Download Classification

Classification
Taxonomy
• Taxonomy – classification of organisms
• Binomial system of nomenclature
(Linnaeus)
– Genus and species
– Ex: Homo sapiens
• Taxon (taxa) – formal grouping of
organisms at any level
• Why classify?
Taxa
• The Linnaeus System works by placing each organism into a
layered hierarchy of groups. The groupings (taxa) of taxonomy from
most general to most specific are:
• Kingdom
• Phylum (animals) or Division (plants)
• Class
• Order
• Family
• Genus
• Species
• Several acronym mnemonics have been made for these, for
instance King Phillip came over for good soup, or Kings Play Chess
On Funny Green Squares.
DOMAIN
Eukarya
KINGDOM
Animalia
PHYLUM
Chordata
CLASS
Mammalia
ORDER
Carnivora
FAMILY
Felidae
GENUS
Felis
SPECIES
Felis catus
Fig. 23-1, p. 485
Example
Phylogeny:
the evolutionary history of a species
Phylogeny
• What do you think the term evolutionary
classification is referring to?
• If you lived in the time of Linnaeus, how would
you have classified dolphins? Barnacles and
crabs?
• Phylogeny – study of evolutionary relationships
– Species in a genus have a common ancestor
– Genuses in a family have a common ancestor, etc.
– Conclusion: the higher the taxon, the further back the
common ancestor
Cladograms
• Cladograms
– Cladistic analysis identifies and considers only those
characteristics that are evolutionary innovations
– Derived characteristics – characteristics that appear in recent
parts of a lineage, but not in older members
– Derived characteristics are used to construct cladograms
• DNA and RNA Analysis to Classify Organisms
(similarities and relationships)
– African vulture and American Vulture (Turkey Vulture) once
thought to be closely related; now we know the American vulture
is more closely related to the stork.
• Molecular clock – uses DNA comparisons to estimate the
length of time 2 species have been evolving
independently. Complex because each genome has
several “ticks” to follow.
Clade
• Consists of a common ancestor and all its
descendants
A Cladogram
Fig. 23-8b, p. 494