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

Researchers sampling environmental DNA from Missouri Ozark streams, working with the state's Department of Conservation, expected to find the common bleeding shiner fish in every stream but instead found it missing from roughly half their samples. Investigating the anomaly, they discovered the missing detections lined up precisely with the divide between northern and southern Ozark drainages.

Follow-up analysis revealed that northern and southern bleeding shiner populations, though visually identical and classified as the same species, carry different genetic histories, with northern fish showing signs of ancient hybridization from hundreds of thousands of years ago. The team attributes the split to Pleistocene glacial activity, which repeatedly reshaped northern river drainages while leaving southern Ozark streams comparatively undisturbed.

The researchers also detected other at-risk species, including lake sturgeon, crystal darter, and a cave-dwelling fish, simply from water samples rather than physical capture.

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