Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment(suspected of being one of the major causes of speciation ),and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species.
Population fragmentation is a form of population segregation. It is often caused by habitat fragmentation.
Ecosystem decay is a term coined by Thomas Lovejoy to define the process of which species become extinct locally based on habitat fragmentation. This process is what led to the extinction of several species, including the Irish Elk. Ecosystem decay can be mainly attributed to population isolation, leading to inbreeding, leading to a decrease in the population of local species. Another factor is the absence of competition, preventing the mechanisms of natural selection to benefit the population. This leads to a lack of a skill set for the animal to adjust and adapt to a new environment.
Allopatric speciation, also referred to as geographic speciation, vicariant speciation, or its earlier name, the dumbbell model, is a mode of speciation that occurs when biological populations of the same species become isolated from each other to an extent that prevents or interferes with gene flow.
The term habitat fragmentation includes five discrete phenomena:
"fragmentation ... not only causes loss of the amount of habitat, but by creating small, isolated patches it also changes the properties of the remaining habitat" (van den Berg et al. 2001)[ not in citation given ]. Habitat fragmentation is the landscape level of the phenomenon, and patch level process. Thus meaning, it covers; the patch areas, edge effects, and patch shape complexity.
In scientific literature, there is some debate whether the term "habitat fragmentation" applies in cases of habitat loss, or whether the term primarily applies to the phenomenon of habitat being cut into smaller pieces without significant reduction in habitat area. Scientists who use the stricter definition of "habitat fragmentation" per sewould refer to loss of habitat area as "habitat loss" and explicitly mention both terms if describing a situation where the habitat becomes less connected and there is less overall habitat.
Evidence of habitat destruction through natural processes such as volcanism, fire, and climate change is found in the fossil record. [ not in citation given ] For example, habitat fragmentation of tropical rainforests in Euramerica 300 million years ago led to a great loss of amphibian diversity, but simultaneously the drier climate spurred on a burst of diversity among reptiles.
Habitat destruction is the process by which natural habitat becomes incapable of supporting its native species. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity is mainly for the purpose of harvesting natural resources for industrial production and urbanization. Clearing habitats for agriculture is the principal cause of habitat destruction. Other important causes of habitat destruction include mining, logging, trawling, and urban sprawl. Habitat destruction is currently ranked as the primary cause of species extinction worldwide. It is a process of natural environmental change that may be caused by habitat fragmentation, geological processes, climate change or by human activities such as the introduction of invasive species, ecosystem nutrient depletion, and other human activities.
Volcanism is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics and volcanic gases erupt through a break in the surface called a vent. It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface.
Climate change occurs when changes in Earth's climate system result in new weather patterns that last for at least a few decades, and maybe for millions of years. The climate system is comprised of five interacting parts, the atmosphere (air), hydrosphere (water), cryosphere, biosphere, and lithosphere. The climate system receives nearly all of its energy from the sun, with a relatively tiny amount from earth's interior. The climate system also gives off energy to outer space. The balance of incoming and outgoing energy, and the passage of the energy through the climate system, determines Earth's energy budget. When the incoming energy is greater than the outgoing energy, earth's energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and earth experiences cooling.
Habitat fragmentation is frequently caused by humans when native plants is cleared for human activities such as agriculture, rural development, urbanization and the creation of hydroelectric reservoirs. Habitats which were once continuous become divided into separate fragments. After intensive clearing, the separate fragments tend to be very small islands isolated from each other by cropland, pasture, pavement, or even barren land. The latter is often the result of slash and burn farming in tropical forests. In the wheat belt of central western New South Wales, Australia, 90% of the native vegetation has been cleared and over 99% of the tall grass prairie of North America has been cleared, resulting in extreme habitat fragmentation.
Native plants are plants indigenous to a given area in geologic time. This includes plants that have developed, occur naturally, or existed for many years in an area.
Agriculture is the science and art of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities. The history of agriculture began thousands of years ago. After gathering wild grains beginning at least 105,000 years ago, nascent farmers began to plant them around 11,500 years ago. Pigs, sheep and cattle were domesticated over 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. Industrial agriculture based on large-scale monoculture in the twentieth century came to dominate agricultural output, though about 2 billion people still depended on subsistence agriculture into the twenty-first.
