Traditionally, some textbooks from the United States used a system of six kingdoms (Animalia, Plantae, Fungi, Protista, Archaea/Archaebacteria, and Bacteria/Eubacteria) while textbooks in countries like Great Britain, India, Greece, Australia, Latin America and other countries used five kingdoms (Animalia, Plantae, Fungi, Protista and Monera).
Some recent classifications based on modern cladistics have explicitly abandoned the term "kingdom", noting that the traditional kingdoms are not monophyletic, i.e., do not consist of all the descendants of a common ancestor.
When Carl Linnaeus introduced the rank-based system of nomenclature into biology in 1735, the highest rank was given the name "kingdom" and was followed by four other main or principal ranks: class, order, genus and species. Later two further main ranks were introduced, making the sequence kingdom, phylum or division, class, order, family, genus and species. In 1990, the rank of domain was introduced above kingdom.
Prefixes can be added so subkingdom (subregnum) and infrakingdom (also known as infraregnum) are the two ranks immediately below kingdom. Superkingdom may be considered as an equivalent of domain or empire or as an independent rank between kingdom and domain or subdomain. In some classification systems the additional rank branch (Latin: ramus) can be inserted between subkingdom and infrakingdom, e.g., Protostomia and Deuterostomia in the classification of Cavalier-Smith.
From around the mid-1970s onwards, there was an increasing emphasis on comparisons of genes at the molecular level (initially ribosomal RNA genes) as the primary factor in classification; genetic similarity was stressed over outward appearances and behavior. Taxonomic ranks, including kingdoms, were to be groups of organisms with a common ancestor, whether monophyletic (all descendants of a common ancestor) or paraphyletic (only some descendants of a common ancestor). Based on such RNA studies, Carl Woese thought life could be divided into three large divisions and referred to them as the "three primary kingdom" model or "urkingdom" model. In 1990, the name "domain" was proposed for the highest rank. This term represents a synonym for the category of dominion (lat. dominium), introduced by Moore in 1974. Unlike Moore, Woese et al. (1990) did not suggest a Latin term for this category, which represents a further argument supporting the accurately introduced term dominion. Woese divided the prokaryotes (previously classified as the Kingdom Monera) into two groups, called Eubacteria and Archaebacteria, stressing that there was as much genetic difference between these two groups as between either of them and all eukaryotes.
According to genetic data, although eukaryote groups such as plants, fungi, and animals may look different, they are more closely related to each other than they are to either the Eubacteria or Archaea. It was also found that the eukaryotes are more closely related to the Archaea than they are to the Eubacteria. Although the primacy of the Eubacteria-Archaea divide has been questioned, it has been upheld by subsequent research. There is no consensus on how many kingdoms exist in the classification scheme proposed by Woese.
In 2004, a review article by Simpson and Roger noted that the Protista were "a grab-bag for all eukaryotes that are not animals, plants or fungi". They held that only monophyletic groups should be accepted as formal ranks in a classification and that – while this approach had been impractical previously (necessitating "literally dozens of eukaryotic 'kingdoms'") – it had now become possible to divide the eukaryotes into "just a few major groups that are probably all monophyletic".
On this basis, the diagram opposite (redrawn from their article) showed the real "kingdoms" (their quotation marks) of the eukaryotes. A classification which followed this approach was produced in 2005 for the International Society of Protistologists, by a committee which "worked in collaboration with specialists from many societies". It divided the eukaryotes into the same six "supergroups". The published classification deliberately did not use formal taxonomic ranks, including that of "kingdom".
In this system the multicellular animals (Metazoa) are descended from the same ancestor as both the unicellular choanoflagellates and the fungi which form the Opisthokonta. Plants are thought to be more distantly related to animals and fungi.
However, in the same year as the International Society of Protistologists' classification was published (2005), doubts were being expressed as to whether some of these supergroups were monophyletic, particularly the Chromalveolata, and a review in 2006 noted the lack of evidence for several of the six proposed supergroups.
As of 2010, there is widespread agreement that the Rhizaria belong with the Stramenopiles and the Alveolata, in a clade dubbed the SAR supergroup, so that Rhizaria is not one of the main eukaryote groups. Beyond this, there does not appear to be a consensus. Rogozin et al. in 2009 noted that "The deep phylogeny of eukaryotes is an extremely difficult and controversial problem." As of December 2010, there appears to be a consensus that the six supergroup model proposed in 2005 does not reflect the true phylogeny of the eukaryotes and hence how they should be classified, although there is no agreement as to the model which should replace it.
