In biology Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy, a genus (plural: genera) is a low-level taxonomic Taxonomy is the practice and science of classification. The word finds its roots in the Greek τάξις, taxis and νόμος, nomos (meaning 'law' or 'science'). Taxonomy uses taxonomic units, known as taxa (singular taxon) rank (a taxon A taxon is a group of (one or more) organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement. Defining what belongs or does not belong to such a taxonomic group is done by a taxonomist. It is not uncommon for one taxonomist to disagree with another on what exactly belongs to) used in the classification of living and fossil Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils across geological time, how organisms In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole. An organism may either be unicellular (single-celled) or be composed of, as in humans, many trillions of cells grouped into, which is an example of definition by genus and differentia. The term comes from Latin genus "descent, family, type, gender",[1] cognate with Greek Greek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical ancient Greek literature and the New Testament of: γένος – genos, "race, stock, kin".[2]
The hierarchy of biological classification Biological classification, or scientific classification in biology, is a method by which biologists group and categorize organisms by biological type, such as genus or species. Biological classification is a form of scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis. Modern biological classification's eight major taxonomic ranks In biological classification, rank is the level in a taxonomic branched ordering of living things. The most specific level is species, the next most specific is genus, and then family, class, etc. Sometimes (but only rarely) the term "taxonomic category" is used and more often the term "rank" is used -- the ranking, or ordering,, which is an example of definition by genus and differentia. A family What does and does not belong to each family is determined by a taxonomist. Similarly for the question if a particular family should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing a family contains one or more genera. Intermediate minor rankings are not shown.
The composition of a genus is determined by a taxonomist Taxonomy is the practice and science of classification. The word finds its roots in the Greek τάξις, taxis and νόμος, nomos (meaning 'law' or 'science'). Taxonomy uses taxonomic units, known as taxa (singular taxon). The standards for genus classification are not strictly codified, and hence different authorities often produce different classifications for genera. In the hierarchy of the binomial classification system, genus comes above species In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are often used, such as similarity of DNA, morphology or and below family.
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Generic name
The scientific name of a genus may be called the generic name or generic epithet: it is always capitalized. It plays a pivotal role in binomial nomenclature The formal system of naming species is called binomial nomenclature , binominal nomenclature (since 1953, the technically correct form in zoology), or binary nomenclature, the system of biological nomenclature.
Binomial nomenclature
The rules for scientific names are laid down in the Nomenclature Codes The Nomenclature Codes are the various rulebooks that govern biological nomenclature, each in their own area. They are united in that they use names of the type Neotragus batesi and Caesalpinia gilliesii for species. To an end-user who only deals with names of species, with some awareness that species are assignable to families, it may not be; depending on the kind of organism and the Kingdom it belongs to, a different Code may apply, with different rules, laid down in a different terminology. The advantages of scientific over common names are that they are accepted by speakers of all languages, and that each species has only one name. This reduces the confusion that may arise from the use of a common name to designate different things in different places (example elk), or from the existence of several common names for a single species.
It is possible for a genus to be assigned to a kingdom governed by one particular Nomenclature Code by one taxonomist, while other taxonomists assign it to a kingdom governed by a different Code, but this is the exception, not the rule.
Pivotal in binomial nomenclature
The generic name often is a component of the names of taxa of lower rank. For example, Canis lupus is the scientific name of the Gray wolf The gray wolf or grey wolf , often known simply as the wolf, is the largest wild member of the Canidae family. It is an ice age survivor originating during the Late Pleistocene around 300,000 years ago. DNA sequencing and genetic drift studies reaffirm that the gray wolf shares a common ancestry with the domestic dog (Canis lupus familiaris), a species, with Canis Canis is a genus containing 7 to 10 extant species, including dogs, wolves, coyotes, and jackals, and many extinct species the generic name for the dog The dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The domestic dog has been one of the most widely kept working, hunting and companion animals in human history and its close relatives, and with lupus particular (specific) for the wolf (lupus is written in lower case). Similarly, Canis lupus familiaris is the scientific name for the domestic dog The dog is a domesticated form of the wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The domestic dog has been one of the most widely kept working and companion animals in human history. The word "dog" may also mean the male of a canine species, as opposed to the word ".
Taxonomic units in higher ranks often have a name that is based on a generic name, such as the family name Canidae Canidae is the biological family of carnivorous and omnivorous mammals that includes the wolves, foxes, jackals, coyotes, and the domestic dog; a member of this family is called a canid (/ˈkeɪnɨd/). The Canidae family is divided into the "wolf-like" and "dog-like" animals of the tribe Canini and the "foxes" of the, which is based on Canis. However, not all names in higher ranks are necessarily based on the name of a genus: for example, Carnivora The diverse order Carnivora (pronounced /kɑrˈnɪvərə/ or sometimes /ˌkɑrnɪˈvɔərə/; from Latin carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" (often popularly applied to members of this is the name for the order to which the dog belongs.
