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Wallace Effect
Reinforcement is a process of speciation where natural selection increases the reproductive isolation (further divided to pre-zygotic isolation and post-zygotic isolation) between two populations of species. This occurs as a result of selection acting against the production of hybrid individuals of low fitness. The idea was originally developed by Alfred Russel Wallace and is sometimes referred to as the Wallace effect. The modern concept of reinforcement originates from Theodosius Dobzhansky. He envisioned a species separated allopatrically, where during secondary contact the two populations mate, producing hybrids with lower fitness. Natural selection results from the hybrid's inability to produce viable offspring; thus members of one species who do not mate with members of the other have greater reproductive success. This favors the evolution of greater prezygotic isolation (differences in behavior or biology that inhibit formation of hybrid zygotes). Reinforcement is on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speciation By Reinforcement Schematic
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book '' On the Origin of Species''. He also identified sexual selection as a likely mechanism, but found it problematic. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments. Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion. Rapid sympatric speciation can take place through polyploidy, such as by doubling of chromosom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate
Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * Agnatha, jawless fish, which include hagfish and lampreys * Gnathostomata, jawed vertebrates, which include: ** Chondrichthyes, cartilaginous fish (sharks, Batoidea, rays, and Chimaeriformes, ratfish) ** Euteleostomi, bony vertebrates, which include: *** Actinopterygii, ray-fins (the majority of living Osteichthyes, bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant taxon, Extant vertebrates range in size from the frog species ''Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastrophryne
''Gastrophryne'', the narrowmouth toads (also American narrowmouth toads, North American narrow-mouthed toads), is a genus of microhylid frogs found in the Americas between Honduras and southern United States. Its name means ‘belly-toad’, referring to its large belly, from the Ancient Greek ' (, ‘belly, stomach’) and ' (, ‘toad’). ''Gastrophryne'' is closely related to '' Hypopachus''. Some species that were earlier placed in ''Gastrophryne'' were more closely related to ''Hypopachus'', rendering the genus paraphyletic. This has been rectified by moving some species (''Gastrophryne usta'' and ''Gastrophryne pictiventris'') to ''Hypopachus''. ''Gastrophryne'' frogs were the first species to be recognized to be experiencing speciation by reinforcement and lead to the coining of the term reinforcement by W. Frank Blair in 1955;Sætre, Glenn-Peter. (2012). Reinforcement. ''eLS''. a concept proposed by Theodosius Dobzhansky decades earlier. Species The currently recogn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maria R
Maria may refer to: People * Mary, mother of Jesus * Maria (given name), a popular given name in many languages Place names Extraterrestrial * 170 Maria, a Main belt S-type asteroid discovered in 1877 * Lunar maria (plural of ''mare''), large, dark basaltic plains on Earth's Moon Terrestrial * Maria, Maevatanana, Madagascar *Maria, Quebec, Canada *Maria, Siquijor, the Philippines * María, Spain, in Andalusia *Îles Maria, French Polynesia * María de Huerva, Aragon, Spain * Villa Maria (other) Arts, entertainment, and media Films * ''Maria'' (1947 film), Swedish film * ''Maria'' (1975 film), Swedish film * ''Maria'' (2003 film), Romanian film * ''Maria'' (2019 film), Filipino film * ''Maria'' (2021 film), Canadian film directed by Alec Pronovost * ''Maria'' (Sinhala film), Sri Lankan upcoming film Literature * ''María'' (novel), an 1867 novel by Jorge Isaacs * ''Maria'' (Ukrainian novel), a 1934 novel by the Ukrainian writer Ulas Samchuk * ''Maria'' (play), a 1935 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mohamed Noor
Mohamed Noor is the Interim Dean of Arts & Sciences and a Professor in the Biology Department at Duke University (formerly holding the rotating titles of Earl D. McLean Professor, department chair, and dean of natural sciences). His specialties include evolution, genetics and genomics. Noor has a BS from the College of William and Mary in 1992 and a PhD from University of Chicago (1996), together with a postdoctoral residency at Cornell University (1996–1998). He specializes in Drosophila evolution. His team's research approaches have included both classical genetic mapping, as well as analyses of whole genome sequences. Likewise, Noor was one of the first scientists to demonstrate by experiment speciation by reinforcement, that is, as a result of natural selection mating preferences diverge against deleterious hybridization and reduce gene flow between species. He is also known for developing (along with others) a model wherein regions of restricted recombination, as b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Genetical Theory Of Natural Selection
