De-extinction , or resurrection biology , or species revivalism is the process of creating organisms, which are members, or resembling extinct species, or populations of breeding organisms the. Cloning is the most widely proposed method, although selective breeding has also been proposed. Similar techniques have been applied to endangered species.
There is a significant controversy about extinction. Critics argue that efforts will be better spent preserving existing species, that the habitats required for previously extinct species to survive are too limited to ensure de-extinction, and that the evolutionary conservation benefits of these operations are questionable.
Video De-extinction
Method
Cloning
Cloning is the method discussed as an option to restore an extinct species, by extracting the core of the preserved cell from an extinct species and exchanging it into the egg of its nearest relative. These eggs can then be fed into the relative host. It is important to note that this method can only be used when preserved cells are available. This means that this is most feasible for newly extinct species.
Although de-extinction efforts have not succeeded in producing proper descendants of previously extinct species, the same process has been successfully applied to endangered species. The bull is an endangered species that has been successfully cloned, and the first survived for more than a week (the first is gaur who died two days after birth). Scientists at Advanced Cell Technology in Worcester, Massachusetts, USA extracted DNA from a buffalo cell stored in the "Frozen Zoo" at the San Diego Zoo, and transferred it into eggs from domestic livestock, a process called somatic cell transfer. Thirty embryonic hybrids are made and sent to Trans Ova Genetics, which implant fertilized eggs on domestic livestock. Two are brought to terms and delivered by the caesar section. The first hybrid was born on April 1, 2003, and the second two days later. The second was euthanized, but the first survived and, until September 2006, remained healthy at the San Diego Zoo.
Scientists from the University of Newcastle and the University of New South Wales, including Andrew French, Michael Mahony, Simon Clulow and Mike Archer reported in May 2013 the success of the extinct frog cloned Rheobatrachus silus using somatic cell nuclear transfer process. Embryos develop for several days but die. In important developments Newcastle scientists report related technologies that provide "proof of concept" to the proposal that the frozen zoo (also called the genom bank and seed bank) is an effective mechanism to provide insurance against the species extinction and loss of genetic diversity of the population. They link the cycle between de-extinction and extinction prevention for threatened animal species. Important progress is the capacity to successfully recover the live frozen embryo cells from animals that produce large yolky eggs (anamniots such as fish and amphibians) When this development combined with somatic cell nuclear transfer (SCNT) allows the genome to be recovered. Scientists show that many embryonic cells can be frozen and when combined with frozen sperm storage allows the genetic diversity of the population to be stored. With groups of vertebrates such as amphibians facing extinction crises they propose this as an effective way to prevent the extinction of temporary causes of decline can be identified and improved. The technical difference between frozen tissue samples commonly used for genetic studies (eg phylogenetic reconstruction) and those in frozen zoos is the use of cryoprotectants and a special freezing rate at the time of freezing and liquefaction.
Genome Editing
With recent advances, in sequencing and assembly of genomes, and editing of genes with CRISPR-Cas9, it is immediately possible to incorporate relevant genes from extinct species into the genomes of their closest remaining relatives. The germ cells can be edited directly, so that the eggs and sperm produced by the remaining parent species will produce offspring from extinct species, or somatic cells can be edited and transferred through the transfer of somatic cell nuclei. Because it is possible to construct and arrange the genomes of extinct organisms from highly degraded tissues, this technique allows scientists to pursue extinctions in a wider range of species, including those with no remnants that are well preserved.
While the methods needed to make the genome editing for de-extinction progressively advance, there are still some limitations. First, the older and damaged tissue of an extinct species, the more fragmented the DNA produced, making the genome assembly more challenging. In addition, close relatives should live and be raised in captivity for the insertion of edited cells. Since the close relatives are used as hosts for edited cells, the individual produced will not be exactly the same as the extinct species, but may also have relative features that still exist.
Selective breeding
Selective breeding is a process in which living relatives of extinct species are identified and specifically mated to reproduce the characteristics of extinct species. This method can recreate the characteristics of an extinct species, but the genome will be different from the original species.
The aurochs, which became extinct in 1627, may be brought back by taking DNA samples from bones and tooth fragments at the museum to obtain genetic material to recreate its DNA. The researchers will then compare DNA with modern European cows to determine which breed still carries the creature's genes, and then perform a selective breeding program to reverse the evolutionary process. The intention is that with every passing generation, the cattle will be more like the ancient auroch.
Quagga, a sub-species of zebra that has been extinct since the 1880s, has been revived using a selective zebra breeding. Since new animals are not genetically identical to an extinct subspecies, this new animal is called Rau quagga.
