River erosion may shape fish evolution

May 26. (EUROPE PRESS) –

River erosion may be a driver of species diversity in tectonically inactive regions, according to a study published in Science by MIT scientists.

They make their case in the southern Appalachians, and specifically in the Tennessee River Basin, a region known for its great diversity of freshwater fish. The team found that as rivers eroded through different types of rocks 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 their own distinct lineages.

The team speculates that erosion likely led the greenfin darter to diversify. Although the separate populations appear outwardly similar, with the characteristic green-tinged fins of the green-finned darter, they differ substantially in their genetic makeup. For now, the separate populations are classified as a single species.

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

The green-finned darter may not be the only species to diversify as a consequence of river erosion. The researchers suspect that erosion may have led many other species to diversify throughout the basin and possibly in other tectonically inactive regions around the world.

“If we can understand the geological factors that contribute to biodiversity, we can do a better job of conserving it,” he says. it’s a statement Taylor Perron, professor of Earth, Atmospheric, and Planetary Sciences at MIT.