The classification of living things into animals and plants is an ancient one. Aristotle (384–322 BC) classified animal species in his History of Animals, while his pupil Theophrastus (c. 371–c. 287 BC) wrote a parallel work, the Historia Plantarum, on plants.
Carl Linnaeus (1707–1778) laid the foundations for modern biological nomenclature, now regulated by the Nomenclature Codes, in 1735. He distinguished two kingdoms of living things: Regnum Animale ('animal kingdom') and Regnum Vegetabile ('vegetable kingdom', for plants). Linnaeus also included minerals in his classification system, placing them in a third kingdom, Regnum Lapideum.
In 1674, Antonie van Leeuwenhoek, often called the "father of microscopy", sent the Royal Society of London a copy of his first observations of microscopic single-celled organisms. Until then, the existence of such microscopic organisms was entirely unknown. Despite this, Linnaeus did not include any microscopic creatures in his original taxonomy.
At first, microscopic organisms were classified within the animal and plant kingdoms. However, by the mid-19th century, it had become clear to many that "the existing dichotomy of the plant and animal kingdoms [had become] rapidly blurred at its boundaries and outmoded". In 1866, Ernst Haeckel proposed a third kingdom of life, the Protista, for "neutral organisms" which were neither animal nor plant. Haeckel revised the content of this kingdom a number of times before settling on a division based on whether organisms were unicellular (Protista) or multicellular (animals and plants).
The development of the electron microscope revealed important distinctions between those unicellular organisms whose cells do not have a distinct nucleus (prokaryotes) and those unicellular and multicellular organisms whose cells do have a distinct nucleus (eukaryotes). In 1938, Herbert F. Copeland proposed a four-kingdom classification, elevating the protist classes of bacteria (Monera) and blue-green algae (Phycochromacea) to phyla in the novel Kingdom Monera.
The importance of the distinction between prokaryotes and eukaryotes gradually became apparent. In the 1960s, Stanier and van Niel popularised Édouard Chatton's much earlier proposal to recognise this division in a formal classification. This required the creation, for the first time, of a rank above kingdom, a superkingdom or empire, later called a domain.
The differences between fungi and other organisms regarded as plants had long been recognised by some; Haeckel had moved the fungi out of Plantae into Protista after his original classification, but was largely ignored in this separation by scientists of his time. Robert Whittaker recognized an additional kingdom for the Fungi. The resulting five-kingdom system, proposed in 1969 by Whittaker, has become a popular standard and with some refinement is still used in many works and forms the basis for new multi-kingdom systems. It is based mainly upon differences in nutrition; his Plantae were mostly multicellular autotrophs, his Animalia multicellular heterotrophs, and his Fungi multicellular saprotrophs. The remaining two kingdoms, Protista and Monera, included unicellular and simple cellular colonies. The five kingdom system may be combined with the two empire system:
In the Whittaker system, Plantae included some algae. In other systems, such as Lynn Margulis's system of five kingdoms—animals, plants, bacteria (prokaryotes), fungi, and protoctists—the plants included just the land plants (Embryophyta).
Despite the development from two kingdoms to five among most scientists, some authors as late as 1975 continued to employ a traditional two-kingdom system of animals and plants, dividing the plant kingdom into Subkingdoms Prokaryota (bacteria and cyanophytes), Mycota (fungi and supposed relatives), and Chlorota (algae and land plants).
Thomas Cavalier-Smith thought at first, as was almost the consensus at that time, that the difference between eubacteria and archaebacteria was so great (particularly considering the genetic distance of ribosomal genes) that they needed to be separated into two different kingdoms, hence splitting the empire Bacteria into two kingdoms. He then divided Eubacteria into two subkingdoms: Negibacteria (Gram negative bacteria) and Posibacteria (Gram positive bacteria).
Technological advances in electron microscopy allowed the separation of the Chromista from the Plantae kingdom. Indeed, the chloroplast of the chromists is located in the lumen of the endoplasmic reticulum instead of in the cytosol. Moreover, only chromists contain chlorophyll c. Since then, many non-photosynthetic phyla of protists, thought to have secondarily lost their chloroplasts, were integrated into the kingdom Chromista.