''The Genetical Theory of Natural Selection'' is a book by Ronald Fisher which combines Mendelian genetics with Charles Darwin's theory of natural selection, with Fisher being the first to argue that "Mendelism therefore validates Darwinism" and stating with regard to mutations that "The vast majority of large mutations are deleterious; small mutations are both far more frequent and more likely to be useful", thus refuting orthogenesis. First published in 1930 by The Clarendon Press, it is one of the most important books of the modern synthesis, and helped define population genetics. It is commonly cited in biology books, outlining many concepts that are still considered important such as Fisherian runaway, Fisher's principle, reproductive value, Fisher's fundamental theorem of natural selection, Fisher's geometric model, the sexy son hypothesis, mimicry and the evolution of dominance. It was dictated to his wife in the evenings as he worked at Rothamsted Research in the day ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ronald Fisher
Sir Ronald Aylmer Fisher (17 February 1890 – 29 July 1962) was a British polymath who was active as a mathematician, statistician, biologist, geneticist, and academic. For his work in statistics, he has been described as "a genius who almost single-handedly created the foundations for modern statistical science" and "the single most important figure in 20th century statistics". In genetics, his work used mathematics to combine Mendelian genetics and natural selection; this contributed to the revival of Darwinism in the early 20th-century revision of the theory of evolution known as the modern synthesis. For his contributions to biology, Fisher has been called "the greatest of Darwin’s successors". Fisher held strong views on race and eugenics, insisting on racial differences. Although he was clearly a eugenist and advocated for the legalization of voluntary sterilization of those with heritable mental disabilities, there is some debate as to whether Fisher support ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group Selection
Group selection is a proposed mechanism of evolution in which natural selection acts at the level of the group, instead of at the level of the individual or gene. Early authors such as V. C. Wynne-Edwards and Konrad Lorenz argued that the behavior of animals could affect their survival and reproduction as groups, speaking for instance of actions for the good of the species. In the 1930s, R.A. Fisher and J.B.S. Haldane proposed the concept of kin selection, a form of altruism from the gene-centered view of evolution, arguing that animals should sacrifice for their relatives, and thereby implying that they should not sacrifice for non-relatives. From the mid 1960s, evolutionary biologists such as John Maynard Smith, W. D. Hamilton, George C. Williams, and Richard Dawkins argued that natural selection acted primarily at the level of the gene. They argued on the basis of mathematical models that individuals would not altruistically sacrifice fitness for the sake of a group unles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jerry Coyne
Jerry may refer to: Animals * Jerry (Grand National winner), racehorse, winner of the 1840 Grand National * Jerry (St Leger winner), racehorse, winner of 1824 St Leger Stakes Arts, entertainment, and media * ''Jerry'' (film), a 2006 Indian film * "Jerry", a song from the album ''Young and Free'' by Rock Goddess * Tom and Jerry (other) People * Jerry (given name), including a list of people and fictional characters with the name * Harold A. Jerry, Jr. (1920–2001), New York politician * Thomas Jeremiah (d. 1775), commonly known simply as "Jerry", a free Negro in colonial South Carolina Places * Branche à Jerry, a tributary of the Baker River in Quebec and New Brunswick, Canada * Jerry, Washington, a community in the United States Other uses * Jerry (company) * Jerry (WWII), Allied nickname for Germans, originally from WWI but widely used in World War II * Jerry Rescue (1851), involving American slave William Henry, who called himself "Jerry" See also * Geri (disam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodiversity
Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') level. Biodiversity is not distributed evenly on Earth; it is usually greater in the tropics as a result of the warm climate and high primary productivity in the region near the equator. Tropical forest ecosystems cover less than 10% of earth's surface and contain about 90% of the world's species. Marine biodiversity is usually higher along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future as a primary result of deforestation. It encompasses the evolutionary, ecological, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical manifestation of its ecological niche. Thus "habitat" is a species-specific term, fundamentally different from concepts such as environment or vegetation assemblages, for which the term "habitat-type" is more appropriate. The physical factors may include (for example): soil, moisture, range of temperature, and light intensity. Biotic factors will include the availability of food and the presence or absence of predators. Every species has particular habitat requirements, with habitat generalist species able to thrive in a wide array of environmental conditions while habitat specialist species requiring a very limited set of factors to survive. The habitat of a species is not necessarily found in a geographical area, it can be the interior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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