Habitat fragmentation describes the emergence of discontinuities in an organism's preferred environment, causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that alter the layout of the physical environment,and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species; the term habitat fragmentation includes five discrete phenomena: Reduction in the total area of the habitat Decrease of the interior: edge ratio Isolation of one habitat fragment from other areas of habitat Breaking up of one patch of habitat into several smaller patches Decrease in the average size of each patch of habitat"fragmentation... not only causes loss of the amount of habitat, but by creating small, isolated patches it changes the properties of the remaining habitat". Habitat fragmentation is the landscape level of the phenomenon, patch level process, thus meaning, it covers. In scientific literature, there is some debate whether the term "habitat fragmentation" applies in cases of habitat loss, or whether the term 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 se would 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 and climate change is found in the fossil record. For example, habitat fragmentation of tropical rainforests in Euramerica 300 million years ago led to a great loss of amphibian diversity, but the drier climate spurred on a burst of diversity among reptiles. Habitat fragmentation is caused by humans when native plants is cleared for human activities such as agriculture, rural development 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 small islands isolated from each other by cropland, pavement, or barren land; the latter is 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. There are two types of processes. There are exogenous endogenous processes. Endogenous are process that develop as a part of a species biology so they include changes in biology and interactions within or between species. Endogenous threats can result in changes to breeding patterns or migration patterns and are 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 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 involves both habitat destruction and the subdivision of continuous habitat. Plants and other sessile organisms are disproportionately affected by some types of habitat fragmentation because they cannot respond 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, 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 fragment and 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 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.
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more they represent problematic species concepts. For example, the boundaries between related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, in a ring species. Among organisms that reproduce only asexually, the concept of a reproductive species breaks down, each clone is a microspecies. All species are given a two-part name, a "binomial"; the first part of a binomial is the genus.
The second part is called the specific epithet. For example, Boa constrictor is one of four species of the genus Boa. None of these is satisfactory definitions, but scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties. If species were fixed and distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, to grade into one another. Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped. Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection; that understanding was extended in the 20th century through genetics and population ecology. Genetic variability arises from mutations and recombination, while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures.
Genes can sometimes be exchanged between species by horizontal gene transfer. Viruses are a special case, driven by a balance of mutation and selection, can be treated as quasispecies. Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics. Early taxonomists such as Linnaeus had no option but to describe what they saw: this was formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or impossible to test. Biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: agamospecies for asexual organisms biospecies for reproductively isolated sexual organisms ecospecies based on ecological niches evolutionary species based on lineage genetic species based on gene pool morphospecies based on form or phenotype and taxonomic species, a species as determined by a taxonomist.
A typological species is a group of organisms in which individuals conform to certain fixed properties, so that pre-literate people recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens would differentiate the species; this method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, different phenotypes are not different species. Species named in this manner are called morphospecies. In the 1970s, Robert R. Sokal, Theodore J. Crovello and Peter Sneath proposed a variation on this, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms, it differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species is a group of sexually reproducing organisms that recognize one another as potential mates.
Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms. A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology, genes can move even between distantly related bacteria extending to the whole bacterial domain; as a rule of thumb, microbiologists have assumed that kinds of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA-DNA hybridisation to decide if they belong to the same species or not. This concept was narrowed in 2006 to a similarity of 98.7%. DNA-DNA hybri
The World's 25 Most Endangered Primates
The World's 25 Most Endangered Primates is a list of endangered primate species selected and published by the International Union for Conservation of Nature Species Survival Commission Primate Specialist Group, the International Primatological Society, Conservation International. The 2012–2014 list added the Bristol Conservation and Science Foundation to the list of publishers; the IUCN/SSC PSG worked with CI to start the list in 2000, but in 2002, during the 19th Congress of the International Primatological Society, primatologists reviewed and debated the list, resulting in the 2002–2004 revision and the endorsement of the IPS. The publication has since been a joint project between the three conservation organizations and has been revised every two years following the biannual Congress of the IPS. Starting with the 2004–2006 report, the title changed to "Primates in Peril: The World's 25 Most Endangered Primates"; that same year, the list began to provide information about each species, including their conservation status and the threats they face in the wild.
The species text is written in collaboration with experts from the field, with 60 people contributing to the 2006–2008 report and 85 people contributing to the 2008–2010 report. The 2004–2006 and 2006–2008 reports were published in the IUCN/SSC PSG journal Primate Conservation, while the 2008–2010 and 2010-2012 report were published as independent publications by all three contributing organizations; the 25 species on the 2012–2014 list are distributed between 16 countries. The countries with the most species on the list are Madagascar and Indonesia; the list is broken into four distinct regions: the island of Madagascar, the continent of Africa, the continent of Asia including the islands of Indonesia, the Neotropics. Five species have been on all seven published lists: the silky sifaka, Delacour's langur, golden-headed langur, grey-shanked douc, the Tonkin snub-nosed monkey; the purpose of the list, according to Russell Mittermeier, the president of CI, is "to highlight those that are most at risk, to attract the attention of the public, to stimulate national governments to do more, to find the resources to implement needed conservation measures."
