For human ladies who want to have a baby without a male partner, there is sperm donation. For smalltooth sawfish ladies, there is parthenogenesis — the scientific term for "virgin birth."
An astounding 3 percent of sawfish living in an estuary in Florida have no biological father at all, according to a study published on June 1 in the journal Current Biology. Instead of having one set of genes from their mother and another set from a father, they have two sets of genes from mom.
"I was looking at their DNA and some of it looked different," lead author Andrew Fields told Tech Times. "When we analyzed those differences, they turned out to be due to parthenogenesis."
Instances of captive female birds, reptiles, and sharks reproducing by parthenogenesis have come up in the past, but this is the first time the phenomenon has been observed in a wild animal. This doesn't mean that males are totally unnecessary, however. Animals that are produced this way are often riddled with genetic defects, and many of the embryos fertilized this way do not even make it to term.
This leads researchers to believe that females only go this reproductive route when they have to. When it comes to finding a mate, it's extremely slim pickings for female smalltooth sawfish. As the most endangered marine fish in the world, they are lucky if they encounter any males at all.
"Because they're so interesting looking, they've been harvested around the world for things like their nose. Sometimes it's just an item for curios, but sometimes they're used as weapons," Fields said.
If females are unable to find any males to mate with, this may trigger changes in their reproductive systems that make parthenogenesis possible. When females of any animal species produce eggs, cells containing extra genetic material get produced as a by-product. Usually, these cells are essentially discarded — but in parthenogenesis, they end up contributing that extra genetic material to the offspring.
"The way we think this works is that those extra cells act kind of like a sperm and fertilize the egg," said Fields.
The ability to reproduce without a partner may seem like a win for the sawfish, but Fields finds this discovery both "exciting" and "a little bit scary." If these seemingly miraculous births do turn out to be a last-ditch attempt at reproduction, soon the only smalltooth sawfish left may be those sitting lifelessly in places like oddity shops.
