DOING IT FOR HERSELF

A female zebra shark in an Australian aquarium has stunned the scientific community by giving birth to three young, despite having been separated from her male partner for a number of years. The shark had previously had 24 pups in her 12 years at the aquarium, but was placed in a separate tank in 2012.

It is well known that some vertebrate species have the ability to reproduce asexually. This has been observed in snakes, some sharks, and rays. However, this form of reproduction normally occurs in individuals that have never reproduced sexually before. The switch from sexual to asexual reproduction has, so far, only been observed twice, once in a boa constrictor and once in an eagle ray.

The team at the aquarium verified that the zebra shark had not somehow stored her partner’s sperm during the years of separation; DNA tests showed that the pups were only carrying the mother’s genetic material.

This form of reproduction is not favoured in vertebrate species as it results in low genetic diversity, low adaptability, and limited resilience, but is believed to function as a temporary mechanism to continue the species until a male partner can be found.