Taxonomy
I.
TAXONOMY
A. Classification
1. Arrangement of organisms into groups
a) Taxonomic groups are referred to as taxa (taxon, singular)
B. Nomenclature
1. Naming of organisms and taxa
C. Identification
1. Placing newly discovered organisms into the proper taxa
II. BINOMIAL NOMENCLATURE
A. Species have latinized names composed of 2 parts
1. The first part is the genus, the second part is the specific epithet
a) The first letter of the genus is capitalized, all other letters of the genus and all
letters of the specific epithet are lower case
b) Both are italicized (underlined when handwritten)
2. The genus is a noun, the specific epithet is an adjective
a) The genus must stand alone and may include several species
b) The specific epithet has no meaning by itself
B. Only the species name is binomial
1. All taxonomic ranks above that are uninominal nouns, written with a capital initial letter
III. CLASSIFICATION
A. Current taxonomic system was invented by Carolus Linnaeus
1. He arranged organisms into groups of ever increasing inclusiveness
B. Current Major Taxa
1. Kingdom, Phylum, Class, Order, Family, Genus, and Species
a) Most inclusive to most exclusive
2. Major taxa can be further divided
a) Superclass, subclass, infraclass, etc.
3. Carl Woese, using rRNA studies, has proposed there are three main lineages of life
a) These lineages are given the status of Domains, which are more inclusive than
kingdoms
b) The three lineages are Eubacteria, Archaea, and Eukarya
C. Goals
1. Taxonomy should emphasize a natural relationship
a) Descent from a common ancestor explains similarities
(1) The more recent the descent, the closer they are grouped
(a) The genera of a family are less diverse than families of an order, since the
common ancestor of the families (within the order) is more remote than
the common ancestor of the genera within the family
IV. GEOLOGICAL TIME PERIODS
A. Cenozoic era -- Age of Mammals
1. Quaternary
a) Recent
(1) Modern humans
b) Pleistocene
(1) Early humans
2. Tertiary
a) Pliocene
(1) Adaptive radiation of apes
b) Miocene
(1) Abundant grazing mammals
c) Oligocene
(1) Angiosperms dominant
d) Eocene
(1) Adaptive radiation of mammals
e) Paleocene
(1) First placental mammals
B. Mesozoic era -- Age of Reptiles
1. Cretaceous
a) Climax of reptiles
b) First angiosperms appear
2. Jurasic
a) Reptiles and birds dominant
3. Triassic
a) First dinosaurs
b) Conifers abundant
C. Paleozoic era
1. Permian
2. Pennsylvanian
a) Amphibians dominant
3. Mississippian
4. Devonian
a) Age of Amphibians and Fishes
5. Silurian
a) First land plants
6. Ordovician
a) First fish
7. Cambrian
a) Abundant marine invertebrates
V. THE KINGDOMS
A. Prokaryotes (Domains Eubacteria and Archaea)
1. The kingdom Monera has recently been divided into two separate kingdoms
a) Eubacteria
(1) Cell walls are made of a polysaccharide called peptidoglycan
b) Archaea
(1) These bacteria do not contain peptidoglycan in their cell walls
(2) Archaeobacteria are more related to eukaryotic kingdoms than to eubacteria
2. Both kingdoms are commonly referred to as bacteria
a) Bacteria have all forms of nutrition except ingestion / phagocytosis
3. Both groups lack a nucleus, and are therefore referred to as prokaryotes
a) They also lack the other membrane-bound organelles
B. Protista
1. A diverse group of mostly single-celled (unicellular) eukaryotic organisms and their
close relatives
a) Protozoa are heterotrophic (ingestion or saprozoic) and are therefore referred to
as animal-like protists
b) Algae are photosynthetic and are therefore referred to as plant-like protists
c) Cell walls vary or are absent
2. Current proposed kingdoms are in a state of flux
C. Fungi
1. Multicellular eukaryotes that absorb food
2. Cells walls are made of a polysaccharide called chitin
D. Plants
1. Multicellular eukaryotes that photosynthesize
2. Cells walls are composed of a polysaccharide called cellulose
E. Animals
1. Multicellular eukaryotes that ingest food
2. Cells lack cell walls
VI. NON-LIVING INFECTIOUS AGENTS
A. Although the following are not living, they do have some life characteristics and do
infect other organisms, therefore, they are studied by biologists
B. Viruses
1. These are inert particles of either RNA or DNA, a protein coat called a capsid, and
possibly an envelope
2. These do not have metabolism and are acellular
3. All groups of life are infected with viruses
C. Viroids
1. These are non-coding RNA molecules that cause disease in plants
D. Prions
1. These are proteins with abnormal configurations that convert normal proteins into their
configuration
2. These cause nervous disorders in animals, including bovine spongiform
encephalopathy and Creutzfeldt-Jakob disease