Forget what you know about the birds and the bees: Sometimes you just have to take matters into your own hands.
Reproduction typically requires sperm from a male to fertilize a woman's egg, but in some cases, nature has outsmarted the system. To cope with living in captivity, or a lack of suitable mates, evolutionary adaptations have enabled some creatures to have babies without sex. And while that may sound miraculous, it's not as uncommon as you may think. Here are nine incredible tales of virgin births in the animal kingdom.
Zebra shark
Credit: Tourism & Events Queensland |
So what gives? At the time, biologists said Leonie could be the first shark ever observed to make the switch from sexual to asexual reproduction. The type of asexual reproduction characterized in Leonie's case is known as parthenogenesis, which occurs when embryos develop and mature without fertilization by a male's sperm. Instead, an egg progenitor cell functions as a surrogate sperm to "fertilize" the egg.
In a study published in January 2017 in the journal Scientific Reports, researchers said Leonie's case suggests that parthenogenesis could be an evolutionary adaptation to a lack of suitable mates.
Yellow-bellied water snake
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Credit: Project Noah |
The female snake's impressive feat boils down to parthenogenesis, during which babies are produced by females absent of genetic contribution from a male. Scientists have seen this type of reproduction in other snake species, including copperheads, green anacondas and pit vipers.
With parthenogenesis, the normal division of cells typically results in four egg-progenitor cells, but instead of the female's body reabsorbing three egg-progenitor cells (leaving one egg), one of the female cells behaves like sperm and fertilizes the egg. Why does this happen? Essentially, this type of asexual reproduction occurs when there is a lack of suitable mates. It's evolution in action, folks.
Komodo dragon
Credit: Steve Finn/Getty Images |
Boa constrictor
Credit: Warren Booth |
Interestingly, the female boa experienced this type of asexual reproduction in years when males were present.
"Is it possible that the female selectively chose not to utilize the male sperm if breeding occurred?" study co-author Warren Booth, a population and evolutionary geneticist at North Carolina State University at Raleigh told Live Science in 2010. "Is it possible that the males were genetically incompatible with the female? We simply do not know enough about parthenogenesis in boas to speculate."
Sawfish
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Credit: Elasmodiver.com |
"Vertebrate animals that we always thought were restricted to reproducing via sex in the wild actually have another option that does not involve sex," study co-author Demian Chapman, a marine biologist at Stony Brook University in New York, told Live Science in 2015.
In the study, the researchers said the babies born from virgin births regularly live in the wild. Parthenogenesis may occur in small or dwindling populations when mates are scarce, the scientists found. And though this may seem like good news for the endangered smalltooth sawfish, parthenogenesis alone is not enough to save species from extinction. Still, the researchers said the findings could inspire conservation efforts.
Pit viper
Credit: Adobe Stock |
"With the availability of DNA fingerprinting technologies, we are now becoming aware that the process of parthenogenesis is in fact more common than we ever imagined," study author Warren Booth, an evolutionary and population geneticist at North Carolina State University at Raleigh, told Live Science in 2011.
In the study, scientists said parthenogenesis may have evolved in pit vipers to overcome a lack of suitable mates.
Atlantic blacktip shark
Credit: Adobe Stock |
"We have never observed her in reproductive behavior or showing typical signs of having been bred," Beth Firchau, a researcher at the Virginia Aquarium, said in 2008.
Firchau said there were no males in Tidbit's tank for the prior eight years, and scientists used genetic testing to confirm that the shark's unborn pup contained only DNA from its mom. The discovery was described in a study published in October 2008 in the Journal of Fish Biology.
Hammerhead shark
Credit: Adobe Stock |
An analysis revealed that the baby hammerhead's DNA only matched up with its mother, indicating there was no father involved when the female shark became pregnant.
"The findings were really surprising because as far as anyone knew, all sharks reproduced only sexually by a male and female mating, requiring the embryo to get DNA from both parents for full development, just like in mammals," study co-author Paulo Prodohl, an evolutionary biologist at Queen's University Belfast in Northern Ireland, said in 2007.
Cockroach
Credit: Shutterstock |
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