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Nomenclature

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Topics

description

  • Nomenclature
  • Identification
  • Need for naming living organisms
  • Types of Nomenclature
  1. Vernacular/Local/Common names
  2. Scientific names
    (a) Binomial Nomenclature
    (b) Trinominal Nomenclature

notes

As you might be able to appreciate, it would be difficult for people speaking or writing in different languages to know when they are talking about the same organism.

This problem was resolved by agreeing upon a ‘scientific’ name for organisms in the same manner that chemical symbols and formulae for various substances are used the world over.

The scientific name for an organism is thus unique and can be used to identify it anywhere in the world.

The system of scientific naming or nomenclature we use today was introduced by Carolus Linnaeus in the eighteenth century. The scientific name of an organism is the result of the process of classification which puts it along with the organisms it is most related to. But when we actually name the species, we do not list out the whole hierarchy of groups it belongs to. Instead, we limit ourselves to writing the name of the genus and species of that particular organism.

World over, it has been agreed that both these names will be used in Latin forms. Certain conventions are followed while writing the scientific names:

  1. The name of the genus begins with a capital letter.
  2. The name of the species begins with a small letter.
  3. When printed, the scientific name is given in italics.
  4. When written by hand, the genus name and the species name have to be underlined separately. 

notes

[ICSE 9]

Naming of Living Organisms

Common names are variable and sometimes confusing. We know animals and plants by the common names used for them in a particular locality. Can you think of any plant or animal which in India is known by several names? Pumpkin and custard apple could be good examples. Pumpkin in the local languages is known as, "sitaphal", "kashiphal", "kumhra", ''petha", "kaddu" and so on. 

Sometimes, a certain common name is not enough to indicate the particular species. There are different kinds of frogs, earthworms, or grasses. Talking of crows again, if you have to distinguish between the two kinds of crows, you have to use some adjectives such as the hill or jungle crow and the plain or house crow. But it.does not mean that 
the jungle crow cannot come to the plains and the plain crow cannot go to the hills. What is most important is that these two crows cannot interbreed, and so they are different species. 

Scientific names:

In science, people from different countries with different languages have to read about each other's research work. So, it was found necessary to eliminate any possible confusion in using local names by substituting them with names especially given in scientific language. The present practice is to use a two-part name for each species. For example, our hill crow is Corvus macrorhynchos and the house crow is Corvus splendens. The first part in these names is the genus which is the same "Corvus" for both, and the second part is the name of the particular species of the genus. This method of naming the organisms is called the binomial nomenclature (bi: two, nomen: name), and was first introduced by Linnaeus (1707-1778). 

Rules in scientific names:

Two main rules to write scientific names are as follows: 

  1. Scientific names are always written in the Roman script and when in print they are always in italics. When hand-written they should always be underlined. 
  2. The first letter of the genus name should be a Capital letter, while the species name should begin with a small letter.

notes

[CBSE 11]

Naming of Living Organisms

As stated earlier, there are millions of plants and animals in the world; we know the plants and animals in our own area by their local names. These local names would vary from place to place, even within a country. Probably you would recognize the confusion that would be created if we did not find ways and means to talk to each other, to refer to organisms we are talking about.

Hence, there is a need to standardise the naming of living organisms such that a particular organism is known by the same name all over the world. This process is called nomenclature. Obviously, nomenclature or naming is only possible when the organism is described correctly and we know to what organism the name is attached to. This is identification.

In order to facilitate the study, number of scientists have established procedures to assign a scientific name to each known organism. This is acceptable to biologists all over the world. For plants, scientific names are based on agreed principles and criteria, which are provided in International Code for Botanical Nomenclature (ICBN). You may ask, how are animals named? Animal taxonomists have evolved International Code of Zoological Nomenclature (ICZN). The scientific names ensure that each organism has only one name. Description of any organism should enable the people (in any part of the world) to arrive at the same name. They also ensure that such a name has not been used for any other known organism. Biologists follow universally accepted principles to provide scientific names to known organisms. Each name has two components – the Generic name and the specific epithet. This system of providing a name with two components is called Binomial nomenclature. This naming system given by Carolus Linnaeus is being practised by biologists all over the world. This naming system using a two word format was found convenient. Let us take the example of mango to understand the way of providing scientific names better. The scientific name of mango is written as Mangifera indica. Let us see how it is a binomial name. In this name, Mangifera represents the genus while Indica is a particular species or a specific epithet.

