California Condors Surprise Scientists With Virgin Births

California Condors
Courtesy of National Parks Gallery (Picryl PDM)

The rarity of the California condor and their sex lives have been the subject of public interest since 1983 when only 22 of the birds survived. Since then, biologists have carefully bred the birds in captivity. They recorded who mated with whom, how many offspring they produced, and when those offspring were reintroduced into the wild, according to Slashdot.

Scientists conducting DNA tests as part of routine research a few years ago were shocked to discover two condors did not possess fathers as recorded in the studbook. Their identities were SB260 and SB517. They were not connected to the fathers recorded in the studbook. In reality, they didn’t have any parents at all. The San Diego Zoo Wildlife Alliance’s Oliver Ryder describes this as an “unexplained data set.”

Scientists were stunned to discover a few years ago that two California condors, SB260 and SB517, had been born without fathers but were related to their mothers. This discovery puzzled Oliver Ryder, a San Diego Zoo Wildlife Alliance conservation geneticist.

California Condors Are Critically Endangered

The Journal of Heredity reported a virgin birth, also known as Parthenogenesis, on October 28. According to the journal, lizards, swellsharks, and water dragons all reproduce via asexual reproduction.

Virgin birth — a type of asexual reproduction in which a female’s egg develops into an embryo without sperm — is when lizards, swellsharks, and water dragons all reproduce. Scientists were astounded to find that California condors also produce in this manner.

However, scientists documented self-fertility in captive turkeys, chickens, and Chinese-painted quails, all vertebrates. On the other hand, Parthenogenesis naturally occurs in sharks, rays, and lizards. This is the first time it has been recorded in California condors.

California Condors
Courtesy of Tjflex2 (Flickr CC0)

Is Asexual Reproduction a Survival Tool?

The critically endangered species, found soaring above California, Arizona, and Utah, numbers only around 300.

Parthenogenesis in birds is a rare phenomenon, but there is some evidence that females capable of Parthenogenesis will reproduce within an endangered population.

For example, Parthenogenesis may save the critically endangered smalltooth sawfish, as mates become harder to locate in the wild.

However, that hypothesis doesn’t hold true for California condors. National Geographic says that these two parthenotes were produced by California condors living with males, in a mysterious twist to the theory. Why would these birds reproduce asexually?

California condors, SB260 and SB517, produced through asexual reproduction, prematurely died before they were eight. Secondly, these captive females had mates. Although none of the asexual offspring survived, some California condors live up to 60 years.

Because scientists carefully screen for potential genetic disorders when breeding captive condors, Ryder says that these self-fertilized birds may have carried gene mutations that resulted in their early deaths.

To achieve this goal, earlier this year, Robinson, Ryder, and colleagues published a study detailing the California condor’s complete genetic sequence, data that in the future may enable people to comprehend Parthenogenesis in these animals better.

Written by Janet Grace Ortigas
Edited by Cathy Milne-Ware

Sources:
National Geographic: Endangered birds experience ‘virgin birth,’ a first for the species; by Jason Bittel
Smithsonian Magazine: California Condors Surprise Scientists With Two ‘Virgin Births;’ by Rasha Aridi
Slashdot: Endangered Birds Experience ‘Virgin Birth,’ a First for the Species; by msmash

Featured and Top Image by National Parks Gallery Courtesy of Picryl – Public Domain License
Inset Image Courtesy of Tjflex2’s Flickr Page – Creative Commons License

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