Chelonoidis elephantopus , an extinct turtle, originally found in the Galapagos Islands by Charles Darwin, has the hope of being revived through selective breeding. A group of scientists has collected more than 1,700 blood samples from a turtle on Isabela Island during an expedition in 2012 after identifying 80 turtles with traces of an extinct species DNA.
Maps De-extinction
Arguments
Arguments against de-extinction
Opponents of extinction have claimed that the efforts and resources used to revive extinct species could be better used trying to preserve endangered species that may themselves become extinct. Featuring in the journal Life Sciences, Society and Policy, a 2014 article states that the cost of reviving just one species can reach millions of dollars. At the same time, more than 20,000 species are currently threatened with extinction.
In some cases, the negative impacts on extant species can be very direct. For example, it is proposed that Asian elephants will act as surrogate moms for hairy mammary embryos. The Asian elephant is currently threatened with extinction, and it may be detrimental to its existence to use some of the remaining individuals to bring back other species.
It has also been noted that the resurrected species, while genetically identical to the living specimen, will not have the same behavior as its predecessors. The first animal to be brought back will be raised by the parents of a different species (fetal mother), not dead and thus have different parenting techniques and other behaviors. Another concern is that the de-blackout plan does not address the bringing back of parasites or mutualists that coexist with extinct species, which may have a powerful effect on the survival and success of the species raised.
Other scholars have published ethical concerns about extinction. In Conservation Biology, Robert Sandler argues that introducing extinct species into the environment can produce damage to modern species, as invasive species. Issues of scientific arrogance, human and animal health, and sensitive environmental ecology have been raised by the scientific community. Further research should be conducted on de-extinction to investigate the advantages and disadvantages of technology. New technology practices should be checked to prevent environmental hazards.
Arguments for de-extinction
Counter arguments have been made, however, in terms of the benefits of bringing back extinct species. Harvard geneticist George Church gave an example of the positive effect of bringing back an extinct hairy mammoth to the environment. He explained that if the newly developed mammoth hybrids were placed in areas such as Siberia and Alaska, the results could reverse the damage caused by global warming. He and his fellow researchers predicted that mammoths would eat dead grass that would allow the sun to reach the spring grass; their weight will allow them to break through the thick snow that isolates so cold air reaches the ground; and their characteristics from tree felling will increase the absorption of sunlight. If the theory proves true, global warming may eventually diminish.
Scientific American, in editorial condemnation of decomposition, suggests that the technologies involved can have secondary applications, particularly to help species on the verge of extinction regain their genetic diversity, such as black-eyed or black-and-white rhinoceros. He noted, however, that such research "should be carried out under the mantle preserving modern biodiversity rather than conjuring up extinct species from graves."
It has been argued that revived species can be used as a tool to support other conservation initiatives by acting as "prime species" - charismatic organisms that generate popular support and funds to conserve the entire ecosystem. Throughout this vein, it is thought that generating auroch will enhance Europe's "rebuilding" movement, in turn, turning abandoned agricultural land into a wildlife corridor. De-extinction will act as a kind of "prime technology" in which excitement is driven from the possibility of seeing extinct species in the wild strengthening the focus on ecosystem preservation. Similarly, environmental conservation Josh Donlan claims that if passenger pigeons are raised, there will be a legal boost for habitat protection under the Endangered Species Act.
Current candidate for de-extinction
Hairy Mammoth
The presence of remnants of soft tissue preserved and hairy mammoth DNA has led to the idea that species can be recreated in scientific ways. Two methods have been proposed to achieve this. The first is cloning, which will involve the removal of female elephant female stem cells containing DNA, and replacement with the nucleus of the hairy mammoth tissue. The cell will then be stimulated into a divisor, and put back into the female elephant. The resulting calf will have a hairy mammoth gene, although the environment of the fetus will be different. Until now, even the most intact mammoths have little DNA that can be used because of its preservation conditions. Not enough to guide the production of embryos. The second method involves the artificial insemination of elephant eggs with sperm cells from the carcass of frozen mammoths. The resulting child will become a mammoth-elephant hybrid, and the process must be repeated so that more hybrids can be used in breeding. After several generations of hybrid cross breeding, almost pure-haired mammoths will be produced. The fact that modern mammalian sperm cells are very strong for 15 years after a deep freezing is a hindrance to this method. In one case, an Asian elephant and African elephant produced a live calf named Motty, but died of a defect at the age of less than two weeks. In 2008, a Japanese team found DNA that could be used in the brains of mice that had been frozen for 16 years. They hope to use similar methods to find usable mammoth DNA. In 2011, Japanese scientists announced plans to clone mammoths within six years. Because the mammoth's giant genome has been mapped, complete DNA strands can be synthesized in the future.
