Ex situ conservation

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Ex situ conservation () is the process of protecting an endangered species, variety, or breed of plant or animal outside its natural habitat. For example, by removing part of the population from a threatened habitat and placing it in a new location, an artificial environment which is similar to the natural habitat of the respective animal and within the care of humans, such as a zoological park or wildlife sanctuary. The degree to which humans control or modify the natural dynamics of the managed population varies widely, and this may include alteration of living environments, reproductive patterns, access to resources, and protection from predation and mortality.

Ex situ management can occur within or outside a species' natural geographic range. Individuals maintained ex situ exist outside an ecological niche. This means that they are not under the same selection pressures as wild populations, and they may undergo artificial selection if maintained ex situ for multiple generations.

Agricultural biodiversity is also conserved in ex situ collections. This is primarily in the form of gene banks where samples are stored in order to conserve the genetic resources of major crops plants and their wild relatives.

Facilities

Botanical gardens, zoos, and aquariums

Botanical gardens, zoos, and aquariums are the most conventional sites for ex situ conservation, housing whole, protected specimens for breeding and reintroduction into the wild. These facilities provide not only housing and care for specimens of endangered species, but also have an educational value. They inform the public of the threatened status of endangered species and of those factors which cause the threat, with the hope of creating public interest in stopping and reversing those factors which jeopardize a species' survival in the first place. They are the most publicly visited ex situ conservation sites, with the WZCS (World Zoo Conservation Strategy) estimating that the 1,100 organized zoos in the world receive more than 600 million visitors annually. Globally there is an estimated total of 2,107 aquaria and zoos in 125 countries. Additionally many private collectors or other not-for-profit groups hold animals and they engage in conservation or reintroduction efforts. In United States, there are approximately 2,000 botanical gardens in 148 counties cultivating or storing an estimated 80,000 taxa of plants in 2004.

Techniques for plants

Cryopreservation

Plant cryopreservation consist of the storage of seeds, pollen, tissue, or embryos in liquid nitrogen. This method can be used for virtually indefinite storage of material without deterioration over a much greater time-period relative to all other methods of ex situ conservation. Cryopreservation is also used for the conservation of livestock genetics through cryoconservation of animal genetic resources. Technical limitations prevent the cryopreservation of many species, but cryobiology is a field of active research, and many studies concerning plants are underway. Animal species can be preserved in genebanks, which consist of cryogenic facilities used to store living sperm, eggs, or embryos. For example, the Zoological Society of San Diego has established a "frozen zoo" to store such samples using cryopreservation techniques from more than 355 species, including mammals, reptiles, and birds.

A potential technique for aiding in reproduction of endangered species is interspecific pregnancy, implanting embryos of an endangered species into the womb of a female of a related species, carrying it to term. It has been carried out for the Spanish ibex.

Another promising technique is isochoric vitrification, where a zygote or mature animal is frozen in vitrification solution and, when slowly thawed using a laser, produces viable organisms.

Genetic management of captive populations

Captive populations are subject to problems such as inbreeding depression, loss of genetic diversity and adaptations to captivity. It is important to manage captive populations in a way that minimizes these issues so that the individuals to be introduced will resemble the original founders as closely as possible, which will increase the chances of successful reintroductions. During the initial growth phase, the population size is rapidly expanded until a target population size is reached. The target population size is the number of individuals that are required to maintain appropriate levels of genetic diversity, which is generally considered to be 90% of the current genetic diversity after 100 years. Maximizing the captive population size and the effective population size can decrease the loss of genetic diversity by minimizing the random loss of alleles due to genetic drift. If the genetic disorder is dominant, it may be possible to eliminate the disease completely in a single generation by avoiding breeding of the affected individuals. in the form of a single plant at a site in western Sonoma County. Seeds were harvested and the species grown in ex situ facilities.

The Wollemi pine is another example of a plant that is being preserved via ex situ conservation, as they are being grown in nurseries to be sold to the general public.

The Orange-bellied parrot, with a wild population of 14 birds as of early February 2017, are being bred in a captive breeding program. The captive population consists of around 300 birds.

Drawbacks

Ex situ conservation, while helpful in humankind's efforts to sustain and protect our environment, is rarely enough to save a species from extinction. It is to be used as a last resort, or as a supplement to in situ conservation because it cannot recreate the habitat as a whole: the entire genetic variation of a species, its symbiotic counterparts, or those elements which, over time, might help a species adapt to its changing surroundings. Instead, ex situ conservation removes the species from its natural ecological contexts, preserving it under semi-isolated conditions whereby natural evolution and adaptation processes are either temporarily halted or altered by introducing the specimen to an unnatural habitat. In the case of cryogenic storage methods, the preserved specimen's adaptation processes are (quite literally) frozen altogether. The downside to this is that, when re-released, the species may lack the genetic adaptations and mutations which would allow it to thrive in its ever-changing natural habitat.

Furthermore, ex situ conservation techniques are often costly, with cryogenic storage being economically infeasible in most cases since species stored in this manner cannot provide a profit but instead slowly drain the financial resources of the government or organization determined to operate them. Seedbanks are ineffective for certain plant genera with recalcitrant seeds that do not remain fertile for long periods of time. Diseases and pests foreign to the species, to which the species has no natural defense, may also cripple crops of protected plants in ex situ plantations and in animals living in ex situ breeding grounds. These factors, combined with the specific environmental needs of many species, some of which are nearly impossible to recreate by man, make ex situ conservation impossible for a great number of the world's endangered flora and fauna.

References

External links

Cloning to revive extinct species, May 28, 2002, Grant Holloway, CNN
Reproductive Technologies and Conservation of Endangered Cats
Louisiana's frozen ark
ONLINE BOOK: In situ conservation of livestock and poultry, 1992, Food and Agriculture Organization of the United Nations and the United Nations Environment Programme
"The Challenges of Ex situ Orchid Conservation", Orchid Conservation Coalition
Botanic Gardens Conservation International – international organisation supporting ex situ conservation of priority plant species
Domestic Animal Diversity Information System
Implementing the Global Plan of Action for Animal Genetic Resources