Fig 1.

(a) Geographical locations of populations of pure Picea glauca (FN), pure P. engelmannii (E1, E2 and E3), and their hybrids (all other populations). Population names corresponding to two-letter codes in Table 1. (b) Map showing the location of the hybrid zone in North America; and (c) posterior estimates of cluster membership for the Picea glauca x P. engelmannii hybrid zone with TESS for K = 2. Populations are ordered by increasing latitude from left to right, finishing with the P. glauca reference population (FN).