Phylogeography of Speckled Dace (Rhinichthys osculus)

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.  Geologic processes have simultaneously shaped the landscape and distribution of fish fauna over the past 20 million years, resulting in narrow endemism of several subspecies.  This broad distribution could thus serve as a template from which phylogeographic hypotheses could be derived for aquatic organisms more restricted in abundance and/ or distribution.  Such a template could also serve to develop a perspective on relationships of drainages, basins, and the biota therein.  We begin this task by employing next generation sequencing techniques to construct a range-wide phylogeny of Speckled Dace.  Double digest restriction associated DNA (ddRAD) sequencing recovered approximately 15,000 loci for this purpose.  Phylogenomic analysis of 200 samples collected from 100 dace populations and 50 sub-basins recovered eleven clades representing major drainages of Western North America. Most clades, such those representing the Colorado River Basin, show concordance with modern drainage systems.  However, others show remnants of Pleistocene connections, such as the Snake River clade.