Ex situ conservation
'off-site conservation') is the process of protecting an endangered species, variety, or breed of plant or animal outside its natural habitat.
[1][2] 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.
This is primarily in the form of gene banks where samples are stored in order to conserve the genetic resources of major crop plants and their wild relatives.
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.
Technical limitations prevent the cryopreservation of many species, but cryobiology is a field of active research, and many studies concerning plants are underway.
Seed bank facilities vary from sealed boxes to climate controlled walk-in freezers or vaults.
This technique is similar to a field gene bank in that plants are maintained in the ambient environment, but the collections are typically not as genetically diverse or extensive.
[6] 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.
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.
[10] The number of individuals required to meet this goal varies based on potential growth rate, effective size, current genetic diversity, and generation time.
[10] This is often difficult because removing large numbers of individuals from the wild populations may further reduce the genetic diversity of a species that is already of conservation concern.
[12] 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.
[12] Preventing certain individuals from the breeding also reduces the effective population size, which is associated with problems such as the loss of genetic diversity and increased inbreeding.
[10] Showy Indian clover, Trifolium amoenum, is an example of a species that was thought to be extinct, but was rediscovered in 1993[13] in the form of a single plant at a site in western Sonoma County.
[16] Ex situ conservation, while helpful in humankind's efforts to sustain and protect our environment, is rarely enough to save a species from extinction.
In the case of cryogenic storage methods, the preserved specimen's adaptation processes are (quite literally) frozen altogether.
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.
