If I still remember my biology class correctly, asexual reproduction (where an organism reproduces without the copulation of the male and female species) only works best in single-cell organisms. When it comes to a multi-cellular organism (which is basically any organism that you don’t need a microscope to see) asexual reproduction is not as efficient.
That is because sexual reproduction (birth that results from the copulation of the male and female animals of the same species) brings about a good diversity of good and bad genes. The less related the male and female are, the more the virility of the resultant offspring.
A certain zebra shark named Leonie has decided to go against the norm and have a ‘virgin birth’. Leonie defied the age-old tale; of boy meets girls, boy likes girl, girl likes boy back, the two go horizontal, and voila you got little boys and girls running around. No, Leonie said sperm-be-damned, and she took matters into her own
Leonie, the zebra shark, has just stunned the scientists’ community by giving birth to three babies all by herself. Well, Leonie is not a virgin, if anything far from it. Back in early 2000, she had a male partner with whom she had a couple of dozen of baby zebra sharks. However, scientiss are confident that her newest litter of three pups were completely an inside job; sperm-be-damned. The ‘How’ part has scientists puzzled.
However, Leonie is not the first girl to get babies without the boy(s). Parthenogenesis, asexual reproduction in a female, is a phenomenon that has been observed in other females as well. It is a rare occurrence that warrants a lot of interest and investigations, especially ones caught on record.
Researchers reported in this week’s Scientific Reports that Leonie is the first shark in recorded history that has switched from sexual reproduction to asexual reproduction. It shows Leonie had to adapt to her circumstances; she was not designed to be an asexual being; it is a behavior she has just picked up given the lack of a male mating partner in her life.
This type of switch is so rare that it is causing a stir within the scientists community, many are excited for such an event to have happened within their lifetime. There are only two other recorded incidences where females took matters into their own hand, and gave ‘virgin births’. One was of a female eagle ray who made the switch from sexual reproduction to asexual following a one-year separation from her male partner. The other case, which was even stranger, was of a female boa constrictor who gave birth to parthenogenic pubs despite the fact there were males around and available to mate with her.
Scientist still do not exactly understand the mechanisms through which sexually reproducing females can end up reproducing asexually. Nonetheless, it is an ingenious evolutionary strategy; though a temporary fix. That is because the offspring produce have an extreme lack of genetic variety, and will make a population that is extremely vulnerable to dangerous mutations and are slower to adaptation to new environmental changes.
There is also the likelihood that Leonie’s offspring will be asexual reproducer, a development that will limit their usefulness in the long-term. There is nothing wonderful, in terms of evolution, about being a single mother. It does get old after a generation or two; not to mention chances are high the offspring will get male sharks who will want to copulate with them.