2.1 | Sampling
We selected one Qc population (eight in total) and one or twoQch populations (10 in total) in each of eight locations as well as additional five Qc and one Qch populations around these locations (Table 1). The eight locations were situated in mountain ranges with alpine zones in northern and central Honshu (2, 4, 6, 7, 8, 9, 10, and 11 in Figure 2). We identified the taxon, Qc orQch , for each population based on growth habit, leaf size, and hair density on the abaxial leaf surface according to Ohba (2006). Three populations (05Hx, 06Hx, and 07Hx) were identified as Qch in the field observation but were grouped to Qc in the following genetic analysis (see Results 3.2). From each of the 24 populations, we sampled leaves of 18–32 trees (693 individuals in total) along mountain trails at intervals of at least 20 m in the summer in 2011–2012.
To measure leaf characters, we selected approximately three leaves from each of 4–8 individuals in each of 12 out of the 24 populations (155 leaves of 53 individuals in total; Table 1). For genetic analysis, we extracted DNA from leaves of all the 693 individuals in the 24 populations using DNeasy Plant Mini Kit (Qiagen, Hilden, Germany).