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HKA Test
The HKA Test, named after Richard R. Hudson, Martin Kreitman, and Montserrat Aguadé, is a statistical test used in genetics to evaluate the predictions of the Neutral Theory of molecular evolution. By comparing the polymorphism within each species and the divergence observed between two species at two or more loci, the test can determine whether the observed difference is likely due to neutral evolution or rather due to adaptive evolution. Developed in 1987, the HKA test is a precursor to the McDonald-Kreitman test, which was derived in 1991. The HKA test is best used to look for balancing selection, recent selective sweeps In genetics, a selective sweep is the process through which a new beneficial mutation that increases its frequency and becomes fixed (i.e., reaches a frequency of 1) in the population leads to the reduction or elimination of genetic variation amon ... or other variation-reducing forces. Neutral Evolution Neutral Evolution Theory, first proposed by Kimura ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard R
Richard is a male given name. It originates, via Old French, from Old Frankish and is a compound of the words descending from Proto-Germanic ''*rīk-'' 'ruler, leader, king' and ''*hardu-'' 'strong, brave, hardy', and it therefore means 'strong in rule'. Nicknames include "Richie", "Dick", "Dickon", " Dickie", "Rich", "Rick", "Rico", "Ricky", and more. Richard is a common English, German and French male name. It's also used in many more languages, particularly Germanic, such as Norwegian, Danish, Swedish, Icelandic, and Dutch, as well as other languages including Irish, Scottish, Welsh and Finnish. Richard is cognate with variants of the name in other European languages, such as the Swedish "Rickard", the Catalan "Ricard" and the Italian "Riccardo", among others (see comprehensive variant list below). People named Richard Multiple people with the same name * Richard Andersen (other) * Richard Anderson (other) * Richard Cartwright (other) * Ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Martin Kreitman
Martin Edward Kreitman is an American geneticist at the University of Chicago, most well known for the McDonald–Kreitman test that is used to infer the amount of adaptive evolution in population genetic studies. Education Kreitman graduated from Stony Brook University with a Bachelor of Science degree Biology in 1975, and from the University of Florida with a Master of Science degree in Zoology, in 1977. He went on to study at Harvard University, graduating with a Ph.D. in Population Genetics, specifically Nucleotide Sequence Variation of Alcohol dehydrogenase in Drosophila melanogaster in 1983. Research The Kreitman lab does research in four main areas: Awards and honors *1991 MacArthur Fellows Program *editor-in-chief of "Journal of Molecular Evolution" from 1999 * Section head of the "Evolutionary/Comparative Genetics" part of Faculty of 1000 biology *2010 named fellow of the American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbrev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montserrat Aguadé
Montserrat Aguadé Porres (Barcelona, Spain; 1949) is a professor emeritus of genetics at University of Barcelona and member of the Institut d'Estudis Catalans. Aguadé is internationally recognized for her research in the fields of evolution and population genetics, and together with Richard R. Hudson and Martin Kreitman, she co-developed the HKA test, a statistical test used in genetics to evaluate the predictions of the neutral theory of molecular evolution. Aguadé has published around 100 scientific articles in prestigious journals in the field of experimental sciences, and she has been awarded the National Genetics Award from the Spanish Society of Genetics. Prof. Aguadé has been recognized as a distinguished researcher by the Generalitat de Catalunya and, in 2022, she was awarded the Gold Medal for Scientific Merit by the City Council of Barcelona. Aguadé has been the president of the Society for Molecular Biology and Evolution The Society for Molecula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutral Theory Of Molecular Evolution
The neutral theory of molecular evolution holds that most evolutionary changes occur at the molecular level, and most of the variation within and between species are due to random genetic drift of mutant alleles that are selectively neutral. The theory applies only for evolution at the molecular level, and is compatible with phenotypic evolution being shaped by natural selection as postulated by Charles Darwin. The neutral theory allows for the possibility that most mutations are deleterious, but holds that because these are rapidly removed by natural selection, they do not make significant contributions to variation within and between species at the molecular level. A neutral mutation is one that does not affect an organism's ability to survive and reproduce. The neutral theory assumes that most mutations that are not deleterious are neutral rather than beneficial. Because only a fraction of gametes are sampled in each generation of a species, the neutral theory suggests that a mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (biology)
