bat • Seagull • Hippo • scorpion
Binomial Nomenclature...a better method of classification • Carolus Linnaeus (1707-1778) developed a classification system based only on structural characteristics. He is the father of modern taxonomy. • Linnaeus used structural characteristics. He recognized that the more features that an organism has in common, the closer their relationship. Without realizing it, Linnaeus was also grouping organisms according to their evolutionary history or phylogeny. (Linnaeus incorrectly viewed species as unchanging.)
...Binomial Nomenclature • Linnaeus used a two name system for assigning names to organisms. This is known as binomial nomenclature. • Two word Latin name. Latin is a dead language (unchanging) • The first name is the genus (a noun) • Second name is the species (an adjective) within the genus. • Genus and species are given together to constitute the species name of an organism. Genus may be indicated with first initial, but only if it is understood. • Examples: • Canis familiaris (dog) • C. lupus (wolf) • C latrans (coyote) • Note that this system shows a connection between dogs, wolves, and coyotes. • Genus is capitalized. Species is lower case.
...Binomial Nomenclature Advantages of Binomial Nomenclature: • Common names can be confusing... A starfish is not a fish, ringworm is not a worm, panda bears and koala bears are not considered true bears. • Many names for one organism (puma = mountain lion = cougar)
Relationships Among Organisms • Organisms are classified according to evolutionary relationships (ancestry). Various forms of evidence are used… • Structure: Organisms that have similar structures may be related. Homologous structures, and vestigial body parts are examined.
…Relationships Among Organisms Homologous Structures are similar in appearance or structure, but not necessarily in function. They may indicate a relationship between two organisms.
…Relationships Among Organisms Homologous Structures are similar in appearance or structure, but not necessarily in function. They may indicate a relationship between two organisms.
…Relationships Among Organisms • Analogous Structures are used for similar function but are not necessarily similar in structure. They do not suggest a relationship between two organisms.
…Relationships Among Organisms • Vestigial Structures are reduced and functionless anatomical features. They can be used to determine relationships.
…Relationships Among Organisms • Embryology Recapitulates Phylogeny… • Huh? Look …and think… • Development. Relationships between various organisms is revealed by comparative embryology Definitions Recapitulate: to summarize briefly Phylogeny: The evolutionary history of a species
…Relationships Among Organisms • What are humans more closely related to? Starfish or crabs?... (body cavity)
…Relationships Among Organisms • What is this organism more closely related to… a crab or a tarantula? • This ‘horseshoe crab’ is more closely related to spiders! • Biochemistry: Biochemistry is another method scientists can use to determine relationships. The horseshoe crab’s biochemistry more closely resembles that of a spider than a crab.
…Relationships Among Organisms • Molecular Studies: DNA and proteins can be used to determine relationships. The more DNA two organisms have in common, the closer the relationship. • Mitochondrial DNA mutates at predictable rates. This allows scientists to determine how long ago two related species have been diverging from one another in their evolution. Hey man, did you know that we have more than 98% of our DNA in common?
…Relationships Among Organisms • Fossil evidence: fossil records can help scientists determine changes in species as they evolved to determine common ancestors of today’s organisms.
Breeding capabilities • Species:a group of organisms that is reproductively isolated from all other groups of organisms; one species can't breed with another species. There are exceptions; the horse and donkey, for example, produce a mule-which is sterile- when bred together. • (There are exceptions where the rule breaks down, especially in the Plant Kingdom. However, in the majority of cases, interbreeding of species does not produce fertile offspring.) + = • Horse + donkey = mule
Six Kingdom Classification System • Eubacteria • Archaebacteria • Protista • Fungi • Plantae • Animalia
Archaebacteria • single-celled organisms lacking nucleus and are therefore, prokaryotes • Many live in extreme environments geysers, acidic conditions, hypersaline, guts of animals (cause flatulence) • Usually harmless to humans • ocean vents • Cell wall does not contain peptidoglycana polymer consisting of sugars and amino acids that forms a mesh-like layer
…Archaebacteria Bacteria Of Boiling Hot Springs In Yellowstone National Park
Eubacteria • Cell wall contains peptidoglycan • Prokaryotic • Heterotrophs or autotrophs
Protista • first eukaryotes • “garbage can” kingdom • not fungi, plants or animals • multicellular or single cell • parasitic or free-living • motile or sessile • sexual or asexual
Fungi • more closely related to animals than to plants • heterotrophs • digest, then ingest (decomposers) • not limited by light - can grow anywhere! • often parasitic / pathogenic • important in symbiosis
Plantae • photoautotrophs • colonized land, produced O2 • adapted to “life in air” • pollination: co-evolved with animals • massive carbon sink • enormous effect on climate
Animalia • heterotrophs • invaded all habitats (restricted by O2) • most animals are insects • most insects are beetles!(~ 350,000 species - 1/5th of all known organisms! • How many species of organisms are known? ~ 1.5 million • How many species of organisms might there be? conservatively: ~ 12.5 million • Consider: oceans = 70% of earth’s surface • < 1% has been explored • 12 people have walked on the moon; 2 have seen deep ocean floor!
Okay, this has nothing to do with anything. I just thought it was cool…
