Fish DNA in Ozark streams reveals region’s complex geologic history
A fish-finding expedition not only detects unexpected species but also uncovers a living link to Missouri’s geological past.
Researchers studying fish DNA in Ozark streams have uncovered the region's intricate geologic history. The team, collaborating with Missouri Department of Conservation, collected water samples from various rivers and streams across the area to identify which fish species were present. They were surprised to find DNA from a cave-dwelling fish, the bleeding shiner, in surface waters emanating from an underground spring.
However, they noticed an anomaly: the bleeding shiner DNA was not detected in all samples. By analyzing the data, they discovered that streams draining to the southern Ozarks contained bleeding shiner DNA, while those draining to the northern Ozarks did not. This led them to a significant discovery: northern Ozark bleeding shiners have a distinct DNA history from their southern counterparts, even though they appear identical.
The scientists realized that northern populations interbred with another species of shiner in the distant past, leaving behind a genetic signature of ancient hybridization. This unique genetic history is only found in specific drainages, despite the fish looking the same across the region. The findings demonstrate that today's rivers are shaped by ancient landscapes and geological processes.
Pleistocene-era glacial advances altered river courses, causing streams to be isolated or connected, ultimately influencing the genetic diversity of fish species in the Ozarks.
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