Female Boa constrictors don't need a male to produce babies, as shown by an extraordinary incident at North Carolina State University - and it's happened not once, but twice!
What's more, the discovery shows that the babies – all females – have no male influence whatsoever. This is known as asexual reproduction, or parthenogenesis.
According to the report in Science Daily, the same Boa constrictor female gave birth to two different broods of all-female babies that had the mother's rare colour mutation. And it's not as though she wasn't given a choice, as males were present and even courted the female before she gave birth. Previous to the two rare asexual births, the female had also produced broods the 'natural' way, with a male.
Dr. Warren Booth, lead author of a paper describing the study, which was published in Biology Letters, says that the results may force scientists to re-examine reptile reproduction, especially among more primitive snake species like Boa constrictors.
"Reproducing both ways could be an evolutionary 'get-out-of-jail-free card' for snakes," Booth says. "If suitable males are absent, why waste those expensive eggs when you have the potential to put out some half-clones of yourself? Then, when a suitable mate is available, revert back to sexual reproduction."
Booth will be interested to see how the all-female babies reproduce when they reach maturity - whether it's with a mate, without - or both ways.
Asexual reproduction is also known in a livebearer called the Amazon molly (Poecilia formosa), a fish that has existed for 100,000 years without sex, producing only female young.
For more information see: Warren Booth, Coby Schal, Edward L. Vargo Daniel H. Johnson and Sharon Moore. Evidence for viable, non-clonal but fatherless Boa constrictors. Biololgy Letters, November 3, 2010 DOI: 10.1098/rsbl.2010.0793