|
Reinforcement (speciation)
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 ... [...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 speciation, allopatric, peripatric speciation, peripatric, parapatric speciation, parapatric, and sympatric speciation, sympatric. 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 chromosome number; the result is progeny wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate
Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebrata with some 65,000 species, by far the largest ranked grouping in the phylum Chordata. The vertebrates include mammals, birds, amphibians, and various classes of fish and reptiles. The fish include the jawless Agnatha, and the jawed Gnathostomata. The jawed fish include both the Chondrichthyes, cartilaginous fish and the Osteichthyes, bony fish. Bony fish include the Sarcopterygii, lobe-finned fish, which gave rise to the tetrapods, the animals with four limbs. Despite their success, vertebrates still only make up less than five percent of all described animal species. The first vertebrates appeared in the Cambrian explosion some 518 million years ago. Jawed vertebrates evolved in the Ordovician, followed by bony fishes in the Devonian. T ... [...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 reco ... [...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 *'' Being Maria'', 2024 French film released as ''Maria'' in France * ''Maria'' (2024 film), American film * ''Maria'' (Sinhala film), Sri Lankan upcoming film Literature * ''María'' (novel), an 1867 novel by Jorge Isaacs * ''M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mohamed Noor
Mohamed Noor is the Executive Vice Provost and a Professor in the Biology Department at Duke University (formerly holding the rotating titles of Earl D. McLean Professor, department chair, dean of natural sciences, Interim Dean of Arts & Sciences, and Interim Vice Provost for Academic Affairs). 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 ... [...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 inheritance, 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 Oxford University Press#Clarendon Press, The Clarendon Press, it is one of the most important books of the Modern synthesis (20th century), modern synthesis, and helped define population genetics. It had been described by James F. Crow, J. F. Crow as the "deepest book on evolution since Darwin". It is commonly cited in biology books, outlining many concepts that are still considered important such as Fisherian runaway, Fisher's principle, Reproductive value (population genetics), reproductive value, ... [...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, Fisher was the one to most comprehensively combine the ideas of Gregor Mendel and Charles Darwin, as 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 (20th century), modern synthesis. For his contributions to biology, Richard Dawkins declared Fisher to be the greatest of Darwin's successors. He is also considered one of the founding fathers of Neo-Darwinism. According to statistician Jeffrey T. Leek, Fisher is the most in ... [...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, Ronald Fisher and J. B. S. Haldane proposed the concept of kin selection, a form of biological 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 s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jerry Coyne
Jerry Allen Coyne (born December 30, 1949) is an American biologist and skeptic known for his work on speciation and his commentary on intelligent design. A professor emeritus at the University of Chicago in the Department of Ecology and Evolution, he has published numerous papers on the theory of evolution. His concentration is speciation and ecological and evolutionary genetics, particularly as they involve the fruit fly, '' Drosophila''. In 2023 he became a fellow with the Committee for Skeptical Inquiry. He is the author of the text ''Speciation'' and the bestselling non-fiction book '' Why Evolution Is True''. Coyne maintains a website and writes for his blog, also called ''Why Evolution Is True''. He is a hard determinist. Coyne gained attention outside of the scientific community as a public critic of religion. As a proponent of New Atheism, he is often cited with atheists such as Richard Dawkins and Sam Harris. He is the author of the book '' Faith Versus Fact''. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodiversity
Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distributed evenly on Earth. It is 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 one-fifth of Earth's terrestrial area and contain about 50% of the world's species. There are latitudinal gradients in species diversity for both marine and terrestrial taxa. Since Abiogenesis, life began on Earth, six major mass extinctions and several minor events have led to large and sudden drops in biodiversity. The Phanerozoic aeon (the last 540 million years) marked a rapid growth in biodiversity via the Cambrian explosion. In this period, the majority of Multicellular organism, multicellular Phylum, phyla first appeared. The next 400 mil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitat
In ecology, habitat refers to the array of resources, 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 Biophysical environment, 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 Luminous intensity, light intensity. Biotic index, Biotic factors include the availability of food and the presence or absence of Predation, predators. Every species has particular habitat requirements, habitat generalist species are able to thrive in a wide array of environmental conditions while habitat specialist species require a very limited set of factors to survive. The habitat of a species is not necessarily found in a ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
