Taxonomy andBinomial Nomenclature

Biology

Post Falls High School

Why Classify?

• To name organisms

• This is binomial nomenclature

• To place them in logical relationships– Separate by differences– Group by similarities

• This is taxonomy

Why give scientific names?

• Many different organisms may share a common name– Buzzard = hawk (England) or vulture (U.S.)– Gopher = rodent in West, turtle in S.E.

Why give scientific names?

• Many organisms have more than one common name– Mt. lion, puma, cougar– Moose, hirvi

Beginnings of Classification

• Aristotle (384-322 BC) classified all living things he knew

• Plant or Animal

• Organized Plants into herb, shrub, or tree according to size and structure

• Organized Animals by habitat and physical differences– Birds, bats, and some insects grouped

together because they all have wings and fly!

Binomial Nomenclature• To avoid confusion each has 2 part

scientific name

• Genus name + specific epithet (species name); genus capitalized/species not

• Species name is often descriptive

• Written in italics (or underlined)

• In Latin– Dead language– Never changes in meaning

Red legged grasshopperMelanoplus femur-rubrum

Father of Modern Taxonomy

Carolus Linnaeus (Carl von Linne)

• born on May 23, 1707, in the province of Småland in southern Sweden

• University of Uppsala, finished his medical degree at the University of Harderwijk

• training in botany was part of the medical curriculum, for every doctor had to prepare and prescribe drugs derived from medicinal plants

Carolus Linnaeus (Carl von Linne)

• published the first edition of his classification of living things, the Systema Naturae

• professorship at Uppsala in 1741, he restored the University's botanical garden (arranging the plants according to his system of classification)

• died in 1778

Linnaean Classification• Hierarchical with 7 levels, or taxa (taxon-

singular)

• Kingdom, phylum (division in plants), class, order, family, genus, species

American Lobster

Market Squid

Blue Mussel

Virginia Oyster

European Oyster

Phylum Arthropoda Mollusca Mollusca Mollusca Mollusca

Class Malacostraca Cephalopoda Bivalvia Bivalvia Bivalvia

Order Decapoda Decapoda Mytiloida Pterioida Pterioida

Family Nephropidae Loliginidae Mytilidae Ostreidae Ostreidae

Genus Homarus Loligo Mytilus Crassostrea Ostrea

Species americanus opalescens edulis virginica edulis

Value of Taxonomy

• 1. Taxonomy works out for us a vivid picture of the existing organic diversity of the earth.2. Taxonomy provides much of the information permitting a reconstruction of the phylogeny of life.3. Taxonomy reveals numerous interesting evolutionary phenomena.4. Taxonomy supplies classifications which are of great explanatory value in most branches of biology and paleontology.

• 5. Taxonomy organizes known lifeforms.

Alterations to Taxonomy

• Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical/chemical similarities

• This means similar genes and DNA is a strong contributor in modern taxonomic decisions

• Ex. American vulture, African vulture, and stork

Cladogram

• Identifies and considers only those characteristics that are evolutionary innovations (new traits that arise as species change over time)

• New traits in later members of lineage called derived characteristics

• Used to construct cladogram, a diagram that shows evolutionary relationships

Cladogram

Cladogram

Molecular Clock• Accumulation of neutral mutations after

separation of relatives

• Dissimilarity in DNA sequences can be used to calculate time since separation

Kingdoms

• 2 (Plantae/Animalia) for Aristotle/Linnaeus

• Then came Protista for microscopic

• Then came Fungi for odd plants

• Then prokaryotes became Monera

• 5 kingdoms !

Kingdoms

• Now Monera has been subdivided

• Now there are 6!– Archaebacteria for the older, primitive bacteria– Eubacteria for the “true” modern bacteria

Determination of Evolutionary Relationships

• Structural similarities

• Breeding behavior

• Geographical distribution

• Chromosome comparison

• Biochemistry

Domains• Now scientists have devised supergroups

to place these related kingdoms

• Eukarya – protists, fungi, plants, animals

• Bacteria – the true bacteria

• Archaea – primitive forms of bacteria

Bacteria

• Unicellular prokaryotes

• Thick, rigid cell walls surrounding a membrane

• Peptidoglycan in walls

Archaea

• Unicellular prokaryotes

• Live in extreme environments and are all anaerobic

• Walls lack peptidoglycan and membranes consist of unusual lipid structure

Eukarya

• All eukaryotes (with nuclei)

• All the rest of organisms known to man

• Without a set of international rules to follow, the results of taxonomy would be confusing at best. The rules of zoological nomenclature are contained in a document known as the International Code of Zoological Nomenclature (ICZN). The object of the code is to promote stability and universality in the scientific names of animals. All names must be unique, universal, and show stability.

Uniqueness Every name has to be unique. If several names have been given to the same taxon, priority decides which name will be the valid name.

Universality Zoologists have adopted, by international agreement, a single language to be used on a worldwide basis. All animals are given a generic and specific name in Latin. These names are in italics or are underlined (i.e. Homo sapiens).

Stability The ICZN attempts to prevent the frequent changing of names to provide stability.

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