GM coloured zebrafish disappear in just 15 generations

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Glofish – zebrafish carrying a colour gene from the sea anemone

Scientists claim they can now anticipate how species will evolve in our increasingly genetically-modified (GM) world. Researchers at Purdue University in Indiana used two species of fish to validate their model. Theirs is the first model capable of predicting if a GM plant or animal would thrive or disappear if introduced into the wild.

Research supervisor and animal scientist, Professor William Muir, says that the model echoes Darwinian ‘survival of the fittest.’ “Natural selection has had billions of years to maximise an organism’s fitness for its environment,” said Muir, “Nature experiments with mutations all the time, and it only saves the best of the best.”

To test the model, researchers observed and analysed over 18,000 offspring of the two species in conditions mimicking nature. Glofish are identical to wild-type zebrafish except for the Glofish’s fluorescent colour. That colour is a genetic trait inserted into their genome from sea anemones.

The male zebrafish competed more successfully than the Glofish for the females’ attention. As a result, the fluorescent gene disappeared within 15 generations, confirming that Glofish would disappear in the wild.

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Normal zebrafish

The US Department of Agriculture funded the study as part of a larger effort to regulate biotechnology by using modelling in GM approval processes. “If [the GM species] appears to not be more fit than the [wild] animal, then evolution should eliminate it if the organism got into the environment and it could advance to the next level of review,” said Muir.

The Institute for Responsible Technology, based in Iowa, doesn’t believe that the US is doing enough to keep up with the GM industry. “Submissions to the [Food and Drug Administration] may be worse than in other countries, since the agency doesn’t actually require any data,” the Institute said.

The study was published in the journal Evolution.

Emma Brown is studying for an MSc in Science Communication

Image: Glofish by Carolina Biological Supply Company (Flickr, Creative Commons)

Citation: Howard, R.D. et al (2015) Mate competition and evolutionary outcomes in genetically modified zebrafish (Danio rerio). Evolution 69: 1143–1157. DOI: 10.1111/evo.12662

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