Immaculate conception? Not quite

Did you know that certain vertebrates (animals with backbones and spinal columns, basically the higher orders of animal life) can reproduce as virgins? Female snakes, sharks and some birds sometimes use a polar body, a cell that lives next to an unfertilized egg, to fertilize the egg when they can’t find a mate or are in captivity. Kind of strange, but true… and nothing new to scientists.

What could be new are the reasons for these “virgin births.”

The evidence springs from research done on wild populations of copperhead and cottonmouth snakes. Scientists at the University of Tulsa in Oklahoma collected pregnant snakes, then checked to see which of the mothers had fertilized their own eggs, also known as parthenogenesis. Of the 22 copperheads collected, one had self-fertilized her egg, and one of the 37 cottonmouths had also self-fertilized — big numbers for such small sample sizes. So the story scientists usually follow didn’t add up; there were plenty of male snakes slithering around.

So why the single moms? One theory is that they weren’t wanted by the males in the field; the copperhead mother was very small and therefore less attractive for a selective male. Other researchers suggest that it was involuntary; that some infection or bacteria triggered the polar body to fertilize the egg.

Whatever the reason, personal choice seems an unlikely option. Many babies born through parthenogenesis are deformed or unhealthy in some way, since it’s a severe form of inbreeding. It can also throw off population structure; snakes born from parthenogenesis are always male, another mystery scientists are still trying to unravel.

Or maybe the vipers are just enlightened. Why would they need some football-watching male that doesn’t clean his scales properly lazing around when they can do the family thing solo? More power to you, girls.


Photo: dw_ross/Flickr


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