Recently, it has been revealed that facultative parthenogenesis does occur among several animal species, including Boa constrictors...
Faculatative parthenogenesis has been known to take place in sharks, birds, some lizard species for some time and lately more snakes are discovered to have this phenomenon, as well.
Parthenogenesis was first described in a Boa constrictor in 2010. Although this asexual reproduction is not too common in boas, recent studies suggest they may have been more common than most of us thought.
Few weeks ago, a private keeper from Dallas reported parthenogenesis in his Hog Island boa (Boa c. imperator) female. His attention was drawn by the fact that his female had never been introduced to a male before. This litter contained 33 slugs and 3 viable youngs. Those 3 live babies are presumably all females, as there was no father, which would have given chromosomes that male sex requires.
Parthenogenetically reproduced offsprings genetics- in contrast with the common belief -are not identical with mother's, nor with each other (they are not clones of the mother and not twins, either). In fact, genetics of offsprings are half identical with their mother's.
It it not known yet, how long these parthenogenetic boas will survive and if they are going to be fertile or not. It is also still unclear what causes could triger the switch from "sexual-to-asexual" breeding behaviour in Boa constrictors.
However, it seems certain that facultative parthenogenesis has an evolutionary aspect. Once it is fully understood, it could also play an important role in conserving wild animals.
Warren Booth, Daniel H. Johnson, Sharon Moore, Coby Schal, Edward L. Vargo: Evidence for viable, non-clonal but fatherless Boa constrictors
1.1 CB 2009 Pearl Island boas
(Boa c. sabogae)details..