Chapter 18 – Classification 18.1 - Finding Order in Diversity

THINK ABOUT IT Scientists have been trying to identify, name, and find order in the diversity of life for a long time. First classification and naming system was made before Darwin. Current shift towards using evolutionary theory to classify and name organisms.

Assigning Scientific Names Early naming methods: Used Greek and Latin Included very long descriptions - Example - the English translation of the scientific name of a tree might be “Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.” There was no standard because different scientists focused on different characteristics

Carolus Linnaeus In the 1730s, Swedish botanist Carolus Linnaeus developed binomial nomenclature.

How to Classify and Why? Binomial nomenclature – formal naming system for living things - each a name is composed of two parts. In Latin It is written in italics. First word begins with a capital letter. (Genus) Second word is lowercased. (Species) Goal = To organize living things into groups that have biological meaning.

Binomial Nomenclature The polar bear, for example, is called Ursus maritimus. The first part of the name —Ursus—is the genus to which the organism belongs. Ursus contains five other species of bears.

Binomial Nomenclature The second part of a scientific name—maritimus for polar bears Unique to each species and is often a description of the organism’s habitat or of an important trait. Example - The Latin word maritimus refers to the sea: polar bears often live on pack ice that floats in the sea.

Binomial Nomenclature The scientific name of the red maple is Acer rubrum. The genus Acer consists of all maple trees. The species rubrum describes the red maple’s color.

Assigning Scientific Names Scientific names are more specific Assures scientists refer to the same organism Common names are less specific Many common names for the same organisms Different common names based on location.

Common Name Confusion! What is the name of this animal? Example, the names cougar, puma, panther, and mountain lion can all be used to indicate the same animal— Felis concolor. Honey Badger – Not closely related to the badger, more closely related to the Weasel Family.

Linnaean Classification System Linnaeus also developed a classification system. Organized species into a hierarchy, or ranking. He grouped species according to structural similarities and differences.

Classifying Species into Larger Groups Systematics -The science of naming and grouping organisms. The groups are called taxa (singular: taxon).

Linnaeus’s Seven Taxa Linnaeus identified just four levels in his original classification system, but expanded to seven taxa! Kingdom Phylum Class Order Family Genus Species More Specific

Kingdom The largest and most inclusive of Linnaeus’s taxonomic categories is the kingdom. All multicellular animals are placed in the kingdom Animalia.

Phylum Includes organisms that are different but that share important characteristics.

Taxa Class - Includes similar orders. Order - Includes closely related families. Families - Includes many closely related genera Genus – Includes many closely related species

Problems With Traditional Classification Physical similarities are not always the result of close relationships. Genetic similarities more accurately show evolutionary relationships. Not in the bear and raccoon families