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Discus (fish)
''Symphysodon'', colloquially known as discus, is a genus of cichlids native to the Amazon river basin in South America. Due to their distinctive shape, behavior, and bright colors and patterns, discus are popular as freshwater aquarium fish, and their aquaculture in several countries in Asia is a major industry.Sands D (1994) ''A fishkeepers guide to Central American cichlids.'' Tetra Press. Belgium pg 59-60. They are sometimes referred to as pompadour fish. The discus fish has attracted a cult following of collectors and has created a multimillion dollar international industry complete with shows, competitions, and reputed online breeders. Species Following a review published in 2006, three species are recognized by FishBase: * ''Symphysodon aequifasciatus'' Pellegrin, 1904 (blue discus or brown discus) * '' Symphysodon discus'' Heckel, 1840 (red discus or Heckel discus) * ''Symphysodon tarzoo'' E. Lyons, 1959 (green discus) Taxonomy Discus are fish from the genus '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Jakob Heckel
Johann Jakob Heckel (23 January 1790 – 1 March 1857) was an Austrian taxidermist, zoologist, and ichthyologist from Mannheim in the Electoral Palatinate. Life Though not a formally trained biologist, he worked his way up through the ranks to eventually become the director of the Fish Collection at the Naturhistorisches Museum in Vienna. For the most part, he was not a traveler or explorer like many of the scientists of the time, he remained in Vienna, where he studied and catalogued specimens sent to him from the field. Among those who brought specimens to him were Karl Alexander Hügel, Joseph Russegger and Theodor Kotschy — involving collection activities in Kashmir, the Middle East and northeastern Africa that greatly enriched the Vienna museum. Fish were his specialty and he worked with many of the greatest ichthyologists of his time including Cuvier, Valenciennes, Bonaparte, Müller, and Troschel. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morphometric
Morphometrics (from Greek μορϕή ''morphe'', "shape, form", and -μετρία ''metria'', "measurement") or morphometry refers to the quantitative analysis of ''form'', a concept that encompasses size and shape. Morphometric analyses are commonly performed on organisms, and are useful in analyzing their fossil record, the impact of mutations on shape, developmental changes in form, covariances between ecological factors and shape, as well for estimating quantitative-genetic parameters of shape. Morphometrics can be used to quantify a trait of evolutionary significance, and by detecting changes in the shape, deduce something of their ontogeny, function or evolutionary relationships. A major objective of morphometrics is to statistically test hypotheses about the factors that affect shape. "Morphometrics", in the broader sense, is also used to precisely locate certain areas of organs such as the brain, and in describing the shapes of other things. Forms Three general appro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trombetas River
The Trombetas is a large river on the northern side of the Amazon River. Course The Trombetas is long, and is navigable by 500 ton vessels for a stretch of . The Trombetas river gives birth to very many rivers, including the Anamu river. It is formed by the junction of the Poana and Anuma rivers on the border between Brazil and Guyana. Where it meets the Paraná de Sapucuá it takes the name of lower Trombetas, and reaches up to in width, with the stream divided by several long and narrow islands. It runs through the municipalities of Oriximiná, Terra Santa, Óbidos and Faro. The river basin has an area of about , with an intricate pattern of tributaries including the Poana, Anamu, Turuna, Inhabu, Mapuera and Paru de Oeste. In the Saracá-Taquera National Forest the main streams in the Trombetas basin are the Papagaio, Água Fria, Moura, Jamari, Ajará, Terra Preta and Saracá. Its confluence with the Amazon is just west of the town of Óbidos, Pará in Brazil. Its sources ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nhamundá River
Nhamundá River or Jamundá River (Yamundá River in Spanish) is a river in northern Brazil, which marks part of the northeastern boundary between states of Amazonas and Pará. The 300 km long Nhamundá River originates in the plateau '' Serra do Jatapu'' near the division of the Brazilian States of Roraima, Amazonas and Pará, and from there it flows in a southeastern direction, forming the natural division between Amazonas and Pará. It then crosses the Nhamundá-Mapuera Reserve (EG033) before joining the Trombetas River near the city of Oriximiná. The river, which flows through the Lago Nhamundá, is the last major right-hand affluent of the Trombetas River before the Trombetas joins the Amazon River. The mouth is located about 480 km east (downstream on the Amazon) of Manaus. The three towns on the river's lower reaches (Terra Santa, Nhamundá, and Faro) are accessible only by boat. See also * List of rivers of Amazonas *List of rivers of Pará List of rivers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uatumã River
The Uatumã River (sometimes spelled Uatamã) is a river flowing through the state of Amazonas in Brazil. It is a northern tributary of the Amazon River, and known for its extensive peacock bass population. It is a blackwater river. The river flows through the Uatuma-Trombetas moist forests ecoregion. During the wet season starting in December, water levels can rise some 25 to 40 feet. Water levels have been strongly affected by the building of the controversial Balbina Dam on the river in the mid to late 1980s to generate electricity. The hydroelectric dam generates an average of 112.2 MW of electricity from the river system and floods a total of 2360 km2 of rainforest around the Uatumã river. From the point where the river emerges from the dam it defines the east boundary of the Caverna do Maroaga Environmental Protection Area, established in 1990. The Uatumã Biological Reserve established in 1990 is a nature reserve around the river in the municipalities of São ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionarily Significant Unit
