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Monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. Theoretical implications Monotypic taxa present several important theoretical challenges in biological classification. One key issue is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs a distinct definition to maintain logical structure. Otherwise, the different taxonomic ranks become effectively identical, which creates problems for organizing biological diversity in a hierarchical syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subspecies
In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morphology), but that can successfully interbreed. Not all species have subspecies, but for those that do there must be at least two. Subspecies is abbreviated as subsp. or ssp. and the singular and plural forms are the same ("the subspecies is" or "the subspecies are"). In zoology, under the International Code of Zoological Nomenclature, the subspecies is the only taxonomic rank below that of species that can receive a name. In botany and mycology, under the International Code of Nomenclature for algae, fungi, and plants, other infraspecific name, infraspecific ranks, such as variety (botany), variety, may be named. In bacteriology and virology, under standard International Code of Nomenclature of Prokaryotes, bacterial nomenclature and virus clas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathaya
''Cathaya'' is a genus in the pine family, Pinaceae, with one known living species, ''Cathaya argyrophylla''. In foliage and cone morphology, ''Cathaya'' has been considered a member of the subfamily Laricoideae, closely related to '' Pseudotsuga'' and '' Larix'', but more recent genetic studies have suggested a closer relationship to ''Pinus'' and ''Picea'' in the subfamily Pinoideae. A second species, ''C. nanchuanensis'', is now treated as a synonym, as it does not differ from ''C. argyrophylla'' in any characters. Description ''Cathaya'' is confined to a limited area in southern China, in the provinces of Guangxi, Guizhou, Hunan and southeast Sichuan. It is an evergreen tree growing to tall and a trunk up to diameter, found on steep, narrow mountain slopes at altitude on limestone soils. A larger population has been reduced by over-cutting before its scientific discovery and protection in 1950. The leaves are needle-like, long, have ciliate (hairy) margins when young ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amborella
''Amborella'' is a monotypic genus of understory shrubs or small trees endemic to the main island, Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family Amborellaceae and the order Amborellales and contains a single species, ''Amborella trichopoda''. ''Amborella'' is of great interest to plant systematists because molecular phylogenetic analyses consistently place it as the sister group to all other flowering plants, meaning it was the earliest group to evolve separately from all other flowering plants. Description ''Amborella'' is a sprawling shrub or small tree up to high. It bears alternate, simple evergreen leaves without stipules. The leaves are two-ranked, with distinctly serrated or rippled margins, and about long. ''Amborella'' has xylem tissue that differs from that of most other flowering plants. The xylem of ''Amborella'' contains only tracheids; vessel elements are absent. Xylem of this form has long b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent common ancestor (or more precisely an ancestral population), i.e. excludes non-descendants of that common ancestor # the grouping contains all the descendants of that common ancestor, without exception Monophyly is contrasted with paraphyly and polyphyly as shown in the second diagram. A ''paraphyletic'' grouping meets 1. but not 2., thus consisting of the descendants of a common ancestor, excepting one or more monophyletic subgroups. A '' polyphyletic'' grouping meets neither criterion, and instead serves to characterize convergent relationships of biological features rather than genetic relationships – for example, night-active primates, fruit trees, or aquatic insects. As such, these characteristic features of a polyphyletic grouping ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and recover. As a species' potential Range (biology), range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxon, Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the Fossil, fossil record) after a period of apparent absence. Over five billion species are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryotes globally, possibly many times more if microorganisms are included. Notable extinct animal species include Dinosaur, non-avian dinosaurs, Machairodontinae, saber-toothed cats, and mammoths. Through evolution, species arise through the process of specia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sciadopitys
''Sciadopitys'', commonly called umbrella pines, is a genus of a unique conifers now endemic to Japan. The sole living member of the family Sciadopityaceae is '' Sciadopitys verticillata'', a living fossil. The oldest fossils of ''Sciadopitys'' are from the Late Cretaceous of Japan, and the genus was widespread in Laurasia during most of the Cenozoic, especially in Europe until the Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Pinales Conifer genera Endemic flora of Japa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family (, : ) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". The delineation of what constitutes a family—or whether a described family should be acknowledged—is established and decided upon by active taxonomists. There are not strict regulations for outlining or acknowledging a family, yet in the realm of plants, these classifications often rely on both the vegetative and reproductive characteristics of plant species. Taxonomists frequently hold varying perspectives on these descriptions, leading to a lack of widespread consensus within the scientific community ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Order (biology)
Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. An immediately higher rank, superorder, is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families. What does and does not belong to each order is determined by a taxonomist, as is whether a particular order 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 an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with a capital letter. For some groups of organisms, their orders may follow consist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ginkgo
''Ginkgo'' is a genus of non-flowering seed plants, assigned to the gymnosperms. The scientific name is also used as the English common name. The order to which the genus belongs, Ginkgoales, first appeared in the Permian, , and ''Ginkgo'' is now the relict taxon, only living genus within the order. The rate of evolution within the genus has been slow, and almost all its species had become extinct by the end of the Pliocene. The sole surviving species, ''Ginkgo biloba'', is Species distribution, found in the wild only in China, but is cultivated around the world. The relationships between ginkgos and other groups of plants are not fully resolved. Prehistory The ginkgo (''Ginkgo biloba'') is a living fossil, with fossils similar to the modern plant dating back to the Permian, 270 million years ago. The ancestor of the genus is estimated to have branched off from other gymnosperms about 325 million years ago, while the last common ancestor of today's only remaining spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ginkgophyta
Ginkgoopsida is a proposed class of gymnosperms defined by Sergei V. Meyen in 1984 to encompass Ginkgoales (which contains the living ''Ginkgo'') alongside a number of extinct seed plant groups, which he considered to be closely related based on similarities of morphology of pollen, seeds, cuticles, short shoots and leaves. The validity of this group as a whole has been considered questionable by other authors, who consider that it is unlikely to be monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co .... Other authors have used the class as a monotypic grouping, including only Ginkgoales. Some authors have used the clade Ginkgophyta to encompass both Ginkgoales and Czekanowskiales/Leptostrobales, which are suggested to be closely related groups. References {{Taxonbar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Division (taxonomy)
Division is a taxonomic rank in biological classification that is used differently in zoology and in botany. In botany and mycology, ''division'' is the traditional name for a rank now considered equivalent to phylum. The use of either term is allowed under the International Code of Botanical Nomenclature. The main Divisions of land plants are the Marchantiophyta (liverworts), Anthocerotophyta (hornworts), Bryophyta (mosses), Filicophyta (ferns), Sphenophyta (horsetails), Cycadophyta (cycads), Ginkgophyta (ginkgo)s, Pinophyta (conifers), Gnetophyta (gnetophytes), and the Magnoliophyta (Angiosperms, flowering plants). The Magnoliophyta now dominate terrestrial ecosystems, comprising 80% of vascular plant species. In zoology, the term ''division'' is applied to an optional rank subordinate to the infraclass and superordinate to the legion and cohort. A widely used classification (e.g. Carroll 1988) recognises teleost fishes as a Division Teleostei within Class Actin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
