Genetic Testing Confirms Condors' Virgin Births

Parthenogenesis has been documented in other species, but not this one
By Newser Editors and Wire Services
Posted Oct 29, 2021 4:35 PM CDT
Researchers Document First Virgin Births by Condors
A California condor takes flight in the Ventana Wilderness east of Big Sur, Calif., in 2017.   (AP Photo/Marcio Jose Sanchez, File)

Endangered California condors can have "virgin births," according to a new study. Researchers with the San Diego Zoo Wildlife Alliance said genetic testing confirmed that two male chicks hatched in 2001 and 2009 from unfertilized eggs were related to their mothers. Neither was related to a male. The study was published Thursday in the Journal of Heredity. It's the first report of asexual reproduction in California condors, per the AP, though parthenogenesis can occur in other species, including sharks, honey bees, and Komodo dragons.

But in birds, it usually only occurs when females don't have access to males. In this case, each mother condor had previously bred with males, producing 34 chicks, and each was housed with a fertile male at the time they produced the eggs through parthenogenesis. The researchers said they believe it is the first case of asexual reproduction in any avian species in which the female had access to a mate. "These findings now raise questions about whether this might occur undetected in other species," said Oliver Ryder, the study's co-author and director of conservation genetics for the San Diego Zoo Wildlife Alliance.

With 10-foot wingspans, California condors are the largest flying birds in North America. They once ranged throughout the West Coast. But only 22 survived in the 1980s when the federal government captured them and placed them in zoos for captive breeding. There are now more than 500 of them, including more than 300 that have been released into the wild in California, Arizona, Utah, and Mexico. The asexual reproduction was discovered some years ago during testing of genetic material collected over decades from condors, both living and dead, in breeding programs and in the wild. "Among 467 male California condors tested in the parentage analysis, no male qualified as a potential sire" of the two birds, the study said.

(More condors stories.)

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