Methods of Conserving Biodiversity Flashcards
Selecting species for captive breeding
Are there a lot of genetically diverse specimen?
Can they be conserved in situ?
Could they breed in captivity?
Is there a suitable place to release them?
Difficulties with keeping species in captivity
Habitat size provided may not be adequate, food requirements may be difficult to meet, natural species interrelationships may be difficult to recreate, expensive, difficult to provide optimum conditions for breeding, gene pool size may be small.
Why have many species kept in captivity not bred successfully?
Difficult to recreate abiotic conditions for breeding, population interactions, breeding habitat or gene pool size may be small.
Conditions for breeding
For many, precise timing is vital to increase survival chances of young, AND breeding is triggered by stimuli (such as day length, light level, temperature, food amount, etc) SO if these conditions are not known/ provided, there will be limited breeding.
Breeding habitat
Some species can only breed if they have a suitable habitat, such as a site for social grouping, courtship displays, etc.
For example, flamingos only breed in large groups, so mirrors are used to give a captive population the illusion of a larger population
Population interactions
In wild, many breeding pairs of birds may choose isolation, while non-breeding individuals may live elsewhere. IN CAPTIVITY, the mix of breeding and non-breeding may cause conflict, reducing egg and chick survival chances.
Gene pool size
Most captive breeding populations have smaller gene pools, the risk of inbreeding; harmful recessive genes can be passed to offspring if both parents carry the gene. In most cases, this is rare, but captive breeding programs do often use closely related individuals.
TO COUNTERACT- stud bbok created to keep record of family trees, eg Marwell zoo has the Scimiter-horned Oryx book
Hybridisation
Species include individuals that naturally interbreed to produce fertile offspring, in captivity, however, individuals may interbreed with closely related species or varieties that would not have naturally met in the wild.
CAN BE PREVENTED in animals, if kept apart, BUT it is a problem with plants where pollen can be carried between plants (by insects/ wind).
The problem with hybridisation is…
Offspring produced have a combo of characteristics not found in those produced by natural breeding, which means they will have NO CONSERVATION value because they are different from wild populations and may not be as well adapted for survival.
Methods of increasing breeding success
Cyropreservation, artificial insemination, embryo transfer, plant micropropogation
Cyropreservation
One method of increasing breeding success.
Storage of eggs, semen, embryos by freezing and these are then used in artificial breeding processes.
BENEFITS: can be transported over long distances, cost-effective, parents never have to meet, can be stored for long periods.
Artificial Insemination
Sample of sperm is treated to remove impurities and dead/ slow sperm, concentrated sample of healthy sperm is then passed into the uterus via a catheter, increasing efficiency etc.
Embryo Transfer
If low numbers of females in a species captive population, then their eggs can be harvested and fertilised via IVF, then implanted in another female of a more common and closely related species.
Micropropagation of plants
This is taking tissue cultures of plants and growing them in hormone rooting powder; cell clusters are then taken from plant tissue, and each cell cluster is grown into a plant (many from one parent). ALL PLANTS PRODUCED ARE GENETICALLY IDENTICAL.
Cloning
Embryos are produced by transferring a nucleus from a stem cell of an endangered species into an empty egg of a closely related species, which is then implanted into a female of a closely related species for gestation.
Cloning is not yet successful in wild species but…
It could be possible to clone from deep frozen stem cells in the future (even after extinction), which could bring back endangered species like the northern white rhino.
CLONING CAN PREVENT HYBRIDISATION (particularly in plant species) AND MAINTAIN PURE POPULATION.
To release new animals into the wild, there would have to be a suitable habitat
There would have to be enough room, food, water and breeding sites; legal protection of the habitat and enough humans nearby to support the animal if needed.
Hard release
Is releasing individuals with no post release support, which is used with species whose behaviour is controlled by instinct because they don’t need to learn survival techniques.
USED WITH INSECTS, FISH, AMPHIBIANS, REPTILES.
Soft release
Is releasing individuals with post-release support, such as gradual release into larger areas and provision of food, which is used with species whose behaviour is NOT controlled by instinct because they must learn survival techniques.
USED WITH MAMMALS, BIRDS.
Problems with release
Animals in captivity often display a loss of natural behaviours needed for success in the wild, like deficiencies in foraging/hunting, social interactions, breeding and nesting, locomotory skills.
Examples of problems that released animals may have
Finding and recognising food, recognising poisonous foods, developing hunting skills, recognising and avoiding predators, being accepted into social groups.
Released predators
Captive-bred predators may not have been taught to hunt by their parents, especially if their parents were also captive bred.
released prey
Captive-bred prey may not have the fight or flight response to the correct stimuli.
