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Parthenogenesis – a form of asexual reproduction in which an egg is never fertilized but develops into an embryo – has been observed in a variety of insects, fish, reptiles, and birds. Now, scientists have discovered that another species is capable of it: The California condor.Scientists from the San Diego Zoo Wildlife Alliance say two of the female condors in its breeding program produced chicks that were not genetically related to a male, meaning that they were fatherless. The alliance notes that this is the first time asexual reproduction has been confirmed in this species. The discovery was shared in the Journal of Heredity.
PHOTO: U.S. FISH AND WILDLIFE SERVICE
Study co-author Dr. Oliver Ryder says, “This is truly an amazing discovery. We were not exactly looking for evidence of parthenogenesis, it just hit us in the face. We only confirmed it because of the normal genetic studies we do to prove parentage.”
In a news release, the alliance explained that parthenogenesis does occur in birds, but it is rare and typically happens when females do not have access to males. The condors in this case were housed with fertile males, with whom they produced multiple chicks. In fact, one was paired with a male for more than 20 years and had more than 20 chicks with him, two of which hatched after the parthenogenesis.

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Cynthia Steiner, study co-author and associate director for the conservation research division at the alliance, says, “We believe that our findings represent the first instance of facultative avian parthenogenesis in a wild bird species, where both a male and a female are housed together. Still, unlike other examples of avian parthenogenesis, these two occurrences are not explained by the absence of a suitable male.”
PHOTO: U.S. FISH AND WILDLIFE SERVICE
The alliance noted that this discovery was made thanks to the long-running collaborative California Condor Recovery Program, which was created to help bring the species back from the brink of extinction. Shortly before it was launched, there were only 23 condors in the world.
Over the course of the past 30 years, conservationists have used this recovery program to conduct genetics and genomics research through blood, tissue, feather, and eggshell membranes taken from more than 900 individual condors. This gave the team extensive genetic records to reference to confirm the parthenogenesis.
Going forward, the alliance plans to continue studying the genetics of the birds to see if any further cases occur. Dr. Ryder also notes that it could be happening undetected in other species.
PHOTO: NATIONAL PARK SERVICE