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Evolutionary Arms Race
In evolutionary biology, an evolutionary arms race is an ongoing struggle between competing sets of co-evolving genes, phenotypic and behavioral traits that develop escalating adaptations and counter-adaptations against each other, resembling an arms race. These are often described as examples of positive feedback.Dawkins, R. 1996. '' The Blind Watchmaker'' New York: W. W. Norton. Note: This book was also published by Penguin in 1991. While the text is identical, page numbers differ The co-evolving gene sets may be in different species, as in an evolutionary arms race between a predator species and its prey (Vermeij, 1987), or a parasite and its host. Alternatively, the arms race may be between members of the same species, as in the manipulation/sales resistance model of communication (Dawkins & Krebs, 1979) or as in runaway evolution or Red Queen effects. One example of an evolutionary arms race is in sexual conflict between the sexes, often described with the term Fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolutionary Biology
Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life forms on Earth. Evolution is based on the theory that all species are related and they gradually change over time. In a population, the genetic variations affect the physical characteristics i.e. phenotypes of an organism. These changes in the phenotypes will be an advantage to some organisms, which will then be passed onto their offspring. Some examples of evolution in species over many generations are the Peppered Moth and Flightless birds. In the 1930s, the discipline of evolutionary biology emerged through what Julian Huxley called the modern synthesis of understanding, from previously unrelated fields of biological research, such as genetics and ecology, systematics, and paleontology. The importance of studying Evolutionary biology is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fisherian Runaway
Fisherian runaway or runaway selection is a sexual selection mechanism proposed by the mathematical biologist Ronald Fisher in the early 20th century, to account for the evolution of ostentatious male ornamentation by persistent, directional female choice. An example is the colourful and elaborate peacock plumage compared to the relatively subdued peahen plumage; the costly ornaments, notably the bird's extremely long tail, appear to be incompatible with natural selection. Fisherian runaway can be postulated to include sexually dimorphic phenotypic traits such as behavior expressed by a particular sex. Extreme and (seemingly) maladaptive sexual dimorphism represented a paradox for evolutionary biologists from Charles Darwin's time up to the modern synthesis. Darwin attempted to resolve the paradox by assuming heredity for both the preference and the ornament, and supposed an "aesthetic sense" in higher animals, leading to powerful selection of both characteristics in subsequent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene-for-gene Relationship
The gene-for-gene relationship was discovered by Harold Henry Flor who was working with rust (''Melampsora lini'') of flax (''Linum usitatissimum''). Flor showed that the inheritance of both resistance in the host and parasite ability to cause disease is controlled by pairs of matching genes. One is a plant gene called the resistance (''R'') gene. The other is a parasite gene called the avirulence (''Avr'') gene. Plants producing a specific R gene product are resistant towards a pathogen that produces the corresponding ''Avr'' gene product. Gene-for-gene relationships are a widespread and very important aspect of plant disease resistance. Another example can be seen with ''Lactuca serriola'' versus '' Bremia lactucae''. Clayton Oscar Person was the first scientist to study plant pathosystem ratios rather than genetics ratios in host-parasite systems. In doing so, he discovered the differential interaction that is common to all gene-for-gene relationships and that is now known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
R Gene
Resistance genes (R-Genes) are genes in plant genomes that convey plant disease resistance against pathogens by producing R proteins. The main class of R-genes consist of a nucleotide binding domain (NB) and a leucine rich repeat (LRR) domain(s) and are often referred to as (NB-LRR) R-genes or NLRs. Generally, the NB domain binds either ATP/ADP or GTP/GDP. The LRR domain is often involved in protein-protein interactions as well as ligand binding. NB-LRR R-genes can be further subdivided into toll interleukin 1 receptor (TIR-NB-LRR) and coiled-coil (CC-NB-LRR). Resistance can be conveyed through a number of mechanisms including: * The R protein interacts directly with an Avr geneAvirulence gene product of a pathogen (see Gene-for-Gene relationship). * The R protein guards another protein that detects degradation by an Avr gene (see Guard Hypothesis). * The R protein may detect a Pathogen-Associated Molecular Pattern or PAMP (alternatively called MAMP for microbe-as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or more distinct types of flagella - tinsel or "decorated", and whiplash, in various combinations. *Tinsellated (straminipilous) flagella have lateral filaments known as mastigonemes perpendicular to their main axis, which allow for more surface area, and disturbance of the medium, giving them the property of a rudder, that is, used for steering. *Whiplash flagella are straight, to power the zoospore through its medium. Also, the "default" zoospore only has the propelling, whiplash flagella. Both tinsel and whiplash flagella beat in a sinusoidal wave pattern, but when both are present, the tinsel beats in the opposite direction of the whiplash, to give two axes of control of motility. Morphological types In eukaryotes, the four main types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bintje
