Female zebra shark reproduces without a male

A female zebra shark in Australia has confirmed what women everywhere have long suspected: men are overrated. She did this by getting pregnant all by herself.

To be clear, her most recent pregnancy was accomplished solo. Leonie the zebra shark had a male companion from 1999 to 2012, when he was moved to a different tank. During that time, the pair gave birth to a whopping two dozen babies.

After her mate was moved, Leonie didn’t let that deter her from joining the Mommy Club yet again. She surprised her caretakers by giving birth to three baby sharks in 2016.

How is this possible? University of Brisbane researcher Christine Dudgeon and her colleagues have cycled through a few theories.

At first, they thought perhaps the female zebra shark was able to turn her body into a sperm bank. This would allow her to use her ex’s sperm to fertilize her eggs at will. Upon further investigation, they found that the baby sharks were only carrying one set of DNA – that of their mother. Congratulations, Leonie’s ex: you are not the father!

This means that Leonie had her babies via asexual reproduction. This is quite common in many vertebrate species such as sharks, snakes, Komodo dragons, rays, and turkeys. Where Leonie has scientists baffled is that while asexual reproduction is typical for females who have never had a male partner, it’s virtually unheard of in females who have previously mated with males.

Animals who move from sexual to asexual reproduction is a phenomenon that will require more study. Researchers like Dudgeon believe that it’s possible that this kind of switch occurs more often than scientists realize; they just didn’t know to look for it before.

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By Dawn Henderson, Earth.com Staff Writer