Any non-religious discussion of virgin birth – when a female of a species can conceive without a male’s sperm fertilizing the egg – sends chills down the spines and into the bedrooms of male humans. However, one small group is rejoicing at recent news about some successful virgin births – California condor breeders. The giant vultures brought back from the brink of extinction in the 1980s to a still critically endangered population of about 500 birds today may get a boost in breeding from a recent discovery of two male chicks hatched in 2001 and 2009 which have DNA from a female but no DNA from any father bird. Are male condors shivering?
“Parthenogenesis is considered to be a rare phenomenon in birds. We discovered it in California condors because we have such a detailed genealogical analysis of the entire population.”
When the entire population of a species numbers just 500 and nearly all of them are breeding in captivity, family tree data is easy to access, as Oliver Ryder, the director of conservation genetics at the San Diego Zoo Wildlife Alliance, explains to The New York Times. He’s the co-author of a study published recently in The Journal of Heredity which announced the discovery of parthenogenesis in California condors (Gymnogyps californianus). More common in fish, lizards and sharks, ‘virgin births’ have also been witnessed in turkeys, finches and domestic pigeons but not in California condors or most other birds. Ryder is the creator of the condor genetic database and it was in 2013 that he noticed a discrepancy that caused him to question the data – two males with no DNA from a male parent.
“Both parthenotes possessed the expected male ZZ sex chromosomes and were homozygous for all evaluated markers inherited from their dams. These findings represent the first molecular marker-based identification of facultative parthenogenesis in an avian species, notably of females in regular contact with fertile males, and add to the phylogenetic breadth of vertebrate taxa documented to have reproduced via asexual reproduction.”
Ryder and his team checked every male in the database and found no matches to the two males. What sealed the deal that they were the result of virgin births was the fact that they were males -- in avian species where parthenogenesis has occurred, only males hatch. Once the virgin births were confirmed, the next question addressed is why they occurred. In most cases, it’s out of desperation when no males are available. In the poultry industry, which has its own extensive body of genetic research, chickens and turkeys may have parthenogenetic births due to genetics – some species like Beltsville small white turkeys have 16.9 percent virgin births – to environmental factors like high temperatures or viral infections. According to The Atlantic, Ryder’s team is sequencing the two birds’ (both are deceased now) full genomes and then will do the same for hundreds of other condors in hopes of finding the cause of the two virgin births and possibly exploiting it to increase their population.
Should male condors be nervous? Parthenogenesis is rare among birds but this example in California condors is the first among any bird species where male partners were readily available for mating and yet the females had no-male virgin births.
How do male condors say “Uh-oh”?