Finally, some protists lacking mitochondria were discovered. As mitochondria were known to be the result of the endosymbiosis of a proteobacterium, it was thought that these amitochondriate eukaryotes were primitively so, marking an important step in eukaryogenesis. As a result, these amitochondriate protists were separated from the protist kingdom, giving rise to the, at the same time, superkingdom and kingdom Archezoa. This was known as the Archezoa hypothesis. This superkingdom was opposed to the Metakaryota superkingdom, grouping together the five other eukaryotic kingdoms (Animalia, Protozoa, Fungi, Plantae and Chromista).
In 1998, Cavalier-Smith published a six-kingdom model, which has been revised in subsequent papers. The version published in 2009 is shown below.[a] Cavalier-Smith no longer accepts the importance of the fundamental eubacteria–archaebacteria divide put forward by Woese and others and supported by recent research. His Kingdom Bacteria includes Archaebacteria as a phylum of the subkingdom Unibacteria which comprises only one other phylum: the Posibacteria. The two subkingdoms Unibacteria and Negibacteria of kingdom Bacteria (sole kingdom of empire Prokaryota) are distinguished according to their membrane topologies. The bimembranous-unimembranous transition is thought to be far more fundamental than the long branch of genetic distance of Archaebacteria, viewed as having no particular biological significance. Cavalier-Smith does not accept the requirement for taxa to be monophyletic ("holophyletic" in his terminology) to be valid. He defines Prokaryota, Bacteria, Negibacteria, Unibacteria, and Posibacteria as valid paraphyla (therefore "monophyletic" in the sense he uses this term) taxa, marking important innovations of biological significance (in regard of the concept of biological niche).
In the same way, his paraphyletic kingdom Protozoa includes the ancestors of Animalia, Fungi, Plantae, and Chromista. The advances of phylogenetic studies allowed Cavalier-Smith to realize that all the phyla thought to be archezoans (i.e. primitively amitochondriate eukaryotes) had in fact secondarily lost their mitochondria, typically by transforming them into new organelles: Hydrogenosomes. This means that all living eukaryotes are in fact metakaryotes, according to the significance of the term given by Cavalier-Smith. Some of the members of the defunct kingdom Archezoa, like the phylum Microsporidia, were reclassified into kingdom Fungi. Others were reclassified in kingdom Protozoa like Metamonada which is now part of infrakingdom Excavata.
Because Cavalier-Smith allows paraphyly, the diagram below is an ‘organization chart’, not an ‘ancestor chart’, and does not represent evolutionary tree.
Cavalier-Smith and his collaborators revised their classification in 2015. In this scheme they reintroduced the division of prokaryotes into two kingdoms, Bacteria (=Eubacteria) and Archaea (=Archaebacteria). This is based on the consensus in the Taxonomic Outline of Bacteria and Archaea (TOBA) and the Catalogue of Life.
|Woese et al.
|Woese et al.
|Ruggiero et al.|
|2 kingdoms||3 kingdoms||2 empires||4 kingdoms||5 kingdoms||6 kingdoms||3 domains||8 kingdoms||6 kingdoms||7 kingdoms|
The kingdom-level classification of life is still widely employed as a useful way of grouping organisms, notwithstanding some problems with this approach:
There is ongoing debate as to whether viruses can be included in the tree of life. The ten arguments against include the fact that they are obligate intracellular parasites that lack metabolism and are not capable of replication outside of a host cell. Another argument is that their placement in the tree would be problematic, since it is suspected that viruses have arisen multiple times, and they have a penchant for harvesting nucleotide sequences from their hosts.
6 (six) is the natural number following 5 and preceding 7.
