Leopard Shark Switches From Sexual To Asexual Reproduction

Posted: Jan 17 2017, 10:42am CST | by , Updated: Jan 17 2017, 10:53am CST, in News | Latest Science News

 

Leopard Shark Switches from Sexual to Asexual Reproduction
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  • Leopard Shark Gives World's First Male-Less Birth
 

It seems to be the case that a particular leopard shark in an Australian aquarium has flipped from sexual to asexual reproduction in the absence of its partner.

There is a leopard shark in an Aussie aquarium that has managed to reproduce asexually in the absence of her mate. This seems to be a strange and curious case of an anomaly that is very rare in Nature.

Parthenogenesis is a phenomenon found in Nature although it is not very common. This is the first time it has been observed in sharks.  

This happens to be the third such case among vertebrates. The leopard shark was nicknamed Leonie. Caught from the deep blue ocean in 1999, it was set free in an aquarium in the presence of a male in Queensland, Australia in the year 2006. These sharks are also called zebra sharks.

Leonie laid a batch of eggs and had baby sharks in 2008. These were via sexual reproduction as was the norm in these sharks. Then in 2012, its mate was separated from it since the aquarium was cutting back on its breeding program, according to CNet

One of the offsprings of Leonie was nicknamed Lolly. She never shared a tank with a male member. Three years ago, both Lolly and Leonie had a batch of eggs which mysteriously seemed to appear out of nowhere.

A doctor who studied these two sharks has said that this unusual transformation from sexual to asexual reproduction was not necessarily an abnormality.

On the contrary, these sharks will lay eggs like chickens do whether they are fertile or infertile. Only the environment has to be supportive. Many of Leonie’s eggs contained embryos that wouldn’t hatch from the shells. Despite incubation no baby sharks came out of the eggs. 

Finally, five live hatchlings emerged at the end of much coaxing. Two of these are still in the aquarium and have been nicknamed Cleo and Kitkat. The research points towards asexual means of reproduction to be the worker behind the scenes in the case of the hatchlings.

It is not asexual reproduction that is unusual, it is the switchover from one mode to another at such short notice. The offspring of this form of reproduction are not exact clones of their mothers, according to Guardian.

Therefore they are not very robust. Sexual reproduction produces the hardiness needed for survival via a mixing of genes. What triggered the switchover here was probably evolutionary pressure. Zebra sharks are on the endangered species list. 

This asexual reprodcution reported in the journal Nature.

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