How Saltwater Fish Evolved to Live in Fresh Water in Only 50 Years (VIDEO)

First Posted: Dec 15, 2015 10:56 AM EST

Most people think evolution occurs over long periods of time. Now, though, scientists have found that tiny fish transformed over just 50 years after an Alaskan earthquake in 1964.

The earthquake was a 9.2 on the Richter scale, and was the second highest ever recorded. It caused geological uplift that captured marine fish in newly formed freshwater ponds on islands in Prince William Sound and the Gulf of Alaska.

The fish in this case are seawater-native threespine stickleback. In just three decades, these fish experienced changes in both their genes and visible external traits such as eyes, shape, color, bone size and body armor when they adapted to survive in fresh water.

"We've now moved the timescale of the evolution of stickleback fish to decades, and it may even be sooner than that," said William Cresko, one of the researchers, in a news release. "In some of the populations that we studied we found evidence of changes in fewer than even 10 years. For the field, it indicates that evolutionary change can happen quickly, and this likely has been happening with other organisms as well."

The findings show just how fast evolution can occur when animals are exposed to a seemingly hostile environment.

"This research perhaps opens a window on how climate change could affect all kinds of species," said Susan L. Bassham, one of the researchers. "What we've shown here is that organisms-even vertebrates, with long generation times-can respond very fast to environmental change. And this is not just a plastic change, like becoming tan in the sun; the genome itself is being rapidly reshaped."

This could be potentially good news in the face of climate change. With that said, it will take further studies to see which species can respond quickly to changing environmental conditions.

The findings are published in the journal Proceedings of the National Academy of Sciences.