  • Universal rules of nomenclature are as follows:

  1. Biological names are generally in Latin and written in italics. They are Latinised or derived from Latin irrespective of their origin.
  2. The first word in a biological name represents the genus while the second component denotes the specific epithet.
  3. Both the words in a biological name, when handwritten, are separately underlined or printed in italics to indicate their Latin origin.
  4. The first word denoting the genus starts with a capital letter while the specific epithet starts with a small letter. It can be illustrated with the example of Mangifera indica.

The name of the author appears after the specific epithet, i.e., at the end of the biological name and is written in an abbreviated form, e.g., Mangifera indica Linn. It indicates that this species was first described by Linnaeus.

notes

[TB 11]

Naming of Living Organisms

Nomenclature:

Giza, Inimene, Emberi, Manna, Doanna, Umano …….

In all probability, these words must be new to you… but they all mean “Human” in different foreign languages! There are presently more than 6000 languages in the world and an animal can be named in more than 6000 ways! Unfortunately, it is impossible for anyone to have a good functioning knowledge of most languages and hence there arises a need for a universally accepted scientific naming system for all organisms. The process of assigning scientific names to animals or taxonomic groups is called nomenclature. For example, worldwide, the scientific name Homo sapiens denotes human. Classification and grouping were done to facilitate a deeper understanding of the unique characteristics of each organism and its interrelationship among closely related species. It plays a vital role in the arrangement of known species based on their similarities and dissimilarities. Numerous characters such as morphology, genetic information, habitat, feeding pattern, adaptations, evolution, etc., are examined before an organism is named. One of the primary responsibilities of systematic biology is the development of biological nomenclature and classification. Nomenclature is not an end to systematics and taxonomy but it is necessary in organizing information about biodiversity. Nomenclature functions to provide names for all taxa at all levels in the hierarchy of life. The naming of the organisms is done based on the guidelines of the International Code of Zoological Nomenclature (ICZN). The scientific name ensures that each organism has only one name.

  • Binomial nomenclature (L. Bi-two; Nomen-Name):

Biologists follow universally accepted principles to provide scientific names to known organisms. Each name has two components, a generic name, and a specific epithet. This system of naming the organism is called Binomial Nomenclature which was popularised by Carolus Linnaeus and practised by biologists all over the world. For example, the National Bird (Indian Peafowl) – Pavo cristatus, the National Animal tiger as Panthera tigris, and the Tamil Nadu State bird is the common Emerald dove Chalcophaps indica.

  • Trinominal nomenclature (Tri – three):

This naming system was proposed by Huxley and Stricklandt, Trinomen means, three names: generic name, species name and sub-species name. When members of any species which have large variations then trinomial system is used. On the basis of 
dissimilarities, this species gets classified into subspecies. It is the extension of binominal nomenclature system which has an addition of subspecies. All the three names are set in italics and only the first letter of generic name is capitalized, if handwritten then it should be underlined separately E.g.Corvus splendens splendens (Indian house crow)

Tautonymy: The practice of naming the animals in which the generic name and species name are the same, is called Tautonymy. e.g. Naja naja (The Indian Cobra).

  • Rules of Nomenclature:

  1. The scientific name should be italicized in printed form and if handwritten, it should be underlined separately.
  2. The generic name’s (Genus) first alphabet should be in uppercase.
  3. The specific name (species) should be in lowercase.
  4. The scientific names of any two organisms are not similar.
  5. The name or abbreviated name of the scientist who first publishes the scientific name may be written after the species name along with the year of publication. For example Lion-Felis leo Linn., 1758, or Felis leo L., 1758.
  6. If the species name is framed after any person’s name the name of the species 
    shall end with i, ii, or ae.
    For example, a new species of a ground-dwelling lizard (Cyrtodactylus) has been 
    discovered and named after Scientist Varad Giri, Cyrtodactylus varadgirii.
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