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Glacial Relict
A glacial relict is a population of a cold-adapted species that has been left behind as the range of the species changed after an ice age ended. Glacial relicts are usually found in enclaves "under relatively benign conditions". Examples: *The biogeography of various aquatic species deemed glacial relicts that are found in Lake Sommen is likely related to a different geography during the early history of the lake. One theory claims that aquatic species were transferred from the Baltic Ice Lake through a natural lock system in connection with a temporary advance of the ice-front during the Younger Dryas. On land, the unusual occurrence of dwarf birch near Sund is also judged to be a leftover from a cold geological past. See also *Biodiversity hotspot *Last Glacial Maximum refugia *Nunatak hypothesis *Rapoport's rule *Relict (biology) In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population (biology)
Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a census, a process of collecting, analysing, compiling, and publishing data regarding a population. Perspectives of various disciplines Social sciences In sociology and population geography, population refers to a group of human beings with some predefined criterion in common, such as location, race, ethnicity, nationality, or religion. Demography is a social science which entails the statistical study of populations. Ecology In ecology, a population is a group of organisms of the same species who inhabit the same particular geographical area and are capable of interbreeding. The area of a sexual population is the area where inter-breeding is possible between any pair within the area and more probable than cross-breeding with ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Last Glacial Maximum Refugia
Last Glacial Maximum refugia were places ('' refugia'') in which humans and other species survived during the Last Glacial Period in the Northern Hemisphere, around 25,000 to 20,000 years ago. Sub-Saharan Africa and Australia were not affected by the glaciation, although vast areas of those continents were too dry for human habitation of any sort, even by the most specialised and well-adapted foragers. New Zealand had no humans at the time. Some recent archaeological evidence suggests the possibility that human arrival in the Americas may have occurred prior to the Last Glacial Maximum more than 20,000 years ago, including possibly areas adjacent to ice sheets, but research is still in an early stage. The best attested shelters are therefore mainly those in Eurasia. Several of them have been studied. Europe *Solutrean *Gravettian *Pavlovian culture *Franco-Cantabrian region *Würm glaciation North Africa * Ibero-Maurusian *Capsian culture Asia *Kebaran culture *Japan, Jōmon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Ages
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. Earth is currently in the Quaternary glaciation. Individual pulses of cold climate within an ice age are termed ''glacial periods'' (or, alternatively, ''glacials, glaciations, glacial stages, stadials, stades'', or colloquially, ''ice ages''), and intermittent warm periods within an ice age are called ''interglacials'' or ''interstadials''. In glaciology, ''ice age'' implies the presence of extensive ice sheets in both northern and southern hemispheres. By this definition, Earth is currently in an interglacial period—the Holocene. The amount of anthropogenic greenhouse gases emitted into Earth's oceans and atmosphere is predicted to prevent the next glacial period for the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biogeography
Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, isolation and habitat area.Brown University, "Biogeography." Accessed February 24, 2014. . 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 environments. Biogeography is an integrative field of inquiry that unites concepts and information from ecology, evolutionary biology, taxonomy, geology, physical geography, palaeontology, and climatology.Dansereau, Pierre. 1957 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytogeography
Phytogeography (from Greek φυτόν, ''phytón'' = "plant" and γεωγραφία, ''geographía'' = "geography" meaning also distribution) or botanical geography is the branch of biogeography that is concerned with the geographic distribution of plant species and their influence on the earth's surface. Phytogeography is concerned with all aspects of plant distribution, from the controls on the distribution of individual species ranges (at both large and small scales, see species distribution) to the factors that govern the composition of entire communities and floras. Geobotany, by contrast, focuses on the geographic space's influence on plants. Fields Phytogeography is part of a more general science known as biogeography. Phytogeographers are concerned with patterns and process in plant distribution. Most of the major questions and kinds of approaches taken to answer such questions are held in common between phyto- and zoogeographers. Phytogeography in wider sense (or geobot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relict (biology)
In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population currently inhabiting a restricted area whose range was far wider during a previous geologic epoch. Similarly, a relictual taxon is a taxon (e.g. species or other lineage) which is the sole surviving representative of a formerly diverse group. Definition A relict (or relic) plant or animal is a taxon that persists as a remnant of what was once a diverse and widespread population. Relictualism occurs when a widespread habitat or range changes and a small area becomes cut off from the whole. A subset of the population is then confined to the available hospitable area, and survives there while the broader population either shrinks or evolves divergently. This phenomenon differs from endemism in that the range of the population was not always restricted to the local region. In other words, the species or group did n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rapoport's Rule
