Female boa constrictors can make babies without mating: Study

Posted Nov 6, 2010 by Subir Ghosh
This is bad news for males. Female boa constrictors can produce babies without mating. Scientists have found that the babies produced from this asexual reproduction have attributes previously believed to be impossible. Males are not needed anymore.
New evidence shows that boa constrictors can reproduce without sex. But one boa constrictor had babi...
New evidence shows that boa constrictors can reproduce without sex. But one boa constrictor had babies asexually and the old-fashioned way. Her sexually produced snake (left) is shown beside one of the asexually produced females (right).
North Carolina State University
This is the first time that asexual reproduction, known in scientific terms as parthenogenesis, has been attributed to boa constrictors, according to scientists from the North Carolina State University (NCSU). They have published their findings online in the latest issue of Biology Letters, a Royal Society journal.
The results may now make scientists re-examine reptile reproduction, especially among more primitive snake species like boa constrictors.
Reproduction in snakes is almost exclusively sexual. There is record of just one exception ― that of the Brahminy blind snake (Ramphotyphlops brahminus), an all-female species. But there have been very rare instances of parthenogenesis in captivity which have produced offsprings. Among the primitive snakes of the families Boidae (boas) and Pythonidae (pythons), reports of parthenogenetic reproduction do exist, but only one instance has been scientifically demonstrated.
The lead author of the study, Dr Warren Booth, explained in a statement issued by NCSU, "Snake sex chromosomes are a bit different from those in mammals – male snakes’ cells have two Z chromosomes, while female snakes’ cells have a Z and a W chromosome. Yet in the study, all the female babies produced by asexual reproduction had WW chromosomes, a phenomenon not seen before and is believed to be impossible. Only through complex manipulation in lab settings could such WW females be produced – and even then only in fish and amphibians."
The study dates back to 2004, when a captive-born female Boa constrictor imperator (a subspecies) produced a small litter through sexual reproduction with a male B. c. constrictor (a closely related subspecies), while both were housed in a private collection. After the male was removed, no additional litters were produced from 2005 through 2007. But in the next two years, the female produced two litters of live offspring (12 in 2009 and 10 in 2010). These litters were unusual because all offsprings were female.
Through DNA fingerprinting and sex determination by surgery, the scientists found that there was no male involvement in the reproductions. Parthenogenesis may be more common among snakes than assumed, they now believe.