Self-fertilising fish discovered

Many plants do it and some worms and molluscs do it – they propagate without a partner by fertilising themselves. Now an international research group, including researchers from the University of Gothenburg, have found a tropical perciform fish from Lake Victoria that is not only a mother, but also a father, to its offspring.

Among vertebrates this is extremely rare. To be sure, some animal species propagate without sex by cloning themselves. The process is called parthenogenesis. In those cases, the origin of the species is usually a cross between two different species.

“The mangrove killi fish is the only vertebrate that has self-fertilisation as a propagation method, and they propagate almost exclusively in this way,” says Ola Svensson, a senior lecturer at the Department of Biological and Environmental Sciences. “The fish we studied belong to the cichlid family that propagates only sexually. But this particular fish appears to be an exception.”

The fish that the researchers studied was a cross between two cichlid species from Lake Victoria. So imagine the researchers’ amazement when the mouth-brooding fish spawned with itself and four of the eggs hatched. When the genetic make-up of the young was investigated, their amazement grew even more.

“The offspring were not a clone of the mother, which is to be expected given that it was a hybrid. Instead the paternity analysis shows that the ‘female’ was also the father of the children.”

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