Classification Essential Question Why is it important to place living things into categories?

WHY CLASSIFY? Organization is necessary when dealing with large numbers of something It’s easier to work if there is a system of how to keep track of things If you have a specific place for something, then you don’t spend time hunting around trying to find it There are some 10-30 million organisms on Earth!

History of Taxonomy Objectives Describe Aristotle’s classification system, and explain why it was replaced. Explain Linnaeus’s system of classification, and identify the main criterion he used to classify organisms. What are the seven levels of organization that Linnaeus used to categorize organisms? What criterion do modern taxonomists use to classify an organism? What are two reasons that species names are more precise than common names?

Early System of Classification Classification is the grouping of information or objects based on similarities Taxonomy is the branch of biology that names and groups organisms according to their characteristics and evolutionary history. Organisms were first classified more than 2,000 years ago by the Greek philosopher Aristotle.

Early System of Classification Organism’s were grouped into land dwellers, water dwellers, and air dwellers. Plants were placed into three categories based on the differences in their stems. As new organism’s were discovered, this system became inadequate. Categories were not specific enough. Common names did not describe a species accurately. Names were long and hard to remember.

Modern System Based on Hierarchy Carl von Linné (Carolus Linnaeus) 1707 – 1778 Swedish biologist considered the father of modern taxonomy. Science of Systematics dates to Linnaeus in the 18th century who devised the basic systems of binomial nomenclature and hierarchical classification. All organisms have a unique binomial name Humans are Homo sapiens

Nested Hierarchy Seven Levels of Organization Linnaeus used morphology (form and structure), to categorize organisms. His system is still used today. He first divided all organisms into two Kingdoms, Plantae (Plants) and Animalia (animals). This was the same as Aristotle’s main categories.

Nested Hierarchy Seven Levels of Organization Modern System: Each kingdom (plant and animal) was divided into a phylum* (division for plants) Each phylum into a smaller groups called class Each class was divided into an order Each order was divided into family (families) Each family was divided into a genus (plural-genera) Each genus was divided into a species (scientific name) *Note: Phyla and Family were not in Linnaeus’s classification system but were added by modern scientists.

Levels of Classification King Kingdom Philip Phylum Came Class Over Order For Family Grandma’s Genus Soup Species

Hierarchical Classification Each categorization at any level is called a taxon.

Hierarchical Classification Variations of a species that occur in different geographic areas or habitats are called subspecies.

Additional Levels of Organization Botanist sometimes split species into subsets known as VARIETIES. Peaches and nectarines are a different variety of the peach tree, Prunus persica peach

Binomial Nominclature We only know about a fraction of the organisms that exist or have existed on Earth. Taxonomists give a unique scientific name to each species they know about whether it’s alive today or extinct. Why not just use common names?

Mountain Lion

Devil Cat

Screaming Cat

Puma

Ghost Cat

Panther

Cougar

Catamount

Binomial Nomenclature There are at least 50 common names for the animal shown on the previous 8 slides. Common names vary according to region. Soooo……why use a scientific name?

What’s in a Name? A common name can be used by more than one species Erithacus rubicula Robin Turdus migratorius Robin A common name can be used by more than one species A scientific name must be unique

Binomial Nomenclature The scientific name comes from one of two “dead” languages – Latin or ancient Greek. Why use a dead language? Because in the 18th century scientists everywhere understood these languages. The FIRST word of the Scientific Name is the Genus to which the organism belongs. The Genus name refers to the relatively small group of organisms that share many similarities The SECOND word of the name is the species. The Species name is usually a Latin description of some important characteristic of the organism.

Binomial Nomenclature: Rules for Writing Scientific Names The first letter of the Genus is ALWAYS capitalized The first letter of the species is NEVER capitalized Scientific names of organisms are always italicized or underlined For example: Red maple tree (common name) Acer rubrum or Acer rubrum (scientific name) Acer is the Latin name for Maple (genus) rubrum is the Latin word for Red (species) The name can also be abbreviated as: A. rubrum

Binomial Nomenclature: Rules for Writing Scientific Names Humans are named: Homo sapiens Homo because of our large brain and upright posture. sapiens because of our intelligence and ability to speak.

Classification of Living Things • Eubacteria: the oldest forms of bacteria. • Archaea: More advanced forms of bacteria. • Eukaryota: All life forms with eukaryotic cells including plants and animals