3.4 Genetic diversity and differentiation
The highest He was detected in NLW2 (0.38) followed by NLW5 (0.35); the lowest was detected in LXS2 (0.31; Table 1). The highestHO was detected in NLW1 (0.34) followed by NLW2 (0.33); the lowest was detected in LXS2 (0.19). On average, Heand Ho in the Nanling Mts. (He = 0.33; Ho = 0.29) were comparable to those of the other populations in the east (He= 0.32; Ho = 0.27). In FastStructure analysis, WYS1 separated from the remaining populations when K = 2. WYS2 and LXS2 clustered as one group and separated from the remaining groups whenK = 3. Seven subpopulations (K = 7) were determined as the optimal clustering for C. chuniana (Figure 4). Differing slightly from the FastStructure result, the PCA analysis clustered LXS1 and LXS2 together and these were distinctly separate from the populations in the Nanling Mts. (Figure S1). Considering the FastStructure, PCA, and phylogenetic results together with the geographical locations of populations, we ultimately circumscribed seven groups of C. chuniana populations for further analyses: WYS1, WYS2, LXS1, LXS2, [NLE1 + NLE2], NLW1, and [NLW2 through NLW5]. Analysis of the molecular variance as based on the GBS data indicated significant genetic differentiation among populations (Fst = 0.99, P = 0.00), of which the variation among the seven groups accounted for 96.28% of the total variation (Table 2).