A zebra shark (Stegostoma fasciatum) inwards Commonwealth of Australia has acquire the kickoff recorded representative of a shark switching from sexual to asexual reproduction.
In Apr final year, Leonie gave nascence to iii pups called Cleo, CC, in addition to Gemini inwards a Queensland aquarium. This sugariness but otherwise unremarkable tale would accept gone unnoticed past times the scientific discipline globe if it weren't for 1 fundamental detail: Leonie hadn't mated amongst a manlike mortal shark since 2012.
Her previous breeding partner, Leo – amongst whom she had produced to a greater extent than than twenty offspring – was moved to a novel tank at the aquarium inwards 2013. Leonie hadn't shared a tank amongst whatever other males inwards that time, pregnant the iii pups delivered inwards 2016 came equally something of a surprise.
"We idea she could hold upwards storing sperm but when nosotros tested the pups in addition to the possible nurture sharks using deoxyribonucleic acid fingerprinting, nosotros establish they exactly had cells from Leonie," says biomedical researcher Christine Dudgeon from the University of Queensland.
So how is this possible?
Well, sharks breeding asexually is extremely rare, but isn't solely unheard of.
This is possible because, beyond sexual reproduction, there's to a greater extent than or less other means that for sure species tin asexually reproduce, called parthenogenesis.
This procedure allows embryos to prepare without existence fertilised similar they are inwards sexual reproduction.
Parthenogenesis mainly occurs inwards plants in addition to invertebrate animals, but these 'virgin births' accept also been documented inwards vertebrate animals, including sharks in addition to lizards.
But what makes Leonie's representative hence odd is it's the kickoff fourth dimension scientists accept seen a shark brand the switch from breeding sexually to asexually.
In other circumstances where sharks accept been observed to breed parthenogenetically, the animals did non accept whatever sense amongst sexual reproduction, having bred asexually from maturity.
In fact, this is exactly the 3rd fourth dimension scientists accept seen whatever species brand the switch dorsum to asexual reproduction from past times sexual experience, amongst the other cases existence an eagle ray in addition to a boa constrictor, both held inwards captivity.
And this fourth dimension around, captivity 1 time again looks to accept been responsible for the alter inwards Leonie's circumstances.
The aquarium decided to deprive Leonie of of her mate, Leo, because they'd been producing also many offspring for the staff to handle.
"Leonie adapted to her circumstances in addition to nosotros believe she switched because she lost her mate. What nosotros desire to know straight off is could this occur inwards the wild and, if so, how oft does it?" says Dudgeon.
"One argue why nosotros haven't seen it earlier could hold upwards because nosotros haven't been looking for it. It powerfulness hold upwards happening inwards the wild, but it's never been recorded inwards this species before."
But spell the powerfulness to breed independently could hold upwards an invaluable survival machinery inwards the absence of suitable mates, it comes amongst its ain fix of problems: the resulting pups endure inwards price of genetic diversity, non picking upwards whatever of the absent male's genes, in addition to exactly receiving one-half of their mother's.
"This is an extreme class of inbreeding," Dudgeon told Casey Briggs at the ABC.
"[I]t's unlikely to hold upwards a really skillful long-term strategy, because eventually they postulate to mix upwards that cistron puddle in addition to growth that genetic diverseness to suit to novel in addition to ever-changing conditions."
But inwards the curt term, it may hold upwards that the procedure tin save equally much of an animal's genetic identity equally possible (if exactly one-half inwards total) until breeding weather condition acquire to a greater extent than favourable.
"It powerfulness hold upwards a holding-on mechanism," Dudgeon told Alice Klein at New Scientist. "Mum's genes acquire passed downwards from woman mortal to woman mortal until at that spot are males available to mate with."
To give away out if that's the case, the researchers straight off excogitation to follow the pups until they attain maturity themselves, to give away out if Cleo, CC, in addition to Gemini are capable of breeding amongst males when their fourth dimension comes.
Let's promise so, because if they can, it would hold upwards bear witness that these sharks accept evolved an amazing powerfulness to proceed surviving, fifty-fifty when they've been pushed into a tight corner.
And amongst zebra sharks existence listed equally endangered on the IUCN Red List of Threatened Species, these animals postulate all the survival aid they tin get.
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The findings are published inwards the nature query mag - Scientific Reports. Sumber http://www.dnbstories.com/