Classification of Organisms

Section 1: Categories of Biological Classification

Section 2: How Biologists Classify Organisms

Taxonomy• Taxonomy is the

science of naming and classifying organisms

• Binomial nomenclature- Linnaeus’ 2 word system (Genus species)

• Scientific name:honey beeApis mellifera

Scientific Name

• 1st letter of Genus is capitalized• 1st letter of species is lower case• Name is usually written in italics • Red Oak = Quercus rubra

Classifying Organisms

• 3 Domains (new ??) Prokaryotes - Archaea

Bacteria

Eukaryotes - Protist, Fungi, Plants, Animals

• Levels of Classification Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

What is a Species?

• Biological species - a group of natural populations that are interbreeding or that could interbreed and are reproductively isolated from other such groups (natural barriers - geography)

# of Species• Some groups of

species do not have barriers and can reproduce unlimitedly

• 1.5 million species identified in world today

• 5-10 million more are believed to be in the tropics alone (rainforests)

• New species identified regularly

Evolutionary History• Phylogeny- system of classification based on

similarities (evolutionary history)• Convergent evol. Species evolve independently of

one another, but have similarities due to similar habitat.

• Analogous characters- similarities that arise through convergent evolution

Evolutionary Systematics • Claudistics- focus on sets of unique traits

found in a group of organisms• Phylogenic Tree- represents a hypothesis of

evolutionary history that may be inferred b/c it wasn’t observed