After Alaska’s 1964 earthquake stranded salt water stickleback fish in freshwater ponds, it took just 50 years for them to evolve into happy pond dwellers.
March 27th, 1964: The world's second-most powerful recorded earthquake hits Alaska.
[Movie clip narrator:] "Out in the Gulf of Alaska the ocean bottom seems to sink, then heaves upward 50 feet, sending a giant wave towards shore."
This is Scientific American’s 60-Second Science. I’m Christopher Intagliata. Got a minute?
[Susan Bassham:] "Things that were submarine platforms before suddenly were lifted above sea level, and then silt could come in and build more island."
And with more island, came new freshwater ponds. Those newly created bodies of water turned out to be the test bed for a natural evolutionary experiment on a finger-sized fish, called the three-spined stickleback.
[Bassham:] "Big silvery well-armored fish entered freshwater ponds, and during the last 50 years they changed their size, they changed the size of their eyes, the length of their spines and became more stereotypical freshwater fish."
But how?
Bassham and her colleagues ran statistical analyses on the genomes and body measurements of fish living in those freshwater ponds today. They were able to move in and rapidly adapt because the sea-dwelling fish have a sort of "sleeper genome" of freshwater traits, just waiting to be activated.
[Bassham:] "These are anadromous fish that have been invading freshwater ecosystems over and over and over. And all those freshwater adaptations have trickled back into the sea, allowing the oceanic population to maintain this huge resource of alternately adapted genotypes."
It takes just several dozen generations—instead of thousands of years—for this evolution to occur.
Not all species, of course, have a genome that makes it easy to respond to sudden environmental challenges, the kind we’re seeing with climate change. But there may be a few species, she says, in possession of the kind of genetic toolkit that enables sticklebacks to deal with adversity so swimmingly.
Thanks for the minute! For Scientific American’s 60-Second Science, I’m Christopher Intagliata.
—Christopher Intagliata
[The above text is a transcript of this video.]
Credits:
CREDITS
Executive Producer Eliene Augenbraun
Producer Lydia Chain
Narrator Christopher Intagliata
Stock Video VideoBlocks
Graphic Artist Amanda Montanez
Special Thanks: Cresko Lab/University of Oregon; Freshwater and Marine Image Bank; U.S. Army; U.S. Geological Survey
