Earthquake Forced Rapid Evolution in Fish

We usually think of evolution as something that happens over millions of years. But according to a just-published study, scientists reveal that the 1964 Alaska earthquake,  which measured 9.2 in magnitude, sped up the process for a tiny saltwater fish species, forcing it to radically change its physical features over a 50 year period so that it could survive in freshwater.

In an article published in Proceedings of the National Academy of Sciences, researchers from the University of Oregon and University of Alaska focused upon the changes in the threespine stickleback, a tiny fish species usually found in saltwater.

After the massive quake, some populations of the fish were stranded by geological uplift in freshwater ponds. The researchers discovered that those fish subsequently experienced changes in both their genes and visible external traits such as eyes, shape, color, bone size and body armor in their adaptation to 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 University of Oregon biology professor William Cresko, one of the study’s co-authors.

“In some of the populations that we studied we found evidence of changes in fewer than even 10 years,” Cresko said. “For the field, it indicates that evolutionary change can happen quickly, and this likely has been happening with other organisms as well.”

The changes were similar to those seen in the same species after it was forced to exist in freshwater when glaciers receded 13,000 years ago. That shift was documented in a 2010 study, of which Cresko also was a co-author.

In the latest article, Cresko and his colleagues noted that stickleback now have regions of their genomes alternatively honed for either freshwater or marine life. That may explain why they were able to adapt so rapidly to their new environment.

From Discovery News