The problem of identical names used for different genera
A genus in one kingdom In biology, kingdom or regnum is a taxonomic rank, which is either the highest rank or in the more recent three-domain system, the rank below domain. Kingdoms are divided into smaller groups called phyla or divisions in botany. The complete sequence of ranks is life, domain, kingdom, phylum, class, order, family, genus, and species is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different Nomenclature Code. Although this is discouraged by both the International Code of Zoological Nomenclature The International Code of Zoological Nomenclature is both a book containing (among others) a set of rules and recommendations on the formal naming of animals, and that set itself[citation needed]. Among zoologists (and in the book) it is often referred to simply as "the Code" (in mixed company, taxonomists refer to it as "the ICZN& and the International Code of Botanical Nomenclature The International Code of Botanical Nomenclature is the set of rules and recommendations dealing with the formal botanical names that are given to plants. Its intent is that each taxonomic group ("taxon", plural "taxa") of plants has only one correct name that is accepted worldwide. The value of a scientific name is that it is, there are some five thousand such names that are in use in more than one kingdom. For instance, Anura Frogs are amphibians in the order Anura , formerly referred to as Salientia (Latin salere (salio), "to jump"). Most frogs are characterized by a short body, webbed digits (fingers or toes), protruding eyes and the absence of a tail. Frogs are widely known as exceptional jumpers, and many of the anatomical characteristics of frogs, is the name of the order The Latin suffix -formes meaning "having the form of" is used for the scientific name of orders of birds and fishes, but not for those of mammals and invertebrates of frogs Frogs are amphibians in the order Anura , formerly referred to as Salientia (Latin salere (salio), "to jump"). Most frogs are characterized by a short body, webbed digits (fingers or toes), protruding eyes and the absence of a tail. Frogs are widely known as exceptional jumpers, and many of the anatomical characteristics of frogs, but also is the name of a genus of plants (although not current: it is a synonym); Aotus is the genus of golden peas and night monkeys The Night monkeys, also known as the Owl monkeys or Douroucoulis, are the members of the genus Aotus of New World monkeys . They are widely distributed in the forests of Central and South America, from Panama south to Paraguay and northern Argentina. The species that live at higher elevations tend to have thicker fur than the monkeys at sea level; Oenanthe is the genus of wheatears and water dropworts, Prunella is the genus of accentors The accentors are in the only bird family, the Prunellidae, which is completely endemic to the Palearctic. This small group of closely related passerines are all in a single genus Prunella. All but the Dunnock and the Japanese Accentor are inhabitants of the mountainous regions of Europe and Asia; these two also occur in lowland areas, as does the and self-heal, and Proboscidea Proboscidea is an order containing one living family, Elephantidae, and several recently extinct families, Gomphotheriidae , possibly Stegodontidae (depending on the assignment of Stegodon) and Mammutidae. Elephantidae contains three living species (the African Bush Elephant, African Forest Elephant, and Asian Elephant) and the now extinct mammoth is the order of elephants Elephants are large land mammals in two genera of the family Elephantidae: Elephas and Loxodonta. Three species of elephant are living today: the African bush elephant, the African forest elephant and the Asian elephant . All other species and genera of Elephantidae are extinct, some since the last ice age: dwarf forms of mammoths may have and the genus of devil's claws.
Within the same kingdom one generic name can apply to only one genus. This explains why the platypus The Platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young. It is the sole living representative of its family (Ornithorhynchidae) and genus ( genus is named Ornithorhynchus—George Shaw George Shaw was an English botanist and zoologist named it Platypus in 1799, but the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst Johann Friedrich Wilhelm Herbst was a German naturalist and entomologist from Petershagen, Minden-Ravensberg in 1793. Names with the same form but applying to different taxa are called homonyms. Since beetles and platypuses are both members of the kingdom Animalia, the name Platypus could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800.
Types and genera
Because of the rules of scientific naming, or "binomial nomenclature The formal system of naming species is called binomial nomenclature , binominal nomenclature (since 1953, the technically correct form in zoology), or binary nomenclature", each genus should have a designated type In biology, a type is that which fixes a name to a taxon. Depending on the nomenclature code which is applied to the organism in question, a type may be a specimen, culture, illustration, description or taxon, although in practice there is a backlog of older names that may not yet have a type. In zoology this is the type species (see Type (zoology)); the generic name is permanently associated with the type specimen A holotype is one of several possible biological types. A type is what fixes a name to a taxon. A holotype is a single physical example of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several such, but explicitly of its type species. Should this specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym, and the remaining taxa A taxon is a group of (one or more) organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement. Defining what belongs or does not belong to such a taxonomic group is done by a taxonomist. It is not uncommon for one taxonomist to disagree with another on what exactly belongs to in the former genus need to be reassessed.
