Ex situ conservation

Ex situ conservation (lit. 'off-site 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
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.[4] Similarly there are approximately 2,000 botanical gardens in 148 counties cultivating or storing an estimated 80,000 taxa of plants.[5]
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.
Seed banking
The storage of seeds in a temperature and moisture controlled environment. This technique is used for taxa with orthodox seeds that tolerate desiccation. Seed bank facilities vary from sealed boxes to climate controlled walk-in freezers or vaults. Taxa with recalcitrant seeds that do not tolerate desiccation are typically not held in seed banks for extended periods of time.
Field gene banking
An extensive open-air planting used maintain genetic diversity of wild, agricultural, or forestry species. Typically species that are either difficult or impossible to conserve in seed banks are conserved in field gene banks. Field gene banks may also be used grow and select progeny of species stored by other ex situ techniques.
Cultivation collections
Plants under horticultural care in a constructed landscape, typically a botanic garden or arboreta. 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. These collections are susceptible to hybridization, artificial selection, genetic drift, and disease transmission. Species that cannot be conserved by other ex situ techniques are often included in cultivated collections.
Inter situ
Plants are under horticulture care, but the environment is managed to near natural conditions. This occurs with either restored or semi-natural environments. This technique is primarily used for taxa that are rare or in areas where habitat has been severely degraded.
Tissue culture (storage and propagation)
Somatic tissue can be stored in vitro for short periods of time. This is done in a light and temperature controlled environment that regulates the growth of cells. As an ex situ conservation technique tissue culture is primary used for clonal propagation of vegetative tissue or immature seeds. This allows for the proliferation of clonal plants from a relatively small amount of parent tissue.
Techniques for animals
Endangered animal species and breeds are preserved using similar techniques.
A potential technique for aiding in reproduction of endangered species is
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.[9] During the initial growth phase, the population size is rapidly expanded until a target population size is reached.[10] 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.[10] The number of individuals required to meet this goal varies based on potential growth rate, effective size, current genetic diversity, and generation time.[9] Once the target population size is reached, the focus shifts to maintaining the population and avoiding genetic issues within the captive population.[10]
Minimizing mean kinship
Managing populations based on minimizing mean kinship values is often an effective way to increase genetic diversity and to avoid inbreeding within captive populations.[10] Kinship is the probability that two alleles will be identical by descent when one allele is taken randomly from each mating individual. The mean kinship value is the average kinship value between a given individual and every other member of the population. Mean kinship values can help determine which individuals should be mated. In choosing individuals for breeding, it is important to choose individuals with the lowest mean kinship values because these individuals are least related to the rest of the population and have the least common alleles.[10] This ensures that rarer alleles are passed on, which helps to increase genetic diversity. It is also important to avoid mating two individuals with very different mean kinship values because such pairings propagate both the rare alleles that are present in the individual with the low mean kinship value as well as the common alleles that are present in the individual with the high mean kinship value.[10] This genetic management technique requires that ancestry is known, so in circumstances where ancestry is unknown, it might be necessary to use molecular genetics such as microsatellite data to help resolve unknowns.[9]
Avoiding loss of genetic diversity
Genetic diversity is often lost within captive populations due to the founder effect and subsequent small population sizes.[10] Minimizing the loss of genetic diversity within the captive population is an important component of ex situ conservation and is critical for successful reintroductions and the long term success of the species, since more diverse populations have higher adaptive potential.[9] The loss of genetic diversity due to the founder effect can be minimized by ensuring that the founder population is large enough and genetically representative of the wild population.[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. An alternative to this is collecting sperm from wild individuals and using this via artificial insemination to bring in fresh genetic material.[11] 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.[10] Minimizing the number of generations in captivity is another effective method for reducing the loss of genetic diversity in captive populations.[10]
Avoiding adaptations to captivity
Selection favors different traits in captive populations than it does in wild populations, so this may result in adaptations that are beneficial in captivity but are deleterious in the wild.[10] This reduces the success of re-introductions, so it is important to manage captive populations in order to reduce adaptations to captivity. Adaptations to captivity can be reduced by minimizing the number of generations in captivity and by maximizing the number of migrants from wild populations.[10] Minimizing selection on captive populations by creating an environment that is similar to their natural environment is another method of reducing adaptations to captivity, but it is important to find a balance between an environment that minimizes adaptation to captivity and an environment that permits adequate reproduction.[10] Adaptations to captivity can also be reduced by managing the captive population as a series of population fragments. In this management strategy, the captive population is split into several sub-populations or fragments which are maintained separately. Smaller populations have lower adaptive potentials, so the population fragments are less likely to accumulate adaptations associated with captivity. The fragments are maintained separately until inbreeding becomes a concern. Immigrants are then exchanged between the fragments to reduce inbreeding, and then the fragments are managed separately again.[10]
Managing genetic disorders
Examples
The
The Orange-bellied parrot, with a wild population of 14 birds as of early February 2017,[15] are being bred in a captive breeding program. The captive population consists of around 300 birds.[16]
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
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.
