Binomial Nomenclature

Binomial Nomenclature Definition

Binomial nomenclature is the system of scientifically naming organisms developed by Carl Linnaeus. Linnaeus published a large work, Systema Naturae (The System of Nature), in which Linnaeus attempted to identify every known plant and animal. This work was published in various sections between 1735 and 1758, and established the conventions of binomial nomenclature, which are still used today. Binomial nomenclature was established as a way to bring clarity to discussions of organisms, evolution, and ecology in general. Without a formalized system for naming organisms the discussion of them, even between peers that speak the same language, becomes nearly impossible. The number of different colloquial names for a single species can be staggering.

Each scientific name in binomial nomenclature consists of two names, also called descriptors or epithets. The first word is the generic epithet and describes the genus that an animal belongs to. The second word is the specific epithet and refers to the species of the organism. Typically, the words have a Latin base and describe the genus or species with references to traits that are specific to the group. When written, the text of a scientific name is usually italicized or underlined, to clarify that it is a scientific name written in binomial nomenclature. The generic epithet is always capitalized, while the specific epithet is written in lower-case. In some older documents, both may be capitalized. Typically, the full name should be written out. However, when discussing many species of the same genus, the generic name is sometimes abbreviated to the first letter, still capitalized.

The generic epithet of binomial nomenclature refers to the taxonomic hierarchy of organisms, genus, of each organisms. This is a clue as to the origins, evolution, and life-history of the organism. Genera, which reside in families, share the traits of those families. In turn, families reside within orders, which also have their own characteristics. This continues up the hierarchy, all the way to the 4 domains of life, which are each distinguished by their own characteristics. Although a species may lose some or most of its ancestral characteristics, binomial nomenclature makes it easier to keep track of these relationships in the larger context of taxonomy.

In some organisms, the species are divided into even smaller subspecies, which are presented after the species name. While this adds to the number of names, it can create even more specificity when the need arises. Many organisms are currently evolving, and fast enough that the need for multiple subspecies designations may exist.

In scientific literature, the first scientist to describe the species is often noted after the scientific name. This practice increases the “authority” over a scientific name, and increases the clarity with which scientists can describe and discuss organisms in the literature. This practice even documents when names have been changed, which helps avoid confusion and uncertainty in papers.

Examples of Binomial Nomenclature

Felis concolor

Whether you know it as the puma, cougar, mountain lion, painter, or catamount, you are talking about the same animal. All of these words describe a large, single-colored predatory cat. Not only are there many versions of the name for this animal in English, but also in Spanish. In South and Central America, this cat is also known as león colorado, onça-vermelha, poema, guasura, and yaguá-pitá. Scientists wishing to discuss this animal with an international audience need a way to cut through all the different colloquial versions of the animals. Therefore, the scientific name Felis concolor is used in the conventional binomial nomenclature. Felis describes the genus that the cats belong two, while concolor describes their uniform color.

Homo sapiens

The scientific name Homo sapiens is used to describe the human species. It combines parts of the Latin words hom, meaning human, and sapien, meaning wise. This descriptor of humans tells us many things about the species. First and foremost it defines humans as part of the genus Homo, which includes several extinct species of early humans and modern humans. While we are the only living species in the genus Homo, the specific epithet describes our supposed separation from other species in the genus. Homo neaderthalensis for example, is hypothesized to have gone extinct because of competition from Homo sapiens, or modern humans. Many theorize that it was advanced tool use and language in Homo sapiens that gave them an edge. Modern DNA analysis has shown that Neanderthal genes still exist within the human population, suggesting the two may have interbred at certain points. The binomial nomenclature used here serves to clarify between different forms of organisms through evolutionary time, as well as clarify that all humans are being discussed.

Related Biology Terms

  • Taxon – A category of biological organization, for example, a genus or phylum.
  • Generic Epithet – The first word of a scientific name, which describes the genus the organism belongs to.
  • Specific Epithet – The second word of a scientific name in binomial nomenclature, describing the species.
  • Systematics – The evolutionary classification of organisms, which uses binomial nomenclature as its base.

Quiz

1. Which of the following is a correctly written scientific name in proper binomial nomenclature?
A. Rungwecebus Kipunji
B. Rungwecebus kipunji
C. Rungwecebus Kipunji

Answer to Question #1

2. A student is reading a book about big cats and reads the scientific name Felis spp.. The student writes a report about the species Felis spp. and the many varieties it contains. What has the student done wrong?
A. Spp. identifies a specific species.
B. Spp. is short-hand for the scientist who discovered the genus.
C. Spp. is short-hand for “a number of different species in the genus Felis”.

Answer to Question #2

3. Which of the following sets of organisms is the most closely related?
A. Panthera tigris and Panthera leo
B. Panthera tigris and Canis lupus
C. Panthera tigris and Neofelis nebulosa

Answer to Question #3
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