How That Female Zebra Shark Reproduced Without a Male Partner
Girl I didn't know you could get down like that.
Zebra Shark. Image: Wikimedia
This lady shark needs no man. She's figured out a way to reproduce on her own.
Leonie, a female zebra shark—the colloquial term for the Stegostoma fasciatum species—has lived alone since 2012. In 2016, she had three baby sharks of her own, according to New Scientist.
To provide some context, Leonie is no Virgin Mary. She lived with a male partner in an aquarium in Townsville, Australia, between 1999 and 2012. Together, they had 24 offspring. But in 2012, Leonie's partner was moved to another tank, and since then, she had no male contact.
So the question is, how did she conceive three more offspring on her own?
One possibility was that Leonie stored sperm from her former partner and user it four years later, but that was quickly discredited since the three offspring only have their mother's DNA, according to Christine Dudgeon, a research officer in biomedical sciences at the University of Queensland. Hence, asexual reproduction may have been more likely.
Asexual reproduction isn't as uncommon as it may seem. Some species of sharks, snakes, turkeys, rays, and Komodo dragons have been able to reproduce without males. However, among those who have done so, the females were virgins. Switching from sexual to asexual reproduction is far less common, although not impossible, Dudgeon told The New Scientist, citing an eagle ray and boa constrictor who have done so.
Asexual reproduction in sharks happens when a polar body, or the cell adjacent to the egg fertilizes it, said Dudgeon. This process causes "extreme inbreeding," she said, and is not conducive to adaptability, or generational longevity and diversity. However, when there are no males around, asexual reproduction, despite its shortcomings, is the best option for species survival.
Dudgeon described asexual reproduction as a "holding-on mechanism," passed down along generations of women until male partners are available. How's that for some girl power?
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