World Library  
Flag as Inappropriate
Email this Article

Nominate subspecies

Article Id: WHEBN0006284964
Reproduction Date:

Title: Nominate subspecies  
Author: World Heritage Encyclopedia
Language: English
Subject: Great Grey Shrike, Crested Serpent Eagle, Bungarus, Oriental Magpie-Robin, Blue-crowned Motmot, Grey-winged Trumpeter, Blue-fronted Amazon, Olivaceous Woodcreeper, Black capuchin, Philippine Eagle-Owl
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Nominate subspecies

This article is about the biological term. For the film series, see Subspecies (film series).

In biological classification, subspecies (abbreviated "subsp." or "ssp."; plural: "subspecies") is either a taxonomic rank subordinate to species, or a taxonomic unit in that rank. A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more (including any that are extinct), never just one.

Organisms that belong to different subspecies of the same species are capable of interbreeding and producing fertile offspring, but they often do not interbreed in nature due to geographic isolation or other factors. The differences between subspecies are usually less distinct than the differences between species. The characteristics attributed to subspecies generally have evolved as a result of geographical distribution or isolation.

Nomenclature

In zoology, the International Code of Zoological Nomenclature (4th edition, 1999) accepts only one rank below that of species, namely the rank of subspecies.[1] Other groupings, "infrasubspecific entities" do not have names regulated by the ICZN. Such forms have no official ICZN status, though they may be useful in describing altitudinal or geographical clines, pet breeds, transgenic animals, etc. While the scientific name of species is a binomen, the scientific name of a subspecies is a trinomen - a binomen followed by a subspecific name. A tiger's binomen is Panthera tigris, so for a Sumatran tiger the trinomen is, for example, Panthera tigris sumatrae.

In bacteriology, the only rank below species that is regulated explicitly by the code of nomenclature is subspecies, but infrasubspecific taxa are extremely important in bacteriology; Appendix 10 of the code lays out some recommendations that are intended to encourage uniformity in describing such taxa. Names published before 1992 in the rank of variety are taken to be names of subspecies[2] (see International Code of Nomenclature of Bacteria)

In botany, subspecies is one of many ranks below that of species, such as variety, subvariety, form, and subform. The subspecific name is preceded by "subsp." or "ssp.", as Schoenoplectus californicus ssp. tatora (Totora). Note that all parts of the binomial are italicised except the actual word "subsp." or "ssp." Any botanical name including a subspecies, variety, etc., is called an infraspecific name.

Nominotypical subspecies and subspecies autonyms

In zoological nomenclature when a species is split into subspecies, the originally described population is retained as the "nominotypical subspecies"[3] or "nominate subspecies", which repeats the same name as the species. For example, Motacilla alba alba (often abbreviated Motacilla a. alba) is the nominotypical subspecies of the White Wagtail (Motacilla alba).

The repetition of the species name is referred to in botanical nomenclature as the subspecies "autonym", and the subspecies as the "autonymous subspecies".

Doubtful cases

When biologists disagree over whether a certain population is a subspecies or a full species, the species name may be written in parentheses. Thus Larus (argentatus) smithsonianus means the American Herring Gull; the notation with parentheses means that some consider it a subspecies of a larger Herring Gull species and therefore call it Larus argentatus smithsonianus, while others consider it a full species and therefore call it Larus smithsonianus (and the user of the notation is not taking a position).

Criteria

Members of one subspecies differ morphologically or by different coding sequences of DNA from members of other subspecies of the species. Subspecies are defined in relation to species.

As knowledge of a particular group increases, its categorisation may need to be re-assessed. The Rock Pipit was formerly classed as a subspecies of Water Pipit, but is now recognised to be a full species. For an example of a subspecies, see Pied Wagtail.

Cryptic species are morphologically similar, but have differences in DNA or other factors.

Monotypic and polytypic species

A polytypic species has two or more subspecies, races or more generally speaking, populations that need a separate description.[4] These are separate groups that are clearly distinct from one another and do not generally interbreed (although there may be a relatively narrow hybridization zone), but which would interbreed freely if given the chance to do so. Note that groups which would not interbreed freely, even if brought together such that they had the opportunity to do so, are not subspecies: they are separate species.

A monotypic species has no distinct population or races, or rather one race comprising the whole species. Monotypic species can occur in several ways:

  • All members of the species are very similar and cannot be sensibly divided into biologically significant subcategories.
  • The individuals vary considerably but the variation is essentially random and largely meaningless so far as genetic transmission of these variations is concerned.
  • The variation among individuals is noticeable and follows a pattern, but there are no clear dividing lines among separate groups: they fade imperceptibly into one another. Such clinal variation always indicates substantial gene flow among the apparently separate groups that make up the population(s). Populations that have a steady, substantial gene flow among them are likely to represent a monotypic species even when a fair degree of genetic variation is obvious.

See also

Notes

References

  • Ernst W. Mayr, Peter D. Ashlock: Principles of Systematic Zoology, Mcgraw-Hill College, 1991, ISBN 0-07-041144-1
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.