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Living fossils? Actually, sturgeon are evolutionary speedsters
Efforts to restore sturgeon in the Great Lakes region have received a lot of attention in recent years, and many of the news stories note that the prehistoric-looking fish are "living fossils" virtually unchanged for millions of years.
But a new study by University of Michigan researchers and their colleagues reveals that in at least one measure of evolutionary change--changes in body size over time--sturgeon have been one of the fastest-evolving fish on the planet.
"Sturgeon are thought of as a living fossil group that has undergone relatively slow rates of anatomical change over time. But that's simply not true," said Professor Daniel Rabosky who is curator of herpetology at the Museum of Zoology.
"Our study shows that sturgeon are evolving very quickly in some ways. They have evolved a huge range of body sizes. There are dwarf sturgeon the size of a bass and several other species that are nearly as big as a Volkswagen."
The sturgeon finding is just one result in a wide-ranging study of the rates of species formation and anatomical change in fish. The work involved assembling one of the largest evolutionary trees ever created for any group of animals. The evolutionary relationships between nearly 8,000 species of fish are delineated in the branches of the tree, allowing the researchers to make inferences about all 30,000 or so species of ray-finned fish.
"We're basically validating a lot of ideas that have been out there since Darwin, but which had never been tested at this scale due to lack of data and the limits of existing technologies," Rabosky said.
The study's findings were published online June 6 in Nature Communications. Rabosky and Dr. Michael Alfaro of the University of California, Los Angeles, are the lead authors. Professor Stephen Smith, computational evolutionary biologist, is a co-author.
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