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Relict
A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a relict is a structure or mineral from a parent rock that did not undergo metamorphosis when the surrounding rock did, or a rock that survived a destructive geologic process. In geomorphology, a relict landform is a landform formed by either erosive or constructive surficial processes that are no longer active as they were in the past. A glacial relict is a cold-adapted organism that is a remnant of a larger distribution that existed in the ice ages. Human populations As revealed by DNA testing, a relict population is an ancient people in an area, who have been largely supplanted by a later group of migrants and their descendants. In various places around the world, minority ethnic groups represent lineages of ancient human migrations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Living Fossil
A living fossil is a Deprecation, deprecated term for an extant taxon that phenotypically resembles related species known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant clade. Living fossils commonly are of species-poor lineages, but they need not be. While the body plan of a living fossil remains superficially similar, it is never the same species as the remote relatives it resembles, because genetic drift would inevitably change its chromosomal structure. Living fossils exhibit punctuated equilibrium, stasis (also called "bradytely") over geologically long time scales. Popular literature may wrongly claim that a "living fossil" has undergone no significant evolution since fossil times, with practically no molecular evolution or Morphology (biology), morphological changes. Scientific investigations have repeatedly discredited such claims. The minimal superficial changes to living foss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endemism
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be ''endemic'' to that particular part of the world. An endemic species can also be referred to as an ''endemism'' or, in scientific literature, as an ''endemite''. Similarly, many species found in the Western ghats of India are examples of endemism. Endemism is an important concept in conservation biology for measuring biodiversity in a particular place and evaluating the risk of extinction for species. Endemism is also of interest in evolutionary biology, because it provides clues about how changes in the environment cause species to undergo range shifts (potentially expanding their range into a larger area or b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Relict
A glacial relict is a population of a species that was common in the Northern Hemisphere prior to the onset of glaciation in the late Tertiary that was forced by climate change to retreat into refugia when continental ice sheets advanced. They are typically cold-adapted species with a distribution restricted to regions and microhabitats that allow them to survive despite climatic changes. Examples There are a wide variety of plant species which fit the category of glacial relict. The ones given here are a small selection of the much larger group. * A tall deciduous tree genus, ''Liriodendron'', was widespread across temperate regions of the Northern Hemisphere until the onset of continental glaciations. The genus took refuge in southeast Asia and southeast North America, expanding to occupy today's temperate habitats. The east-west orientation of mountains in Europe is thought to be the geographic barrier that prevented the genus from migrating far enough southward to avoid exti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Widow
A widow (female) or widower (male) is a person whose spouse has Death, died and has usually not remarried. The male form, "widower", is first attested in the 14th century, by the 19th century supplanting "widow" with reference to men. The adjective for either sex is ''widowed''. These terms are not applied to a Divorce, divorcé(e) following the death of an ex-spouse. The state of having lost one's spouse to death is termed ''widowhood''. The term ''widowhood'' can be used for either sex, at least according to some dictionaries, but the word ''widowerhood'' is also listed in some dictionaries. An archaic term for a widow is "relict", literally "someone left over"; this word can sometimes be found on older gravestones. Occasionally, the word ''viduity'' is used. Effects on health The increased mortality rate after the death of a spouse is called the ''widowhood effect''. It is "strongest during the first three months after a spouse's death, when they had a 66-percent increase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relic
In religion, a relic is an object or article of religious significance from the past. It usually consists of the physical remains or personal effects of a saint or other person preserved for the purpose of veneration as a tangible memorial. Relics are an important aspect of some forms of Buddhism, Christianity, Islam, shamanism, and many other religions. ''Relic'' derives from the Latin ''reliquiae'', meaning "remains", and a form of the Latin verb ''relinquere'', to "leave behind, or abandon". A reliquary is a shrine that houses one or more religious relics. In classical antiquity In ancient Greece, a polis, city or Greek temple, sanctuary might claim to possess, without necessarily displaying, the remains of a venerated hero as a part of a Greek hero cult, hero cult. Other venerable objects associated with the hero were more likely to be on display in sanctuaries, such as spears, shields, or other weaponry; chariots, ships or Figurehead (object), figureheads; furniture such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agronomy
Agronomy is the science and technology of producing and using plants by agriculture for food, fuel, fiber, chemicals, recreation, or land conservation. Agronomy has come to include research of plant genetics, plant physiology, meteorology, and soil science. It is the application of a combination of sciences such as biology, chemistry, economics, ecology, earth science, and genetics. Professionals of agronomy are termed agronomists. Plant breeding This topic of agronomy involves selective breeding of plants to produce the best crops for various conditions. Plant breeding has increased crop yields and has improved the nutritional value of numerous crops, including corn, soybeans, and wheat. It has also resulted in the development of new types of plants. For example, a hybrid grain named triticale was produced by crossbreeding rye and wheat. Triticale contains more usable protein than does either rye or wheat. Agronomy has also been instrumental for fruit and vegetable pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Terminology
