In a first for its species and reptilian Agamidae family, a female Asian water dragon at the National Zoo successfully produced offspring without the help of a male.
The process, known as facultative parthenogenesis, occurs when a female that can reproduce sexually instead does so without breeding or receiving genetic material from a male, the Smithsonian says.
The team of researchers at Smithsonian’s National Zoo in Washington, D.C., published their findings in the peer-reviewed journal PLoS One on Wednesday.
“These scientific discoveries are always very exciting, and having the opportunity to confirm parthenogenesis at all is really cool,” Kyle Miller, who works at the zoo’s reptile center and was the lead author on the paper, said in a statement.
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The Smithsonian has a lone female Asian water dragon that came to the zoo in 2006 without the intention of her breeding.
However, in 2009, the reptile began producing eggs. At first, animal keepers did nothing with the eggs, thinking they were infertile, the study said. Once more research was done in other reptile species on parthenogenesis, the team decided to incubate her eggs in 2015.
Surprisingly, the team found that the eggs were fertile. While none of the eggs produced living offspring, fully developed hatchlings were found after 70 days inside some of the eggs, the study says.
A year later, one of the eggs the lizard produced hatched, and a living offspring emerged. In 2018, another living offspring successfully hatched from the mother Asian water dragon’s eggs, though it later died due to a gastrointestinal problem, the Smithsonian said.
Although the reptile had been living isolated from males, the team was cautious and considered that it was possible she had stored sperm over many years from a previous interaction with a male lizard.
To test it, the zoo keepers compared the DNA of the mother and her daughter, and analyzed the genetic material in 14 places along their genetic codes, or microsatellites.
In six, the mother lizard had two different alleles, or variants of the same gene, that came from a mother and a father. In those same six microsatellites, the daughter lizard had only one allele, coming solely from one parent: the mother water dragon.
“The question we wanted to confirm was whether the Asian water dragon’s offspring had genetic material from only one parent – mom – or two parents – mom and a mystery male,” Robert Fleischer, one of the paper’s authors said in a statement.
“In all of our tests, we found that the daughter only had one allele. If egg and sperm fusion had occurred, the offspring would have two alleles. It was very clear to us that the mother’s eggs were developing directly into offspring without assistance from a male,” he added.
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The team says it now wonders whether the daughter will be able to produce offspring without the assistance of a male, too.
A variety of animals – including pythons, bonnethead sharks, Komodo dragons and birds – are able to reproduce via parthenogenesis, and in some reptiles, it is a common form of reproduction, according to the Smithsonian.
“We are just scratching the surface with parthenogenesis in snakes and lizards that primarily reproduce sexually,” Miller said in a statement. “Advances in technology continue to take research to new heights, and I hope our work inspires other zoos to pursue these types of projects.”
Follow USA TODAY’s Ryan Miller on Twitter @RyanW_Miller
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