Desperate times call for desperate measures, which may explain why some critically endangered smalltooth sawfish are reproducing asexually in the wild.
The smalltooth sawfish is a member of the ray family, and under normal circumstances it reproduces sexually like most other vertebrates. However, in a study published in Current Biology, scientists report seven instances of juvenile sawfish that appear to be the product of a virgin birth — no dad involved.
The researchers were able to tell that these fish were produced asexually because routine DNA tests showed there was little to no variability in the genetic material of the seven specimens.
It has been observed before in birds, reptiles and sharks, but only when they are living in captivity.
Asexual reproduction in a sexually reproducing species is called facultative parthenogenesis. Scientists think it occurs when an unfertilized egg absorbs a genetically identical sister cell called a polar body. Smalltooth sawfish are a long-lived species that take years to develop into sexual maturity, so it is still unclear how well these virgin-birth fish survive and if they will be able to reproduce sexually.
In the meantime, Fields is hoping other researchers who study endangered sharks, rays, lizards, snakes and birds will look for evidence of asexual reproduction that they may have missed.
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