Discipline of classifying organisms and assigning each organism a universally accepted name.
Chapter 9 - Taxonomy. Taxonomy – the science of classifying organisms – has two purposes: To...
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Transcript of Chapter 9 - Taxonomy. Taxonomy – the science of classifying organisms – has two purposes: To...
Chapter 9 - Taxonomy
Taxonomy – the science of classifying organisms – has two purposes:
• To identify the organism• To represent relationships among them
•
History of Taxonomy:
• Aristotle – believed in the “ladder of nature” – sponges were at the bottom and humans were at the top – he classified things as either plants or animals ( see fig.1 pg.326)
9.1 Taxonomic Systems
• Carl Linnaeus- 18th century – he classified organisms based on structure
• The more features organisms have in common, the closer their relationship
He introduced binomial nomenclature: a 2 name system for naming organism using Latin or Greek ( Latin is a dead language)
• Ex. Castor canadensis – beaver • Genus species - the Genus name is
always a capital letter
The 2 names indicate similarities in anatomy, embryology & evolution
ancestry
• Ex. – Ursus americanus (black bear) Ursus horribilis (grizzly bear)
• koala bear Genus: Phascolarctos Species: cinereus
• Panda bear Genus Ailuropoda Species: melanoleuca
Modern Taxonomy
Today we use these major categories and evidence to support classification:
• Fossil records – they provide clues, but are rarely complete.
• Anatomy – a) homologous structures – similar in structure but may have different functions.b) vestigial structures – structures that once had a purpose but no longer serve a function.
• Comparative embryology – ex. – all vertebrates have a stage as an embryo where they look alike.
• Comparative biochemistry – comparing DNA, genes and proteins.
Fossil Records
Homologous Structures
Vestigial Structures
Vestigial hind legs in a python. Evidence that snakes descended from lizzards.
Comparative Embryology
Comparative Biochemistry
Levels of ClassificationOrganisms are classified based on 7
taxa (levels) • Kingdom• Phylum• Class • Order• Family • Genus• Species
Until recently organisms were grouped into 5 kingdoms:
Now it is believed that Monera should be 2 separate kingdoms: Eubacteria
And Archaebacteria
Phylogeny – the history of the evolution of organisms – often shown in a diagram called a phylogenetic tree
– see pg.329
A three Domain system of Classification