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 refuge 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 in the Indo-Pacific Warm Pool only.
In anthropology, refugia often refers specifically to Last Glacial Maximum refugia, where some ancestral human populations may have been forced back to glacial refugia, similar small isolated pockets in the face of the continental ice sheets during the last glacial period. Going from west to east, suggested examples include the Franco-Cantabrian region (in northern Iberia), the Italian and Balkan peninsulas, the Ukrainian LGM refuge, and the Bering Land Bridge. Archaeological and genetic data suggest that the source populations of Paleolithic humans survived the glacial maxima (incl. the Last Glacial Maximum) in sparsely wooded areas and dispersed through areas of high primary productivity while avoiding dense forest cover.
As an example of a locale refugia study, Jürgen Haffer first proposed the concept of refugia to explain the biological diversity of bird populations in the Amazonian river basin. Haffer suggested that climatic change in the late Pleistocene led to reduced reservoirs of habitable forests in which populations become allopatric. Over time, that led to speciation: populations of the same species that found themselves in different refugia evolved differently, creating parapatric sister-species. As the Pleistocene ended, the arid conditions gave way to the present humid rainforest environment, reconnecting the refugia.
Scholars have since expanded the idea of this mode of speciation and used it to explain population patterns in other areas of the world, such as Africa, Eurasia, and North America. Theoretically, current biogeographical patterns can be used to infer past refugia: if several unrelated species follow concurrent range patterns, the area may have been a refugium. Moreover, the current distribution of species with narrow ecological requirements tend to be associated with the spatial position of glacial refugia.
One can provide a simple explanation of refugia involving core temperatures and exposure to sunlight. In the northern hemisphere, north-facing sites on hills or mountains, and places at higher elevations count as cold sites. The reverse are sun- or heat-exposed, lower-elevation, south-facing sites: hot sites. (The opposite directions apply in the southern hemisphere.) Each site becomes a refugium, one as a "cold-surviving refugium" and the other as a "hot-surviving refugium". Canyons with deep hidden areas (the opposite of hillsides, mountains, mesas, etc. or other exposed areas) lead to these separate types of refugia.
A concept not often referenced is that of "sweepstakes colonization": when a dramatic ecological event occurs, for example a meteor strike, and global, multiyear effects occur. The sweepstake-winning species happens to already be living in a fortunate site, and their environment is rendered even more advantageous, as opposed to the "losing" species, which immediately fails to reproduce.
In systematic conservation planning, the term refugium has been used to define areas that could be used in protected area development to protect species from climate change. The term has been used alternatively to refer to areas with stable habitats or stable climates. More specifically, the term in situ refugium is used to refer to areas that will allow species that exist in an area to remain there even as conditions change, whereas ex situ refugium refers to an area into which species distributions can move to in response to climate change. Sites that offer in situ refugia are also called resilient sites in which species will continue to have what they need to survive even as climate changes.
One study found with downscaled climate models that areas near the coast are predicted to experience overall less warming than areas toward the interior of the US State of Washington. Other research has found that old-growth forests are particularly insulated from climatic changes due to evaporative cooling effects from evapotranspiration and their ability to retain moisture. The same study found that such effects in the Pacific Northwest would create important refugia for bird species. A review of refugia-focused conservation strategy in the Klamath-Siskiyou Ecoregion found that, in addition to old-growth forest, the northern aspects of hillslopes and deep gorges would provide relatively cool areas for wildlife and seeps or bogs surrounded by mature and old-growth forests would continue to supply moisture even as water availability decreases.
Beginning in 2010 concept of geodiversity (a term used previously in efforts to preserve scientifically important geological features) entered into the literature of conservation biologists as a potential way to identify climate change refugia and as a surrogate (in other words, a proxy used when planning for protected areas) for biodiversity. While the language to describe this mode of conservation planning hadn't fully developed until recently, the use of geophysical diversity in conservation planning goes back at least as far as the work by Hunter and others in 1988, and Richard Cowling and his colleagues in South Africa also used "spatial features" as surrogates for ecological processes in establishing conservation areas in the late 1990s and early 2000s. The most recent efforts have used the idea of land facets (also referred to as geophysical settings, enduring features, or geophysical stages), which are unique combinations of topographical features (such as slope steepness, slope direction, and elevation) and soil composition, to quantify physical features. The density of these facets, in turn, is used as a measure of geodiversity. Because geodiversity has been shown to be correlated with biodiversity, even as species move in response to climate change, protected areas with high geodiversity may continue to protect biodiversity as niches get filled by the influx of species from neighboring areas. Highly geodiverse protected areas may also allow for the movement of species within the area from one land facet or elevation to another.
Conservation scientists, however, emphasize that the use of refugia to plan for climate change is not a substitute for fine-scale (more localized) and traditional approaches to conservation, as individual species and ecosystems will need to be protected where they exist in the present. They also emphasize that responding to climate change in conservation is not a substitute for actually limiting the causes of climate change.
In biology, extinction is the termination of an organism or of a group of organisms (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence.
More than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to have died out. Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. In 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described.Through evolution, species arise through the process of speciation—where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche—and species become extinct when they are no longer able to survive in changing conditions or against superior competition. The relationship between animals and their ecological niches has been firmly established. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils, survive with virtually no morphological change for hundreds of millions of years.
