Thursday June 1, 2023
Futurity —
The finding offers insight into the causes of species richness in the ancient mountain range.
Researchers have previously associated high biodiversity in mountain ranges, including the Andes and Himalaya, with tectonic uplift—the shifting of plates in the Earth’s crust that forms mountains, plateaus, and other geologic structures—triggering environmental changes that create conditions ripe for species diversification. But this explanation does not account for the high biodiversity found in older mountain ranges, such as the species-rich Appalachians, where tectonic uplift ceased hundreds of millions of years ago.
For the new study, published in the journal Science, researchers analyzed populations of greenfin darters, Nothonotus chlorobranchius, a fish species only found in the upper Tennessee River system in the southern Appalachians, and the river basin’s underlying geology.
They found that river water has gradually eroded a top layer of metamorphic rock in portions of the upper Tennessee River basin, exposing softer sedimentary rock that acts as a barrier, isolating populations of the greenfin darter in river channels still flowing over metamorphic rock.