Fig. 1

Sampling locations of Dallia in Beringia. Distribution of sampling locations of Dallia in this study from Alaska, USA and Chukotka, Russia adapted from [19]. Details of collections including number of fish, species, and geographic coordinates are available in Table 1. Major geographic features are labelled that are referred to in the manuscript. Sample locations are indicated by a circle or a star and are color coded to the major mitochondrial lineages identified in [19] as red, blue, green, or yellow. Sample location 23 indicated with a star represents Dallia admirabilis, the remainder of sample locations are from D. pectoralis. Sample location 3 represents fish from an introduced population of D. pectoralis. The physical map contains portions of Alaska and Russia from the Global 30 Arc-Second Elevation (GTOPO30) Digital Elevation Model. Hydrologic features in Alaska are represented through hydrography layers from the Alaska State Geo-Spatial Data Clearinghouse. Major rivers in Chukotka were added to the map by hand