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To avoid confusion caused by regional names,
biologists use a classification system to group
organisms in a logical manner and to assign
names.
Linnaeus developed the method used to name
organisms and group them in a logical manner
which gives a universally accepted name.
the scientific name is the universally accepted
name given to every species.
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– the system of naming organisms
according to genus and species
Taxonomy is used to classify and assign
each organism a universally accepted name.
In taxonomy, each level is called a taxon:
Kingdom
Phylum
Class
Order
Family
Genus
Species
Grizzly bear
Black bear
Panda bear
Red fox
Abert
squirrel
Coral
snake
Sea
Star
Animalia
Kingdom
Chordata
Phylum
Mammalia
C;lass
Carnivora
Order
Ursidae
Family
Ursae
Genus
Ursus arctos
Species
Which Similarities Are Most Important?
Conical shell
Early systems of classification grouped organisms
together based on visible similarities
Organisms are grouped into
categories that represent lines of
evolutionary descent, or phylogeny,
not just physical similarities
Phylogeny – evolutionary relationships
among organisms
A cladogram is a diagram that shows
evolutionary relationships among organisms
based on shared derived characters.
African vulture
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Marabou stork
American vulture
The American vulture and the
Marabou stork are more closely
related than the American vulture
and the African vulture
Similarities at the DNA level in the
genes of organisms can be used to
help determine classification
◦ By comparing the DNA sequences of two or more
species, biologists estimate how long the species
have been separated
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The three-domain system was first invented in
1990, but not generally accepted until later.
One main characteristic of the three-domain
method is the separation of Archaea and Bacteria
◦ previously grouped into the single kingdom
Bacteria (also called Monera).
Archaea are the most ancient organisms on Earth and they exist in extreme environments
Streptococcus bacteria can live in
a persons body and cause
illnesses like strep throat
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The majority of biologists accept the
domain system, but a large minority use the
five-kingdom method.
Extremophilic microbes can be found thriving in some of the most
hostile environments imaginable —
swimming in near-boiling water
eating rocks
in subzero temperatures
where radiation levels rival nuclear reactors
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An extremophile is an organism that thrives under
"extreme" conditions.
The term frequently refers to prokaryotes and is
sometimes used interchangeably with Archaea.
extremophiles come in all shapes and sizes
our understanding of the diversity of extreme habitats
increases daily.
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They are a combination of the suffix –phile,
meaning "lover of," and a prefix specific to
their environment. For example, acidophiles
are organisms that love (phile) acid (acido).
Acidophile: An organism that grows
best at acidic (low) pH values.
Alkaliphile: An organism that grows
best at high pH values.
Anaerobe: An organism that can grow
in the absence of oxygen.
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In biology, binomial nomenclature is the
formal system of naming specific species.
Each species name is in (modern scientific)
Latin and has two parts, so that it is popularly
known as the “scientific name " of the
species.
The species is the lowest level in the system
for classifying organisms.
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As the words "binomial", "binominal" and
"binary" the scientific name of each species is
formed by the combination of two words
the genus name (also called the generic
name).
a second word identifying the species within
that genus, (also called the specific epithat)
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Species names are usually in italics; for
example, Homo sapiens. When handwritten,
they should be underlined; for example,
Homo sapiens. Each name should be
underlined individually.
The genus name is always written with an
initial capital letter.
◦ For example, the entire tiger species is Panthera
tigris
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Cladistics is the hierarchical classification of
species based on evolutionary ancestry.
Cladistics is distinguished from other taxonomic
systems because it focuses on evolution rather
than similarities between species
Cladistics generates diagrams called cladograms
that represent the evolutionary tree of life.
DNA and RNA sequencing data are used in
cladistics.
The word cladistics is derived from the ancient
Greek meaning "branch."