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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
A neologism Greek νέο- ''néo''(="new") and λόγος /''lógos'' meaning "speech, utterance"] is a relatively recent or isolated term, word, or phrase that may be in the process of entering common use, but that has not been fully accepted into mainstream language. Neologisms are often driven by changes in culture and technology. In the process of language formation, neologisms are more mature than '' protologisms''. A word whose development stage is between that of the protologism (freshly coined) and neologism (new word) is a ''prelogism''. Popular examples of neologisms can be found in science, fiction (notably science fiction), films and television, branding, literature, jargon, cant, linguistics, the visual arts, and popular culture. Former examples include ''laser'' (1960) from Light Amplification by Stimulated Emission of Radiation; ''robot'' (1941) from Czech writer Karel Čapek's play ''R.U.R. (Rossum's Universal Robots)''; and ''agitprop'' (1930) (a portmanteau of " ... [...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 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. Such individuals can grow to extremely large sizes, althoug ... [...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 genetic polymorphism data, such as single-nucleotide polymorphisms (SNP) or microsatellites. Developed as a special case of Wright's F-statistics, it is one of the most commonly used statistics in population genetics. Definition Two of the most commonly used definitions for FST at a given locus are based on 1) the variance of allele frequencies between populations, and on 2) the probability of Identity by descent. If \bar is the average frequency of an allele in the total population, \sigma^2_S is the variance in the frequency of the allele between different subpopulations, weighted by the sizes of the subpopulations, and \sigma^2_T is the variance of the allelic state in the total population, FST is defined as : F_ = \frac = \frac Wright's definition illustrates that FST measures the amount of genetic variance that can be explained by population stru ... [...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 continuously, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lingcod
The lingcod or ling cod (''Ophiodon elongatus''), also known as the buffalo cod or cultus cod, is a fish of the greenling family Hexagrammidae. 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 weight of . 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 colour is destroyed by cooking. The colour may be due to biliverdin, but this has not been established beyond doubt. Distribution and lifecycle Lingcod are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Striped Marlin
The striped marlin (''Kajikia audax'') is a species of marlin found in tropical to temperate Indo-Pacific oceans not far from the surface. It is a desirable commercial and game fish. The striped marlin is a predator that hunts during the day in the top 100 m or so of the water column, often near the surface. One of their chief prey is sardines. Description The Striped Marlin consists of 42-48 rays on its tall first dorsal fin that is almost the same or longer than its body depth while the second dorsal fin is much smaller. They have torpedo-like and compressed bodies. They have around 10-20 clear, visible bluish stripes on the sides of their bodies even after death. The color of their bodies is dark blue or black above and silvery-white on the bottom. Striped Marlin has an average length of and a maximum length of and can weight up to . Life Cycle Striped Marlin reached sexual maturity at a age of 1-2 years or for males and 1.5-2.5 years or for females. They can live up ... [...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 Perciformes. 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 most 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 ... [...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 language, Hawaiian , a name also used there for the closely related bigeye tuna. 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 language, 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 bluefin tuna, Atlantic and Pacific bluefin tuna, 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 ... [...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 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Stocks
Fish stocks are 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 stock's population dynamics, while extrinsic factors (immigration and emigration) are traditionally ignored. Concepts The stock concept All species have geographic limits to their distribution, which are determined by their tolerance to environmental conditions, and their ability to compete successfully with other species. In marine environments this may be less evident than on land because there are fewer topographical boundaries, however, discontinuities still exist, produced for example by mesoscale and sub-mesoscale circulations that minimize long-distance dispersal of fish larvae. For fish, it is rare for an individual to reproduce randomly with all other individuals of that species within its biological range. There is a tendency to form a structur ... [...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. Movements are associated with ocean currents and with the availability of food in different areas at different times of year. The migratory movements ma ... [...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] |
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