‘Virgin births’ recorded in endangered fish

Scientists have discovered that the smalltooth sawfish (Pristis pectinata) has developed the ability to reproduce without the need for males. 

 

The study was published in the journal Current Biology.

 

These births are an example of facultative parthenogenesis—the ability of a species (that usually reproduces sexually) to sometimes reproduce asexually. In parthenogenesis, after a precursor cell splits into an egg cell and three polar bodies, one of the polar bodies acts like a sperm cell and fuses with the egg cell. It’s a phenomenon that’s been recorded in vertebrates in captivity, but researchers say that this is the first time it’s happened in the wild with rays.

 

The researchers were actually looking into sawfish inbreeding when they came across the seven offspring that was born via parthenogenesis.

 

Sawfish are a kind of ray that can grow up to 5.5 m long. They’re currently an endangered species, with low numbers caused by habitat loss and overfishing. Scientists believe that less than 5% of the wild population remains, compared to population size when the Europeans first settled in the US.

 

“It is reasonable to hypothesize that parthenogenesis would be found most often at low population density, when females risk reproductive failure because finding mates is difficult,” the study said.

 

According to Andrew Fields, one of the researchers involved in the study, the question now is whether these virgin births are common among wild animals or if this is just “a special case because we have an endangered species with very few individuals and they don't run into each other, or is it because they're sawfish and sawfish have something interesting going on?” — With a report from Reuters/Bea Montenegro/TJD, GMA News