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The koala is extinct: “It is time to do everything possible to save it”, cry scientists

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The megafires that devastated Australia’s wildlife in the so-called ‘black summer’ 2019-20 seriously endangered the survival of an iconic species of the island, the koala (Phascolarctos cinereus). A study then revealed that the devastating fires had killed more than 5,000 koalas in the state of New South Wales alonewhich led to declaring them ‘in danger of extinction‘, after a request from the country’s conservation groups, who had been denouncing their decline due to habitat destruction, climate change, and drought.

That ecological disaster led researchers to intensify captive breeding of several species, especially koalas. But there are two serious problems. The first, that breeding koalas in captivity is very expensive and it is often difficult to secure funding for breeding facilities. The second, that it is not easy to maintain genetic diversity due to inbreeding.

To face these difficulties, a group of scientists has carried out a study, published in the scientific journal publisher ‘MDPI’, which highlights the convenience of resort to frozen semen and assisted reproduction. “It is time to do everything possible to save the koala from extinction”, claim the researchers.

“Managed (captive) wildlife breeding faces high economic costs and genetic diversity challenges associated with caring for small captive populations.

The biobanks (freezing of sex cells and tissues for use in assisted reproduction) and associated reproductive technologies could help alleviate these problems in captive koala management by improving retention of genetic diversity and lowering program costs reducing the size of live captive colonies”, collects the summary of the report.

Objective, reduce inbreeding

“Genetic and economic models studying koala populations in closed captivity suggest that supplementing them with external sperm cryopreserved by artificial insemination or intracytoplasmic sperm injection could substantially reduce inbreeding”, point out the researchers.

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The idea is integrate biobanks into the network of zoos and wildlife hospitalswhich would enable “a profitable and financially feasible model for the adoption of these tools, taking advantage of the technical and research experience, the colonies of koalas in captivity and the ex situ facilities that already exist in these networks”.

External semen input would help reduce the colony sizes required for conservation breeding programs and thus greatly lower program costs.

Although genetic retention goals are ambitiousmaintaining 90% of the heterozygosity (genetic variation) of the source population for 100 years, it would be possible to achieve them “within realistic cost frameworks, with koalas suitable for release into the wild,” the text collects.

Although these reproductive tools have hardly been used for species conservation, the situation of extreme danger that koalas live has led scientists to expound the need for “explore your full potential”.

Researchers in the study compared conventional natural breeding programs with ones that mix it with frozen koala sperm from wild animals by artificial insemination or direct sperm injection.

Scientists discovered that supplementing captive breeding with frozen sperm from wild animals “would dramatically reduce inbreeding rates, produce genetically healthier animals, and require fewer animals in breeding colonies”as detailed by the authors of the study in ‘The Conversation’.

much smaller colonies

They also reveal that to reach the genetic goal, that 90% heterozygosity, 223 koalas would be needed in a conventional captive program, but only 17 with the help of assisted reproduction. The cost reduction would be enormous, as the colony is much smaller. Specific, these techniques would lead to a reduction to a fifth of the costs of executing breeding programs in captivityeven taking into account the costs of assisted reproduction, sperm freezing, and artificial insemination or sperm injection.

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“While these technologies have proven their value to us and to livestock, we have largely not put them to work in wildlife recovery. It is a lost opportunity to reduce costs and increase genetic diversity”, point out the authors, who emphasize that the few programs that adopted these techniques were successful.

Scientists encourage further research and technology development in areas such as the use of frozen sperm, embryo transfer or sperm cryopreservation. And they point out a series of “new possibilities” for the conservation of the koala:

–Using genetic material from dead or sick koalas that would otherwise be lost.

–Preserving the gene pools of koala populations genetically important species at risk of extinction.

–Protect the species against catastrophic events in nature related to climate change, disease and forest fires, which can cause great genetic loss.

–Reduce inbreeding in captive breeding programs and produce genetically fit koalas for release.

–Overcoming the problems of separated populations and ensure that desirable breeding pairs can actually reproduce.

–Address relocation issues arising from the different diets of koalas in all regions and the risk of disease transmission.

The koala is a very delicate marsupial and especially sensitive to any changes in the environmentspends about 20 hours a day dozing or resting, and uses the remaining four hours to feed on the leaves of a few dozen species of eucalyptus.

Reference report: https://www.mdpi.com/2076-2615/12/8/990/htm

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Environment section contact: crisisclimatica@prensaiberica.es

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