Finding Order in Diversity: 1

Key Words

-Binomial Nomenclature -Class -Family -Genus -Kingdom -Order -Phylum -Systematics -Taxon

Objectives

-Describe the goals of binomial nomenclature and systematics -Identify the taxa in the classification system devised by Linnaeus

Dichotomous Key

A dichotomous key is used to identify organisms. It consists of a series of paired statements or questions that describe alterative possible characteristics of an organism. The paired statements usually describe the presence or absence of certain visible characteristics or structures. Each set of choices is arranged so that each step produces a smaller subset.

Genus

A group of closely related species.

Biology Organized

Before the system of binomial nomenclature, scientists relied on common names to identify plants and animals around the world. This system caused difficulties in name consistency since different people in different places often named the same plant or animal different things. Scientists needed a standardized system in which to organize all the organisms they were discovering.

Phylum

Classes are grouped into a phylum. A phylum includes organisms that are different but share important characteristics. The class Mammalia is grouped with birds (class Aves), reptiles (class Reptilia), amphibians (class Amphibia), and all classes of fish into the phylum Chordata. These organisms share important body-plan features, among them a nerve cord along the back.

Order

Closely related families are grouped into the next larger rank--an order. Camels and llamas (family Camelidae) are grouped with several other animal families, including deer (family Cervidae) and cattle (family Bovidae), into the order Artioactyla, hoofed animals with an even number of toes.

Classifying Species Into Larger Groups

In addition to naming organisms, biologists also try to organize, or classify, living and fossil species into larger groups that have biological meaning. In a useful classification system, organisms in a particular group are more similar to one another than they are to organisms in other groups.

Genus/Species

In binomial nomenclature, the first word of an organism's name, its genus, is capitalized. The second name, its species, is written in lowercase letters. By looking at an organism's scientific name, you can tell how closely related it is to another species.

Binomial Nomenclature

In the 1730s, Swedish botanist Carolus Linnaeus, developed a two-word naming system called binomial nomenclature. In binomial nomenclature, each species is assigned a two-part scientific name. Scientific names are written in italics. The first word begins with a capital letter, and the second word is lowercased.

Binomial Nomenclature

In the 1730s, a Swedish botanist named Carolus Linnaeus developed a two-word naming system known as binomial nomenclature.

What seven categories do taxonomoists use to group organisms?

Kingdom, phylum (or division), class, order, family, genus, and species

Class

Similar orders, in turn, are grouped into the next larger rank, a class. The order Artiodactyla is placed in the class Mammalia, which includes all animals that are warmblooded, have body hair, and produce milk for their young.

What is taxonomy?

Taxonomy is the science of classifying and naming living things.

Family

The South American llama bears some resemblance to Bactrian camels and dromedaries. But the llama is more similar to other South American species than it is to European and Asian camels. Therefore, llamas are placed in a different genus, Lama; their species name is Lama glama. Several genera that share many similarities like Camelus and Lama, are grouped into a larger category, the family--in this case, Camelidae.

Assigning Scientific Names

The first step in understanding and studying diversity is to describe and name each species. To be useful, each scientific name must refer to one and only one species, and everyone must use the same name for that species. Common names can be confusing, because they vary among languages and from place to place. Back in the eighteenth century, European scientists recognized that these kinds of common names were confusing, so they agreed to assign Latin or Greek names to each species. Unhappily, that didn't do much to clear up the confusion. Each scientific names often described species in greate detail, so the names could be long.

Kingdom

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

Systematics/Taxa

The science of naming and grouping organisms is called systematics. The goal of systematics is to organize living things into groups that have biological meaning. Biologists ofter refer to these groups as taxa.