An endangered zebra shark has had a virgin birth in which the female fertilised the eggs with her own genetic material.
The extremely rare occurrence, which is referred to as parthenogenesis, is a type of reproduction in which female animals fertilise eggs without using a male, with the young conceived asexually.
Aquarium caretaker Lise Watson and Field Museum scientist Kevin Feldheim described the incident as a ‘virgin birth’ and said that in natural terms it was a ‘last-ditch’ effort for an animal to reproduce in circumstances where a mate is unavailable – or, in this case, where the males that were available were rejected.
In a prepared statement, they said: ‘Scientists have assumed that vertebrates that usually reproduce sexually turn to parthenogenesis as a ‘hail Mary pass’, a last-ditch effort at reproduction when there aren’t enough mates to go around.’
But he added that the latest offspring were an ‘example of a female zebra shark in an aquarium reproducing via parthenogenesis, even though there were healthy, reproductive males in the same enclosure.
‘This finding has implications for not only the continued care of zebra sharks in zoos and aquariums, but also for conservation efforts focused on their wild counterparts.’
In the statement, Feldheim said: ‘We’ve known for several years that parthenogenesis occurs in animals like sharks, but some aspects of it remain unknown, like why it occurs and what triggers it.’
The fact that it was a virgin birth was confirmed via genetic testing, which found that both the pups and the mother had the same genetic make-up.
The disadvantage of this form of reproduction is that there is not any genetic variation and, as such, the young tend to have shorter lives.
But in the statement, the aquarium added that their very existence ‘challenges long-standing ideas in biology” and can impact the conservation of all sorts of endangered species.
Feldheim added: ‘This discovery throws a wrench in what we thought we knew about how and why parthenogenesis happens, and it illustrates a key aspect of science: We’re continually learning.’
The phenomenon was used as part of the plot in the film Jurassic Park, in which only female animals were allowed to be raised in belief that this would keep populations under control.
But the idea collapsed when the female dinosaurs used parthenogenesis to reproduce anyway.
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