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.

6. 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 Mammalia Mammals Early reptiles Traditional phylogeny and taxonomic classificationCladogram and cladistic classification Class ReptiliaMammalia Archosaurs Class Aves TurtlesCrocodilians Birds Dinosaurs Lizards and snakes MammalsTurtles Crocodilians BirdsDinosaurs Lizards and snakes

10. Reading a Cladogram