Subdivision is the act of dividing land into pieces that are easier to sell or otherwise develop, usually via a plat. The former single piece as a whole is then known in the United States as a subdivision. If it is used for housing it is typically known as a housing subdivision or housing development, although some developers tend to call these areas communities.
There are two types of processes that can lead to habitat fragmentation. There are exogenous processes and endogenous processes. Endogenous are process that develop as a part of a species biology so they typically include changes in biology, behavior and interactions within or between species. Endogenous threats can result in changes to breeding patterns or migration patterns and are often triggered by exogenous processes. Exogenous processes are independent of species biology and can include habitat degradation, habitat subdivision or habitat isolation. These processes can have a substantial impact on endogenous processes by fundamentally altering species behavior. Habitat subdivision or isolation can lead to changes in dispersal or movement of species including changes to seasonal migration. These changes can lead to decrease in a density of species, increased competition or even increased predation.
One of the major ways that habitat fragmentation affects biodiversity is by reducing the amount of suitable habitat available for organisms. Habitat fragmentation often involves both habitat destruction and the subdivision of previously continuous habitat.Plants and other sessile organisms are disproportionately affected by some types of habitat fragmentation because they cannot respond quickly to the altered spatial configuration of the habitat.
Habitat loss, which can occur through the process of habitat fragmentation, is considered to be the greatest threat to species.But, the effect of the configuration of habitat patches within the landscape, independent of the effect of the amount of habitat within the landscape (referred to as fragmentation per se ), has been suggested to be small. A review of empirical studies found that, of the 381 reported significant effect of habitat fragmentation per se on species occurrences, abundances or diversity in the scientific literature, 76% were positive whereas 24% were negative. Despite these results, the scientific literature tends to emphasize negative effects more than positive effects. Positive effects of habitat fragmentation per se imply that several small patches of habitat can have higher conservation value than a single large patch of equivalent size. Land sharing strategies could therefore have more positive impacts on species than land sparing strategies.
Area is the primary determinant of the number of species in a fragmentand the relative contributions of demographic and genetic processes to the risk of global population extinction depend on habitat configuration, stochastic environmental variation and species features. Minor fluctuations in climate, resources, or other factors that would be unremarkable and quickly corrected in large populations can be catastrophic in small, isolated populations. Thus fragmentation of habitat is an important cause of species extinction. Population dynamics of subdivided populations tend to vary asynchronously. In an unfragmented landscape a declining population can be "rescued" by immigration from a nearby expanding population. In fragmented landscapes, the distance between fragments may prevent this from happening. Additionally, unoccupied fragments of habitat that are separated from a source of immigrants by some barrier are less likely to be repopulated than adjoining fragments. Even small species such as the Columbia spotted frog are reliant on the rescue effect. Studies showed 25% of juveniles travel a distance over 200m compared to 4% of adults. Of these, 95% remain in their new locale, demonstrating that this journey is necessary for survival.
Additionally, habitat fragmentation leads to edge effects. Microclimatic changes in light, temperature and wind can alter the ecology around the fragment, and in the interior and exterior portions of the fragment. Fires become more likely in the area as humidity drops and temperature and wind levels rise. Exotic and pest species may establish themselves easily in such disturbed environments, and the proximity of domestic animals often upsets the natural ecology. Also, habitat along the edge of a fragment has a different climate and favours different species from the interior habitat. Small fragments are therefore unfavourable for species which require interior habitat. The percentage preservation of contiguous habitats is closely related to both genetic and species biodiversity preservation. Generally a 10% remnant contiguous habitat will result in a 50% biodiversity loss.
Habitat fragmentation is often a cause of species becoming threatened or endangered. The existence of viable habitat is critical to the survival of any species, and in many cases the fragmentation of any remaining habitat can lead to difficult decisions for conservation biologists. Given a limited amount of resources available for conservation is it preferable to protect the existing isolated patches of habitat or to buy back land to get the largest possible continuous piece of land. In rare cases a conservation reliant species may gain some measure of disease protection by being distributed in isolated habitats. This ongoing debate is often referred to as SLOSS (Single Large or Several Small).
