River erosion may shape fish evolution

They make their case in the southern Appalachians, and especially in the Tennessee River Basin, which is known for its great diversity of freshwater fish. The team found that as rivers eroded through different rock types in the region, the changing landscape pushed a species of fish known as the greenfin dart into different tributaries of the river network. Over time, these separate populations developed into separate lineages of their own.

The team speculates that erosion likely prompted the greenfin darter to diversify. Although the different populations appear outwardly similar, with the green-winged darter’s distinctive green-tinged plumage, they differ greatly in their genetic makeup. For now, the separate populations are classified as a single species.

“Give this erosion process any more time, and I think these separate lineages will become separate species,” says Maya Stokes, who did some of the research as a graduate student in MIT’s Department of Planetary, Atmospheric and Earth Sciences. work done.

The green-winged darter may not be the only species to have diversified as a result of river erosion. The researchers suspect that erosion may have driven many other species to diversify throughout the basin, and possibly into other tectonically inactive regions around the world.

“If we can understand the geologic factors that contribute to biodiversity, we can do a better job of preserving it,” Taylor Perron, professor of Earth, Atmospheric and Planetary Sciences at MIT, said in a statement.