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There are 16,928 species currently listed as threatened, and the present world-wide extinction rate is 1,000 to 10,000 times higher than the natural rate
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Jetzt kostenlos anmeldenThere are 16,928 species currently listed as threatened, and the present world-wide extinction rate is 1,000 to 10,000 times higher than the natural rate
This is how Nature PBS opened up an article in 20091, to discuss conservation efforts during the current "Holocene" extinction.
Research and articles such as this have sparked more interest in successful breeding attempts, in order to preserve the biodiversity that is left. Do you want to better understand how breeding success works in both captivity and nature? Read on to find out!
In order to accurately measure wildlife breeding success, both the number of births and the number of fatalities must be considered.
Captive breeding or reproduction success (RS) is the reproductive output of an animal or plant species in a given area or place. In captivity, it is often defined as the number of young that are produced per mating pair. This is usually established either per breeding attempt or per lifetime.
If a pair of lions produce two cubs, but only one survives to adulthood, then the breeding success for that pair would be 50%.
Vulnerability to poaching and habitat destruction in parts where protection laws are not enforced are among the reasons why a species is not able to thrive or survive in the wild. These threats can make captive breeding more successful by comparison.
Breeding success needs to stand the test of wilderness, where the reintroduced individuals can continue to survive and reproduce. In some cases, breeding success in the wild may not be possible anymore.
Panama had a Batrachochytrium dendrobatidis fungus epidemic, which nearly wiped out the endemic Atelopus zeteki golden frogs. There are only 1500 specimens remaining in captivity, and it is thought they disappeared from the wild. Captive breeding saved the species from extinction in this instance.
The most expensive but widely known captive programme was the attempt to save the Californian condor from extinction. The programme started in 1987 with the capturing of 22 individuals thought to be the last remaining specimens. There are about 500 Californian condors to date, making them critically endangered.
One species even managed to keep its numbers up in the wild, as well as in captivity. Did you know that domestic chickens are a breeding success story?
The domestic chicken has specific reproductive cycles that they inherited from their ancestors, the Red junglefowl. The wild species still survives today, and it doesn't look all that different either! By providing food at all times, humans took advantage of and "hacked" their reproductive disposition, which was linked to the rare flowering events of bamboo forests in South-East Asia.
Research, funding and public interest are the first steps toward positive reproduction efforts.
The red hemp Galeopsis angustifolia is a type of flowering plant that used to be common in southern England and Wales. it is critically endangered, so the Royal Agricultural University (RAU) is currently attempting to rehabilitate it by growing and reintroducing it in the wild.
General factors affecting breeding success include biological (parental quality), group dynamics, as well as environmental (size of habitat or enclosure).
Parental quality is typically based on their health and fitness level. Animals may have various ways through which they display mate selection behaviours.
It includes, but is not limited to, the brightness and colourization preferences of feathers in the case of Indian peafowls or Capercaillies, aggression and dominance such as in the case of elephant seals, or male pheromones, like in Drosophila flies, or song patterns, such as in whales.
Group dynamics influence the mating behaviour in individuals and drive competition and social hierarchies. Humpback whales are most well known for being able to produce sounds underwater in intricate patterns of "songs". These songs may last more than 30 minutes and be repeated by males for days or weeks during the mating season. This breeding behaviour is matched by their group dynamics. The whales have layered hierarchical structures and the ability to learn through the social observations of their peers. This influences the males' songs in adulthood.
Our human perception of colours, smells and sounds is drastically different from that of some other species!
Most songbirds can see ultraviolet light. The UV light reflected by the feathers of an individual impacts bird mating choices. Canids (mammals of the dog family, such as wolves) can smell reproductive pheromones over long distances, which they use to track down potential partners.
The exact formula for breeding success is not actually known for the majority of plant and animal species. Some species, which we will go into more detail about below, have not bred in captivity yet. Critical information about their breeding strategies in the wild remains essential to breeding programmes.
Some of the most important human-mediated factors in breeding projects are the socio-economic factors.
The reintroduction of Californian condors, a programme which hasn't ended yet, has cost over 35 million dollars.
Food availability is an important part of reproduction.
The Colchester zoo wrote in 2020 that it costs them around "£30 to feed one sea lion and £35 to feed one chimpanzee" per day. This is without being fed the native food that they would come across in the wild. Instead, they are fed with what can be procured in the British Isles that satisfies their nutritional needs.
The coordination of different individuals and organizations, as well as nations, in their breeding efforts, is usually key to the survival of certain species.
In breeding pandas, the cooperation of multiple zoos around the world is needed due to their lack of reproductive enthusiasm in captivity.
Genetic manipulation and artificial insemination possibilities are great influencing factors in the breeding success of captive species.
A minimum number of “founders” is needed: 20-30 are selected. The individuals must be selected to avoid inbreeding.
Breeding methods are considered: they may include artificial insemination and implanting embryos from a threatened species into a least-concern species. This means that the young animal develops in and will be fed by a surrogate mother. Cloning has recently also been suggested to bring extinct species such as the Tasmanian tiger back to life.
The procedure is performed according to the required medical-veterinary standards.
Artificial insemination is typically the least expensive form of artificially breeding both wild and husbandry animals (livestock), often being preferred instead of natural mating if the species is facing imminent extinction. The process involves collecting sperm from a male animal and then artificially introducing it into the reproductive tract of a female. This can be done using either artificial vaginal insemination or artificial intrauterine insemination. Artificial insemination can also ensure that only offspring with desired characteristics are born - useful if the animals are kept in groups and not given contraceptives.