Mammoth expert Adrian Lister questions the ethics of the recreation effort. In addition to technical issues, he noted that not many remaining habitats would be suitable for hairy mammoths. Because the species is gregarious, making some specimens will not be ideal. He also noted that the time and resources needed would be enormous, and that the scientific benefits would not be clear; these resources should be used to preserve endangered species of elephants. However, it was reported in March 2014 that blood recovered from frozen mammoth carcasses in 2013 now gives "a high chance" to clone a hairy mammoth, despite previous obstacles. Another way to revive hairy mammoths is to migrate genes from the mammoth genome into genes from their closest closest relative, the Asian elephant, to create a hybrid animal with an important adaptation that it has to live in a much colder environment than modern day. elephant. This is currently being done by the Harvard geneticist, George Church, and they have succeeded in making changes to the elephant genome with genes that give the wool hairy mammoth, longer blood, and extra fatty layers. A mammoth hybrid or a raised giant mammoth elephant may find a suitable habitat in the tundra and taiga forests, and may also find shelter in the Pleistocene Park, a Pleistocene remade experiment by Russian scientist Sergey Zimov to recreate the mammoth steppe, the previous mammoth habitat hairy. Although mammoths are not needed for grassland recreation, they will be very effective at doing so by clearing the bushes and forests quickly and allowing grass to colonize the area, the ability of modern Arctic megafauna that is not owned.
Pyrenean ibex
The Pyrenean ibex is one of the four original subspecies of the Spanish ibex that roam the Iberian peninsula. However, while it was abundant during medieval times, over-hunting in the 19th and 20th centuries caused its destruction. In 1999, only one woman named Celia was left to live in Ordesa National Park. The scientists caught him, took tissue samples from his ears, tied them up, then released his back into the wild, where he lived until he was found dead in 2000, was destroyed by fallen trees. In 2003, scientists used tissue samples to try to clone Celia and revive an extinct subspecies. Although it has successfully transferred nuclei from its cells into domestic goat egg cells and impregnation of 208 female goats, only one comes to terms. The ibex baby born has a lung defect, and lives only 7 minutes before suffocating from not being able to breathe oxygen. However, his birth was seen as a victory and was considered the first extinction. However, by the end of 2013, scientists announced that they will try again re-create the Pyrenean ibex. The problem to be faced, in spite of the many reproductive challenges of mammals with cloning, is that only females can be produced by cloning female Celia females, and there are no males for females to reproduce. This could potentially be mitigated by breeding female clones with the closely related Southeast Spanish ibex, and gradually creating a hybrid animal that would eventually resemble the Pyrenean ibex rather than the southeast Spanish ibex.
Aurochs
Aurochs are widespread throughout Eurasia, North Africa, and Indian subcontinent during the Pleistocene, but only the European auroch (Primigenius Bos primigenius ) that lasts until historic time. This species is particularly prominent in European cave paintings, such as Lascaux and Chauvet caves in France, and is still widespread during the Roman era, where they are used as a battle animal for entertainment, and recorded by Julius Caesar for their strength and prowess.. After the fall of the Roman Empire, however, the overhunting of aurochs by nobles and royalty caused its population to be reduced to one population in the JaktorÃÆ'³w jungle in Poland, where the last wild aurochs, a woman, died of natural causes in 1627. However, since auroch is an ancestor of cow breeds most modern and has close relatives in primitive cattle breeds, it is possible for that (or a shallow ecological substitute) to be brought back through artificial selection. The first attempt at this is with Heinz and Lutz Heck using modern cow breeds, which resulted in the creation of Heck's cattle. This breed has been introduced to sanctuaries across Europe; However, it differs greatly from aurochs both in physical characteristics and behavior, and modern attempts have been made to make animals almost identical to aurochs in morphology, behavior, and even genetics. The TaurOs project aims to recreate auroch through the breeding of primitive cattle breeds selectively for twenty years to create a self-sufficient cattle herd in a herd of at least 150 animals in natural areas that are reforested throughout Europe. The organization is partnering with the Rewcing Europe organization to help restore balance to the European realm. A competing project to recreate auroch is the Uruz Project by the True Nature Foundation, which aims to recreate auroch through more efficient breeding strategies and through genome editing, to reduce the number of breeding generations required and the ability to quickly eliminate undesired traits from the population new aurochs. It is hoped that the new auroch will revive the nature of Europe by restoring its ecological role as a key species, and bringing back the lost biodiversity after the decline of European megafauna, as well as helping bring new economic opportunities associated with the European wildlife outlook.