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] |
Divergence (biology)
Divergent evolution or divergent selection is the accumulation of differences between closely related populations within a species, leading to speciation. Divergent evolution is typically exhibited when two populations become separated by a geographic barrier (such as in allopatric or peripatric speciation) and experience different selective pressures that drive adaptations to their new environment. After many generations and continual evolution, the populations become less able to interbreed with one another. The American naturalist J. T. Gulick (1832–1923) was the first to use the term "divergent evolution", with its use becoming widespread in modern evolutionary literature. Classic examples of divergence in nature are the adaptive radiation of the finches of the Galapagos or the coloration differences in populations of a species that live in different habitats such as with pocket mice and fence lizards. The term can also be applied in molecular evolution, such as to p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balancing Selection
Balancing selection refers to a number of selective processes by which multiple alleles (different versions of a gene) are actively maintained in the gene pool of a population at frequencies larger than expected from genetic drift alone. Balancing selection is rare compared to purifying selection. It can occur by various mechanisms, in particular, when the heterozygotes for the alleles under consideration have a higher fitness than the homozygote. In this way genetic polymorphism is conserved. Evidence for balancing selection can be found in the number of alleles in a population which are maintained above mutation rate frequencies. All modern research has shown that this significant genetic variation is ubiquitous in panmictic populations. There are several mechanisms (which are not exclusive within any given population) by which balancing selection works to maintain polymorphism. The two major and most studied are heterozygote advantage and frequency-dependent selection. Mech ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selective Sweeps
In genetics, a selective sweep is the process through which a new beneficial mutation that increases its frequency and becomes fixed (i.e., reaches a frequency of 1) in the population leads to the reduction or elimination of genetic variation among nucleotide sequences that are near the mutation. In selective sweep, positive selection causes the new mutation to reach fixation so quickly that linked alleles can "hitchhike" and also become fixed. Overview A selective sweep can occur when a rare or previously non-existing allele that increases the fitness of the carrier (relative to other members of the population) increases rapidly in frequency due to natural selection. As the prevalence of such a beneficial allele increases, genetic variants that happen to be present on the genomic background (the DNA neighborhood) of the beneficial allele will also become more prevalent. This is called ''genetic hitchhiking''. A selective sweep due to a strongly selected allele, which arose on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HKA Test Example
HKA may refer to: * HKA test, of molecular evolution * Blytheville Municipal Airport, in Arkansas, US * Henryka Beyer (1782–1855), German painter * Hong Kong Academy * Hong Kong Attitude, an esports organization * Hong Kong Airlines, founded 2006 * Hong Kong Airways, active 1947–1959 * Kahe language The Kahe are an ethnic and linguistic group based southeast of Moshi in Kilimanjaro Region Tanzania. The Kahe language, or ''Kikahe'', is in the Chagga cluster of Bantu languages The Bantu languages (English: , Proto-Bantu: *bantʊ̀) are a ... * Superior Aviation, an American airline {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Evolution
Molecular evolution is the process of change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genetics to explain patterns in these changes. Major topics in molecular evolution concern the rates and impacts of single nucleotide changes, neutral evolution vs. natural selection, origins of new genes, the genetic nature of complex traits, the genetic basis of speciation, evolution of development, and ways that evolutionary forces influence genomic and phenotypic changes. History The history of molecular evolution starts in the early 20th century with comparative biochemistry, and the use of "fingerprinting" methods such as immune assays, gel electrophoresis and paper chromatography in the 1950s to explore homologous proteins. The field of molecular evolution came into its own in the 1960s and 1970s, following the rise of molecular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
