The California condor is one of the rarest birds in the world, but now it seems that nature is giving it an unexpected leg-up. Scientists have discovered two condor chicks that were born from unfertilized eggs, indicating a form of asexual reproduction that’s extremely uncommon in birds.
The breeding habits of the California condor are of keen interest to scientists. The critically endangered bird was down to just 27 individuals in 1987, when the last wild specimens were all captured and entered into a managed breeding program. In the decades since, numbers have bounced back to over 500, with many released back into the wild.
Through the close monitoring of these animals in the breeding program, scientists have now made a surprising discovery. Genetic tests on two chicks revealed that biologically, they had no fathers – instead they had hatched from eggs which had never been fertilized by sperm, meaning they only have genetic material from their mother. This form of asexual reproduction, known as parthenogenesis, has never been recorded in California condors before, and rarely in any type of bird.
“This is truly an amazing discovery,” says Oliver Ryder, co-author of the study. “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. Our results showed that both eggs possessed the expected male ZZ sex chromosomes, but all markers were only inherited from their dams (mothers), verifying our findings.”
Parthenogenesis is well documented in some species of bees, cockroaches, crayfish, and even sharks. Studies have suggested that it can occur in some bird species, such as turkeys, finches and pigeons, but it was hard to verify prior to genetic testing.
There’s another wrinkle to this story though. Normally female animals will resort to parthenogenesis when there aren’t any males around to mate with – but these condors had been living with viable males for years, and had had chicks through sexual reproduction both before and after the parthenogenesis.
The team says that more genotype studies will be conducted to see if there are other examples of parthenogenesis in California condors, .
“These findings now raise questions about whether this might occur undetected in other species,” says Ryder.
The research was published in the Journal of Heredity.
Source: San Diego Zoo Wildlife Alliance