An evolutionarily significant unit (ESU) is a population of organisms that is considered distinct for purposes of conservation. Delineating ESUs is important when considering conservation action. This term can apply to any species, subspecies, geographic race, or population. Often the term "species" is used rather than ESU, even when an ESU is more technically considered a subspecies or variety rather than a biological species proper. In marine animals the term "stock" is often used as well. Definition Definitions of an ESU generally include at least one of the following criteria:Jeffrey Conner, Daniel Hartl. ''A Primer of Ecological Genetics''. 2004, # Current geographic separation, # Genetic differentiation at neutral markers among related ESUs caused by past restriction of gene flow, or # Locally adapted phenotypic traits caused by differences in selection. Criterion 2 considers the gene flow between populations, measured by FST. A high degree of differentiation between tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book ''The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symphysodon Aequifasciatus (1) 03May2010
''Symphysodon aequifasciatus'', the blue discus or brown discus, is a species of cichlid native to rivers of the eastern and central Amazon Basin downriver from the Púrus Arch. This discus is found in black-, clear- and whitewater, but its preference for lentic habitats such as floodplains and flooded forests means that the whitewater it inhabits contain little suspended material (unlike main sections of whitewater rivers). It is largely restricted to water with a high temperature of and a pH of 5.2–7.7. It typically reaches a length of up to SL, but captives have been claimed to reach . It is commonly kept in aquariums. Taxonomy The taxonomy is disputed, but FishBase follows a review of the genus from 2006. In 2007 it was suggested that the correct scientific name of the blue/brown discus is ''S. haraldi'', whereas ''S. aequifasciatus'' is the correct name for the green discus. In 2011 a study indicated that it should be split into three: Brown discus (''S. aequifasc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Morph
In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative ''phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating). Ford E.B. 1965. ''Genetic polymorphism''. Faber & Faber, London. Put simply, polymorphism is when there are two or more possibilities of a trait on a gene. For example, there is more than one possible trait in terms of a jaguar's skin colouring; they can be light morph or dark morph. Due to having more than one possible variation for this gene, it is termed 'polymorphism'. However, if the jaguar has only one possible trait for that gene, it would be termed "monomorphic". For example, if there was only one possible skin colour that a jaguar could have, it would be termed monomorphic. The term polyphenism can be used to clarify that the different forms arise from the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rio Negro (Amazon)
The Rio Negro ( pt, Rio Negro, br ; es, Río Negro} "''Black River''"), or Guainía as it is known in its upper part, is the largest left tributary of the Amazon River (accounting for about 14% of the water in the Amazon basin), the largest blackwater river in the world, and one of the world's ten largest rivers by average discharge. Geography Upper course The source of the Rio Negro lies in Colombia, in the Department of Guainía where the river is known as the ''Guainía River''. The young river generally flows in an east-northeasterly direction through the Puinawai National Reserve, passing several small indigenous settlements on its way, such as Cuarinuma, Brujas, Santa Rosa and Tabaquén. After roughly 400 km the river starts forming the border between Colombia's Department of Guainía and Venezuela's Amazonas State. After passing the Colombian community of Tonina and Macanal the river turns Southwest. Maroa is the first Venezuelan town the river passes. 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosomal Translocation
In genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes balanced and unbalanced translocation, with two main types: reciprocal-, and Robertsonian translocation. Reciprocal translocation is a chromosome abnormality caused by exchange of parts between non-homologous chromosomes. Two detached fragments of two different chromosomes are switched. Robertsonian translocation occurs when two non-homologous chromosomes get attached, meaning that given two healthy pairs of chromosomes, one of each pair "sticks" and blends together homogeneously. A gene fusion may be created when the translocation joins two otherwise-separated genes. It is detected on cytogenetics or a karyotype of affected cells. Translocations can be balanced (in an even exchange of material with no genetic information extra or missing, and ideally full functionality) or unbalanced (where the exchange of chromosome material is unequal resulting in extra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lineage Sorting
Incomplete lineage sorting, also termed hemiplasy, deep coalescence, retention of ancestral polymorphism, or trans-species polymorphism, describes a phenomenon in population genetics when ancestral gene copies fail to coalesce (looking backwards in time) into a common ancestral copy until deeper than previous speciation events. It is caused by lineage sorting of genetic polymorphisms that were retained across successive nodes in the species tree. In other words, the tree produced by a single gene differs from the population or species level tree, producing a discordant tree. Whatever the mechanism, the result is that a generated species level tree may differ depending on the selected genes used for assessment. This is in contrast to complete lineage sorting, where the tree produced by the gene is the same as the population or species level tree. Both are common results in phylogenetic analysis, although it depends on the gene, organism, and sampling technique. Concept The conce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
