In these cases, researchers believe there’s a hitch in the normal steps of cell division and development that cause eggs to only carry half the DNA they need to form a living creature, resulting in an egg with a full set of DNA from just one parent, though scientists haven’t fully worked out all the details. It’s happened before, says Reshma Ramachandran, a researcher with Mississippi State University’s department of poultry science, noting that reports of parthenogenesis in pigeons, quails, chickens and turkeys date back to the 1960s. Males have two Z chromosomes while females have a Z and a W, meaning that an unfertilized egg already has the genetic material needed to form a male chick. There are exceptions, such as people with Klinefelter syndrome, who are XXY males, but that’s the general rule. In humans, females have two X chromosomes, while males have an X and a Y. That’s because while it may seem bizarre for a female bird to have male chicks on her own, sex in birds and people isn’t determined the same way. The fact that researchers couldn’t find evidence the birds had DNA from a father was a telling sign that they didn’t have one. Most animals (humans included) inherit two sets of genes, one from mom and one from dad.
Ryder and colleagues reported their results in the Journal of Heredity, the official publication of the century-old American Genetic Association. Want more of our free, weekly newsletters in your inbox? Let’s get started. Oliver Ryder she needed to talk with him about some puzzling findings. That all changed when Leona Chemnick, who was then a researcher at the zoo’s institute for conservation research, told director of genetics Dr. Researchers didn’t expect any major surprises when they began testing samples from more than 900 condors around 2013. The DNA in these samples can reveal how closely two condors are related and how traits are passed down from one generation to the next.
Throughout this ongoing effort, researchers have collected a vast repository of condor blood, feathers and tissue. A captive breeding program run out of the Safari Park has accounted for much of that rebound, and the zoo and Safari Park have hatched more than 160 condors over the years.
By the end of 2019, that count rose to 525, with 306 condors flying freely across California, Arizona, Utah and Baja California. The nonprofit organization has played a key role in helping California condors claw their way back from the brink of extinction.īy 1982, there were only 22 of the iconic birds left. It’s no accident the discovery was made by the San Diego Zoo Wildlife Alliance, which runs the zoo and Safari Park. “That raises the issue that we should be looking for this more, I think.” “I thought it was pretty remarkable,” said Kevin Burns, an ornithologist at San Diego State University, who was not involved in the study. Another unanswered question: Why did this happen? The mothers of both condors had each mated successfully before and were housed with a male at the time they reproduced asexually.