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Idealised Population
In population genetics an idealised population is one that can be described using a number of simplifying assumptions. Models of idealised populations are either used to make a general point, or they are fit to data on real populations for which the assumptions may not hold true. For example, coalescent theory is used to fit data to models of idealised populations. The most common idealized population in population genetics is described in the Wright-Fisher model after Sewall Wright and Ronald Fisher (1922, 1930) and (1931). Wright-Fisher populations have constant size, and their members can mate and reproduce with any other member. Another example is a Moran model, which has overlapping generations, rather than the non-overlapping generations of the Fisher-Wright model. The complexities of real populations can cause their behavior to match an idealised population with an effective population size that is very different from the census population size of the real population. For ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population Genetics
Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as Adaptation (biology), adaptation, speciation, and population stratification, population structure. Population genetics was a vital ingredient in the emergence of the Modern synthesis (20th century), modern evolutionary synthesis. Its primary founders were Sewall Wright, J. B. S. Haldane and Ronald Fisher, who also laid the foundations for the related discipline of quantitative genetics. Traditionally a highly mathematical discipline, modern population genetics encompasses theoretical, laboratory, and field work. Population genetic models are used both for statistical inference from DNA sequence data and for proof/disproof of concept. What sets population genetics apart from newer, more phenotypic approaches to modelling evolution, such as evolutionary game theory and evolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binomial Square Principle
Binomial may refer to: In mathematics *Binomial (polynomial), a polynomial with two terms *Binomial coefficient, numbers appearing in the expansions of powers of binomials *Binomial QMF, a perfect-reconstruction orthogonal wavelet decomposition *Binomial theorem, a theorem about powers of binomials *Binomial type, a property of sequences of polynomials *Binomial series, a mathematical series In probability and statistics *Binomial distribution, a type of probability distribution *Binomial process *Binomial test, a test of significance In computing science *Binomial heap, a data structure In linguistics *Binomial pair, a sequence of two or more words or phrases in the same grammatical category, having some semantic relationship and joined by some syntactic device In biology * Binomial nomenclature, a Latin two-term name for a species, such as ''Sequoia sempervirens'' In finance *Binomial options pricing model In finance, the binomial options pricing model (BOPM) provides a gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Program
A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangible components. A ''computer program'' in its human-readable form is called source code. Source code needs another computer program to Execution (computing), execute because computers can only execute their native machine instructions. Therefore, source code may be Translator (computing), translated to machine instructions using a compiler written for the language. (Assembly language programs are translated using an Assembler (computing), assembler.) The resulting file is called an executable. Alternatively, source code may execute within an interpreter (computing), interpreter written for the language. If the executable is requested for execution, then the operating system Loader (computing), loads it into Random-access memory, memory and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simulation
A simulation is an imitative representation of a process or system that could exist in the real world. In this broad sense, simulation can often be used interchangeably with model. Sometimes a clear distinction between the two terms is made, in which simulations require the use of models; the model represents the key characteristics or behaviors of the selected system or process, whereas the simulation represents the evolution of the model over time. Another way to distinguish between the terms is to define simulation as experimentation with the help of a model. This definition includes time-independent simulations. Often, computer simulation, computers are used to execute the simulation. Simulation is used in many contexts, such as simulation of technology for performance tuning or optimizing, safety engineering, testing, training, education, and video games. Simulation is also used with scientific modelling of natural systems or human systems to gain insight into their functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stepping Stone Model
Stepping may refer to: * Walking, one of the main gaits of locomotion among legged animals Computing * Stepping level, an aspect of microprocessor version designation * Stepping (debugging) Program animation or stepping refers to the debugging method of executing code one instruction or line at a time. The programmer may examine the state of the program, machine, and related data before and after execution of a particular line of cod ..., a method of debugging Dance * Chicago stepping, a type of dance originating in Chicago * Step dance, generic term for dance styles where the footwork is the most important part of the dance * Stepping (African-American), a percussive dance in which the participant's entire body is used as an instrument * '' Steppin''', album by the Pointer Sisters See also * Step (other) * Stepping stone (other) * Mast Stepping {{Disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaic Human Admixture With Modern Humans
