DO­ING IT FOR HER­SELF

Scuba Diver Australasia - - News -

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.

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