Bintje is a middle-early ripening potato variety bred in the Netherlands by the Frisian schoolmaster K.L. de Vries in 1904 from (Munstersen x Fransen) and marketed for the first time in 1910. The name of the potato, a diminutive of Benedict, was borrowed from one of his former students. Bintje plants are medium-sized and erect, with purplish stems, dark green leaves and white flowers. Bintje produces large oval-shaped tubers with pale yellow skin and yellow flesh. It has shallow eyes. The sprouts are purplish. This high-yielding variety is widely grown in Europe and North Africa. It is used for boiling, baking, and for fries, mashed potato and potato chips. It is the most widely cultivated potato in France and Belgium. Bintje is immune to Potato virus A. It has moderate resistance to Potato leafroll virus. It is susceptible to netted scab, common scab, Fusarium dry rot (''Fusarium oxysporum''), potato wart (''Synchytrium endobioticum''), Potato virus X, Potato virus Y, and la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plants Certifiés Bintje
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria). By one definition, plants form the clade Viridiplantae (Latin name for "green plants") which is sister of the Glaucophyta, and consists of the green algae and Embryophyta (land plants). The latter includes the flowering plants, conifers and other gymnosperms, ferns and their allies, hornworts, liverworts, and mosses. Most plants are multicellular organisms. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria. Their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the ability ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leigh Van Valen
Leigh Van Valen (August 12, 1935 – October 16, 2010) was a U.S. evolutionary biologist. At the time of his death, he was professor emeritus in the Department of Ecology and Evolution at the University of Chicago. Research and interests Amongst other work, Van Valen's proposed "Law of Extinction", known as Van Valen's law, drew upon the apparent constant probability (as opposed to rate) of extinction in families of related organisms, based on data compiled from existing literature on the duration of tens of thousands of genera throughout the fossil record. Van Valen proposed the Red Queen Hypothesis (1973), as an explanatory tangent to the Law of Extinction. The Red Queen Hypothesis captures the idea that there is a constant 'arms race' between co-evolving species. Its name is a reference to the Red Queen's race in Lewis Carroll's ''Through the Looking-Glass'', in which the chess board moves such that Alice must continue running just to stay in the same place. Van Valen also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Queen's Hypothesis
The Red Queen hypothesis is a hypothesis in evolutionary biology proposed in 1973, that species must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species. The hypothesis was intended to explain the constant (age-independent) extinction probability as observed in the paleontological record caused by co-evolution between competing species; however, it has also been suggested that the Red Queen hypothesis explains the advantage of sexual reproduction (as opposed to asexual reproduction) at the level of individuals,Bell, G. (1982). The Masterpiece Of Nature: The Evolution and Genetics of Sexuality. University of California Press, Berkeley, 378 pp. and the positive correlation between speciation and extinction rates in most higher taxa. Origin In 1973, Leigh Van Valen proposed the hypothesis as an "explanatory tangent" to explain the "law of extinction" known as "Van Valen's law", which states that the probability of exti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antagonistic Coevolution
Sexual antagonistic co-evolution is the relationship between males and females where sexual morphology changes over time to counteract the opposite's sex traits to achieve the maximum reproductive success. This has been compared to an arms race between sexes. In many cases, male mating behavior is detrimental to the female's fitness. For example, when insects reproduce by means of traumatic insemination, it is very disadvantageous to the female's health. During mating, males will try to inseminate as many females as possible, however, the more times a female's abdomen is punctured, the less likely she is to survive. Females that possess traits to avoid multiple matings will be more likely to survive, resulting in a change in morphology. In males, genitalia is relatively simple and more likely to vary among generations compared to female genitalia. This results in a new trait that females have to avoid in order to survive. Additionally, sexual antagonistic co-evolution can be the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
