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Meiotic Drive
Meiotic drive is a type of intragenomic conflict, whereby one or more loci within a genome will effect a manipulation of the meiotic process in such a way as to favor the transmission of one or more alleles over another, regardless of its phenotypic expression. More simply, meiotic drive is when one copy of a gene is passed on to offspring more than the expected 50% of the time. According to Buckler et al., "Meiotic drive is the subversion of meiosis so that particular genes are preferentially transmitted to the progeny. Meiotic drive generally causes the preferential segregation of small regions of the genome". Meiotic drive in plants The first report of meiotic drive came from Marcus Rhoades who in 1942 observed a violation of mendelian segregation ratios for the R locus - a gene controlling the production of the purple pigment anthocyanin in maize kernels - in a maize line carrying abnormal chromosome 10. This violation of mendelian segregation was later shown to be the result ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intragenomic Conflict
Intragenomic conflict refers to the evolutionary phenomenon where genes have phenotypic effects that promote their own transmission in detriment of the transmission of other genes that reside in the same genome. The selfish gene theory postulates that natural selection will increase the frequency of those genes whose phenotypic effects cause their transmission to new organisms, and most genes achieve this by cooperating with other genes in the same genome to build an organism capable of reproducing and/or helping kin to reproduce. The assumption of the prevalence of intragenomic cooperation underlies the organism-centered concept of inclusive fitness. However, conflict among genes in the same genome may arise both in events related to reproduction (a selfish gene may "cheat" and increase its own presence in gametes or offspring above the expected according to fair Mendelian segregation and fair gametogenesis) and altruism (genes in the same genome may disagree on how to value ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R2d2 (mouse Gene)
R2d2 is a mouse gene that is sometimes a selfish gene. R2d2 is short for "Responder to meiotic drive 2", It was discovered by UNC School of Medicine researchers to display transmission bias. R2d2 is a stretch of DNA on mouse chromosome 2 that contains multiple copies of the Cwc22 gene. When seven or more copies of that latter gene are present, ''R2d2'' becomes selfish. In one lab breeding population, in a selective sweep, ''R2d2'' increased from being in 50 percent of the lab mice's chromosomes to 85 percent in 10 generations. By 15 generations, it reached fixation. In female mice, ''R2d2'' somehow displaces the chromosome that doesn’t contain it and it is preferentially incorporated into eggs. It has spread in the wild to several parts of the world. See also *gene drive *Homing endonuclease gene The homing endonucleases are a collection of endonucleases encoded either as freestanding genes within introns, as fusions with host proteins, or as self-splicing inteins. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Testacea
''Drosophila testacea'' is a member of the ''testacea'' species group of ''Drosophila''. Testacea species are specialist fruit flies that breed on the fruiting bodies of mushrooms. ''Drosophila testacea'' can be found in temperate regions of Europe, extending to east Asia. ''Drosophila testacea'' and '' Drosophila orientacea'' can produce viable hybrids, though they are separated by geography and behavioural barriers. ''Drosophila testacea'' females will also readily mate with ''Drosophila neotestacea'' males, but viable hybrids are never produced. This hybrid inviability (see Haldane's rule)) may be due to selfish X chromosomes and co-evolved suppressors. Alternately, differences in sex pheromone (e.g. vaccenyl acetate) reception could underlie female readiness and male willingness to copulate. The antimicrobial peptide gene '' Diptericin B'' has been pseudogenized in ''D. testacea'' and likely its sister species ''D. neotestacea''. See also * Drosophila testacea species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Quinaria
''Drosophila quinaria'' is a species of fruit fly in the ''Drosophila quinaria'' species group. Most Quinaria group species feed largely on mushrooms. However ''D. quinaria'' instead eats decaying vegetative matter, a trait it evolved independently. References Further reading * quinaria A quinaria (plural: quinariae) is a Roman unit of area, roughly equal to . Its primary use was to measure the cross-sectional area of pipes in Roman water distribution systems. A "one quinaria" pipe is in diameter. In Roman times, there was c ... Articles created by Qbugbot Insects described in 1866 {{drosophilidae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Paramelanica
''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae, a related family, which are also called fruit flies (sometimes referred to as "true fruit flies"); tephritids feed primarily on unripe or ripe fruit, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly. One species of ''Drosophila'' in particular, ''D. melanogaster'', has been heavily used in research in genetics and is a common model organism in developmental biology. The terms "fruit fly" and "''Drosophila''" are often used synonymously with ''D. melanogaster'' in modern biological literature. The entire genus, however, contains more than 1,500 species and is very diverse in appearance, beha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Mediopunctata
''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae, a related family, which are also called fruit flies (sometimes referred to as "true fruit flies"); tephritids feed primarily on unripe or ripe fruit, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly. One species of ''Drosophila'' in particular, ''D. melanogaster'', has been heavily used in research in genetics and is a common model organism in developmental biology. The terms "fruit fly" and "''Drosophila''" are often used synonymously with ''D. melanogaster'' in modern biological literature. The entire genus, however, contains more than 1,500 species and is very diverse in appearance, beha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Simulans
''Drosophila simulans'' is a species of fly closely related to ''D. melanogaster'', belonging to the same ''melanogaster'' species subgroup. Its closest relatives are ''D. mauritiana'' and ''D. sechellia''. Taxonomy This species was discovered by the fly geneticist Alfred Sturtevant in 1919, when he noticed that the flies used in Thomas Hunt Morgan's laboratory at the Columbia University were actually two distinct species: ''D. melanogaster'' and ''D. simulans''. Males differ in the external genitalia, while trained observers can separate females using colour characteristics. ''D. melanogaster'' females crossed to ''D. simulans'' males produce sterile F1 females and no F1 males. The reciprocal cross produces sterile F1 males and no female progeny. ''Drosophila simulans'' was found later to be closely related to two island endemics, ''D. sechellia'' and ''D. mauritiana''. ''D. simulans'' will mate with these sister species to form fertile females and sterile males, a fact that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Dependent Selection
Frequency-dependent selection is an evolutionary process by which the fitness of a phenotype or genotype depends on the phenotype or genotype composition of a given population. * In positive frequency-dependent selection, the fitness of a phenotype or genotype increases as it becomes more common. * In negative frequency-dependent selection, the fitness of a phenotype or genotype decreases as it becomes more common. This is an example of balancing selection. * More generally, frequency-dependent selection includes when biological interactions make an individual's fitness depend on the frequencies of other phenotypes or genotypes in the population. Frequency-dependent selection is usually the result of interactions between species (predation, parasitism, or competition), or between genotypes within species (usually competitive or symbiotic), and has been especially frequently discussed with relation to anti-predator adaptations. Frequency-dependent selection can lead to polymorphic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locus (genetics)
In genetics, a locus (plural loci) is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of protein-coding genes in a complete haploid set of 23 chromosomes is estimated at 19,000–20,000. Genes may possess multiple variants known as alleles, and an allele may also be said to reside at a particular locus. Diploid and polyploid cells whose chromosomes have the same allele at a given locus are called homozygous with respect to that locus, while those that have different alleles at a given locus are called heterozygous. The ordered list of loci known for a particular genome is called a gene map. Gene mapping is the process of determining the specific locus or loci responsible for producing a particular phenotype or biological trait. Association mapping, also known as "linkage disequilibrium mapping", is a method of ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