On the other end, embryo implantation is among the most expensive viable methods, with cloning still in research.
This table summarizes what elements people can't easily influence in the breeding success of some species:
| Characteristic | Examples |
| Size of the habitat or enclosure | Cheetahs require large territories for movement and genetic diversity to mate successfully, both difficult to achieve in captivity. |
| Food requirements | Food items such as zoo- and phytoplankton are more difficult to grow or obtain, and therefore animals requiring them may not be fit for captive breeding, e.g. the whale shark. |
| Interrelationships between species | Most plants (flowers, trees, etc.) associate with symbiotic mycorrhizal fungi and root bacteria, but some of these soil symbiotic conditions are highly specific and cannot be accurately recreated. |
| (Other) Mating behaviour | Blue whales Balaenoptera musculus reach 30 m in length and typically dive to abyssal depths between 3 and 6 km beneath the water surface as part of their mating ritual. |
| Climate change | Soil and water acidity, rainfall patterns and temperatures influence the immune system and skin microbiota of tropical amphibian species.2 |
Additionally, special analysis techniques such as infrared (nighttime) cameras and electronic devices with chemical sensors, allow us to "see" into their world and measure their reproductive ability more accurately.
One of the most important factors of breeding success remains the reproductive health of individuals!
The endocrine and reproductive systems of many species are in relative homeostasis (equilibrium) with their environment and environmental conditions.
Delayed implantation refers to the ability of different animals to delay fecundation and/or embryonic growth. This allows mating and parturition (giving birth) to occur at the most convenient times of the year.
Over 100 mammals, such as bears, have actively evolved this mechanism. This could be an ancestral dormant trait of all mammals (including humans) according to some hypotheses.3
Desirable conditions for reproductive (breeding) success include water pH, air and water temperature, the ability to find mates over long distances, or the species' ability to accumulate fat stores and reserves as influenced by food availability.
Mate selection for breeding success influences gene expression to such a degree, that it sometimes overrides other selection factors.
In primate species such as chimpanzees, there is a significant difference in canine size between male and female, despite meat usually making up only up to 10% of their diet. Numerous studies suggest that this is because the length of canines is an important part of the sexual selection and reproductive success of male chimpanzees.4
The reasons why breeding success is important sometimes includes unexpected answers.
Breeding success brings moral benefits to the group of people or societies who enable it, strengthening the science in the field and ecological knowledge.
Important ecosystems would be gone without certain species, for example, African savannahs would shrink in size without its largest grazers, the elephants, as they eat or trample trees, stopping them from forming forests.
Natural resources such as food sources, medicine, and jewellery would be difficult to obtain if their sources wouldn't be able to breed successfully, for example, fish roes, horseshoe crab blood or abalone shells.
In Scotland, re-wilding plans made possible by breeding programmes include the reintroduction of Eurasian lynxes, beavers, grey wolves and bison, in an effort to rehabilitate landscapes and promote forest health.
The Highland Wildlife Park of Scotland currently has a herd of European bison.
Living organisms are important climate change mediators through their participation in the planetary cycles. Moreover, a more diverse ecosystem and its genetic diversity make for a resilient “natural entity”.
Breeding in captivity can alter an animal's phenotype over generations.
If an animal has evolved a beak adapted to cracking hard seeds and nuts but it and its progenitors are fed soft food instead, its beak might once again change over time, and certain genes could even be lost.
Phenotype represents the observable characteristics such as break length, height and colour of an individual, and is a result of the inherited genes from their parents combined with the influence of the environment on those genes (environmental pressure).
After short-haired domestic pigs are released into the wild, each subsequent generation starts to develop longer hair as a protective mechanism against abrasion, cold, or predation.
It is likely for a species that is bred in captivity only to adapt to captive conditions over a few generations, or even start to become domesticated.
Captive animals also display changed behaviours and usually need time to readapt to wildlife conditions.
Animals may prefer to mate with other previously captive individuals like themselves rather than with wild individuals.
Breeding success is a rather intricate topic, as most of us don't think it can get this complicated! Wildlife species will have developed unique mating displays and preferences in order to cope with the challenges that their environments bring. Most of the time, they also perceive potential mates differently from us, in terms of smell, sight, as well as sounds, and many more, depending on their biology.
Breeding success is the reproductive output of an animal or plant species, often defined as the number of young that are produced per mating pair.
Breeding success is influenced by habitat or enclosure size, nutritional requirements, mating preferences, climate change, and other environmental conditions such as temperature, water pH, rainfall patterns, etc.
Breeding success examples include the domestic chicken, the Californian condor, and the Panama golden frogs.
The importance of breeding success is that it preserves genetic resources, enhances scientific knowledge and a community's morale, and prevents trophic collapses.
Changes that occur in breeding include genetic changes such as beak or body size, or behavioural changes, such as domestication.
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SIGNUP SIGNUPFlashcards in Breeding Success15
Start learningWhat does RS mean?
Reproductive success
Which simple way accurately measures wildlife breeding success?
Number of births and number of deaths.
What is the breeding success rate in percentages in a pair that produces 6 offspring but only 3 survive?
50%
What anthropogenic factors can make captive breeding more successful than breeding in the wild?
Poaching, habitat destruction, deforestation, etc.
Which animals are prone to emerging fungal diseases that prevent them from reproducing in the wild?
South-American poison dart frogs
What animal did the most expensive breeding programme successfully save from extinction?
Californian condor
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