Species are selected for the list based on two primary reasons: small population sizes and rapid drops in numbers. These reasons are influenced by habitat loss and hunting, the two greatest threats primates face. More threats listed in the report include deforestation due to slash-and-burn agriculture, clearing for pasture or farmland, charcoal production, firewood production, illegal logging, selective logging, land development, cash crop production. With each new publication, species are both removed from the list. In some cases, removal from the list signifies improvement for the species. With the publication of the 2006–2008 list, four species were removed because of increased conservation efforts: the black lion tamarin, golden lion tamarin, mountain gorilla, Perrier's sifaka. In 2008, the black lion tamarin went from critically endangered to endangered and the golden lion tamarin was promoted in 2003 after three decades of collaborative conservation efforts by zoos and other institutions.
Well-protected species such as these still have small populations, due to deforestation, new habitat is still needed for their long-term survival. The Hainan black crested gibbon, removed from the 2008–2010 list, still has fewer than 20 individuals left, but significant efforts to protect it are now being made. Mittermeier claimed in 2007 that all 25 species could be elevated off the list within five to ten years if conservation organizations had the necessary resources. Unlike the changes in the 2006–2008 report, not all species were removed from the 2008–2010 list due to improvement in their situation. Instead, new species were added to bring attention to other related species with small populations that are at risk of extinction. For example, the endangered eastern black crested gibbon replaced the Hainan black crested gibbon; the Javan slow loris replaced the Horton Plains slender loris because the former has been hit the hardest of Asian lorises, all of which are declining due to capture for the exotic pet trade, as well as use in traditional medicines and forest loss.
In another case, the brown-headed spider monkey was omitted from the list since no spokesperson could be found for the species. The same approach was taken with the 2012–2014 list. With the exception of the 2000–2002 publication, written collaboratively by the IUCN/SSC PSG and CI, the list has been revised every two years following the biannual Congress of the IPS; the 2002–2004 list resulted from the 19th Congress of the IPS in Beijing, China. The 2008 IUCN Red List of
Lists of organisms by population
This is a collection of lists of organisms by their population. While most of the numbers are estimates, they have been made by the experts in their fields. Species population is a science falling under the purview of population biogeography. Individuals are counted by census. More than 99 percent of all species, amounting to over five billion species, that lived on Earth are estimated to be extinct. 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. According to another study, the number of described species has been estimated at 1,899,587. 2000–2009 saw 17,000 species described per year. The total number of undescribed organisms is unknown, but marine microbial species alone could number 20,000,000; the number of quantified species will ipso facto always lag behind the number of described species, species contained in these lists tend to be on the K side of the r/K selection continuum.
More in May 2016, scientists reported that 1 trillion species are estimated to be on Earth with only one-thousandth of one percent described. The total number of related DNA base pairs on Earth is estimated at 5.0 x 1037 and weighs 50 billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as 4 TtC. In July 2016, scientists reported identifying a set of 355 genes from the Last Universal Common Ancestor of all organisms living on Earth, it is estimated that the most numerous bacteria are of a species of the Pelagibacterales clade Pelagibacter ubique, the most numerous viruses are bacteriophages infecting these species. It is estimated; the Deep Carbon Observatory has been exploring living forms in the interior of the Earth. "Life in deep Earth totals 15 to 23 billion tons of carbon". Mammals by population Artiodactyla Carnivora Cetacea Chiroptera Perissodactyla Primates Birds by population Anseriformes Apodiformes Caprimulgiformes Charadriiformes Ciconiiformes Columbiformes Coraciiformes Cuculiformes Falconiformes Galliformes Gaviiformes Gruiformes Passeriformes Pelecaniformes Phoenicopteriformes Piciformes Podicipediformes Procellariiformes Psittaciformes Sphenisciformes Strigiformes Struthioniformes Tinamiformes Trogoniformes There are an estimated 3,500,000,000,000 fish in the ocean.
