BINOMIAL NOMENCLATURE

CLADOGRAMS

DICHOTOMOUS KEYS

Why Binomial Nomenclature?

Linnaeus’s method of naming organisms, called binomial nomenclature, gives each species a scientific name with two parts.

The first part is the genus name, and the second part is the specific name that identifies the species.

Biologists use binomial nomenclature for species because common names vary in their use.

Why Binomial Nomenclature?

Glacier or Blue Bear

Why Binomial Nomenclature?

Louisiana Black Bear

Why Binomial Nomenclature?

Cinnamon Bear

Why Binomial Nomenclature?

Florida Black Bear

Why Binomial Nomenclature?

Kermode or Spirit Bear

Why Binomial Nomenclature?

American Black Bear

Why Binomial Nomenclature?

Ursus americanus (Pallas, 1780)

Binomial Nomenclature

When writing a scientific name, scientists use these rules:

The first letter of the genus name always is capitalized, but the rest of the genus name and all letters of the specific epithet are lowercase.

If a scientific name is written in a printed book or magazine, it should be italicized.

When a scientific name is written by hand, both parts of the name should be underlined.

After the scientific name has been written completely, the genus name will be abbreviated to the first letter in later appearances (e.g., U. americanus).

Binomial Nomenclature

"Formal" scientific names should have a third part, the authority.     The authority is not italicized or underlined.

The authority is written as an abbreviation of the last name of the person responsible for naming the organism. Since Peter Simon Pallas was the first person to name the black bear, the Pall. Or Pallas will be behind the scientific name and possibly with the date in parehtheses.

Ursus americanus Pall. 1780

or

Ursus americanus (Pallas, 1780)

Cladistics

Cladistics: is a relatively new system of phylogenetics classification that uses shared derived characters to establish evolutionary relationships (characters).

Scientists consider two main types of characters when doing cladistic analysis.

An ancestral character is found within the entire line of descent of a group of organisms.

Derived characters are present members of one group of the line but not in the common ancestor. Derived character is a feature that apparently evolved only within the group under consideration.

Cladogram

Cladogram: The greater the number of derived characters shared by groups, the more recently the groups share a common ancestor.

Dichotomous Key

• Dichotomous Key : A device for easily and quickly identifying an unknown organism.

• The dichotomous key is the most widely used type in biological sciences.

• The user is presented with a sequence of choices between two statements, couplets, based on characteristics of the organism. By always making the correct choice, the name of the organism will be revealed.

Dichotomous Key