Biology Chapter 8
The Classification of Organisms
8A - The Necessity of Classifying
People group things together for convenience. (spices, pans, tools,
instruments in orchestra)
Taxonomy (or systematics) from Greek taxis arrangement, order
definition- arranging organisms into groups based on
similarities
(the science of classifying organisms into groups.)
Why do we need a biological classification system?
1)It is necessary for accurate communication among
scientists.
-Quite often a common name applies to several
different organisms.
-"gophers" salamander, turtle, frog, snake, large
rodent (50 types)
2)It allows information about organisms to be studied
and used in an organized way.
-Taxonomist has over 1 million different kinds of
organisms to group
-approximately 5,200 species are being discovered
and added to the classification system each year
The Classification Hierarchy
first recorded classification of organisms was attempted by
Aristotle: Greek scientist and philosopher
He classified living organisms into 1 of 3 plant or 3 animal groups:
PLANTS
1)Herbs- if they lacked
woody parts
2)Shrubs- if they had
several short
woody stems
3)Trees- 1 large, woody
stem
ANIMALS
1)Fish- lived in water
2)Birds- if the could fly
3)Land animals- those that
lived on land
Artificial classification system- based on appearance
Aristotle's system was used for approximately 2,000 years.
Mid 1700's Carolus Linnaeus, a Swedish naturalist, set forth a
new classification system also based on appearance.
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Linnaeus developed his classification system using some ideas of
John Ray an English clergyman who devoted much of his time to natural
studies and became very well known for his work with plants. It was
John Ray who clarified the concept of species. In 1691, toward the
end of his career, John Ray published a book called The Wisdom of God
Manifested in the Creation. In this book, which became very popular
and was translated into several languages, Ray illustrated the wisdom
of God by describing the design in nature. This work by John Ray
became a foundation for Linnaeus's study.
Linnaeus published his findings in 2 books:
Species Plantarum- dealing with plants (1753)
Systema Naturae- dealing with animals (1758)
-Linnaeus' system is still used today.
-It's flexible and it has had some changes.
International scientific committees meet every few years to
decide questions of taxonomy and recommend changes in the
classification system.
-
Today's System of Classification
7 basic levels in the modern classification hierarchy:
Kingdom, phylum, class, order, family, genus, species
-The outline moves from general to specific.
-The kingdoms are general groups that include many animals or
plants.
-The species are specific groups that usually include only 1 or
very few organisms.
a
General rules for using the biological classification hierarchy:
1) Each group on one level of the hierarchy may be divided
into several groups on the next lower level.
2) Each group in the hierarchy has various characteristics
that all of the levels under the group possess.
3) Each level of the hierarchy can be divided into various
smaller units before reaching the next lower level.
see p. 222 [Example: subphyla
supra(above) ]
sub(below) infra(below)
The Kingdoms
There is a disagreement among taxonomists as to the number of
kingdoms that exist.
Aristotle- 2 main divisions: plants and animals
Linnaeus- 2 groups: Kingdom Plantae and Kingdom Animalia
Linnaeus did not include people in his
classification scheme because he recognized their
special creation in the image of God.
These men had no knowledge of microscopic organisms.
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Two
Kingdoms
Linnaeus
1750's
(Traditiona
l)
Three
kingdoms
Hogg and
Haeckel
1860's
Four
Kingdoms
Copeland
1930's
Five
Kingdoms
Whittaker
1960's
Two Superkingdoms,
Four
Kingdoms
Parker,
Corliss,
and Bock
1980's
1.PLANTAE
Vascular
plants
Bryopgytes
True fungi
Slime molds
Algae
Prochlorophytes2
Blue-green
algae
Bacteria
1.PLANTAE
1.PLANTAE
1.PLANTAE
Superkingdom
Eukaryotae3
2.ANIMALIA
Multicellular
animals
Protozoa
Sponges
See p. 223-224
Know the material on the chart on p. 224
6A-5
Scientific Names
Binomial Nomenclature: a system of naming an organism with two
names.
binomial-"two names"
nomenclature-"naming"
Carolus Linnaus proposed and consistently used this system.
Linnaus used Latin and Latinized Greek-the scientific languages
of this day
Why did Linnaus use Latin?
1) unchanging (since it was no longer in use it would
not change)
2) descriptive (many Latin words were very well suited for
describing the traits of organism)
3) a root of many modern languages (Latin was under by the
scientist of all countries)
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see p. 223-224
Know the material in the chart p. 224 6a-5
Scientific Names: binomial "2-name"
nomenclature "naming"
def.- a system of naming organisms in which each organism is given a genus species name.
Carolus Linnaius proposed and consistently used this system.
Linnaius used Latin and Latinized Greek ( the scientific language of his day)
Why did Linnaius choose Latin?
(1)unchanging (since it was no longer in use it would not change)
(2)descriptive (many Latin words were very well suited for describing the traits)
(3)a root of many modern languages ( Latin was understood by the scientist of all countries)
genus- species names
The scientific name of an organism's is actually the name of the genus to which it belongs and the
species which it is in.
Because it's a foreign term it is printed in italics; if written or typed the name is underlined.
Only the genus name is usually a noun and the species name an adjective.
Linnaius used the genus and species name in much the same way that your own family and given
names are used
(1)To tell what family you are a member
(2)TO distinguish you from all the other members of your family
varieties- different forms or types of organisms within a species.
8B - The Species and the Kind
Read pp. 227-228
Species def. - a group of similar organisms
Two commonly accepted parts of the def. of a species:
1. Members of a species are structurally similar but do
have a degree of variation.
2. Members of a species can interbreed and produce fertile
offspring under natural conditions.
Problems with the species concept: Artificial characteristics
Why is there a problem with grouping members of a
species by physical characteristics?
Environment can greatly affect physical appearance
(example: p. 228 tiger salamander and axolotls lacked iodine)
Problems with species concept: Interbreeding
Why is there a problem with grouping members of a
species on the basis of interbreeding?
1. Many organisms reproduce by means other than sexual
reproduction.
(example: bacteria and some protozoans don't reproduce
sexually)
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2.
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After many generations of breeding, the offspring of one
ecotype may be able to interbreed with another ecotype
that it normally would not have been able to breed with.
(example: chihuahua and St. Bernard, see p. 229;
also Rana pipiens - green, spotted grass frog)
Ecotype - organisms that appear the same but are suited for one
environment rather than another and often cannot interbred.
The Key to keep in mind "the classification of organisms was done
by man for convenience"
The Biblical "Kind"
Gen. 1:9-25 tells us that the organisms God created were designed to
reproduce "after its kind."
Kind - Hebrew: min means group of organisms that can interbreed
freely in nature
What is the primary characteristic which would place an organism into
a biblical kind?
The ability to reproduce
Read pp. 230-231 and 231-232
Natural system of classification - based on genetic similarities
Evolutionists emphasize migration, adaptation, and selection since
they are crucial parts of their theory. (They do happen but
evolutionists twist them around to fit their need.)
Migration - the moving of organisms from one area to another
Adaptation - according to evolutionists, the change of an
organism that enables it to survive in a new environment.
(Resembles Lamarck's theories of need, use and disuse, and
inheritance of acquired characteristics.)
Selection - nonrandom mating
Evolutionists state that migration and selection bring about a new
species. They combine this with adaptation to claim the development
of a new species.
migration, selection, & adaptation: do not produce or develop
new genes or new species. They only account for rearrangement and selection of already existing ones.
(The 8 people on the ark are the ancestors of all people
alive today.)