See scientific classification Biological classification, or scientific classification in biology, is a method by which biologists group and categorize organisms by biological type, such as genus or species. Biological classification is a form of scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis. Modern biological classification and Nomenclature Codes The Nomenclature Codes are the various rulebooks that govern biological nomenclature, each in their own area. They are united in that they use names of the type Neotragus batesi and Caesalpinia gilliesii for species. To an end-user who only deals with names of species, with some awareness that species are assignable to families, it may not be for more details of this system. Also see type genus.
Guidelines
There are no hard and fast rules that a taxonomist has to follow in deciding what does and what does not belong in a particular genus. This does not mean that there is no common ground among taxonomists in what constitutes a "good" genus. For instance, some rules-of-thumb for delimiting a genus are outlined in Gill.[3] According to these, a genus should fulfill three criteria to be descriptively useful:
- monophyly In common cladistic usage, monophyletic describes a group of organisms that form a clade, consisting of a last common ancestor and all of its descendants. The term is not synonymous with the less common term holophyly, which does not include a last common ancestor. It is contrasted with the terms paraphyly, which is a taxonomic group consisting of – all descendants of an ancestral taxon are grouped together;
- reasonable compactness – a genus should not be expanded needlessly; and
- distinctness – in regards of evolutionarily relevant criteria, i.e. ecology Ecology is the scientific study of the distributions, abundance and relations of organisms and their interactions with the environment. Ecology includes the study of plant and animal populations, plant and animal communities and ecosystems. Ecosystems describe the web or network of relations among organisms at different scales of organization, morphology In biology "morphology" is the study of the form, structure and configuration of an organism. This includes aspects of the outward appearance [citation needed] as well as the form and structure of the internal parts like bones and organs. This is in contrast to physiology, which deals primarily with function, or biogeography Biogeography is the study of the distribution of species spatially and temporally. Over areal ecological changes, it is also tied to the concepts of species and their past, or present living 'refugium', their survival locales, or their interim living sites. It aims to reveal where organisms live, and at what abundance. As writer David Quammen put; note that DNA sequences A DNA sequence or genetic sequence is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, with the capacity to carry information as described by the central dogma of molecular biology are a consequence rather than a condition of diverging evolutionary lineages except in cases where they directly inhibit gene flow In population genetics, gene flow is the transfer of alleles of genes from one population to another (e.g. postzygotic barriers).
Nomenclature
...difficulties occurring in generic nomenclature: similar cases abound, and become complicated by the different views taken of the matter by the various taxonomists.
Prof. C. S. Rafinesque. 1836[4]None of the Nomenclature Codes The Nomenclature Codes are the various rulebooks that govern biological nomenclature, each in their own area. They are united in that they use names of the type Neotragus batesi and Caesalpinia gilliesii for species. To an end-user who only deals with names of species, with some awareness that species are assignable to families, it may not be require such criteria for defining a genus, because these are concerned with the nomenclature rules, not with taxonomy. These regulate formal nomenclature, aiming for universal and stable scientific names.
See also
References
- ^ Merriam Webster Dictionary
- ^ Genos, Henry George Liddell, Robert Scott, 'A Greek-English Lexicon, at Perseus
- ^ Gill, F. B., B. Slikas, and F. H. Sheldon. “Phylogeny of titmice (Paridae): II. Species relationships based on sequences of the mitochondrial cytochrome-b gene.” Auk 122(1): 121-143, 2005. (Google Scholar)
- ^ Rafinesque, Prof. C. S. (1836). "Generic Rules". Flora telluriana Pars Prima First Part of the Synoptical Flora Telluriana, Centuries I, II, III, IV. With new Natural Classes, Orders and families: containing the 2000 New or revised Genera and Species of Trees, Palms, Shrubs, Vines, Plants, Lilies, Grasses, Ferns, Algas, Fungi, & c. from North and South America, Polynesia, Australia, Asia Europe and Africa, omitted or mistaken by the authors, that were observed or ascertained, described or revised, collected or figured, between 1796 and 1836.. 1. Philadelphia Philadelphia is the largest city in Pennsylvania and the sixth-most-populous city in the United States: H. Probasco. http://www.us.archive.org/GnuBook/?id=floratelluriana00rafi#99. Retrieved 2009-04-02. "...difficulties occurring in generic nomenclature: similar cases abound, and become complicated by the different views taken of the matter by the various botanists."
Dispatch Online
There are several genera . The most common worm is Lumbricus terrestris, or the nightcrawler. Red wrigglers, or Eisenia fetida, are the most commonly- used ...
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