Genus ( / ˈ dʒ iː n ə s / ; pl. : genera / ˈ dʒ ɛ n ər ə / ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses . In binomial nomenclature , the genus name forms the first part of the binomial species name for each species within the genus.
54-529: The "typical" pheasant genus Phasianus in the family Phasianidae consists of two species . The genus name is Latin for pheasant. The genus Phasianus was introduced in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae . The genus name is Latin for "pheasant". The word is derived from the Ancient Greek φἀσιἀνος, phāsiānos , meaning "(bird) of
108-587: A Phasianus pheasant have been found in Late Miocene rocks in China. Additionally, fossil material belonging to a new species of Phasianus was described in 2020 as P. bulgaricus . The fossils were recovered from Miocene ( Turolian ) strata in Bulgaria . Thus, like many other phasianid genera, this lineage dates back more than 5,000,000 years. Phasianus pheasants are a harem polygynous species that are
162-672: A Wittig reaction . Two equivalents of the proper ylide combined with the proper dialdehyde in a solvent of methanol, ethanol, or a mixture of the two, yields astaxanthin in up to 88% yields. The cost of astaxanthin extraction, high market price, and lack of efficient fermentation production systems, combined with the intricacies of chemical synthesis, discourage its commercial development. The metabolic engineering of bacteria ( Escherichia coli ) enables efficient astaxanthin production from beta-carotene via either zeaxanthin or canthaxanthin . In addition to structural isomeric configurations, astaxanthin also contains two chiral centers at
216-493: A food dye with E number E161j. The European Food Safety Authority has set an Acceptable Daily Intake of 0.2 mg per kg body weight, as of 2019. As a food color additive, astaxanthin and astaxanthin dimethyldisuccinate are restricted for use in Salmonid fish feed only. Astaxanthin is present in most red-coloured aquatic organisms. The content varies from species to species, but also from individual to individual as it
270-541: A Seattle judge dismissed the case, ruling that enforcement of the applicable food laws was up to government and not individuals. The primary human application for astaxanthin is as a dietary supplement , and it remains under preliminary research. In 2020, the European Food Safety Authority reported that an intake of 8 mg astaxanthin per day from food supplements is safe for adults. Lobsters, shrimp, and some crabs turn red when cooked because
324-407: A genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of
378-792: A highly sexually dimorphic genus, where males are large and elaborately ornamented with brightly coloured plumage, ear tufts , wattles , spurs , and long tails, compared to females that are non-ornamented with a dull cryptic plumage. They have a polygynous mating system that is based upon males defending mating territories during breeding season in the early spring to control access to females with higher quality resources and defence against predation. Females are free to move between different male territories, allowing them to benefit from direct or indirect benefits by choosing high quality mates and areas with better resources for their offspring. Phasianus chicks are precocial so males provide no parental care for their young. A male's ornaments and weaponry are
432-651: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as
486-628: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,
540-488: A more dominant male. The general brightness of the plumage may also be used to identify healthy males from unhealthy males. Only in cases where males exhibit similar characteristics, do males attack one another. To display these traits throughout breeding season entails a physiological cost, leading to an endurance rivalry between males, where only males that can afford to display these breeding rituals will pass on their genes to their offspring. An example of this can be seen in
594-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for
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#1732798604642648-459: A scientific opinion on a similar xanthophyll carotenoid, lutein, stating that "following passage through the gastrointestinal tract and/or uptake lutein esters are hydrolyzed to form free lutein again". While it can be assumed that non-esterified astaxanthin would be more bioavailable than esterified astaxanthin due to the extra enzymatic steps in the intestine needed to hydrolyse the fatty acid components, several studies suggest that bioavailability
702-671: A symbol of status that allow females and rivals to examine a male's fitness and fighting ability. During breeding season, males court females or challenge other males by enlarging their sexual traits, sloping their body towards their opponent or mate while spreading their tail and plumage, inflating the wattle and raising their ear tufts. Older males usually have more exaggerated ornaments and weaponry than younger males, and are more likely to mate and control larger territories. Submissive or juvenile males will conceal their wattle display from bigger males, reducing their chance of mating but minimizing their risk of injury by avoiding physical conflict with
756-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;
810-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and