One solution to the problem of habitat fragmentation is to link the fragments by preserving or planting corridors of native vegetation. In some cases, a bridge or underpass may be enough to join two fragments.This has the potential to mitigate the problem of isolation but not the loss of interior habitat.
Another mitigation measure is the enlargement of small remnants in order to increase the amount of interior habitat. This may be impractical since developed land is often more expensive and could require significant time and effort to restore.
The best solution is generally dependent on the particular species or ecosystem that is being considered. More mobile species, like most birds, do not need connected habitat while some smaller animals, like rodents, may be more exposed to predation in open land. These questions generally fall under the headings of metapopulations island biogeography.
As the remaining habitat patches are smaller, they tend to support smaller populations of fewer species.Small populations are at an increased risk of a variety of genetic consequences that influence their long-term survival. Remnant populations often contain only a subset of the genetic diversity found in the previously continuous habitat. In these cases, processes that act upon underlying genetic diversity, such as adaptation, have a smaller pool of fitness-maintaining alleles to survive in the face of environmental change. However in some scenarios, where subsets of genetic diversity are partitioned among multiple habitat fragments, almost all original genetic diversity can be maintained despite each individual fragment displaying a reduced subset of diversity .
Gene flow occurs when individuals of the same species exchange genetic information through reproduction. Populations can maintain genetic diversity through migration. When a habitat becomes fragmented and reduced in area, gene flow and migration is typically reduced. Fewer individuals will migrate into the remaining fragments, and small disconnected populations that may have once been part of a single large population will become reproductively isolated. Scientific evidence that gene flow is reduced due to fragmentation depends on the study species. While trees that have long-range pollination and dispersal mechanisms may not experience reduced gene flow following fragmentation,most species are at risk of reduced gene flow following habitat fragmentation.
Reduced gene flow, and reproductive isolation can result in inbreeding between related individuals. Inbreeding does not always result in negative fitness consequences, but when inbreeding is associated with fitness reduction it is called inbreeding depression. Inbreeding becomes of increasing concern as the level of homozygosity increases, facilitating the expression of deleterious alleles that reduce the fitness. Habitat fragmentation can lead to inbreeding depression for many species due to reduced gene flow.Inbreeding depression is associated with conservation risks, like local extinction.
Small populations are more susceptible to genetic drift. Genetic drift is random changes to the genetic make up of populations and always leads to reductions in genetic diversity. The smaller the population is, the more likely genetic drift will be a driving force of evolution rather than natural selection. Because genetic drift is a random process, it does not allow species to become more adapted to their environment. Habitat fragmentation is associated with increases to genetic drift in small populations which can have negative consequences for the genetic diversity of the populations.However, research suggests that some tree species may be resilient to the negative consequences of genetic drift until population size is as small as ten individuals or less .
In order for populations to evolve in response to natural selection, they must be large enough that natural selection is a stronger evolutionary force than genetic drift. Recent studies on the impacts of habitat fragmentation on adaptation in some plant species have suggested that organisms in fragmented landscapes may be able to adapt to fragmentation.However, there are also many cases where fragmentation reduces adaptation capacity because of small population size.
Some species that have experienced genetic consequences due to habitat fragmentation are listed below:
Although the way habitat fragmentation affects the genetics and extinction rates of species has been heavily studied, fragmentation has also been shown to affect species' behaviours and cultures as well. This is important because social interactions have the ability to determine and have an effect on a species' fitness and survival. Habitat fragmentation alters the resources available and the structure of habitats, as a result alters the behaviours of species and the dynamics between differing species. Behaviours affected can be within a species such as reproduction, mating, foraging, species dispersal, communication and movement patterns or can be behaviours between species such as predator prey relationships.
