“Life found a way” at National Zoo where female water dragon reproduced without a male

Written by on June 8, 2019 in Rare Critters - No comments

She has no mate. Her daughter has no father. Together they form scientific first.

Now, the Smithsonian’s National Zoo confirms their 12-year-old female Asian water dragon successfully reproduced without a mate or receiving male genetic material.

In scientific terms, it’s called facultative parthenogenesis, or asexual reproduction.

“Life found a way at Smithsonian’s National Zoo,” the facility announced earlier this week.

The findings, publishing in a PLOS ONE paper June 5, are the first to confirm parthenogenesis in this species, which is Thailand, Vietnam, Cambodia, Laos, Myanmar and southern China.

DNA were samples were used by experts at the Smithsonian Conservation Biology Institute’s (SCBI) Center for Conservation Genomics, along with help from the St. Louis Zoo in Missouri and the University of the Sunshine Coast in Australia.

Mother Asian water dragon (right) hangs with her daughter (left) hatched in August, 2016 Photo: Skip Brown/Smithsonian’s National Zoo

The authors hope it will spark more research.

“These scientific discoveries are always very exciting, and having the opportunity to confirm parthenogenesis at all is really cool,” Kyle Miller, animal keeper at the Reptile Discovery Center and lead author on the paper. “… We are just scratching the surface with parthenogenesis in snakes and lizards that primarily reproduce sexually.”

The mother Asian water dragon arrived at the zoo in November 2006 from the St. Louis Zoo when she was 4-months-old.

The zoo, never had an eye on breeding her.

She was there to be an “animal ambassador,” so people could learn about the species.

The Smithsonian’s National Zoo’s 12-year-old female was never intended to be a mother, but rather an “animal ambassador.” Photo: Skip Brown/Smithsonian’s National Zoo

But she started producing eggs in 2009, which were discarded as part of the zoo’s  “infertile egg protocol.”

But in 2015, zookeepers asked if they incubate all eggs laid by female reptiles that were not bred to study fertility through sperm storage and parthenogenesis.

The embryos in the first two clutches of eggs looked to be developing, but did not survive.

But a female hatchling emerged from her shell Aug. 24, 2016 in a third clutch of eggs.

This 2-year-old female Asian water dragon was produced without a father. Photo: Skip Brown/Smithsonian’s National Zoo

A second hatched from the same mother on Nov. 21, 2018, but it later died from a gastrointestinal tract block.

But that female hatchling is now almost 3-years-old.

And she’s doing just fine with her mother at her side.

A female Asian water dragon (left) hatched August 2016 and is the only surviving offspring of her 12-year-old mother (right). Photo: Skip Brown/Smithsonian’s National Zoo

Scientists used DNA samples from mother and the offspring and essentially found only one allele, and it matched one of the two from the mother.

“In all of our tests, we found that the daughter only had one allele,” Robert Fleischer, head of SCBI’s Center for Conservation Genomics and an author on the paper, explained. “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.”

The daughter is not genetically identical to the mother through this process.

She has only one of her mother’s two gene copies.

Mother (right) and daughter (left) are very photogenic, but they are not identical. Photo: Skip Brown/Smithsonian’s National Zoo

Asian water dragons, so named because they can submerge themselves in water and hold their breath for up to 25 minutes, usually start producing eggs at around 3-years-old.

So now, zookeepers are waiting to see if the offspring will be able to produce offspring on her own or with a future mate.

In the meantime, you can see the precedent-setting family at the zoo’s Reptile Discovery Center.


Photos Skip Brown/Smithsonian’s National Zoo

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Dawn Walton

Recovering newspaper reporter.

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