Mass extinctions are relatively rare events; however, isolated extinctions are quite common. Only recently have extinctions been recorded and scientists have become alarmed at the current high rate of extinctions. Most species that become extinct are never scientifically documented. Some scientists estimate that up to half of presently existing plant and animal species may become extinct by 2100. A 2018 report indicated that the phylogenetic diversity of 300 mammalian species erased during the human era since the Late Pleistocene would require 5 to 7 million years to recover.According to the 2019 Global Assessment Report on Biodiversity and Ecosystem Services by IPBES, the biomass of wild mammals has fallen by 82%, natural ecosystems have lost about half their area and a million species are at risk of extinction – all largely as a result of human actions. 25% of plant and animal species are threatened with extinction.In June 2019, 1 million species of plants and animals were at risk of extinction. At least 571 species are lost since 1750 but likely many more. The main cause of the extinctions is the destruction of natural habitats by human activities, such as cutting down forests and converting land into fields for farming.A dagger symbol (†) placed next to the name of a species or other taxon normally indicates its status as extinct.Glacial refugium
A glacial refugium (plural refugia) is a geographic region which made possible the survival of flora and fauna in times of ice ages and allowed for post-glacial re-colonization. Different types of glacial refugia can be distinguished, namely nunatak, peripheral and lowland refugia. Glacial refugia have been suggested as a major cause of the distributions of flora and fauna in both temperate and tropical latitudes. However, in spite of the continuing use of historical refugia to explain modern-day species distributions, especially in birds, doubt has been cast on the validity of such inferences, as much of the differentiation between populations observed today may have occurred before or after their restriction to refugia.Glacial survival hypothesis
According to the northern cryptic glacial refugial hypothesis (or glacial survival hypothesis), during the last ice age cold tolerant plant and animal species (e.g. Norway spruce and Norwegian lemmings) persisted in ice-free microrefugia north of the Alps in Europe. The alternative hypothesis of no persistence and postglacial immigration of plants and animals from southern refugia in Europe (southern refugia paradigm) is sometimes also called the tabula rasa hypothesis.
Over the past plants and animals have persisted through long periods of climate change including several glacial and interglacial periods. There is a long-standing debate on what happened to the species that were inhabiting high-latitidue regions during the Pleistocene ice age. Two main scenarios are usually considered. The first scenario proposes a total extinction of species within glaciated areas with survival events in peripheral refugia in the south and successive massive postglacial migration into empty areas (tabula rasa hypothesis). The second scenario proposes long-term in situ survival within glaciated regions (glacial survival hypothesis), either in isolated northern ice-free micro-refugia at the edge of the ice sheet, or on exposed mountains not covered with ice within the ice sheet (nunatak hypothesis).
For boreal and cold-tolerant species the glacial survival hypothesis is credible, though controversial, and a growing body of molecular data is now supporting it for both plant and animal species. A number of recent studies have shown that several northern regions (above latitudes >45° N) have supported low-density boreal and temperate tree populations during the late-glacial or Early Holocene [e.g. North America, Eurasia, Alps, Scandinavia].In recent years several studies have combined lines of evidences coming from three major disciplines to infer the existence of past refugia: fossil records, species distribution models and molecular/phylogeographic surveys. In this way it should be possible to better describe complex migration routes followed by species and populations in and out of refugia through time and space.Refuge (ecology)
A refuge is a concept in ecology, in which an organism obtains protection from predation by hiding in an area where it is inaccessible or cannot easily be found. Due to population dynamics, when refuges are available, populations of both predators and prey are significantly higher, and significantly more species can be supported in an area.Refugium
Refugium, plural refugia, the Latin for "refuge" or "hideaway", may refer to:
Refugium (fishkeeping), an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply
Refugium (population biology), a location of an isolated or relict population of a once widespread animal or plant species
Last Glacial Maximum refugia specifically, in anthropology
Refugium Range, a mountain range on Vancouver Island, British Columbia, CanadaRelict
A relict is a surviving remnant of a natural phenomenon.
In 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.A glacial relict is an cold-adapted organism that is remnant of a larger distribution that existed in the ice agesIn ecology, an ecosystem which originally ranged over a large expanse, but is now narrowly confined, may be termed a relict.
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.
In agronomy, a relict crop is a crop which was previously grown extensively, but is now only used in one limited region, or a small number of isolated regions.
In history (as revealed in 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 real estate law, reliction is the gradual recession of water from its usual high-water mark so that the newly uncovered land becomes the property of the adjoining riparian property owner.Other uses:
In addition, relict was an ancient term still used in colonial (British) America, and in England of that era, but now archaic, for a widow; it has come to be a generic or collective term for widows and widowers.
In historical linguistics, a relict is a word that is a survivor of a form or forms that are otherwise archaic.Sky island
Sky islands are isolated mountains surrounded by radically different lowland environments. The term originally referred to those found near the southern borders of Arizona and New Mexico, and has extended to similarly isolated high-altitude forests. The isolation has significant implications for these natural habitats. The American Southwest region began warming up between ∼20,000–10,000 years BP and atmospheric temperatures increased substantially, resulting in the formation of vast deserts that isolated the Sky Islands. Endemism, altitudinal migration, and relict populations are some of the natural phenomena to be found on sky islands.
The complex dynamics of species richness on sky islands draws attention from the discipline of biogeography, and likewise the biodiversity is of concern to conservation biology. One of the key elements of a sky island is separation by physical distance from the other mountain ranges, resulting in a habitat island, such as a forest surrounded by desert.
Some sky islands serve as refugia for boreal species stranded by warming climates since the last glacial period. In other cases, localized populations of plants and animals tend towards speciation, similar to oceanic islands such as the Galápagos Islands of Ecuador.Zomia
Zomia is a geographical term coined in 2002 by historian Willem van Schendel of the University of Amsterdam to refer to the huge mass of mainland Southeast Asia that has historically been beyond the control of governments based in the population centers of the lowlands.
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