Interbreeding between archaic and modern humans occurred during the Middle Paleolithic and early Upper Paleolithic. The interbreeding happened in several independent events that included Neanderthals and Denisovans, as well as several unidentified hominins. In Europe, Asia and North Africa, interbreeding between archaic humans and modern humans took place several times. The introgression events into modern humans are estimated to have happened about 47,000–65,000 years ago with Neanderthals and about 44,000–54,000 years ago with Denisovans. Neanderthal-derived DNA has been found in the genomes of most contemporary populations, varying noticeably by region. It accounts for 1–4% of modern genomes for people outside Sub-Saharan Africa, although estimates vary, and either none or up to 0.3% for those in Sub-Saharan Africa. Cushitic and Semitic speaking populations from the Horn of Africa (such as Ethiopians), who derive a large portion of their ancestry from West Eurasian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science (journal)
''Science'' is the peer review, peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. ''Science'' is based in Washington, D.C., United States, with a second office in Cambridge, UK. Contents The major focus of the journal is publishing important original scientific research and research reviews, but ''Science'' also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals, which focus on a specific field, ''Science'' and its rival ''Nature (journal), Nature'' cover the full range of List of academ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sex Ratio
A sex ratio is the ratio of males to females in a population. As explained by Fisher's principle, for evolutionary reasons this is typically about 1:1 in species which reproduce sexually. However, many species deviate from an even sex ratio, either periodically or permanently. These include parthenogenic and androgenetic species, periodically mating organisms such as aphids, some eusocial wasps, bees, ants, and termites. Types In most species, the sex ratio varies according to the age profile of the population. It is generally divided into four subdivisions: * — ratio at fertilization * — ratio at birth * — ratio in sexually mature organisms ** The tertiary sex ratio is equivalent to the (ASR), which is defined as the ratio of adult males to females in a population. ** The operational sex ratio (OSR) is the ratio of ''sexually active'' males to females in a population, and is therefore derived from a subset of the individuals included when calculating the ASR. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effective Population
The effective population size (''N''''e'') is the size of an idealised population that would experience the same rate of genetic drift as the real population. Idealised populations are those following simple one- locus models that comply with assumptions of the neutral theory of molecular evolution. The effective population size is normally smaller than the census population size ''N'', partly because chance events prevent some individuals from breeding, and partly due to background selection and genetic hitchhiking. The same real population could have a different effective population size for different properties of interest, such as genetic drift (or more precisely, the speed of coalescence) over one generation vs. over many generations. Within a species, areas of the genome that have more genes and/or less genetic recombination tend to have lower effective population sizes, because of the effects of selection at linked sites. In a population with selection at many loci and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Diversity
Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is distinguished from '' genetic variability'', which describes the tendency of genetic characteristics to vary. Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Those individuals are more likely to survive to produce offspring bearing that allele. The population will continue for more generations because of the success of these individuals. The academic field of population genetics includes several hypotheses and theories regarding genetic diversity. The neutral theory of evolution proposes that diversity is the result of the accumulation of neutral substitu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephen R
Stephen or Steven is an English first name. It is particularly significant to Christians, as it belonged to Saint Stephen ( ), an early disciple and deacon who, according to the Book of Acts, was stoned to death; he is widely regarded as the first martyr (or " protomartyr") of the Christian Church. The name, in both the forms Stephen and Steven, is often shortened to Steve or Stevie. In English, the female version of the name is Stephanie. Many surnames are derived from the first name, including Stephens, Stevens, Stephenson, and Stevenson, all of which mean "Stephen's (son)". In modern times the name has sometimes been given with intentionally non-standard spelling, such as Stevan or Stevon. A common variant of the name used in English is Stephan ( ); related names that have found some currency or significance in English include Stefan (pronounced or in English), Esteban (often pronounced ), and the Shakespearean Stephano ( ). Origins The name "Stephen" (and it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joe Roman
Joe Roman is a conservation biologist, marine ecologist, and author of the books ''Whale'', '' Listed: Dispatches from America's Endangered Species Act'', and ''Eat, Poop, Die: How Animals Make Our World''. His conservation research includes studies of the historical population size of whales, the role of cetaceans in the nitrogen cycle, the relationship between biodiversity and disease, and the genetics of invasions. He is the founding editor of "Eat the Invaders", a website dedicated to controlling invasive species by eating them. Roman is a Fellow at the Gund Institute for Ecological Economics at the University of Vermont. He earned an AB with Honors in Visual and Environmental Studies from Harvard University in 1985 and an MA in wildlife ecology and conservation from the University of Florida. Roman was awarded his PhD from Harvard's Department of Organismic and Evolutionary Biology in 2003; his dissertation was titled ''Tracking Anthropogenic Change in the North ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
