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Cladistic Analysis
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived characteristics (synapomorphies'')'' that are not present in more distant groups and ancestors. However, from an empirical perspective, common ancestors are inferences based on a cladistic hypothesis of relationships of taxa whose character states can be observed. Theoretically, a last common ancestor and all its descendants constitute a (minimal) clade. Importantly, all descendants stay in their overarching ancestral clade. For example, if the terms ''worms'' or ''fishes'' were used within a ''strict'' cladistic framework, these terms would include humans. Many of these terms are normally used paraphyletically, outside of cladistics, e.g. as a ' grade', which are fruitless to precisely delineate, especially when including extinct species. Ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxonomy (biology)
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (''division'' is sometimes used in botany in place of ''phylum''), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a ranked system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms. With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Chalmers Mitchell
Sir Peter Chalmers Mitchell (23 November 1864 – 2 July 1945) was a Scottish zoologist who was Secretary of the Zoological Society of London from 1903 to 1935. During this time, he directed the policy of the Zoological Gardens of London and created the world's first open zoological park, ZSL Whipsnade Zoo. Early life Peter Chalmers Mitchell was the son of the Rev. Alexander Mitchell, a Presbyterian minister in Dunfermline, Scotland, and Marion Chalmers. Mitchell gained an MA at the University of Aberdeen, and moved to Christ Church, Oxford, where he read for natural science, specialising in zoology. After success in the honours examination of 1888, he was appointed University Demonstrator in Zoology. In 1896, he was the anonymous author of an article in the '' Saturday Review'' entitled "A Biological View of English Foreign Policy" which proposed the inevitability of a final battle between Britain and Germany, in which one would have to be destroyed. (Having acknowledged hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biochemical
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells, Karp (2009), p. 2. in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function. Miller (2012). p. 62. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymerase Chain Reaction
The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) to a large enough amount to study in detail. PCR was invented in 1983 by the American biochemist Kary Mullis at Cetus Corporation; Mullis and biochemist Michael Smith, who had developed other essential ways of manipulating DNA, were jointly awarded the Nobel Prize in Chemistry in 1993. PCR is fundamental to many of the procedures used in genetic testing and research, including analysis of ancient samples of DNA and identification of infectious agents. Using PCR, copies of very small amounts of DNA sequences are exponentially amplified in a series of cycles of temperature changes. PCR is now a common and often indispensable technique used in medical laboratory research for a broad variety of applications including biomedical resear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Sokal
Robert Reuven Sokal (January 13, 1926 in Vienna, Austria – April 9, 2012 in Stony Brook, New York) was an Austrian-American biostatistician and entomologist. Distinguished Professor Emeritus at the Stony Brook University, Sokal was a member of the National Academy of Sciences and the American Academy of Arts and Sciences. He promoted the use of statistics in biology and co-founded the field of numerical taxonomy, together with Peter H. A. Sneath. Life Robert Sokal was born in 1926 in a Jewish family in Vienna, Austria. In 1939, following the annexation of Austria by Nazi Germany, he escaped with his family to China. He earned his bachelor's degree at St. John's College in Shanghai, where he married, and from there moved with his wife Julie to the University of Chicago, where he also worked as a librarian to complement his scholarship. He took his Ph.D. degree under the supervision of the well-known termite systematist Alfred E. Emerson. He was also strongly influenced by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Sneath
Peter Henry Andrews Sneath FRS, MD (17 November 1923 – September 9, 2011) was a microbiologist who co-founded the field of numerical taxonomy Numerical taxonomy is a classification system in biological systematics which deals with the grouping by numerical methods of taxonomic units based on their character states. It aims to create a taxonomy using numeric algorithms like cluster ..., together with Robert R. Sokal. Sneath and Sokal wrote ''Principles of Numerical Taxonomy'', revised in 1973 as ''Numerical Taxonomy''. Sneath reviewed the state of numerical taxonomy in 1995 and wrote some autobiographical notes in 2010. A special issue of the journal Antonie van Leeuwenhoek, on microbial systematics, is dedicated to the memory of Peter Sneath. References External linksPeter H. A. Sneath (1923 - 2011) 1923 births 2011 deaths British microbiologists Fellows of the Royal Society Place of birth missing British taxonomists {{Geneticist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numerical Taxonomy