In the last 100 years, the number of small fish – such as pilchards, anchovies and sardines – has more than doubled. It is caused by a major decline in big ‘predator fish’ such as sharks and cod due to over-fishing. Recent figures indicate that there are more than 1.4 billion insects for each human on the planet An article in The New York Times claimed that the world holds 300 pounds of insects for every pound of humans. Ants have colonised every landmass on Earth, their population is estimated as 1016–1017. According to NASA in 2005, there were over 400 billion trees on our globe. However, more in 2015, using better methods, the global tree count has been estimated at about 3 trillion. Other studies show that the Amazonian forest alone yields 430 billion trees. Extrapolations from data compiled over a period of 10 years suggest that greater Amazonia, which includes the Amazon Basin and the Guiana Shield, harbors around 390 billion individual trees
International Union for Conservation of Nature
The International Union for Conservation of Nature is an international organization working in the field of nature conservation and sustainable use of natural resources. It is involved in data gathering and analysis, field projects and education. IUCN's mission is to "influence and assist societies throughout the world to conserve nature and to ensure that any use of natural resources is equitable and ecologically sustainable". Over the past decades, IUCN has widened its focus beyond conservation ecology and now incorporates issues related to sustainable development in its projects. Unlike many other international environmental organisations, IUCN does not itself aim to mobilize the public in support of nature conservation, it tries to influence the actions of governments and other stakeholders by providing information and advice, through building partnerships. The organization is best known to the wider public for compiling and publishing the IUCN Red List of Threatened Species, which assesses the conservation status of species worldwide.
IUCN has a membership of over 1400 non-governmental organizations. Some 16,000 scientists and experts participate in the work of IUCN commissions on a voluntary basis, it employs 1000 full-time staff in more than 50 countries. Its headquarters are in Switzerland. IUCN has observer and consultative status at the United Nations, plays a role in the implementation of several international conventions on nature conservation and biodiversity, it was involved in establishing the World Wide Fund for Nature and the World Conservation Monitoring Centre. In the past, IUCN has been criticized for placing the interests of nature over those of indigenous peoples. In recent years, its closer relations with the business sector have caused controversy. IUCN was established in 1948, it was called the International Union for the Protection of Nature and the World Conservation Union. Establishment IUCN was established on 5 October 1948, in Fontainebleau, when representatives of governments and conservation organizations signed a formal act constituting the International Union for the Protection of Nature.
The initiative to set up the new organisation came from UNESCO and from its first Director General, the British biologist Julian Huxley. The objectives of the new Union were to encourage international cooperation in the protection of nature, to promote national and international action and to compile and distribute information. At the time of its founding IUPN was the only international organisation focusing on the entire spectrum of nature conservation Early years: 1948–1956 IUPN started out with 65 members, its secretariat was located in Brussels. Its first work program focused on saving species and habitats and applying knowledge, advancing education, promoting international agreements and promoting conservation. Providing a solid scientific base for conservation action was the heart of all activities. IUPN and UNESCO were associated, they jointly organized the 1949 Conference on Protection of Nature. In preparation for this conference a list of gravely endangered species was drawn up for the first time, a precursor of the IUCN Red List of Threatened Species.
In the early years of its existence IUCN depended entirely on UNESCO funding and was forced to temporarily scale down activities when this ended unexpectedly in 1954. IUPN was successful in engaging prominent scientists and identifying important issues such as the harmful effects of pesticides on wildlife but not many of the ideas it developed were turned into action; this was caused by unwillingness to act on the part of governments, uncertainty about the IUPN mandate and lack of resources. In 1956, IUPN changed its name to International Union for Conservation of Nature and Natural Resources. Increased profile and recognition: 1956–1965 In the 1950s and 1960s Europe entered a period of economic growth and formal colonies became independent. Both developments had impact on the work of IUCN. Through the voluntary involvement of experts in its Commissions IUCN was able to get a lot of work done while still operating on a low budget, it established links with the Council of Europe. In 1961, at the request of United Nations Economic and Social Council, the United Nations Economic and Social Council, IUCN published the first global list of national parks and protected areas which it has updated since.
IUCN's best known publication, the Red Data Book on the conservation status of species, was first published in 1964. IUCN began to play a part in the development of international treaties and conventions, starting with the African Convention on the Conservation of Nature and Natural Resources. Environmental law and policy making became a new area of expertise. Africa was the focus of many of the early IUCN conservation field projects. IUCN supported the ‘Yellowstone model’ of protected area management, which restricted human presence and activity in order to protect nature. IUCN and other conservation organisations were criticized for protecting nature against people rather than with people; this model was also applied in Africa and played a role in the decision to remove the Maasai people from Serengeti National Park and the Ngorongoro Conservation Area. To establish a stable financial basis for its work, IUCN participated in setting up the World Wildlife Fund
A near-threatened species is a species, categorized as "Near Threatened" by the International Union for Conservation of Nature as that may be considered threatened with extinction in the near future, although it does not qualify for the threatened status. The IUCN notes the importance of re-evaluating near-threatened taxon at appropriate intervals; the rationale used for near-threatened taxa includes the criteria of vulnerable which are plausible or nearly met, such as reduction in numbers or range. Near-threatened species evaluated from 2001 onwards may be ones which are dependent on conservation efforts to prevent their becoming threatened, whereas prior to this conservation-dependent species were given a separate category. Additionally, the 402 conservation-dependent taxa may be considered near-threatened. Prior to 2001, the IUCN used the version 2.3 Categories and Criteria to assign conservation status, which included a separate category for conservation-dependent species. With this category system, Near Threatened and Conservation Dependent were both subcategories of the category "Lower Risk".
