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Genetic Distance
Genetic distance is a measure of the genetic divergence between species or between populations within a species, whether the distance measures time from common ancestor or degree of differentiation. Populations with many similar alleles have small genetic distances. This indicates that they are closely related and have a recent common ancestor. Genetic distance is useful for reconstructing the history of populations, such as the multiple human expansions out of Africa. It is also used for understanding the origin of biodiversity. For example, the genetic distances between different breeds of domesticated animals are often investigated in order to determine which breeds should be protected to maintain genetic diversity. Biological foundation In the genome of an organism, each gene is located at a specific place called the locus for that gene. Allelic variations at these loci cause phenotypic variation within species (e.g. hair colour, eye colour). However, most alleles do not hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The History And Geography Of Human Genes Luigi Luca Cavalli-Sforza Map Genetic
''The'' () is a grammatical article in English, denoting persons or things already mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the most frequently used word in the English language; studies and analyses of texts have found it to account for seven percent of all printed English-language words. It is derived from gendered articles in Old English which combined in Middle English and now has a single form used with pronouns of any gender. The word can be used with both singular and plural nouns, and with a noun that starts with any letter. This is different from many other languages, which have different forms of the definite article for different genders or numbers. Pronunciation In most dialects, "the" is pronounced as (with the voiced dental fricative followed by a schwa) when followed by a consonant sound, and as (homophone of pronoun ''thee'') when followed by a v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luigi Luca Cavalli-Sforza
Luigi Luca Cavalli-Sforza (; 25 January 1922 – 31 August 2018) was an Italian geneticist. He was a population geneticist who taught at the University of Parma, the University of Pavia and then at Stanford University. Works Schooling and positions Cavalli-Sforza entered Ghislieri College in Pavia in 1939 and he received his M.D. from the University of Pavia in 1944. In 1949, he was appointed to a research post at the Department of Genetics, Cambridge University by the statistician and evolutionary biologist Ronald A. Fisher in the field of '' E. coli'' genetics. In 1950, he left the University of Cambridge to teach in northern Italy (Parma, and Pavia) before taking up a professorship at Stanford in 1970. He remained at Stanford until he retired in 1992. In 1999 he won the Balzan Prize for the Science of human origins. He has been a member of the Pontifical Academy of Sciences since 1994. In 1992 he was elected Foreign Member of the Royal Society of London. He was awarded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allele Frequency
Allele frequency, or gene frequency, is the relative frequency of an allele (variant of a gene) at a particular locus in a population, expressed as a fraction or percentage. Specifically, it is the fraction of all chromosomes in the population that carry that allele over the total population or sample size. Microevolution is the change in allele frequencies that occurs over time within a population. Given the following: # A particular locus on a chromosome and a given allele at that locus # A population of ''N'' individuals with ploidy ''n'', i.e. an individual carries ''n'' copies of each chromosome in their somatic cells (e.g. two chromosomes in the cells of diploid species) # The allele exists in ''i'' chromosomes in the population then the allele frequency is the fraction of all the occurrences ''i'' of that allele and the total number of chromosome copies across the population, ''i''/(''nN''). The allele frequency is distinct from the genotype frequency, although they are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetics
In biology, phylogenetics (; from Greek language, Greek wikt:φυλή, φυλή/wikt:φῦλον, φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by Computational phylogenetics, phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, Protein, protein Amino acid, amino acid sequences, or Morphology (biology), morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a phylogenetic tree can be living taxa or fossils, and represent the "end" or the present time in an evolutionary lineage. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the tree. An un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Genetic Variation
Human genetic variation is the genetic differences in and among populations. There may be multiple variants of any given gene in the human population (alleles), a situation called polymorphism. No two humans are genetically identical. Even monozygotic twins (who develop from one zygote) have infrequent genetic differences due to mutations occurring during development and gene copy-number variation. Differences between individuals, even closely related individuals, are the key to techniques such as genetic fingerprinting. As of 2017, there are a total of 324 million known variants from sequenced human genomes. As of 2015, the typical difference between an individual's genome and the reference genome was estimated at 20 million base pairs (or 0.6% of the total of 3.2 billion base pairs). Comparatively speaking, humans are a genetically homogenous species. Although a small number of genetic variants are found more frequently in certain geographic regions or in people with ance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree Of Consanguinity
