There are creatures in the animal kingdom that are capable of giving birth even without a male reproductive partner. It is a rare occurrence for sharks to do so, but research says that it is entirely possible for virgin sharks to give birth without male interference.
Creating Life by Oneself
You can usually see asexual reproduction from animals like starfishes, worms, stick insects, and so on. This phenomenon is incredibly rare for vertebrates. Biology astonishes researchers again as they observe a virgin shark giving birth.
Back in 2021, a smooth-hound shark located at the Cala Gonone Aquarium in Sardinia, Italy, gave birth to a shark without the help of a male companion. The shark did so with a process called parthenogenesis, as mentioned in Interesting Engineering.
Zebra sharks are an endangered specie and can be found at the Shedd Aquarium in Chicago. Upon studying them, the female zebra shark appeared to have reproduced through parthenogenesis as well, despite having reproductive male sharks with them.
Parthogenesis is said to be the last-ditch effort at reproduction when a female cannot find a male for egg fertilization. What makes the zebra shark case unique is that it had the choice to procreate with reproductive male sharks but still did so by itself.
Not only do the findings affect how caretakers should treat zebra sharks in zoos and aquariums, but it also provides new insights for conservation efforts for zebra sharks that can be found in the wild, as mentioned in a news release from EurekAlert.
Scientific Aspects of the Study
Researchers were already aware of the occurrence of parthenogenesis in sharks before, but they are still unclear why it happens or what triggers it, according to Kevin Feldheim, a researcher at Chicago's Field Museum as well as the author of "Journal of Fish Biology."
They began genetic testing to determine which of the male shark were responsible for the successful breeding of zebra sharks back in 2004, according to Lise Watson, the assistant director of animal operations and habitats at Shedd Aquarium.
Also an author of the study, Watson says that the genetic test was to confirm the lineage of the pups, so they can make sound decisions when it comes to breeding and maintaining maximum genetic diversity for the survival of the species.
Upon testing the shark offspring, the results show that it did not match any of the mature males within the enclosure, only the female shark that laid the eggs. They also found homozygous copies of some alleles, meaning that both DNA strands came from only one parent.
There is, however, a downside to parthenogenesis. The pups born from this process tend to live short lives, seeing as they are more likely to have rare recessive genetic conditions. The pups observed for the study only lived for a few months.
Watson expressed that the study was just the beginning of their understanding of the genetic phenomenon in zebra sharks. She added that zoos and aquariums like Shedd have a key role to play in the conservation of the species.