864-399: Is a lipid -soluble pigment with red coloring properties, which result from the extended chain of conjugated (alternating double and single) double bonds at the center of the compound. The presence of the hydroxyl functional groups and the hydrophobic hydrocarbons render the molecule amphiphilic. Astaxanthin is produced naturally in the freshwater microalgae Haematococcus pluvialis ,
918-612: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms
972-583: Is highly dependent on diet and living conditions. Astaxanthin and other chemically related asta-carotenoids have also been found in a number of lichen species of the Arctic zone. The primary natural sources for industrial production of astaxanthin comprise the following: Astaxanthin concentrations in nature are approximately: Algae are the primary natural source of astaxanthin in the aquatic food chain . The microalgae Haematococcus pluvialis contains high levels of astaxanthin (about 3.8% of dry weight), and
1026-446: Is influenced by the source organism as well as growth conditions. The astaxanthin fed to salmon to enhance flesh coloration is in the non-esterified form The predominance of evidence supports a de-esterification of fatty acids from the astaxanthin molecule in the intestine prior to or concomitant with absorption resulting in the circulation and tissue deposition of non-esterified astaxanthin. European Food Safety Authority (EFSA) published
1080-442: Is more dependent on formulation than configuration. Astaxanthin is used as a dietary supplement and feed supplement as food colorant for salmon, crabs, shrimp, chickens and egg production. The primary use of synthetic astaxanthin today is as an animal feed additive to impart coloration, including farm-raised salmon and chicken egg yolks. Synthetic carotenoid pigments colored yellow, red or orange represent about 15–25% of
1134-588: Is only found on the island of Taiwan off the southern coast of continental China , and the rest on the Asian mainland, reaching west to the Caucasus . Some subspecies have been introduced to Europe , North America and elsewhere, where they have hybridized and become well established. The green pheasant ( P. versicolor ) is a species from Japan that which the fossil record suggest diverged about 2.0–1.8 million years ago from P. colchicus . Fossil remains of
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#17327986046421188-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,
1242-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with
1296-796: Is the primary industrial source of natural astaxanthin. In shellfish, astaxanthin is almost exclusively concentrated in the shells, with only low amounts in the flesh itself, and most of it only becomes visible during cooking as the pigment separates from the denatured proteins that otherwise bind it. Astaxanthin is extracted from Euphausia superba (Antarctic krill) and from shrimp processing waste. Astaxanthin biosynthesis starts with three molecules of isopentenyl pyrophosphate (IPP) and one molecule of dimethylallyl pyrophosphate (DMAPP) that are combined by IPP isomerase and converted to geranylgeranyl pyrophosphate (GGPP) by GGPP synthase. Two molecules of GGPP are then coupled by phytoene synthase to form phytoene. Next, phytoene desaturase creates four double bonds in
1350-638: The European Union , astaxanthin-containing food supplements derived from sources that have no history of use as a source of food in Europe, fall under the remit of the Novel Food legislation, EC (No.) 258/97. Since 1997, there have been five novel food applications concerning products that contain astaxanthin extracted from these novel sources. In each case, these applications have been simplified or substantial equivalence applications, because astaxanthin
1404-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to
1458-824: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;
1512-746: The Phasis ". The birds were found by the Argonauts on the banks of the River Phasis (now the Rioni ) in Colchis on the east coast of the Black Sea (now western Georgia). The type species of the genus is the common pheasant ( Phasianus colchicus ). The genus contains just two species. The common pheasant ( P. colchicus ) has about 30 recognised subspecies forming five or six distinct groups; one
1566-419: The nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,
1620-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,
1674-434: The yeast fungus Xanthophyllomyces dendrorhous (also known as Phaffia rhodozyma ) and the bacteria Paracoccus carotinifaciens . When the algae are stressed by lack of nutrients, increased salinity, or excessive sunshine, they create astaxanthin. Animals who feed on the algae, such as salmon , red trout, red sea bream , flamingos , and crustaceans (shrimp, krill, crab, lobster, and crayfish), subsequently reflect
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1728-504: The 3- and 3 ′ -positions, resulting in three unique stereoisomers (3R,3 ′ R and 3R,3'S meso and 3S,3'S). While all three stereoisomers are present in nature, relative distribution varies considerably from one organism to another. Synthetic astaxanthin contains a mixture of all three stereoisomers, in approximately 1:2:1 proportions. Astaxanthin exists in two predominant forms, non-esterified (yeast, synthetic) or esterified (algal) with various length fatty acid moieties whose composition
