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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] |
Franklinia Alatamaha
''Franklinia'' is a monotypic genus in the tea family, Theaceae. The sole species in this genus is a flowering tree, ''Franklinia alatamaha'', commonly called Franklinias or the Franklin tree, and native to the Altamaha River valley in Georgia in the southeastern United States. It has been extinct in the wild since the early 19th century, but survives as a cultivated ornamental tree. In the past, some botanists have included ''Franklinia'' within the related genus '' Gordonia''. The southeastern North American species '' Gordonia lasianthus'' differs in having evergreen foliage, flowers with longer stems, winged seeds, and conical seed capsules. ''Franklinia'' was often known as ''Gordonia pubescens'' until the middle of the 20th century. Description ''Franklinia alatamaha'' is a small deciduous tree or large shrub growing tall, but commonly . The tree has a symmetrical, somewhat rounded shape. It frequently suckers and can have one to five trunks. The bark is gray with vertic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sund, Ydre
Sund is a hamlet in Ydre Municipality Ydre Municipality () is a municipality in Östergötland County, southeast Sweden. The municipal seat is located in the town of Österbymo. The municipality was created through the local government reform of 1952, when six former entities were u ... 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 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 Populated lakeshore places in Sweden Populated places in Ydre Municipality {{Östergötland-geo-stub ... [...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 ... [...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 mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...s (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 a ... [...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''; : 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 kno ... [...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, around 25,000 to 18,000 years ago. Glacial refugia are areas that climate changes were not as severe, and where species could recolonize after deglaciation. Globally, the temperatures during the Last Glacial Maximum (LGM) were 4.0 ± 0.8 °C cooler than present day. The colder climate contributed to ice sheet growth in North America, Europe, and Antarctica. At this time there were further major climate shifts around the world. Some areas became too dry to support much life; others housed more vegetation and animals. The northern hemisphere was heavily impacted by ice sheets during the LGM. Some recent archaeological evidence suggests the possibility that human arrival in the Americas may have occurred prior to the Last Glacial Maximum more than 30,000 years ago. This evidence was found adjacent to ice sheets, but research is still in an early s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Island
An ecological island is a term used in New Zealand, and increasingly in Australia, to refer to an area of land (not necessarily an actual island) isolated by natural or artificial means from the surrounding land, where a natural micro-habitat exists amidst a larger differing ecosystem. In New Zealand the term is used to refer to one of several types of nationally protected areas. In artificial ecological islands (also known as mainland islands): * all non-native species (at least predator species) have been eradicated, * native species are reintroduced and nurtured, and * the natural or artificial border is maintained to prevent reintroduction of non-native species. The ultimate goal is to recreate an ecological microcosm of the country as a whole as it was before human arrival. There is usually provision for controlled public access, and scientific study and research. The definition does not include land within a fence erected to: * protect farm animals from wild predators * prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodiversity Hotspot
A biodiversity hotspot is a ecoregion, 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 Endemism, 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 hots ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Picea Critchfieldii
''Picea critchfieldii'' is an extinct species of spruce tree formerly present on the landscape of North America, where it was once widely distributed throughout the southeastern United States. Plant macrofossil evidence reveals that this tree became extinct during the Late Quaternary period of Earth's history. At present, this is the only documented plant extinction from this geologic era. Hypotheses as to what specifically drove the extinction remain unresolved, but rapid and widespread climatic changes coincided with ''Picea critchfieldii'''s decline and ultimate extinction. History and classification ''Picea critchfieldii'' was first described by Stephen T. Jackson and Chengyu Weng in a 1999 paper titled, "Late Quaternary Extinction of a Tree Species in Eastern North America" published in the journal ''Proceedings of the National Academy of Sciences of the United States of America''. They coined the specific epithet ''critchfieldii'' as a patronym honoring botanist William B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxus Floridana
''Taxus floridana'', the Florida yew, is a species of yew, endemic to a small area of the Apalachicola River. This species has a restricted extent of occurrence (EOO) of 24km along the Apalachicola River and resides in the mesophytic forests of northern Florida at altitudes of 15–40 m. It is listed as critically endangeredFlora of North America''Taxus floridana''/ref> and is protected in reserves at the Torreya State Park and at the Nature Conservancy's Apalachicola Bluffs and Ravines Preserve. The Florida yew has legal protection under the United States and Florida Endangered Species laws. This species is considered endangered because of how rare it is and its limited range. Description It is an evergreen coniferous shrub or small tree growing to 6 m (rarely 10 m) tall, with a trunk up to 38 cm diameter. The bark is thin, scaly purple-brown, and the branches are irregularly orientated. The shoots are green at first, becoming brown after three or four years. The le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torreya Taxifolia
''Torreya taxifolia'', commonly known as Florida torreya or stinking-cedar, but also sometimes as Florida nutmeg or gopher wood, is an endangered canopy (biology), subcanopy tree of the yew Family (biology), family, Taxaceae. It is native to only a small glacial refugium in the southeastern United States, at the state border region of northern Florida and southwestern Georgia (U.S. state), Georgia. Species discovery In 1821, colonial control of Spanish Florida shifted from Spain to the United States through the Adams–Onís Treaty, Adams-Onis Treaty. American settlers, including plantation owners and their slaves, began to move into the Florida Territory, exacerbating the Seminole Wars, on-going conflict with the refugee Red Sticks, Red Stick Creek and their allies from the Creek War and the emigrant population of Seminole, Seminoles and Maroons. One such plantation owner was the patriarch of the Croom family, who in 1826 purchased land around the town of Tallahassee. When he d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene
The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene is an interglacial period within the ongoing Ice age, glacial cycles of the Quaternary, and is equivalent to Marine isotope stages, Marine Isotope Stage 1. The Holocene correlates with the last maximum axial tilt towards the Sun of the Earth#Axial tilt and seasons, Earth's obliquity. The Holocene corresponds with the rapid proliferation, growth, and impacts of the human species worldwide, including Recorded history, all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban culture, urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global significance for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
