Contents:

• Background Vocabulary
• Fundamental Concepts

Taxonomy

The branch of science that deals with the orderly arrangement of organisms based on phylogenetic relationships.

Taxonomists

The scientists who study classification, and attempt to arrange organisms into groups based on their relationships.

Diversity

The adjective describing the broad range of forms that organisms exhibit.

Classification

When pertaining to Biology, the process of placing organisms into groups on the basis of similarity.

Misnomers

Misleading names for organisms.

Dichotomous Key

A chart made up of many numbered steps that helps scientists arrive at the name of an organism using the process of elimination on the organism1s features.

Binomial Nomenclature

The two-part method of naming species. The first word, the genus, is always capitalized. The second word, the specific epithet, is never capitalized. The two words are always set in italics, as in Homo sapiens. This system was invented by Carolus Linneaus.

Specific Epithet

The second name in the Binomial Nomenclature, this word is in adjective in Latin that describes the species. This is often the color of the species or the area in which it is found.

Phylogeny

The evolutionary history of a species.

Eukaryote

A cell that contains a nucleus.

Prokaryote

A cell that lacks a nucleus.

Heterotroph

An organism that cannot make its own food and must take in nourishment form its environment.

Autotroph

An organism, such as a plant, that can manufacture its own food from simple inorganic substances.

An explaination and illustration of Linnaeus1s system of classification.

Linnaeus deemed that all of the systems of classification of his time were confusing and inaccurate, and set about inventing a new one.
He gave each organism a scientific name, which consisted of the genus and specific epithet, which described the species. In this name, which he called the binomial nomenclature, the genus is always capitalized. The second word, the specific epithet, is never capitalized. The two words are always set in italics, such as in Homo sapiens.
The other section of his system created a system for organizing organisms based on their similarities. In this system, he put all organisms into vast groups called kingdoms. These were divided into phyla, which were broken down into classes, which were subdivided into orders, which were partitioned into families, which were segregated into genera, which were finally separated into species. In the plant kingdom, divisions are used in place of phyla. Figure 1.1 illustrates this system.

Fig. 1.1

As shown by the diagram, Linnaeus1s system starts out all-encompassing, and becomes increasingly specific as it moves inward.
After its invention, the two-kingdom system went undisputed until 1866. At that time, Ernst Haeckel, a German scientist, suggested that the kingdom Protista be added. Since many one-celled organisms that did not fit into Plantae or Animalia fit into Protista, it was accepted and added into the classification system.
After this, few major changes were made until 1969, when Robert Whittaker proposed the kingdoms Monera and Fungi. These two new kingdoms were added to the system.
However, the classification system is still not perfect. Because such a wide variety of organisms must be classified, a few do not fit into any of the current kingdoms. Therefore, research is still taking place that will, hopefully, give the world a classification system into which all organisms fit.

How the levels of classification are used to identify a species.

An organism1s full scientific name gets increasingly more specific from left to right. The first division that an organism is placed in is its kingdom. This is easily determined for most organisms, although it may require a microscope for some. A human being would go into kingdom Animalia.
The next division would be the phylum. Phyla are the largest divisions in a kingdom, and they often separate organisms based on major characteristics. Humans would fit into phylum Chordata, as they have backbones.
The next largest subdivisions are the classes. Classes are smaller than phyla, yet they still contain many different subdivisions of themselves. Humans, being mammals, would fir into class Mammalia.
Orders are yet another division, and they break classes down into smaller portions. Humans belong in the order Primates. Orders are where species distinctions become noticeable. Although humans and wolves are both mammals with backbones, their differences become evident in their order.
Families, the next smallest division, separate similar groups. Although humans and chimpanzees may be similar, their similarities end here. Humans are classified into the Hominidae family.
Genera are the second smallest divisions under Linnaeus1s system of classification. Under a given genus are organisms that differ only in small ways, such as coloration or behavior. Humans belong in the genus Homo.
Finally, the species are the most specific classification. All organisms within a given species have the same characteristics, with few differences. Humans belong in the species sapiens.

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