Environmental DNA Reveals Hidden Genetic Divide Among Ozark Bleeding Shiners

A student team partnered with the Missouri Department of Conservation to sample water from six Ozark rivers and streams for environmental DNA (eDNA). The analysis detected a range of species, including at‑risk fish such as lake sturgeon, crystal darter, and Alabama shad, and even revealed DNA from a cave‑dwelling fish in surface waters that would otherwise go unnoticed. The study’s unexpected finding was that eDNA for the common bleeding shiner (Luxilus zonatus) appeared only in southern Ozark streams, while northern streams showed no signal. Further genetic analysis uncovered that northern bleeding shiners carry a distinct DNA signature from an ancient hybridization event with another shiner species, a legacy of Pleistocene glacial reshaping of drainage patterns. This genetic split, invisible to visual surveys, illustrates how historic river course changes have produced separate evolutionary lineages within what appears to be a continuous landscape.