Riverscape Genetics of Speckled Dace (Rhinichthys osculus): A Contrasting Study of the Colorado River and Great Basin Drainages

Authors: Steven M Mussmann, Marlis R Douglas, Michael E Douglas

Year: 2016 (xlviii)

Abstract

The ubiquitous distribution of Speckled Dace (Rhinichthys osculus) throughout all major drainage basins of the western United States is a direct result of an ever changing landscape. Hydrological processes have altered the distribution and diversity o f Speckled Dace across the western landscape, resulting in narrow endemism for many unique subspecies and promoting secondary contact between previously isolated lineages. This study conducts a population-level assessment of Speckled Dace within the exorheic Colorado River Basin (CRB), and the many endorheic drainages of the Great Basin (GB). To do so, we employ double digest restriction associated DNA (ddRAD) sequencing to recover approximately 9,000 loci for the purpose of evaluating geneti c diversity of Speckled Dace in these contrasting basins. Assessment of 1,000 samples collected from 100 dace populations throughout the west identified varying levels of population structure. In the CRB, four unique, widely distributed groups wer e detected, corresponding to the Upper Colorado, Gila River, Virgin River, and Little Colorado drainages. Ten lineages with much more restrictive distributions were detected in the GB. Population analyses are currently being used to evaluate the potential for historic mixing of populations, with the unique properties of these riverine systems being inferred as the driver of Speckled Dace evolution.