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences, including hydrology. It is integrated with Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface and the processes that have shaped that structure. Geologists study the mineralogical composition of rocks in order to get insight into their history of formation. Geology determines the relative ages of rocks found at a given location; geochemistry (a branch of geology) determines their absolute ages. By combining various petrological, crystallographic, and paleontological tools, geologists are able to chronicle the geological history of the Earth as a whole. One aspect is to demonstrate the age of the Earth. Geology provides evidence for plate tectonics, the evolutio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biogeography
Biogeography is the study of the species distribution, distribution of species and ecosystems in geography, geographic space and through evolutionary history of life, geological time. Organisms and biological community (ecology), communities often vary in a regular fashion along geographic gradients of latitude, elevation, allopatric speciation, isolation and habitat species-area curve, area. Phytogeography is the branch of biogeography that studies the distribution of plants. Zoogeography is the branch that studies distribution of animals. Mycogeography is the branch that studies distribution of fungi, such as mushrooms. Knowledge of spatial variation in the numbers and types of organisms is as vital to us today as it was to our early human ancestors, as we adapt to heterogeneous but geographically predictable Natural environment, environments. Biogeography is an integrative field of inquiry that unites concepts and information from ecology, evolutionary biology, taxonomy (bio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeochannel
In the Earth sciences, a palaeochannel, also spelled paleochannel, is a significant length of a river or stream channel which no longer conveys fluvial discharge as part of an active fluvial system. The term ''palaeochannel'' is derived from the combination of two words, ''palaeo'' or ''old'', and '' channel''; i.e., a palaeochannel is an old channel. Palaeochannels may be preserved either as abandoned surface channels on the surface of river floodplains and terraces or infilled and partially or fully buried by younger sediments. The fill of a palaeochannel and its enclosing sedimentary deposits may consist of unconsolidated, semi-consolidated, or well-cemented sedimentary strata depending on the action of tectonics and diagenesis during their geologic history after deposition. The abandonment of an active fluvial channel and the resulting formation of a palaeochannel can be the result of tectonic processes, geomorphologic processes, anthropogenic activities, climatic changes, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refugium (population Biology)
In biology, a refugium (plural: ''refugia'') is a location which supports an isolated or relict population of a once more widespread species. This isolation ( allopatry) can be due to climatic changes, geography, or human activities such as deforestation and overhunting. Present examples of refugial animal species are the mountain gorilla, isolated to specific mountains in central Africa, and the Australian sea lion, isolated to specific breeding beaches along the south-west coast of Australia, due to humans taking so many of their number as game. This resulting isolation, in many cases, can be seen as only a temporary state; however, some refugia may be longstanding, thereby having many endemic species, not found elsewhere, which survive as relict populations. The Indo-Pacific Warm Pool has been proposed to be a longstanding refugium, based on the discovery of the "living fossil" of a marine dinoflagellate called '' Dapsilidinium pastielsii'', currently found only in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hysteresis
Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of the moment often form a loop or hysteresis curve, where there are different values of one variable depending on the direction of change of another variable. This history dependence is the basis of memory in a hard disk drive and the remanence that retains a record of the Earth's magnetic field magnitude in the past. Hysteresis occurs in ferromagnetic and ferroelectricity, ferroelectric materials, as well as in the deformation (mechanics), deformation of rubber bands and shape-memory alloys and many other natural phenomena. In natural systems, it is often associated with irreversible process, irreversible thermodynamic change such as phase transitions and with internal friction; and dissipation is a common side effect. Hysteresis can be fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Historical Linguistics
Historical linguistics, also known as diachronic linguistics, is the scientific study of how languages change over time. It seeks to understand the nature and causes of linguistic change and to trace the evolution of languages. Historical linguistics involves several key areas of study, including the reconstruction of ancestral languages, the classification of languages into families, ( comparative linguistics) and the analysis of the cultural and social influences on language development. This field is grounded in the uniformitarian principle, which posits that the processes of language change observed today were also at work in the past, unless there is clear evidence to suggest otherwise. Historical linguists aim to describe and explain changes in individual languages, explore the history of speech communities, and study the origins and meanings of words ( etymology). Development Modern historical linguistics dates to the late 18th century, having originally grown o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