1782-910: The astaxanthin, which was bound to the protein in the shell, becomes free as the protein denatures and unwinds. The freed pigment is thus available to absorb light and produce the red color. In April 2009, the United States Food and Drug Administration approved astaxanthin as an additive for fish feed only as a component of a stabilized color additive mixture. Color additive mixtures for fish feed made with astaxanthin may contain only those diluents that are suitable. The color additives astaxanthin, ultramarine blue , canthaxanthin , synthetic iron oxide , dried algae meal, Tagetes meal and extract, and corn endosperm oil are approved for specific uses in animal foods. Haematococcus algae meal (21 CFR 73.185) and Phaffia yeast (21 CFR 73.355) for use in fish feed to color salmonoids were added in 2000. In
1836-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of
1890-422: The cost of production of commercial salmon feed. In the 21st century, most commercial astaxanthin for aquaculture is produced synthetically. Class action lawsuits were filed against some major grocery store chains for not clearly labeling the astaxanthin-treated salmon as "color added". The chains followed up quickly by labeling all such salmon as "color added". Litigation persisted with the suit for damages, but
1944-497: The final molecule, astaxanthin, is obtained. The structure of astaxanthin by synthesis was described in 1975. Nearly all commercially available astaxanthin for aquaculture is produced synthetically, with an annual market of about $ 1 billion in 2019. An efficient synthesis from isophorone , cis -3-methyl-2-penten-4-yn-1-ol and a symmetrical C 10 -dialdehyde has been discovered and is used in industrial production. It combines these chemicals together with an ethynylation and then
1998-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this
2052-737: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,
2106-633: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,
2160-672: The length of a male's spur and the wattle display that is enlarged during sexual displays; both are considered costly as they are highly dependent on nutrition and testosterone levels. Females generally prefer brighter wattles and longer spurs. The brightness in the wattle comes from storing a carotenoid pigment known as astaxanthin in their diet that is inhibited by an infestation of parasites. Only healthy individuals in good physical condition can afford to fully express bigger and brighter wattles, which may also be associated with disease resistance. Spurs function not only as weapons in combat between males but also as an important cue in female choice as
2214-516: The length of the spur signifies the male's phenotypic condition (age, weight, size) and viability. Studies have found that longer spurs resulted in bigger harem sizes compared to males with shorter spurs. Females will benefit from choosing males with higher expressed ornaments, as her offspring will also inherit these genes, increasing their survival and chance for reproduction ( sexy son hypothesis ). [REDACTED] Media related to Phasianus at Wikimedia Commons Genus The composition of
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2268-530: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Astaxanthin Astaxanthin / æ s t ə ˈ z æ n θ ɪ n / is a keto- carotenoid within a group of chemical compounds known as carotenones or terpenes . Astaxanthin is a metabolite of zeaxanthin and canthaxanthin , containing both hydroxyl and ketone functional groups. It
2322-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus
2376-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom 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. Names with the same form but applying to different taxa are called "homonyms". Although this
2430-426: The phytoene molecule to form lycopene. After desaturation, lycopene cyclase first forms γ-carotene by converting one of the ψ acyclic ends of the lycopene as a β-ring, then subsequently converts the other to form β-carotene. From β-carotene, hydrolases (blue) are responsible for the inclusion of two 3-hydroxy groups, and ketolases (green) for the addition of two 4-keto groups, forming multiple intermediate molecules until
2484-541: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for
2538-511: The red-orange astaxanthin pigmentation. Astaxanthin is used as a dietary supplement for human, animal, and aquaculture consumption. Astaxanthin from algae, synthetic and bacterial sources is generally recognized as safe in the United States. The US Food and Drug Administration has approved astaxanthin as a food coloring (or color additive) for specific uses in animal and fish foods. The European Commission considers it as
2592-470: The same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or
2646-408: The scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of a species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in
2700-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,
2754-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being
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#17327986046422808-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for
2862-576: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up
2916-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in
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