Drainage divide

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

<figure><img src="https://images.theconversation.com/files/754908/original/file-20260819-50-3bfonp.jpg?ixlib=rb-4.1.1&rect=0%2C168%2C4032%2C2688&q=45&auto=format&w=1050&h=700&fit=crop" /><figcaption><span class="caption">A student collects a water sample for DNA analysis.</span> <span class="attribution"><span class="source">David Duvernell</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>My students and I encountered a mystery. We were partnering with the Missouri Department of Conservation to <a href="https://doi.org/10.1002/edn3.510">monitor for fish presence and abundance</a> in the Missouri Ozarks. We visited half a dozen rivers and streams across the region and collected a few cups of water from each.</p> <p>We were testing for <a href="https://doi.org/10.1016/j.gecco.2019.e00547">DNA in the environment</a> to determine which species had left behind their genetic material and were there