Riverscape Genetics of Mountain Sucker in the Intermountain West of North America

An extended drought, in tandem with anthropogenic modifications to hydrology, has brought two United Nations’ global sustainability programs (i.e., ‘Water for Life’ and ‘Deserts and Desertification’) into a sharper focus within southwestern North America. To discern natural and anthropogenic drivers in this region, we juxtaposed the genetic diversity of endemic Mountain Sucker [Catostomus platyrhynchus] against fluvial topography in 57 study sites within the intermountain West (i.e., Colorado River = 51; Bonneville Basin = 5; Columbia River = 1; Missouri River = 1). Mitochondrial DNA sequence analysis (842 base pairs / 447 specimens) defined four ESUs (evolutionarily significant units: Missouri, Bonneville/ Snake, and Colorado River basins, and Price River within the Colorado River drainage). Microsatellite DNA analysis (16 loci / 847 specimens) identified 12 drainage-specific gene pools, but only 9 qualified as demographically independent management units (i.e., migrants/ generation <10%). Price River Mountain Sucker seemingly represents ancient Lake Bonneville as it clustered with Missouri and Bonneville/ Snake basin populations. Extreme endemism in Mountain Sucker is not surprising given its propensity for smaller streams and higher elevations. These life history characteristics also make it much more vulnerable to rapid climate change.