Genetic variation of hazel (Corylus heterophylla) populations at different altitudes in Xingtangsi forest park in Huoshan, Shanxi, China

摘要

The change pattern of genetic diversity along an altitude gradient has become an increasingly attractive subject in both theoretical studies and utilization and conservation practices because altitude variations regulate the ecological conditions in a particular plant habitat; sometimes, even a relatively small change in altitude can cause a drastic change in environmental conditions. Corylus heterophylla, which grows along an altitude gradient ranging from 1200 m to 2400 m, is an important economic shrub species that helps maintain vegetation stability and ecological equilibrium in Xingtangsi forest park in Huoshan, Shanxi. In this study, eight C. heterophylla populations were sampled along an altitude gradient (each sampling interval was about 100m). By using a SRAP molecular marker, the genetic diversity and variation of C. heterophylla populations in Xingtangsi forest park were studied. The results showed that the C. heterophylla populations had high genetic diversity. The effective number of alleles (Ne), Nei’s gene diversity index (H), and Shannon diversity index (I) were 1.5106, 0.3130, and 0.4790, respectively. The total percentage of polymorphic loci (PPB) was 98.03%. Of the eight populations, population 3 had the highest genetic diversity（Na:1.8465, Ne:1.5759, H:0.3203, I:0.4683, PPB:84.65%), whereas population 1 had the lowest (Na:1.6102, Ne:1.2997, H:0.1841, I:0.2841, PPB:61.02%). The variation in genetic diversity of all eight studied populations indicated a low-high-low pattern along the elevation gradients. The mid-elevation populations (1700m, 1800m, and 2000m) were more genetically diverse than both low-elevation (1500m) and high-elevation populations (2100m and 2200m). AMOVA analysis showed that only 16% of the total genetic variation occurred among populations, whereas 84% of the variance was within populations; this was in line with the coefficient of genetic differentiation (GST = 0.225) and the STRUCTURE analysis. The cluster analysis (UPGMA) results indicated that eight C. heterophylla populations were mainly grouped into 5 clusters; the PCoA results also showed the populations of C. heterophylla approximately divided into 5 groups. Based on the available data, it is likely that the biological characteristics, effective gene flow, and environmental heteroplasmy of C. heterophylla are enough to significantly differentiate the populations of C. heterophylla in Xingtangsi forest park in Huoshan, Shanxi.