Biological

Classification and Phylogenies

Why Do We Classify Organisms?

Facilitates the study of the vast number of species on the planet.

Reflects relationships between organisms.

Enables scientists to talk to each other in the same language

Tacitus bellus

Carolus von Linnaeus (1707-1778) Swedish scientist who laid foundation for modern taxonomy

Binomial Nomenclature

Carolus von Linnaeus

Two-word naming system

Genus Noun, Capitalized,

Underlined or Italicized

Species Descriptive, Lower Case,

Underlined or Italicized

Hierarchical Classification

Taxonomic categories

DOMAIN

Kingdom King

Phylum Philip

Class Came

Order Over

Family For

Genus Green

Species Soup

Kingdoms and Domains

Eubacteria Archaea Eukarya

Eubacteria Archaea Protoctista Plantae Fungi Animalia

Monera Protoctista Plantae Fungi Animalia

The three-domain system

The six-kingdom system

The traditional five-kingdom system

Phylogeny and Taxonomy

The evolutionary history of a group of related species is called phylogeny.

Reconstructing phylogenies involves identifying and classifying species to show their evolutionary relatedness

Phylogenic trees depict the evolutionary relationships between organisms

Trees are built based on data from:.

Fossil record

Anatomy

Sequences of DNA/RNA

Also called CLADOGRAMS

Phylogenic trees often represent standard classifications

Leaves represent present day species

Interior nodes represent hypothesized common ancestors

Some important terms used to describe phylogenetic trees

A clade includes all and only the descendants of a particular ancestor

These trees depict equivalent relationships despite different styles

Equivalent relationships, even though internal branches rotated

The Importance of Phylogenetic Trees

1. Increasing use of phylogenetic trees in the

biological sciences

2. Need to know what trees diagrams do and do

not communicate

3. Provide an efficient structure for organizing

biodiversity info

4. Develop accurate conception of totality of

evolutionary history