Female Boa constrictor reproduces without help from males


There is, perhaps, nothing terribly shocking about a female snake, placed in an enclosure with four male snakes, giving birth to two litters of baby snakes.

But what if those babies carry only their mother's genetic material?

Parthenogenesis—breeding without the, you know, breeding—has been documented in only a small handful of vertebrate species, but it does happen. However, usually, it takes the complete absence of males to get the vertebrate ladies going all virgin birthy. These baby boa constrictors, on the other hand, had plenty of potential fathers. But genetic tests have shown that none of the available male snakes is the dad. In addition, the babies are all female. All carry a rare caramel coloration. And all have a very weird mix of sex chromosomes.

In place of X and Y, snakes and many other reptiles have Z and W chromosomes. In all snakes, ZZ produces males and ZW produces females.

Bizarrely, all the snakes in these litters were WW.

This was further proof that the snakes inherited all their genetic material from their mother, as only females carry the W chromosome. "Essentially they are half clones of their mother," says Dr Booth. That is because the baby snakes have inherited two copies of one half of their mother's chromosomes, including one W chromosome.

You know the drill—I, for one, welcome our new female snake-Jesus overlords.

Biology Letters: Evidence for viable, non-clonal but fatherless Boa constrictors (And you can read the full text of the article for free! Also rare!)

BBC: Snake gives 'virgin birth' to extraordinary babies

Via Peter Kobel

Image: Wikipedia user DestructiveEyes, via CC