Classification and Evolution

1
Classification and Evolution

• Lab 15

2
Taxonomy

• Taxonomy is the field devoted to the
  classification of living things.
• First devised by Carolus Linnaeus.
• Hierarchical nested categories.

3
Modern Taxonomic System

• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

4
Modern Taxonomic System

• The genus and species together make up the
  scientific name.
• Genus is capitalized, species is not.
• Both are italicized.
• Homo sapiens

5
Modern Taxonomic System

• Our modern taxonomic system reflects evolutionary
  history.

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Modern Taxonomic System

• Organisms that are closely related to each other
  share a more recent common ancestor than those
  that are more distantly related.

7
Modern Taxonomic System

• Some traits are more useful than others when
  determining relatedness.
• Homologous traits evolved from a trait present in
  a common ancestor.
• Useful for determining relatedness.
• Analogous traits evolved from different traits in
  unrelated groups, but look similar due to
  convergent evolution.
• Not useful for determining relatedness.

8
Modern Taxonomic System

• Homologous traits that are shared very far back
  (primitive traits) do not help us define smaller,
  more recent groups.
• Multicellularity or backbones do not help to
  define mammals.
• Derived traits that are shared just be the group
  we are defining are the most useful.
• Hair and mammary glands do define mammals.

9
Two ways to classify terrestrial vertebrates
Reptilia
Class Reptilia
Mammalia
Class Mammalia
Archosaurs
Class Aves
Lizards and snakes
Lizards and snakes
Mammals
Turtles
Crocodilians
Birds
Crocodilians
Mammals
Turtles
Birds
Dinosaurs
Dinosaurs
Early reptiles
Traditional phylogeny and taxonomic classification
Cladogram and cladistic classification
10
Reading a Cladogram