classification and evolution lab 15. taxonomy taxonomy is the field devoted to the classification...

Classification and Evolution

Lab 15

Taxonomy

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

Modern Taxonomic System

Kingdom Phylum Class Order Family Genus Species

Modern Taxonomic System

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

Modern Taxonomic System

Our modern taxonomic system reflects evolutionary history.

Modern Taxonomic System

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

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.

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.

Two ways to classify terrestrial vertebrates

ReptiliaClass

Mammalia

Mammals

Early reptilesTraditional phylogeny and taxonomic classification Cladogram and cladistic classification

Class Reptilia Mammalia

ArchosaursClass Aves

Turtles Crocodilians Birds

Dinosaurs

Lizards andsnakes Mammals Turtles Crocodilians Birds Dinosaurs

Lizards andsnakes

Reading a Cladogram