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Population Genomics
Population genomics is the large-scale comparison of DNA sequences of populations. Population genomics is a neologism that is associated with population genetics. Population genomics studies genome-wide effects to improve our understanding of microevolution so that we may learn the phylogenetic history and demography of a population.Luikart, G.; England, P. R.; Tallmon, D.; Jordan S.; Taberlet P. (2003). "The Power and Promise of Population Genomics: From Genotyping to Genome Typing". ''Nature Reviews'' (4): 981-994 History Population genomics has been of interest to scientists since Darwin. Some of the first methods used for studying genetic variability at multiple loci included gel electrophoresis and restriction enzyme mapping. Previously genomics was restricted to only the study of a low amount of loci. However recent advancements in sequencing and computer storage and power have allowed for the study of hundreds of thousands of loci from populations. Analysis of this data requ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neologism
In linguistics, a neologism (; also known as a coinage) is any newly formed word, term, or phrase that has achieved popular or institutional recognition and is becoming accepted into mainstream language. Most definitively, a word can be considered a neologism once it is published in a dictionary. Neologisms are one facet of lexical innovation, i.e., the linguistic process of new terms and meanings entering a language's lexicon. The most precise studies into language change and word formation, in fact, identify the process of a "neological continuum": a '' nonce word'' is any single-use term that may or may not grow in popularity; a '' protologism'' is such a term used exclusively within a small group; a ''prelogism'' is such a term that is gaining usage but is still not mainstream; and a ''neologism'' has become accepted or recognized by social institutions. Neologisms are often driven by changes in culture and technology. Popular examples of neologisms can be found in science, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlantic Salmon
The Atlantic salmon (''Salmo salar'') is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae, behind Hucho taimen, Siberian taimen and Pacific Chinook salmon, growing up to a meter in length. Atlantic salmon are found in the northern Atlantic Ocean and in rivers that flow into it. Most populations are anadromous, hatching in streams and rivers but moving out to sea as they grow where they mature, after which the adults seasonally move upstream again to spawn. When the mature fish re-enter rivers to spawn, they change in colour and appearance. Some populations of this fish only migrate to large lakes, and are "landlocked", spending their entire lives in freshwater. Such populations are found throughout the range of the species. Unlike Pacific species of salmon, ''S. salar'' is iteroparous, which means it can survive spawning and return to sea to repeat the process again in another year with 5–10% returning to the sea to spawn again ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fixation Index
The fixation index (FST) is a measure of population differentiation due to genetic structure. It is frequently estimated from Polymorphism (biology), genetic polymorphism data, such as single-nucleotide polymorphisms (SNP) or Microsatellite (genetics), microsatellites. Developed as a special case of Sewall WWright's F-statistics, it is one of the most commonly used statistics in population genetics. Its values range from 0 to 1, with 0 being no differentiation and 1 being complete differentiation. Interpretation This comparison of genetic variability within and between populations is frequently used in applied population genetics. The values range from 0 to 1. A zero value implies complete panmixia; that is, that the two populations are interbreeding freely. A value of one implies that all genetic variation is explained by the population structure, and that the two populations do not share any genetic diversity. For idealized models such as Isolation_by_distance#Sewall_Wright-_Ec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantitative Trait Locus
A quantitative trait locus (QTL) is a locus (section of DNA) that correlates with variation of a quantitative trait in the phenotype of a population of organisms. QTLs are mapped by identifying which molecular markers (such as SNPs or AFLPs) correlate with an observed trait. This is often an early step in identifying the actual genes that cause the trait variation. Definition A quantitative trait locus (QTL) is a region of DNA which is associated with a particular phenotypic trait, which varies in degree and which can be attributed to polygenic effects, i.e., the product of two or more genes, and their environment. . These QTLs are often found on different chromosomes. The number of QTLs which explain variation in the phenotypic trait indicates the genetic architecture of a trait. It may indicate that plant height is controlled by many genes of small effect, or by a few genes of large effect. Typically, QTLs underlie continuous traits (those traits which vary continuou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lingcod
The lingcod or ling cod (''Ophiodon elongatus'') is a fish of the greenling family Hexagrammidae. Despite its name, the lingcod is neither a cod nor a ling. It is also known as the buffalo cod, cultus cod, or Buckethead. It is the only extant member of the genus Ophiodon. A slightly larger, extinct species, '' Ophiodon ozymandias'', is known from fossils from the Late Miocene of Southern California. ''Ophiodon elongatus'' is native to the North American west coast from Shumagin Islands in the Gulf of Alaska to Baja California, Mexico. It has been observed up to a size of and a confirmed weight of , with unconfirmed reports of fish weighing more than . It is spotted in various shades of gray. The lingcod is a popular eating fish and is thus prized by anglers. Though not closely related to either ling or cod, the name "lingcod" originated because it somewhat resembles those fish. Around 20% of lingcods have blue green to turquoise flesh.p. 298 The color, which is no longer p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Striped Marlin