The SI prefix for 10006 is exa- (E), and for its reciprocal atto- (a).Delta 6 desaturase
Delta 6 desaturase (D6D or Δ-6-desaturase) is a desaturase enzyme that converts between types of fatty acids (termed 6 after omega-6 fatty acids), which are essential nutrients in the human body. The enzyme is molecularly identical across all living things (preserved across Kingdom (biology)) it is present in animals, plants, and cyanobacteria.D6D is one of the 3 fatty acid desaturases present in humans along with Δ-5 and Δ-9, named so because it was thought to convert only omega-6 fatty acids, but actually converts some others also, and is obligatory to build the longer chain omega-3 fatty acids from other simpler fatty acids in humans. In humans, it is encoded by the FADS2 gene.Grinder (biohacking)
Grinders are people who apply the hacker ethic to improve their own bodies with do it yourself cybernetic devices or introducing Biochemicals into the body to enhance or change their bodies' functionality. Many grinders identify with the biopunk movement, open-source transhumanism, and techno-progressivism. The Grinder movement is strongly associated with the body modification movement and practices actual implantation of cybernetic devices in organic bodies as a method of working towards transhumanism, such as designing and installing do-it-yourself body-enhancements such as magnetic implants. Biohacking emerged in a growing trend of non-institutional science and technology development.According to Biohack.me, "Grinders are passionate individuals who believe the tools and knowledge of science belong to everyone. Grinders practice functional extreme body modification in an effort to improve the human condition. [Grinders] hack [them]selves with electronic hardware to extend and improve human capacities. Grinders believe in action, [thei]r bodies the experiment.""Biohacking" can also refer to managing one's own biology using a combination of medical, nutritional and electronic techniques. This may include the use of nootropics, non-toxic substances, and/or cybernetic devices for recording biometric data (as in the Quantified Self movement).International Prize for Biology
The International Prize for Biology (国際生物学賞, Kokusai Seibutsugaku-shō) is an annual award for "outstanding contribution to the advancement of research in fundamental biology." The Prize, although it is not always awarded to a biologist, is one of the most prestigious honours a natural scientist can receive. There are no restrictions on the nationality of the recipient.
Past laureates include John B. Gurdon, Motoo Kimura, Edward O. Wilson, Ernst Mayr, Thomas Cavalier-Smith, Yoshinori Ohsumi and many other great biologists in the world.Lam Son High School
Lam Son High School for the Gifted (Vietnamese: Trường Trung Học Phổ Thông Chuyên Lam Sơn) is a public high school in Thanh Hoa, Vietnam. Established in 1931 with the name of Collège de Thanh Hoa, the school is one of the oldest schools still operating in Vietnam and is the first high school in Thanh Hoa. The school's name has been subsequently changed to Collège de Dao Duy Tu (1943–1950), and then its current name, Lam Son since 1950.
Similar to other schools for the gifted in Vietnam, Lam Son high school is the only specialized school in Thanh Hoa Province with the aim to nurture students who excelled in sciences and foreign languages.List of Max Planck Institutes
Max Planck Institutes are research institutions operated by the Max Planck Society. There are 83 institutes as of March 2015. Most of them are located in Germany, but some of them are located in other European countries and the United States.Institutes are organized into three sections according to their research area:
Biology & Medicine
Chemistry, Physics & Technology
Human ScienceOne institute can belong to several research areas. In addition, it can also belong to several more specialized research fields.Lists of extinct species
This page features lists of extinct species, organisms that have become extinct, either in the wild or completely disappeared from Earth. In practice, a species not definitely located in the wild in the last 50 years is called extinct.
Lists of extinct animals
List of extinct plants
List of recently extinct amphibians
List of recently extinct arthropods
List of recently extinct bird species
List of recently extinct fishes
List of recently extinct insects
List of recently extinct invertebrates
List of recently extinct mammals
List of recently extinct molluscs
List of recently extinct reptilesMonera
Monera () (Greek - μονήρης (monḗrēs), "single", "solitary") is a kingdom that contains unicellular organisms with a prokaryotic cell organization (having no nuclear membrane), such as bacteria. They are single-celled organisms with no true nuclear membrane (prokaryotic organisms).
The taxon Monera was first proposed as a phylum by Ernst Haeckel in 1866. Subsequently, the phylum was elevated to the rank of kingdom in 1925 by Édouard Chatton. The last commonly accepted mega-classification with the taxon Monera was the five-kingdom classification system established by Robert Whittaker in 1969.
Under the three-domain system of taxonomy, introduced by Carl Woese in 1977, which reflects the evolutionary history of life, the organisms found in kingdom Monera have been divided into two domains, Archaea and Bacteria (with Eukarya as the third domain). Furthermore, the taxon Monera is paraphyletic (does not include all descendants of their most-recent common ancestor), as Archaea and Eukarya are currently believed to be more closely related than either is to Bacteria. The term "moneran" is the informal name of members of this group and is still sometimes used (as is the term "prokaryote") to denote a member of either domain.Most bacteria were classified under Monera; however, Cyanobacteria (often called the blue-green algae) were initially classified under Plantae due to their ability to photosynthesize.Regium
Regium may refer to:
Reggio Calabria, town in Calabria, Italy; Latin name Regium
[[Reggio Emilia], town in Emilia, Italy; Latin name Regium
Regium Donum, an annual grant formerly voted by Parliament to augment the stipends of the Presbyterian clergy in Ireland
Collegium Regium (disambiguation), Latin for King's College or Royal CollegeRegnum
Regnum may refer to:
Latin for kingdom or dominion, see realm
Regnum, Latin word for Kingdom (biology)
REGNUM News Agency, a Russian news agency
Champions of Regnum, a computer game
An online database for PhyloCodeTwo-empire system
The two-empire system (two-superkingdom system) was the top-level biological classification system in general use before the establishment of the three-domain system. It classified life into Prokaryota and Eukaryota. When the three-domain system was introduced, some biologists preferred the two-superkingdom system, claiming that the three-domain system overemphasized the division between Archaea and Bacteria. However, given the current state of knowledge and the rapid progress in biological scientific advancement, especially due to genetic analyses, that view has all but vanished.