See also
- Artificial insemination
- Asiatic cheetah
- Captive breeding
- Cloning
- Conservation biology
- Convention on Biological Diversity
- Cryoconservation of animal genetic resources
- De-extinction
- Embryo transfer
- Endangered species
- Frozen zoo
- Genetic erosion#Ex situ conservation
- Intracytoplasmic sperm injection
- Introduced species
- In vitro fertilisation
- IUCN Red List
- List of animals that have been cloned
- List of introduced species
- Pleistocene Park
- Reintroduction
- Wildlife conservation
- World Conservation Union(IUCN)
References
- ^ "IUCN Species Survival Commission Guidelines on the Use of Ex situ Management for Species Conservation" (PDF). IUCN. 2014. Retrieved 27 May 2016.
- ^ "Convention on Biological Diversity" (PDF). United Nations. 1992. Retrieved 27 May 2016.
- ^ Ramanatha Rao, V.; Brown, A. H. D.; Jackson, M. (2001). Managing plant genetic diversity. CABI. p. 89.
- ^ Guerrant, Edward; Havens, Kayri; Maunder, Mike (2004). Ex situ plant conservation: supporting species survival in the wild. Island Press. p. 91.
- ^ Guerrant, Edward; Havens, Karyi; Maunder, Mike (2004). Ex situ plant conservation: supporting species survival in the wild. Island Press. pp. 10–11.
- ^ FAO. 2012. Cryoconservation of animal genetic resources. FAO Animal Production and Health Guidelines. No. 12. Rome.
- S2CID 20825507.
- PMID 10729070.
- ^ a b c d e f Kleiman, Devra; Thompson, Katerina; Baer, Charlotte (2010). Wild Mammals in Captivity: Principles and Techniques for Zoo Management. University of Chicago Press.
- ^ ISBN 978-0-521-70271-3.
- ^ "Zoo elephant conceived with wild male's frozen sperm". BBC News. 14 August 2012.
- ^ .
- ^ Connors, P. G. (1994) Rediscovery of showy Indian clover. Fremontia 22: 3–7
- ^ U.S. Fish and Wildlife Service, Arcata Division, 1655 Heindon Road, Arcata, Ca.
- ^ "The race to save the endangered orange-bellied parrot". Australian Broadcasting Corporation. 14 February 2017. Retrieved 14 February 2017.
- ^ Pritchard, Rachel. "Update on the Orange-bellied Parrot Recovery Program" (PDF). Orange-bellied Parrot Recovery Team. Retrieved 6 August 2012.
Further reading
- Engels, J.M.M.; L. Visser, eds. (2003). A Guide to Effective Management of Germplasm Collections. CABI, IFPRI, IPGRI, SGRP. Archived from the original on 25 May 2007. 174 p.
- FAO. (2007). The Global Plan of Action for Animal Genetic Resources and the Interlaken Declaration. Rome.
- FAO. (2015). The Second Report on the State of the World's Animal Genetic Resources for Food and Agriculture. Archived 18 September 2018 at the Wayback Machine Rome.
- Guerrant, Edward O.; Havens, Kayri; Maunder, Mike, eds. (2004). Ex situ plant conservation: supporting species survival in the wild. Island Press.
- Kameswara, N.; J. Hanson; M. E. Dulloo; K. Ghosh; A. Nowell; M. Larinde. Manual of Seed Handling in Genebanks. Bioversity International, CTA (Technical Center for Agricultural and Rural Cooperation), FAO, ILRI. Archived from the original on 21 January 2008. 147 p.
- Koo, B.; Pardey, P. G.; Wright, B. D.; et al. (2004). Saving Seeds. CABI, IFPRI, IPGRI, SGRP. Archived from the original on 11 December 2008.
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