Taxa which were last evaluated prior to 2001 may retain their LR/cd or LR/nt status, although had the category been assigned with the same information today the species would be designated "Near Threatened" in either case. IUCN Red List near threatened species, ordered by taxonomic rank. Category:IUCN Red List near threatened species, ordered alphabetically. List of near threatened amphibians List of near threatened arthropods List of near threatened birds List of near threatened fishes List of near threatened insects List of near threatened invertebrates List of near threatened mammals List of near threatened molluscs List of near threatened reptiles List of Near Threatened species as identified by the IUCN Red List of Threatened Species
An endangered species is a species, categorized as likely to become extinct. Endangered, as categorized by the International Union for Conservation of Nature Red List, is the second most severe conservation status for wild populations in the IUCN's schema after Critically Endangered. In 2012, the IUCN Red List featured 3,079 animal and 2,655 plant species as endangered worldwide; the figures for 1998 were 1,102 and 1,197. Many nations have laws that protect conservation-reliant species: for example, forbidding hunting, restricting land development or creating preserves. Population numbers and species' conservation status can be found at the lists of organisms by population; the conservation status of a species indicates the likelihood. Many factors are considered; the IUCN Red List of Threatened Species is the best-known worldwide conservation status listing and ranking system. Over 50% of the world's species are estimated to be at risk of extinction. Internationally, 199 countries have signed an accord to create Biodiversity Action Plans that will protect endangered and other threatened species.
In the United States, such plans are called Species Recovery Plans. Though labelled a list, the IUCN Red List is a system of assessing the global conservation status of species that includes "Data Deficient" species – species for which more data and assessment is required before their status may be determined – as well species comprehensively assessed by the IUCN's species assessment process; those species of "Near Threatened" and "Least Concern" status have been assessed and found to have robust and healthy populations, though these may be in decline. Unlike their more general use elsewhere, the List uses the terms "endangered species" and "threatened species" with particular meanings: "Endangered" species lie between "Vulnerable" and "Critically Endangered" species, while "Threatened" species are those species determined to be Vulnerable, Endangered or Critically Endangered; the IUCN categories, with examples of animals classified by them, include: Extinct no remaining individuals of the species Extinct in the wild Captive individuals survive, but there is no free-living, natural population.
Critically endangered Faces an high risk of extinction in the immediate future. Endangered Faces a high risk of extinction in the near future. Vulnerable Faces a high risk of endangerment in the medium term. Near-threatened May be considered threatened in the near future. Least concern No immediate threat to species' survival. A) Reduction in population size based on any of the following: An observed, inferred or suspected population size reduction of ≥ 70% over the last 10 years or three generations, whichever is the longer, where the causes of the reduction are reversible AND understood AND ceased, based on any of the following: direct observation an index of abundance appropriate for the taxon a decline in area of occupancy, extent of occurrence or quality of habitat actual or potential levels of exploitation the effects of introduced taxa, pathogens, competitors or parasites. An observed, inferred or suspected population size reduction of ≥ 50% over the last 10 years or three generations, whichever is the longer, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on any of to under A1.
A population size reduction of ≥ 50%, projected or suspected to be met within the next 10 years or three generations, whichever is the longer, based on any of to under A1. An observed, inferred, projected or suspected population size reduction of ≥ 50% over any 10 year or three generation period, whichever is longer, where the time period must include both the past and the future, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on any of to under A1. B) Geographic range in the form of either B1 OR B2 OR both: Extent of occurrence estimated to be less than 5,000 km², estimates indicating at least two of a-c: Severely fragmented or known to exist at no more than five locations. Continuing decline, observed or projected, in any of the following: extent of occurrence area of occupancy area, extent or quality of habitat number of locations or subpopulations number of mature individuals Extreme fluctuations in any of the following: extent of occurrence area of occupancy number of locations or subpopulations number of mature individuals Area of occupancy estimated to be less than 500 km², estimates indicating at least two of a-c: Severely fragmented or known to exist at no more than five locations.
Continuing decline, observed or projected, in any of the following: extent of occurrence area of occupancy area, extent or quality of habitat number of locations or subpopulations number of mature individuals Extreme fluctuations in any of the following: extent of occurrence area of occupancy number of locations or subpopulations number of mature individualsC) Population estimated to number fewer than 2,500 mature individuals and either: An estimated continuing decline of at least 20% within five years or two generations, whichever is longer, OR A continuing decline, projected