High genetic variability and complex population structure of the native Chinese hazelnut

Corylus mandshurica Maxim. belongs to the family Betulaceae and is an important economically and ecologically tree in China. Wild Corylus mandshurica resources have been gradually destroyed recently. Thus, investigation into the genetic diversity and genetic differentiation is indispensable for the efficient protection and breeding of Corylus mandshurica resources. A total of 347 individuals collected from 12 natural populations were investigated using amplified fragment length polymorphism markers. All 12 Corylus mandshurica populations showed various degrees of genetic diversity, with the value for the Mudanjiang, Heilongjiang Province population reflecting maximum genetic diversity. A UPGMA dendrogram was classified into two main clusters (Cluster I and Cluster II). Moreover, STRUCTURE analysis showed that the result of the divisions at K = 2 was highly related to the UPGMA dendrogram and PCoA scatter plot. The results of both F-ST and AMOVA suggested that there was low genetic differentiation among different populations. The high level of gene flow among populations can effectively prevent genetic drift. BARRIER analysis indicated that the first barrier boundary located between Cluster I and Cluster II was probably caused by the Yanshan Mountains. Our study provides valuable information for Corylus mandshurica conservation and breeding in the future.