CBA #4 Review
Part 2
Spring 2015
Classification
IV. Classification
A. Finding Order in Diversity
1. Why Classify?
a. 1.5 million species named. 2 to 100
million species yet to be discovered
b. Need to organize and group
according to biological significance
2. Scientific names- developed to avoid confusion of
common names
a. Binomial nomenclaturedeveloped by Carolus Linnaeus
1). Each species given two-part
scientific name
Ursus arctos
genus
species
2). Name is descriptive (usually Latin)
a
f
b
g
d
c
h
1.
2.
3.
4.
5.
6.
7.
8.
e
Washtulbbia circularis
Bluebottlia buzztilentia
Phattfacia stupenda
Tigerlillia terribilis
Plumbunnia nutritiosa
Manypeeplia upsidownia
Guittara pensilis
Pollybirdia singularis
B. Linnaeus’s System of Classification (taxonomyscience of classifying and naming organisms)
a. Species- most specific group. Can reproduce
among themselves and produce fertile offspring
b. Genus- group of closely related species. Share
many characteristics
c. Family- group of related genus
d. Order- broad taxonomic group composed of
similar families
e. Class- Composed of similar orders
f. Phylum- made up of several different classes
that share important characteristics
g. Kingdom- largest and most inclusive category
C. Modern Evolutionary Classification
1. Problems with traditional classification- relied on
body structure comparisons. Problems arise due to
convergent evolution. (eg. Barnacle and Limpet)
Classifying species based on
their anatomy sometimes
posed problems for
taxonomists. Sometimes due
to convergent evolution,
organisms that are quite
different from each other
evolve similar body
structures.
2. Evolutionary classification- organisms now grouped
into categories that represent lines of evolutionary
descent (not just physical similarities)
3. Cladograms- shows evolutionary
relationships among group of organisms (family
tree)
4. Similarities in DNA and RNA- look at
similarities of genes between organisms
Traditionally, African vultures (top)
and American vultures (center) were
classified together in the falcon family.
But DNA analysis has revealed that
American vultures are actually more
closely related to storks (bottom)
D. Kingdoms and Domains
1. Tree of Life evolves- from original two Kingdoms
(Plant and Animal) there are now 6 Kingdoms
2. Three Domain System –recent molecular analysis has
given rise to new taxonomic category- Domain (3
Domains)
a. Domain Bacteria- unicellular prokaryotes with thick
cell walls. Includes Kingdom Eubacteria
b. Domain Archaea- unicellular prokaryotes with cells
walls. Live in extreme environments. Includes Kingdom
Archaebacteria
c. Domain Eukarya- Includes all organisms with nucleus.
Includes 4 Kingdoms: Kingdom Protista, Kingdom Fungi,
Kingdom Plantae, Kingdom Animalia
V. How to Classify Organisms
A. Identification Keys- an aid biologists have developed
to identify unknown organisms
1. Requires that you know something about
organism- skeletal structure, segmentation,
symmetry, etc.
2. Dichotomous key- most common type of key
a. Gives two choices (opposite statements)
b. Choose best answer
c. Led to further choices that narrow selection
d. Eventually identify organism
B. Different keys developed for different purposes
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