Rapoport's rule is an ecogeographical rule that states that latitudinal ranges of plants and animals are generally smaller at lower latitudes than at higher latitudes. Background Stevens (1989) named the rule after Eduardo H. Rapoport, who had earlier provided evidence for the phenomenon for subspecies of mammals (Rapoport 1975, 1982). Stevens used the rule to "explain" greater species diversity in the tropics in the sense that latitudinal gradients in species diversity and the rule have identical exceptional data and so must have the same underlying cause. Narrower ranges in the tropics would facilitate more species to coexist. He later extended the rule to altitudinal gradients, claiming that altitudinal ranges are greatest at greater altitudes (Stevens 1992), and to depth gradients in the oceans (Stevens 1996Stevens, G. C. (1996). Extending Rapoport's rule to Pacific marine fishes. Journal of Biogeography 23:149–154.). The rule has been the focus of intense discussion and give ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nunatak Hypothesis
In biogeography, particularly phytogeography, the nunatak hypothesis about the origin of a biota in formerly glaciated areas is the idea that some or many species have survived the inhospitable period on icefree land such as nunataks. Its antithesis is the '' tabula rasa hypothesis'', which posits that all species have immigrated into completely denuded land after the retreat of glaciers. By the mid-20th Century, the nunatak hypothesis was widely accepted among biologists working on the floras of Greenland and Scandinavia. However, while modern geology has established the presence of ice-free areas during the last glacial maximum in both Greenland and Scandinavia, molecular techniques have revealed limited between-region genetic differentiation in many Arctic taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodiversity Hotspot
A biodiversity hotspot is a biogeographic region with significant levels of biodiversity that is threatened by human habitation. Norman Myers wrote about the concept in two articles in ''The Environmentalist'' in 1988 and 1990, after which the concept was revised following thorough analysis by Myers and others into “Hotspots: Earth’s Biologically Richest and Most Endangered Terrestrial Ecoregions” and a paper published in the journal ''Nature'', both in 2000. To qualify as a biodiversity hotspot on Myers' 2000 edition of the hotspot map, a region must meet two strict criteria: it must contain at least 1,500 species of vascular plants (more than 0.5% of the world's total) as endemics, and it has to have lost at least 70% of its primary vegetation. Globally, 36 zones qualify under this definition. These sites support nearly 60% of the world's plant, bird, mammal, reptile, and amphibian species, with a high share of those species as endemics. Some of these hotspots support up ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaciation
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate between glacial periods. The Last Glacial Period ended about 15,000 years ago. The Holocene is the current interglacial. A time with no glaciers on Earth is considered a greenhouse climate state. Quaternary Period Within the Quaternary, which started about 2.6 million years before present, there have been a number of glacials and interglacials. At least eight glacial cycles have occurred in the last 740,000 years alone. Penultimate Glacial Period The Penultimate Glacial Period (PGP) is the glacial period that occurred before the Last Glacial Period. It began about 194,000 years ago and ended 135,000 years ago, with the beginning of the Eemian interglacial. Last Glacial Period The last glacial period was the most recent glacial period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sund, Ydre
Sund is a hamlet in Ydre Municipality in the South Swedish highlands. According to Svenskt ortnamnslexikon the name of the locality means "narrow" referring to its position at the bottleneck position between Norra Sundsjön and Södra Sundsjön. According to Leonhard Fredrik Rääf Leonhard Fredrik Rääf (1786 – 1872) also known as Ydredrotten was a Swedish folklorist, local historian and conservative politician from Ydre. During a time Rääf had a literary salon in Tomestorp which was frequented by among others Per Dani ... the church in Sund was built in the 12th century. This church is described by Rääf as having stone arches, however it burned down in arson in 1631 and was rebuilt shortly afterward. References Villages in Sweden Populated lakeshore places in Sweden Populated places in Ydre Municipality {{Östergötland-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Betula Nana
''Betula nana'', the dwarf birch, is a species of birch in the family Betulaceae, found mainly in the tundra of the Arctic region. Description It is a monoecious, deciduous shrub growing up to high. The bark is non-peeling and shiny red-copper colored. The leaves are rounded, diameter, with a bluntly toothed margin. The leaves are a darker green on their upper surface. Leaf growth occurs after snow melt and become red in autumn. The wind-pollinated fruiting catkins are erect, long and broad. Distribution ''Betula nana'' is native to arctic and cool temperate regions of Greenland, Iceland, northern Europe, northern Asia and northern North America and it will grow in a variety of conditions. Outside of far northern areas, it is usually found growing only in mountains above , up to in Great Britain and in the Alps. Its northern range limit is on Svalbard, where it is confined to favourable sites. In the UK ''Betula nana'' is at its southern range limit, with many populations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
