Every traveler who visits the mountains and catches a glimpse of the graceful flight of a condor is stunned. The bird’s wings sweep across the sky, leaving a trail behind its sleek body. Condors dominate the mountainous landscapes of arid regions of the world, from the Andes Mountains to the Grand Canyon, where California condors once stood on the brink of extinction. Scientists believe that in a desperate attempt to save them, natural selection led to parthenogenesis: a process by which the mother can produce a chick without a male.
On the brink of extinction
California condors are endangered, undergoing a slow process of reproduction assisted by biologists, veterinarians, and conservationists who have been working for decades to ensure the continuity of the species. In 1983 there were only 22 registered California condors alive. They were taken in captivity and transported to a unique habitat, where conservationists studied and protected them, prioritizing their reproduction.
During that time, the experts kept data of all kinds on the birds and extracted DNA samples for further study. Only in 2021 was an article published in the Journal of Heredity illustrating the study led by Oliver Ryder. This study analyzed DNA samples from condors from the population recovery program and found atypical specimens: SB260 and SB517. These two condors had no father. Their DNA revealed that the mother had fertilized them without insemination.
Sorry boys, you are no longer requested
This phenomenon is known as parthenogenesis, and it’s more common in nature than we thought. It has been previously identified in other small animal species, such as tardigrades, crustaceans, amphibians, fish, and reptiles. It consists of segmentation into two poles of the ovule that has not been fertilized. Usually, one of the poles acts as a “spare” containing an exact copy of the mother’s DNA and is reabsorbed into the uterus once the other egg has been inseminated. But in an atypical process, the two ovules may recombine again, emulating insemination and giving rise to the fertilization of an embryo.
The case of condors SB260 and SB517 surprised researchers, as Ryden and his colleague studied the birds’ DNA for clues to common bone diseases in these condors. Unfortunately, they could not investigate these specimens while alive, as they discovered their parthenogenic nature years after death. However, behavioral records ensure that neither of the two specimens was particularly strong. One died two years after being released from captivity, having difficulty adjusting to the natural environment, and the other died early in captivity.
Although experts cannot adjudicate this to be parthenogenesis, previous results from studies of this phenomenon in other bird and reptile species suggest that this phenomenon could be a debilitating factor for hatchlings.
Applications of parthenogenesis
In contrast to episodes of parthenogenesis in other species, the documented cases in California condors are not so bad: both specimens lived to maturity and were able to successfully perform the main functions of survival, such as hunting, flying, mating, seeking refuge, and fending.
Ryder and his colleagues believe that the in-depth study of this phenomenon could significantly contribute to advances in techniques for the reproduction and preservation of endangered species. Other authors propose that it would be helpful to implement this type of fertilization on an industrial scale to favor poultry production. In any case, the state of the art in this field is developing, so we may have to wait at least a decade to see applications on a larger scale.
Meanwhile, experts are still trying to discover the causes of this phenomenon. Ryder and his team surmise that this behavior may be a natural response of the species responding to the need for preservation in the face of extinction risk. Other possibilities are bacteria that cause genetic alterations that affect reproduction, and the unviable crossing of species, among other proposals.