Habitat fragmentation due to anthropogenic activities has been shown to greatly affect the predator-prey dynamics of many species by altering the amount of species and the members of those species.This affects the natural predator-prey relationships between animals in a given community and forces them to alter their behaviours and interactions, therefore resetting the so called "behavioral space race". The way in which fragmentation changes and re-shapes these interactions can occur in many different forms. Most prey species have patches of land that are refuge from their predators, allowing them the safety to reproduce and raise their young. Human introduced structures such as roads and pipelines alter these areas by facilitating predator activity in these refuges, increasing predator-prey overlap. The opposite could also occur in the favour of prey, increasing prey refuge and subsequently decreasing predation rates. Fragmentation may also increase predator abundance or predator efficiency and therefore increase predation rates in this manner. Several other factors can also increase or decrease the extent to which the shifting predator-prey dynamics affect certain species, including how diverse a predators diet is and how flexible habitat requirements are for predators and prey. Depending on which species are affected and these other factors, fragmentation and its resulting effects on predator-prey dynamics may contribute to a species extinction. In response to these new environmental pressures, new adaptive behaviours may be developed. Prey species may adapt to increased risk of predation with strategies such as altering mating tactics or changing behaviours and activities related to food and foraging.
In the boreal woodland caribous of British Columbia the effects of fragmentation are clearly demonstrated. The species refuge area is peatland bog which has been interrupted by linear features such as roads and pipelines.These features have allowed their natural predators, the wolf and the black bear to more efficiently travel over landscapes and between patches of land. Since their predators can more easily access the caribous' refuge, the females of the species attempt to avoid the area, affecting their reproductive behaviours and offspring produced.
Fragmentation affecting the communication behaviours of birds has been well studied in Dupont's Lark. The Larks primarily reside in regions of Spain and are a small passerine bird which use songs as a means of cultural transmission between members of the species.The Larks have two distinct vocalizations, the song and the territorial call. The territorial call is used by males to defend and signal territory from other male Larks and is shared between neighbouring territories when males respond to a rivals song. Occasionally it is used as a threat signal to signify an impending attack on territory. A large song repertoire can enhance a males ability to survive and reproduce as he has a greater ability to defend his territory from other males, and a larger number of males in the species means a larger variety of songs being transmitted. Fragmentation of the Dupont's Lark territory from agriculture, forestry and urbanization appears to have a large effect on their communication structures. Males only perceive territories of a certain distance to be rivals and so isolation of territory from others due to fragmentation leads to a decrease in territorial calls as the males no longer have any reason to use it or have any songs to match.
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Forest fragmentation is a form of habitat fragmentation where forests are reduced (either naturally or man-made) to relatively small, isolated patches of forest known as forest fragments or forest remnants.The intervening matrix that separates the remaining woodland patches can be natural open areas, farmland, or developed areas. Following the principles of island biogeography, remnant woodlands act like islands of forest in a sea of pastures, fields, subdivisions, shopping malls, etc. These fragments will then begin to undergo the process of ecosystem decay.
Forest fragmentation also includes less subtle forms of discontinuities such as utility right-of-ways (ROWs). Utility ROWs are of ecological interest because they have become pervasive in many forest communities, spanning areas as large as 5 million acres in the United States.Utility ROWs include electricity transmission ROWs, gas pipeline and telecommunication ROWs. Electricity transmission ROWs are created to prevent vegetation interference with transmission lines. Some studies have shown that electricity transmission ROWs harbor more plant species than adjoining forest areas, due to alterations in the microclimate in and around the corridor. Discontinuities in forest areas associated with utility right-of-ways can serve as biodiversity havens for native bees and grassland species, as the right-of-ways are preserved in an early successional stage.
Forest fragmentation is one of the greatest threats to biodiversity in forests, especially in the tropics.The problem of habitat destruction that caused the fragmentation in the first place is compounded by:
The effect of fragmentation on the flora and fauna of a forest patch depends on a) the size of the patch, and b) its degree of isolation. Isolation depends on the distance to the nearest similar patch, and the contrast with the surrounding areas. For example, if a cleared area is reforested or allowed to regenerate, the increasing structural diversity of the vegetation will lessen the isolation of the forest fragments. However, when formerly forested lands are converted permanently to pastures, agricultural fields, or human-inhabited developed areas, the remaining forest fragments, and the biota within them, are often highly isolated.
Forest patches that are smaller or more isolated will lose species faster than those that are larger or less isolated. A large number of small forest "islands" typically cannot support the same biodiversity that a single contiguous forest would hold, even if their combined area is much greater than the single forest. However, forest islands in rural landscapes greatly increase their biodiversity.
Two approaches that are typically used to understand habitat fragmentation and its ecological impacts.
The species-oriented approach focuses specifically on individual species and how they each respond to their environment and habitat changes with in it. This approach can be limited because it does only focus on individual species and does not allow for a broad view of the impacts of habitat fragmentation across species.
