Invasive Species Notes
what are types of conservation?
In situ: -Conservation of species in their natural habitat -E.g. natural parks, nature reserves Ex situ: -Conserving species in isolation of their natural habitat -E.g. zoos, botanical gardens, seed banks -First the area that is suitable for the creation of a reserve has to be identified and delimited -This requires surveys to collect data on key species -Property may have to be expropriated -A legal framework may need to be set up to control human activities in the area and in it’s immediate surroundings -Policing the area may also be necessary -If part of the area has been degraded due to bad land use it may need restoring -Alien species that have penetrated the area may need excluding or eliminating -Constant management will be needed to maintain the habitat of the species being conserved -This may mean arresting natural succession |
what are the advantages and disses?
-The species will have all the resources that it is adapted too -The species will continue to evolve in their environment -The species have more space -Bigger breeding populations can be kept -It is cheaper to keep an organism in its natural habitat -It is difficult to control illegal exploitation (e.g. poaching) -The environment may need restoring and alien species are difficult to control -The Hawaiian goose was practically extinct in the wild -12 birds were taken into captivity -A population of 9000 was released back into the wild -The experiment failed because the original cause rats had not been eliminated. -The rats eat the eggs and the nestlings of the geese -Captive breeding of endangered species is a last resort -These species have already reached the point where their populations would not recover in the wild -It works well for species that are easily bred in captivity but more specialised animals are difficult to keep (aye aye) -Isolated in captivity they do not evolve with their environment -They have a very small gene pool in which to mix their genes -Inbreeding is a serious problem -Zoos and parks try to solve this by exchanging specimens or by artificial insemination where it is possible -In vitro fertilisation and fostering by a closely related species has even been tried (Indian Guar – large species of cattle - cloned) -Even if it is possible to restore a population in captivity the natural habitat may have disappeared in the wild -Species that rely on this much help are often considered to be “the living dead” -Seeds can be maintained for decades or even centuries if the conditions are controlled -<5% humidity and –20°C -Not all species are suited to this treatment -Seeds need to be regularly germinated to renew stock or the seeds will eventually loose their viability -Seed banks are at risk from power failure, natural disasters and war -Duplicate stocks can be maintained -Seeds kept in seed banks do not evolve with changes in the environment what things we do to maintain? -CITES (The Convention in International Trade in Endangered Species) -Set up in 1988 to control and encourage the sustainable exploitation of species -The CITES conferences determine the status of a species and whether or not its exploitation requires regulation -Species are placed into different appendices depending on their status |