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Monday, May 21, 2012



Taxonomy - the science of classifying organisms
Common Names
spider monkey
sea monkey
sea horse
gray wolf
Firefly
Crayfish
mud puppy
horned toad
Ringworm
black bear
Jellyfish

*Common names can be confusing and names can vary by region.
Why Classify?
About 1.5 million species named
2-100 million species yet to be discovered
Taxonomy =science of classifying organisms
--groups similar organisms together
--assigns each a name

Naming Organisms:
Organisms have common & scientific name -all organisms have only 1 scientific name
-usually Latin or Greek
-developed by Carolus Linnaeus
The scientific name is always italicized or underlined. Genus is capitalized. Species is not. Scientific names can be abbreviated by using the capital letter of the genus and a period: Example.P. leo (lion)

Members of the same genus are closely related. 
Only members of the same species can interbreed (under natural conditions)
Some hybrids do occur under unnatural conditions:
 Ligers are crosses between tigers and lions.
This two-word naming system is called 
Binomial Nomenclature
-written in italics (or underlined)
-1st word is Capitalized --Genus
-2nd word is lowercase ---species
Examples: Felis concolor, Ursus arctos, Homo sapiens,Panthera leo , Panthera tigris 

Linneaus - devised the current system of classification, which uses the following schema
Kingdom
Phylum/Division
Class
Order
Family
Genus
Species

Human
Cougar
Tiger
Pintail Duck
Kingdom
Animalia
Animalia
Animalia
Animalia
Phylum/Division
Chordata
Chordata
Chordata
Chordata
Class
Mammalia
Mammalia
Mammalia
Aves
Order
Primate
Carnivora
Carnivora
Anseriformes
Family
Homindae
Felidae
Felidae
Anatidae
Genus
Homo
Felis
Panthera
Anas
Species
sapiens
concolor
tigris
Acuta
18-2 Modern Evolutionary Classification
  • Linnaeus grouped species mainly on visible similarities & differences
  • Today, taxonomists group organisms into categories that represent lines of evolutionary descent (phylogeny)
  • Evolutionary relationships among a group of organisms can be shown on a cladogram 
Similarities in DNA and RNA
  • DNA & RNA is similar across all life forms
  • Genes of many organisms show important similarities at the molecular level
  • DNA shows evolutionary relationships & helps classify organisms

The Six Kingdoms and Domains
number of Cells
Energy
cell type
Examples
archaebacteria
Unicellular
some autotrophic, most chemotrophic
Prokaryote
"extremophiles"
Eubacteria
Unicellular
autotrophic and heterotrophic
Prokaryote
bacteria, E. coli
Fungae
most multicellular
Heterotrophic
Eukaryote
mushrooms, yeast
Plantae
Multicellular
Autotrophic
Eukaryote
trees, grass
Animalia
Multicellular
Heterotrophic
Eukaryote
humans, insects, worms
Protista
most unicellular
heterotrophic or autotrophic
Eukaryote
ameba, paramecium, algae

Using Dichotomous Keys
A dichotomous key is a written set of choices that leads to the name of an organism. Scientists use these to identify unknown organisms.
Consider the following animals. They are all related, but each is a separate species. Use the dichotomous key below to determine the species of each.
1.
Has green colored body ......go to 2
Has purple colored body ..... go to 4
2.
Has 4 legs .....go to 3
Has 8 legs .......... Deerus octagis
3.
Has a tail ........ Deerus pestis
Does not have a tail ..... Deerus magnus
4.
Has a pointy hump ...... Deerus humpis
Does not have a pointy hump.....go to 5
5.
Has ears .........Deerus purplinis

Does not have ears ......Deerus deafus



Answers:
A. Deerus magnus
B.
 Deerus pestis
C.
 Deerus octagis
D.
 Deerus purplinis
E.
 Deerus deafus
F.
 Deerus humpis
*note that all of these organisms are in the same genus.













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