x Abu Dhabi, UAESunday 23 July 2017

Single-minded evolution

Asexual reproduction is not uncommon in nature but for the first time the process has been documented in a zebra shark.

The male of the species, it appears, may have been irrelevant all along. No, we are not making a comment on husbands doing the housework or time spent watching weekend football. Instead, exhibit A is Zebe the zebra shark at the Burj Al Arab aquarium, which has apparently managed to reproduce all on her own.

Parthegenesis, or asexual reproduction, is not terribly uncommon in nature, but this is the first time that the process has been documented in a zebra shark. In the absence of a male mate, for the last few years Zebe has been laying eggs that are self-fertilising. At first there was speculation that Zebe might have been reproducing hybrids with the assistance of a shark of another species in the aquarium, but DNA tests have confirmed that the shark pups have just the single parent. Results of this peculiar feat were published in last month's Journal of Fish Biology.

There are greater consequences here than just the love life of one lonely fish. Sharks are among the oldest species on earth, with fossil records of more or less the same animal dating back 200 million years before the first dinosaurs. When exactly in that evolutionary epoch the species developed the ability to go it alone, as it were, will probably never be known. But it shows how much we still have to learn about the weird world of nature, even from an aquarium in Dubai.