The pattern-oriented approach is based on land cover and its patterning in correlation with species occurrences. One model of study for landscape patterning is the patch-matrix-corridor model developed by Richard Forman The pattern-oriented approach focuses on land cover defined by human means and activities. This model has stemmed from island biogeography and tries to infer causal relationships between the defined landscapes and the occurrence of species or groups of species within them. The approach has limitations in its collective assumptions across species or landscapes which may not account for variations amongst them.
The other model is the variegation model. Variegated landscapes retain much of their natural vegetation but are intermixed with gradients of modified habitatThis model of habitat fragmentation typically applies to landscapes that are modified by agriculture. In contrast to the fragmentation model that is denoted by isolated patches of habitat surrounded by unsuitable landscape environments, the variegation model applies to landscapes modified by agriculture where small patches of habitat remain near the remnant original habitat. In between these patches are a matrix of grassland that are often modified versions of the original habitat. These areas do not present as much of a barrier to native species.
In ecology, edge effects are changes in population or community structures that occur at the boundary of two or more habitats. Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range. As the edge effects increase, the boundary habitat allows for greater biodiversity.
Small populations can behave differently from larger populations. They are often the result of a population bottlenecks from larger populations, leading to loss of heterozygosity and reduced genetic diversity and loss or fixation of alleles and shifts in allele frequencies. A small population is then more susceptible to demographic and genetic stochastic events, which can impact the long-term survival of the population. Therefore, small populations are often considered at risk of endangerment or extinction, and are often of conservation concern.
Habitat conservation is a management practice that seeks to conserve, protect and restore habitats and prevent species extinction, fragmentation or reduction in range. It is a priority of many groups that cannot be easily characterized in terms of any one ideology.
In population genetics, gene flow is the transfer of genetic variation from one population to another. If the rate of gene flow is high enough, then two populations are considered to have equivalent allele frequencies and therefore effectively be a single population. It has been shown that it takes only "One migrant per generation" to prevent populations from diverging due to drift. Gene flow is an important mechanism for transferring genetic diversity among populations. Migrants change the distribution of genetic diversity within the populations, by modifying the allele frequencies. High rates of gene flow can reduce the genetic differentiation between the two groups, increasing homogeneity. For this reason, gene flow has been thought to constrain speciation by combining the gene pools of the groups, thus preventing the development of differences in genetic variation that would have led to full speciation. In some cases migration may also result in the addition of novel genetic variants to the gene pool of a species or population.
The prickly skink, or prickly forest skink, is a morphologically and genetically distinctive species of skink endemic to rainforests of the Wet Tropics of Queensland World Heritage Area, in north-eastern Australia. Unlike most small skinks, which have smooth scales, this species has rough, ridged and pointed scales. These keeled scales may be an adaptation to its high-rainfall habitat, to its microhabitat in rotting logs, or to camouflage it when moving through forest leaf-litter.
A metapopulation consists of a group of spatially separated populations of the same species which interact at some level. The term metapopulation was coined by Richard Levins in 1969 to describe a model of population dynamics of insect pests in agricultural fields, but the idea has been most broadly applied to species in naturally or artificially fragmented habitats. In Levins' own words, it consists of "a population of populations".
Insular biogeography or island biogeography is a field within biogeography that examines the factors that affect the species richness and diversification of isolated natural communities. The theory was originally developed to explain the pattern of the species–area relationship occurring in oceanic islands. Under either name it is now used in reference to any ecosystem that is isolated due to being surrounded by unlike ecosystems, and has been extended to mountain peaks, seamounts, oases, fragmented forests, and even natural habitats isolated by human land development. The field was started in the 1960s by the ecologists Robert H. MacArthur and E. O. Wilson, who coined the term island biogeography in their inaugural contribution to Princeton's Monograph in Population Biology series, which attempted to predict the number of species that would exist on a newly created island.
The Allee effect is a phenomenon in biology characterized by a correlation between population size or density and the mean individual fitness of a population or species.
