Download Chapter 14 - Central Lyon CSD

Chapter 14
Classification
I. The concept of Classification
-
A classification system brings order and logic to a
group of related objects.
A. The Need for Classifying Organisms
1. Biologists classify organisms in
categories called taxa.
2. The science of classification is called
taxonomy.
3. Having a classification system not only
brings order, it also serves as a tool to identify
new organisms.
4. Classification also provides a logical
means of naming organisms.
a. common names are not specific
enough
Ex. ?
5. One scientific name needed
a. Latin or Latin style
B. Binomial Nomenclature
- Many early scientists developed
classification schemes.
1. Aristotle
a. divided everything into two
groups: plants and animals
b. split plants into sizes
c. split animals into groups of where
they lived
d. Didn’t work because groups need
to be based on the same basis.
2. Carolus Linnaeus
a. based his groups on structural
features only
b. each type of organism was a
species and if two organisms had the same
features they were the same species
c. introduced the two part naming
system called binomial nomenclature
1. 1st word is a noun and is the genus of the
organism
2. 2nd word is an adjective and is the specific
name
3. Genus + Species = species name
d. Genus and species are different taxa
(categories).
e. A genus is a broader category then
species, so one genus may contain several
species.
For example: cats belong to the genus Felis.
wildcat = Felis sylvestris
ocelot = Felis pardalis
cougar = Felis concolor
house cat = Felis catus
Oak trees are the genus Quercus
red oak = Quercus rubra
white oak = Quercus alba
f. Always capitalize the genus but not the
species.
Always underlined or italicized.
May abbreviate with first letter of genus
and full species, F. catus
C. Determining Relationships
- organisms with a common ancestor are
considered related and are grouped together
1. Classifying Based on Structure
a. sometimes fossil records help a lot with
evolutionary lines ex: horse, tapir and rhino
b. most of the time other lines of evidence
are needed also
ex. Homologous structures show that
walruses, sea lions, and seals belong to the
same group
c. Linnaeus used homologous structures,
so he was also using evolutionary
relationships – sort of by accident
d. sometimes fossil records and
homologous structures can give misleading
information
2. Classifying Using Biochemistry and
Development
a. as new tools were invented, new
information could be used for classifying
ex. Biochemistry showed that the
horseshoe crab is not a true crab but related
to spiders
3. Classifying on a molecular basis
a. analysis of protein and DNA can
often reveal relationships that could not be
determined any other way.
ex. Guinea pigs were classified as rodents but
their amino acid sequences were too different
to be rodents. Now they are their own group.
D. Phylogeny – evolutionary history
1. each taxon (group) can be thought of as
representing a different step in an organisms
phylogeny.
ex. Giant Panda
a. phylogeny in doubt for over 100 years
b. 1869 they thought it was a bear / appearance
c. later it was thought that it behaved like a red panda
and was moved to the raccoons
d. combining structure and behavior made it into its
own group
e. has a thumb – is it related to a monkey?
f. DNA and biochemistry places it closer to bears
Chapter 14 Section 2
II. A System of Classificatioin
- start broad and then narrow the field
ex. Motor vehicles……….
A. Taxa – 7 different levels so it is as specific as
possible.
Kingdom
Phylum
Class
Order
Family
Genus
Species
a. each group gets smaller
b. each taxa can be divided into sub-divisions
to be even more specific.
ex. Subspecies = breeds, varieties, races
B. Some examples of classification – pg. 377
Do Making a Key pg. 378 in groups of 3 or 4
- objects are shoes, ex. Bob’s shoe
C. The Kingdom Problem
1. At first there were only 2 kingdoms –
plants and animals – work okay until the
discovery of microscopic organisms
ex. Euglena – mobile like animals, makes
food like plants
2. the 5 kingdom system is used today
Monera, Protista, Fungi, Plantae, Animalia
3. Some want to add a 6th kingdom to
include some ancient bacteria.
Do the Thinking Lab on pg. 380 and hand in – on
your own.