Researchers have documented several cases of virgin births, which has been described as a desperate attempt by females with no access to males to procreate, by wild female snakes that have no help from the males.
The study represents the first time that virgin births have been detected in the wild. It also suggests that absence of males does not always instigate the phenomenon, which occurs among chickens, turkeys, lizards, sharks, insects and many other animals.
For this latest study, the researchers focused on two closely related species of North American pit viper snakes - the copperhead and the cottonmouth.
"In these populations, males are relatively common, hence females were not restricted from access to males, and therefore isolation from males is not a driving factor for parthenogenic reproduction (virgin births) here," Warren Booth, lead author of the study from the University of Tulsa, said.
Booth studied field-collected pregnant snakes and worked on the research with colleagues Charles Smith, Pamela Eskridge, Shannon Hoss, Joseph Mendelson III, and Gordon Schuett.
Out of a total of 59 litters from the snakes, the scientists selected two for DNA analysis.
These two already showed signs of virgin birthing, since the eggs had multiple yolks and the litters included just a single male offspring.
The genetic analysis supported the suspected lack of paternal DNA contribution.
According to Booth, in each case the female's egg cell "fused to a part of itself, and her chromosomes doubled."
The offspring wound up having two copies of her set of chromosomes, and therefore half the genetic materials.
"This means she has very reduced diversity across her genome," Discovery News quoted Booth as saying.
"This is essentially an extreme form of inbreeding," he said.
The latest findings suggest that this form of birth may be far more common among some animals than previously realized. Booth said that, based on his own past research on boa constrictors and cottonmouths, virgin births produce about 2.5 to 5 percent of litters.
While those numbers aren't huge, they indicate that father-less snakes aren't just an every-so-often novelty.
It remains a mystery now as to why these births happen, and what triggers them. The copperhead that gave virgin birth was small, Booth said.
"If she had never mated, it is possible that she was overlooked by males in favour of larger, more fecund females," he said.
Another theory is that females produce a single male offspring so that they can later establish a population with their son via inbreeding. Yet another is that bacteria or disease may trigger virgin births.
The study has been published in the Royal Society Biology Letters. (ANI)