Numerical taxonomy is a classification system in biological systematics which deals with the grouping by numerical methods of taxonomic units based on their character states. It aims to create a taxonomy using numeric algorithms like cluster analysis rather than using subjective evaluation of their properties. The concept was first developed by Robert R. Sokal and Peter H. A. Sneath in 1963 and later elaborated by the same authors.Sneath and Sokal: ''Numerical Taxonomy'', San Francisco: W.H. Freeman, 1974 by Tejanshu Ravesh They divided the field into phenetics in which classifications are formed based on the patterns of overall similarities and cladistics in which classifications are based on the branching patterns of the estimated evolutionary history of the taxa.{{cn span, In recent years many authors treat numerical taxonomy and phenetics as synonyms despite the distinctions made by those authors., date=May 2017 Although intended as an objective method, in practice the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionary Taxonomy
Evolutionary taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification that seeks to classify organisms using a combination of phylogenetic relationship (shared descent), progenitor-descendant relationship (serial descent), and degree of evolutionary change. This type of taxonomy may consider whole taxa rather than single species, so that groups of species can be inferred as giving rise to new groups. The concept found its most well-known form in the modern evolutionary synthesis of the early 1940s. Evolutionary taxonomy differs from strict pre-Darwinian Linnaean taxonomy (producing orderly lists only), in that it builds evolutionary trees. While in phylogenetic nomenclature each taxon must consist of a single ancestral node and all its descendants, evolutionary taxonomy allows for groups to be excluded from their parent taxa (e.g. dinosaurs are not considered to ''include'' birds, but to have ''given rise'' to them), thus permit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenetics
In biology, phenetics ( el, phainein – to appear) , also known as taximetrics, is an attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation. It is closely related to numerical taxonomy which is concerned with the use of numerical methods for taxonomic classification. Many people contributed to the development of phenetics, but the most influential were Peter Sneath and Robert R. Sokal. Their books are still primary references for this sub-discipline, although now out of print. Phenetics has largely been superseded by cladistics for research into evolutionary relationships among species. However, certain phenetic methods, such as neighbor-joining, have found their way into phylogenetics, as a reasonable approximation of phylogeny when more advanced methods (such as Bayesian inference) are too computationally expensive. Phenetic techniques include various forms of cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernst Mayr
Ernst Walter Mayr (; 5 July 1904 – 3 February 2005) was one of the 20th century's leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept. Although Charles Darwin and others posited that multiple species could evolve from a single common ancestor, the mechanism by which this occurred was not understood, creating the '' species problem''. Ernst Mayr approached the problem with a new definition for species. In his book '' Systematics and the Origin of Species'' (1942) he wrote that a species is not just a group of morphologically similar individuals, but a group that can breed only among themselves, excluding all others. When populations within a species become is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Cain
Arthur James Cain FRS (25 July 1921 – 20 August 1999) was a British evolutionary biologist and ecologist. He was elected a Fellow of the Royal Society in 1989. Life Arthur James Cain was awarded an open scholarship in 1939 ( Demyship) to Magdalen College, Oxford, where he graduated with first class honors in zoology in 1941. Entering the British Army in December 1941, Cain was commissioned Second Lieutenant in the Royal Army Ordnance Corps (engineering) and was later transferred to the Royal Electrical and Mechanical Engineers (R.E.M.E.) on its formation. He was promoted to Captain in 1942. After leaving the military in November 1945 Cain returned to Oxford to pursue research in the Department of Zoology. He became a Departmental Demonstrator in October 1946, and received his M.A. in November 1947. From January 1949 until 1964 Cain was employed as University Demonstrator (now referred to as Lecturer) in Animal Taxonomy. Career Cain's main interests lay in evolutionary bio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lucien Cuénot
Lucien Claude Marie Julien Cuénot (; 21 October 1866 – 7 January 1951) was a French biologist. In the first half of the 20th century, Mendelism was not a popular subject among French biologists. Cuénot defied popular opinion and shirked the “pseudo-sciences” as he called them. Upon the rediscovery of Mendel's work by Correns, De Vries, and Tschermak, Cuénot proved that Mendelism applied to animals as well as plants. Cuénot's experiments Cuénot spent two years working on mice and came to the conclusion that three “mnemons” (genes) are responsible for the production of one “chromogen” or pigment and two “distases” enzymes. The pigment (if present) is acted upon by the enzymes to produce black or yellow colour. If no pigment is present the result is an albino mouse. Cuénot studied the offspring of various crosses between mice and concluded that these “mnemons” or genes were inherited in a Mendelian fashion. Subsequently, Cuénot was the first person to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
