Fish DNA in Ozark streams reveals region's complex geologic history

Researchers working with the Missouri Department of Conservation collected water samples from numerous rivers and streams in the Ozark region to detect genetic material from various fish species. They were surprised to find cave-dwelling fish DNA in surface waters, as this species typically isn't found in those areas. The team expected to find a specific species, the bleeding shiner, in every sample, but discovered its DNA was only present in streams draining the southern Ozarks.

Further investigation revealed that northern Ozark bleeding shiners have a distinct genetic history from their southern counterparts, despite their similar appearance. This discovery highlights how the Ozarks' complex geology, shaped by past glacial advances and river drainage patterns, has resulted in genetically unique populations of fish even among species that look identical.

The genetic information in environmental DNA samples not only shows which species are present but also provides a record of the ancient landscapes that shaped those species, offering valuable insights into the evolutionary history of the region's watersheds.