Quagga
The Quagga is a subspecies of a different zebra plain because it is streaked in the face and upper body, but the back of its belly is dark brown. It originated in South Africa, but was destroyed in the wild by too much hunting for sport, and the last individual died in 1883 at the Amsterdam zoo. However, since technically the same species as the surviving zebra plains, it has been argued that quagga can be revived through artificial selection. The Quagga project aims to create quagga through the artificial selection of the zebra plains, and aims to release these animals to the western promontory after animals fully resembling quagga are achieved, which can have the benefit of eradicating non-native trees. By 2014, the project has 110 zebra plains in 10 locations for selective nurseries, and individuals begin to show lineage and brownish downs, due to project success. In 2016, there are 6 rau quaggas produced through selective marriage. These animals appear identical to quagga but may have different genetic codes.
Thylacine
Thylacine comes from the continent of Australia, Tasmania, and New Guinea. It is believed to have gone extinct in the 20th century. Thylacines have become extremely rare or extinct on the Australian mainland before British settlements on the continent, but the Thylacine survives on Tasmania along with several other endemic species, including the Tasmanian devil. Intensive hunting that is driven by grace is generally blamed for its extinction, but other contributing factors may be disease, dog recognition, and human encroachment into its habitat. Although the official classification is extinct, sightings are still being reported, although none have been proven convincingly. The last known thylacine tree died at the Beaumaris Zoo in Hobart, Tasmania, on September 7, 1936. It is believed to have died as a result of negligence - locked away from the sheltered bed, exposed to the rare occurrence of extreme weather of Tasmania. : extreme heat during the day and freezing temperatures at night. National Threatened Species Day has been held annually since 1996 on September 7 in Australia, to commemorate the latest officially recorded death of the Tasmanian tiger. Although there has been a conservation movement that suppressed thylacine protection since 1901, partly driven by increasing difficulty in obtaining specimens for overseas collections, political difficulties prevented all forms of protection from taking effect until 1936.
The official protection of the species by the Tasmanian government was introduced on 10 July 1936, 59 days before the last specimen known to die in captivity. The Thylacine held the status of an endangered species until the 1980s. The international standard at the time declared that an animal could not be declared extinct until 50 years had passed without a confirmed record. Since no definitive proof of the existence of the Thylacine in the wild has been obtained for more than 50 years, it fulfilled official criteria and was declared extinct by the International Union for Nature Conservation in 1982 and by the Tasmanian government in 1986. This species was removed from Appendix I of The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) by 2013.
The Australian Museum in Sydney started a cloning project in 1999. The aim was to use genetic material from specimens taken and preserved early in the 20th century to clone new individuals and return species from extinction. Some molecular biologists have rejected this project as a public relations act and its main supporter, Mike Archer, received a 2002 nomination for the Australian Skeptics Bent Spoon Award for "the most unreasonable paranormal or pseudo-scientific piece." By the end of 2002, researchers had some success because they were able to extract DNA replicas from specimens. On February 15, 2005, the museum announced that the project was discontinued after tests showed DNA taken from a specimen had been poorly degraded for use. In May 2005, Archer, the University of New South Wales University Science Dean at the time, former director of the Australian Museum, and evolutionary biologist, announced that the project was restarted by a group of interested universities and a research institute. The International Thylacine Specimen Database was completed in April 2005, and is the culmination of a four-year research project for catalogs and digital photographs, where possible, all material of surviving thylacine specimens stored in museums, universities and private collections. Master's notes are held by the Zoological Society of London. In 2008, researchers Andrew J. Pask and Marilyn B. Renfree from the University of Melbourne and Richard R. Behringer from the University of Texas at Austin reported that they managed to restore the functionality of the Col2A1 enhancer gene obtained from thylacine tissue ethanol-remains 100 years from museum collections. Genetic material was found to work in transgenic mice. This study raises hopes for restoring the thylacines population. In the same year, another group of researchers managed to sequence the complete mitochondrial genome from two museum specimens. Their success indicates that it may be feasible to sequence a complete thylacine nuclear genome from museum specimens. Their results were published in the journal Genome Research in 2009.
Merpati passenger
Source of the article : Wikipedia
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