The striped marlin (''Tetrapturus audax'', also ''Kajikia audax'') is a species of marlin found globally in tropical to temperate oceans not far from the surface. It is a desirable commercial and game fish, although conservation measures are in place to restrict its commercial landings. An epipelagic predator, it hunts during the day in the top or so of the water column, often near the surface. One of its chief prey is sardines. Description The striped marlin has a torpedo-like body, dark blue or black above and silvery-white below, with an average length of , a maximum length of , and weight up to . Its first dorsal fin is tall, of the same dimension or greater than its body depth, with 42–48 ; the second is much smaller. It has around 12–20 pronounced bluish stripes on the sides of its body, which display even after death. Chromatophores, specialized pigmentation cells, contract or expand to enable the stripes to transform from blue-tinged to lavender when the fish is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albacore
The albacore (''Thunnus alalunga''), known also as the longfin tuna, is a species of tuna of the order Scombriformes. It is found in temperate and tropical waters across the globe in the epipelagic and mesopelagic zones. There are six distinct stocks known globally in the Atlantic, Pacific, and Indian oceans, as well as the Mediterranean Sea. The albacore has an elongate, fusiform body with a conical snout, large eyes, and remarkably long pectoral fins. Its body is a deep blue dorsally and shades of silvery white ventrally. Individuals can reach up to in length. Albacore are pelagic predators that eat a wide variety of foods, including but not limited to fish, crustaceans, and cephalopods. They are unique among tuna in that their primary food source is cephalopods, with fish making up a much smaller portion of their diet. Reproduction usually occurs from November to February and is oviparous. An adult female can release over two million eggs in a single cycle. Fry (juvenile fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yellowfin Tuna
The yellowfin tuna (''Thunnus albacares'') is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide. Yellowfin is often marketed as ahi, from the Hawaiian , a name also used there for the closely related bigeye tuna (''Thunnus obesus''). The species name, ''albacares'' ("white meat") can also lead to confusion: in English, the albacore (''Thunnus alalunga'') is a different species, while yellowfin is officially designated ''albacore'' in French and referred to as ''albacora'' by Portuguese fishermen. Description The yellowfin tuna is among the larger tuna species, reaching weights over , but is significantly smaller than the Atlantic and Pacific bluefin tunas, which can reach over , and slightly smaller than the bigeye tuna and the southern bluefin tuna. The second dorsal fin and the anal fin, as well as the finlets between those fins and the tail, are bright yellow, giving this fish its common name. The second dorsal and anal fins can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Restriction Site Associated DNA Markers
Restriction site associated DNA (RAD) markers are a type of genetic marker which are useful for association mapping, QTL-mapping, population genetics, ecological genetics and evolutionary genetics. The use of RAD markers for genetic mapping is often called RAD mapping. An important aspect of RAD markers and mapping is the process of isolating RAD tags, which are the DNA sequences that immediately flank each instance of a particular restriction site of a restriction enzyme throughout the genome. Once RAD tags have been isolated, they can be used to identify and genotype DNA sequence polymorphisms mainly in form of single nucleotide polymorphisms (SNPs). Polymorphisms that are identified and genotyped by isolating and analyzing RAD tags are referred to as RAD markers. Although genotyping by sequencing presents an approach similar to the RAD-seq method, they differ in some substantial ways. Isolation of RAD tags The use of the flanking DNA sequences around each restriction site is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Stocks
Fish stocks are population, subpopulations of a particular species of fish, for which intrinsic parameters (growth, recruitment, mortality and fishing mortality) are traditionally regarded as the significant factors determining the Population dynamics of fisheries, stock's population dynamics, while extrinsic factors (immigration and emigration) are traditionally ignored. Stocks fished within biologically sustainable levels decreased from 90% in 1974 to 62.3% in 2021. Concepts The stock concept All species have geographic limits to their distribution, which are determined by their Physiological tolerance, tolerance to natural environment, environmental conditions, and their ability to competition, compete successfully with other species. In ocean, marine environments this may be less evident than on land because there are fewer topography, topographical boundaries, however, discontinuities still exist, produced for example by mesoscale and sub-mesoscale circulations that m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Highly Migratory Species
Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Such migrations are usually done for better feeding or to reproduce, but in other cases the reasons are unclear. Fish migrations involve movements of schools of fish on a scale and duration larger than those arising during normal daily activities. Some particular types of migration are ''anadromous'', in which adult fish live in the sea and migrate into fresh water to spawn; and ''catadromous'', in which adult fish live in fresh water and migrate into salt water to spawn. Marine forage fish often make large migrations between their spawning, feeding and nursery grounds. Their movements are associated with ocean currents and with the availability of food in different areas at different times of the year. The migratory m ... [...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. An ESU is not always equivalent to a biological species but can be also a subspecies, variety, geographic race, or population. 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 two populations among genes that provide no adaptive advantage to either population (known as ''neutral markers'') i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
