ANN ARBOREfforts 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 changechanges in body size over timesturgeon 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 Daniel Rabosky, assistant professor in the U-M Department of Ecology and Evolutionary Biology and a 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.
The study's findings are scheduled for online publication in Nature Communications on June 6. Rabosky and Michael Alfaro of the University of California, Los Angeles, are the lead authors. U-M computational evolutionary biologist Stephen Smith is a co-author.
The main goal of the project was to test a longstanding idea in evolutionary biology that has anecdotal support but which had never been rigorously evaluated, Rabosky said. It was Charles Darwin who coined the term "livin
|Contact: Jim Erickson|
University of Michigan