Conservation genetics is an interdisciplinary subfield of Population Genetics that aims to understand the dynamics of genes in populations principally to avoid extinction. Therefore, it applies genetic methods to the conservation and restoration of biodiversity. Researchers involved in conservation genetics come from a variety of fields including population genetics, molecular ecology, biology, evolutionary biology, and systematics. Genetic diversity is one of the three fundamental levels of biodiversity, so it is directly important in conservation. Genetic variability influences both the health and long-term survival of populations because decreased genetic diversity has been associated with reduced fitness, such as high juvenile mortality, diminished population growth, reduced immunity, and ultimately, higher extinction risk.
The SLOSS debate was a debate in ecology and conservation biology during the 1970s and 1980s as to whether a single large or several small (SLOSS) reserves were a superior means of conserving biodiversity in a fragmented habitat.
The Biological Dynamics of Forest Fragments Project (BDFFP), originally called the Minimum Critical Size of Ecosystems Project is a large-scale ecological experiment looking at the effects of habitat fragmentation on tropical rainforest; it is one of the most expensive biology experiments ever run. The experiment, which was established in 1979 is located near Manaus, in the Brazilian Amazon. The project is jointly managed by the Smithsonian Institution and the Brazilian Institute for Research in the Amazon (INPA).
Landscape connectivity in ecology is, broadly, "the degree to which the landscape facilitates or impedes movement among resource patches". Alternatively, connectivity may be a continuous property of the landscape and independent of patches and paths. Connectivity includes both structural connectivity and functional connectivity. The degree to which a landscape is connected determines the amount of dispersal there is among patches, which influences gene flow, local adaptation, extinction risk, colonization probability, and the potential for organisms to move as they cope with climate change.
Cross-boundary subsidies are caused by organisms or materials that cross or traverse habitat patch boundaries, subsidizing the resident populations. The transferred organisms and materials may provide additional predators, prey, or nutrients to resident species, which can affect community and food web structure. Cross-boundary subsidies of materials and organisms occur in landscapes composed of different habitat patch types, and so depend on characteristics of those patches and on the boundaries in between them. Human alteration of the landscape, primarily through fragmentation, has the potential to alter important cross-boundary subsidies to increasingly isolated habitat patches. Understanding how processes that occur outside of habitat patches can affect populations within them may be important to habitat management.
Ecological extinction is "the reduction of a species to such low abundance that, although it is still present in the community, it no longer interacts significantly with other species".
The Perote ground squirrel is a species of rodent in the family Sciuridae. It is endemic to Mexico and is currently at risk of extinction. Perote ground squirrels live within the same area as rock squirrels but they use different microhabitats. In one case it also shares its habitat with the Mexican ground squirrel. Perote ground squirrels have traits similar to those of spotted ground squirrels found in the northern Mexican Plateau; however they are larger, have shorter tails and yellow backs. Its skull is relatively narrow with a large braincase and they have heavy, thick teeth. Perote ground squirrels have two annual cycles, an active phase (March–November) and a hibernation phase (December–February). Some overlap may occur in March and November however.
Genetic erosion is a process where the limited gene pool of an endangered species diminishes even more when reproductive individuals die off before reproducing low population. The term is sometimes used in a narrow sense, such as when describing the loss of particular alleles or genes, as well as being used more broadly, as when referring to the loss of a phenotype or whole species.
Defaunation is the global, local or functional extinction of animal populations or species from ecological communities. The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient exploitation of the environment. This has resulted in the depletion of large vertebrates from ecological communities, creating what has been termed "empty forest". Defaunation differs from extinction; it includes both the disappearance of species and declines in abundance. Defaunation effects were first implied at the Symposium of Plant-Animal Interactions at the University of Campinas, Brazil in 1988 in the context of neotropical forests. Since then, the term has gained broader usage in conservation biology as a global phenomenon.
Island ecology is the study of island organisms and their interactions with each other and the environment. Islands account for nearly 1/6 of earth’s total land area, yet the ecology of island ecosystems is vastly different from that of mainland communities. Their isolation and high availability of empty niches lead to increased speciation. As a result, island ecosystems comprise 30% of the world’s biodiversity hotspots, 50% of marine tropical diversity, and some of the most unusual and rare species. Many species still remain unknown.
In ecology, extinction debt is the future extinction of species due to events in the past. The phrases dead clade walking and survival without recovery express the same idea.
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