Researchers have shone a new light on the history of the deep ocean and how fish have colonized it over the millennia.
Researchers from the University of Washington have found that during the earth’s history, there were many periods where fish preferred the deep, cold ocean to the warm shallows.
The scientists studied speciation rates (the rate at which new species evolved) using genetic records over a 200-million-year period. They found species evolution swings backward and forward between the deep ocean and the shallows. Evolution in the depths was faster for long periods lasting over tens of millions of years.
Commenting on the work, lead researcher Elizabeth Miller from UW’s School of Aquatic and Fishery Sciences and now a postdoctoral fellow at the University of Oklahoma stated:
“It’s easy to look at shallow habitats like coral reefs, which are very diverse and exciting, and assume that they’ve always been that way. These results really challenge that assumption, and help us understand how fish species have adapted to major changes to the climate. The first was the breakup of Pangea, which occurred between 200 and 150 million years ago. That created new coastlines and new oceans, which meant there were more opportunities for fishes to move from shallow to deep water. There were suddenly a lot more access points.”
Commenting on the deep ocean today, she added:
“If you look at who lives in the deep sea today, some species have a tapered body and others have big, scary, toothy jaws. Those two body plans represent ancestors that colonized the deep sea millions of years apart. What we learned from this study is that deep-sea fishes tend to do well when oceans are colder, but with climate change, oceans are getting warmer….We can expect that this is really going to impact fish in the deep-sea in the coming years.”
You can find the original study here.