Consanguinity ("blood relation", from Latin '' consanguinitas'') is the characteristic of having a kinship with another person (being descended from a common ancestor). Many jurisdictions have laws prohibiting people who are related by blood from marrying or having sexual relations with each other. The degree of consanguinity that gives rise to this prohibition varies from place to place. Such rules are also used to determine heirs of an estate according to statutes that govern intestate succession, which also vary from jurisdiction to jurisdiction. In some places and time periods, cousin marriage is allowed or even encouraged; in others, it is taboo, and considered to be incest. The degree of relative consanguinity can be illustrated with a ''consanguinity table'' in which each level of lineal consanguinity (''generation'' or ''meiosis'') appears as a row, and individuals with a collaterally consanguineous relationship share the same row. The Knot System is a numerical notatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coefficient Of Relationship
The coefficient of relationship is a measure of the degree of consanguinity (or biological relationship) between two individuals. The term coefficient of relationship was defined by Sewall Wright in 1922, and was derived from his definition of the coefficient of inbreeding of 1921. The measure is most commonly used in genetics and genealogy. A coefficient of inbreeding can be calculated for an individual, and is typically one-half the coefficient of relationship between the parents. In general, the higher the level of inbreeding the closer the coefficient of relationship between the parents approaches a value of 1, expressed as a percentage, and approaches a value of 0 for individuals with arbitrarily remote common ancestors. Coefficient of relationship The coefficient of relationship ( r ) between two individuals B and C is obtained by a summation of coefficients calculated for every line by which they are connected to their identical ancestors point, common ancestors. Each su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PHYLIP
PHYLogeny Inference Package (PHYLIP) is a free computational phylogenetics package of programs for inferring evolutionary trees (phylogenies). It consists of 65 portable programs, i.e., the source code is written in the programming language C. As of version 3.696, it is licensed as open-source software; versions 3.695 and older were proprietary software freeware. Releases occur as source code, and as precompiled executables for many operating systems including Windows (95, 98, ME, NT, 2000, XP, Vista), Mac OS 8, Mac OS 9, OS X, Linux ( Debian, Red Hat); and FreeBSD from FreeBSD.org. Full documentation is written for all the programs in the package and is included therein. The programs in the phylip package were written by Professor Joseph Felsenstein, of the Department of Genome Sciences and the Department of Biology, University of Washington, Seattle. Methods (implemented by each program) that are available in the package include parsimony, distance matrix, and likelihood met ... [...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] |
Genetic Similarities Between 51 Worldwide Human Populations (Euclidean Genetic Distance Using 289,160 SNPs)
Genetic may refer to: *Genetics, in biology, the science of genes, heredity, and the variation of organisms **Genetic, used as an adjective, refers to genes ***Genetic disorder, any disorder caused by a genetic mutation, whether inherited or de novo ***Genetic mutation, a change in a gene ****Heredity, genes and their mutations being passed from parents to offspring **Genetic recombination, refers to the recombining of alleles resulting in a new molecule of DNA * Genetic relationship (linguistics), in linguistics, a relationship between two languages with a common ancestor language *Genetic algorithm In computer science and operations research, a genetic algorithm (GA) is a metaheuristic inspired by the process of natural selection that belongs to the larger class of evolutionary algorithms (EA). Genetic algorithms are commonly used to gene ..., in computer science, a kind of search technique modeled on evolutionary biology See also * Genetic memory (other) {{disa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malecot's Method Of Coancestry
Malecot's coancestry coefficient, f, refers to an indirect measure of genetic similarity of two individuals which was initially devised by the French mathematician Gustave Malécot. f is defined as the probability that any two alleles, sampled at random (one from each individual), are identical copies of an ancestral allele. In species with well-known lineages (such as domesticated crops), f can be calculated by examining detailed pedigree records. Modernly, f can be estimated using genetic marker data. Evolution of inbreeding coefficient in finite size populations In a finite size population, after some generations, all individuals will have a common ancestor : f \rightarrow 1 . Consider a non-sexual population of fixed size N, and call f_i the inbreeding coefficient of generation i. Here, f means the probability that two individuals picked at random will have a common ancestor. At each generation, each individual produces a large number k \gg 1 of descendants, from the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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