Download Ch 18 Classification Outline

HT 1
Classification
I. History of Taxonomy
*Thousands of species are discovered each year
*Organisms are grouped together or classified according
to shared characteristics
*The way organisms are classified continues to change through
the years
*Today classification is based on the evolutionary history of
organisms
A. Early Systems of Classification
*Taxonomy branch of bio that names and groups
organisms according to characteristics and evolutionary
history
*Aristotlegreek philosopherfirst to classify2000
yrs. Agogrouped organisms into either plant or
animal, then by where they lived, and also by the stem
they had
*As science progressed, Aristotle system became
Inadequate.
B. Linnaeus’s System
*Linnaeus grouped organisms by their morphology
form and structure
1. Levels of Classification
*hierarchy of seven different levels of classification
*Kingdom, phylum or division, class, order, family,
genus, species
2. Binomial Nomenclature
*Species name (scientific name)  two parts
Species identifier ex. Sapiens and genushomo
*system of 2 part naming Binomial Nomenclature
*genus namecapitalized and both names are
underlined or written in italics.
*In Latin so scientists around the world can use
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system
*Linnaeus’s seven level system is still used today
however taxonomists today may add more
levels Varieties or Subspecies
*modern taxonomists also consider phylogeny
(evolutionary history) of organisms.
*Linnaeus’s system still relevantbased on
Morphologyphylogeny todayspecies w/
Common ancestor share common characteristics
II. Modern Phylogenetic Taxonomy
*todaytaxonomists classifyby morphology, chromosomal
characteristics, nucleotide, amino acid sequences, and
embryological developmentthis + fossil record =
phylogeny of organism…..(phylogeny or”evolution”)
A. Systematics
*Classification should reflect phylogeny (evolution)
this is called Systematic taxonomy
*Systematics organizes living things in the context of
Evolution
*Phylogenic tree family tree that shows evolutionary
relationships among organisms. (fig. 18-3)
1. The Fossil Record
*works well often but sometimes fossil record is
incomplete in some areas for certain organism
2. Morphology
* Taxonomists compare morphologies of living and
also nonliving organisms (homologous features)
(common ancestor)
3. Embryological Patterns of Development
*Blastulaball of cells (stem cells)(1st)
*Blastopore (2nd) indentation in blastula that
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Becomes digestive system
*Blastoporebecomes posterior end (anus) in
Enchinoderms and vertabrates
other organisms such as arthropods
Blastopore becomes anterior end (mouth)
4. Chromosomes and Macromolecules
*classify by comparing karyotypes (fig. 18-5)
* classify by comparing DNA, RNA nucleotide
Sequence (characteristic sequences)(A,T,G,C)
*classify by comparing Protein amino acid
Sequences (the 20 different amino acids)
5. Cladistics
*Cladisticsuses derived characteristics 
characteristics that evolved into existence within
a certain group of organismsEX.-->BIRDS
only animals that have FEATHERS
*CladogramsAncestry diagrams made from
cladistic information
III. Two Modern Systems of Classification
A. Six-Kingdom System
Table 18-2;
1. Kingdom Archaebacteria
*archae “ancient” bacteriasimilar to first
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first organisms on Earthheterotrophic prokaryote
then some became autotrophic prokaryotes
*Many live in harsh environmentsanimal
Intestines, anaerobic environments, salty env., hot
springs…
2. Kingdom Eubacteria
*EubacteriaEu”true” bacteria
*most use oxygen
*w/Archaebacteria make up most of life on Earth
*reproduce by binary fission
*can evolve fast (some only live 30 min.)
3. Kingdom Protista
*A lot look very similar to plants (ocean kelp)
but DO NOT have specialized tissues like
Plants
*Contains all Eukaryotes that are not Plants,
Animals, or Fungi
*Ex. Euglena and amoebas
4. Kingdom Fungi
*absorb nutrients
*fungi, mushrooms, rusts, mildews, molds…
5. Kingdom Plantae
*Ex. Mosses, ferns, conifers, flowering plants…
*reproduce sexually by meiosis
6. Kingdom Animalia
*most have symmetrical bodies (two similar halves)
B. Three Domain System