Some prominent scientists, such as Thomas Cavalier-Smith, still hold to the two-empire system. The late Ernst Mayr, one of the 20th century's leading evolutionary biologists, wrote dismissively of the three-domain system, "I cannot see any merit at all in a three empire cladification." Additionally, the scientist Radhey Gupta argues for a return to the two-empire system, claiming that the primary division within prokaryotes should be among those surrounded by a single membrane (monoderm), including gram-positive bacteria and archaebacteria, and those with an inner and outer cell membrane (diderm), including gram-negative bacteria.
This system was preceded by Haeckel's three-kingdom system: Animalia, Plantae and Protista.Wildlife of India
India is home to a variety of animals. Apart from a handful of domesticated animals, such as cows, water buffaloes, goats, chickens, and both Bactrian and Dromedary camels, India has a wide variety of animals native to the country. It is home to Bengal and Indochinese tigers, Asiatic lions, Indian and Indochinese leopards, snow leopards, clouded leopards, various species of Deer, including Chital, Hangul, Barasingha; the Indian Elephant, the Great Indian Rhinoceros, and many others. The region's diverse wildlife is preserved in more than 120 national parks, 18 Bio-reserves and more than 500 wildlife sanctuaries across the country. India has some of the most biodiverse regions of the world and contains four of the world’s 36 biodiversity hotspots – the Western Ghats, the Eastern Himalayas, Indo-Burma and Sunda Land. Wildlife management is essential to preserve the rare and endangered endemic species. India is one of the seventeen megadiverse countries. According to one study, India along with the other 16 megadiverse countries is home to about 60-70% of the world's biodiversity. India, lying within the Indomalaya ecozone, is home to about 7.6% of all mammalian, 12.6% of avian (bird), 6.2% of reptilian, and 6.0% of flowering plant species.Many Indian species are descendants of taxa originating in Gondwana, of which India originally was a part. Peninsular India's subsequent movement towards, and collision with, the Laurasian landmass set off a mass exchange of species. However, volcanism and climatic change 20 million years ago caused the extinction of many endemic Indian forms. Soon thereafter, mammals entered India from Asia through two zoogeographical passes on either side of the emerging Himalaya. As a result, among Indian species, only 12.6% of mammals and 4.5% of birds are endemic, contrasting with 45.8% of reptiles and 55.8% of amphibians. Notable endemics are the Nilgiri leaf monkey and the brown and carmine Beddome's toad of the Western Ghats. India contains 172, or 2.9%, of IUCN-designated threatened species. These include the Asian elephant, the Asiatic lion, Bengal tiger, Indian rhinoceros, mugger crocodile, and Indian white-rumped vulture, which suffered a near-extinction from ingesting the carrion of diclofenac-treated cattle.In recent decades, human encroachment has posed a threat to India's wildlife; in response, the system of national parks and protected areas, first established in 1935, was substantially expanded. In 1972, India enacted the Wildlife Protection Act and Project Tiger to safeguard crucial habitat; further federal protections were promulgated in the 1980s. Along with over 515 wildlife sanctuaries, India now hosts 18 biosphere reserves, 10 of which are part of the World Network of Biosphere Reserves; 26 wetlands are registered under the Ramsar Convention.
The peepul tree, shown on the seals of Mohenjo-daro, shaded Gautama Buddha as he sought enlightenment. The varied and rich wildlife of India has had a profound impact on the region's popular culture. The wildlife has also been made famous in The Jungle Book by Rudyard Kipling. India's wildlife has been the subject of numerous other tales and fables such as the "Panchatantra".