Population Genetic Diversity and Structure of Parrotia persica C.A. Mey. (Hamamelidaceae), a Relict Tree in Iran

Parrotia persica (Hamamelidaceae) is a relict tree species restricted to the Hyrcanian district of Iran and Azerbaijan. Parrotia had a wide Eurasian distribution before the Pleistocene glaciations and the western Eurasian P. persica diverged from its East Asian sister species P. subaequalis during the Miocene. We investigated infraspecific genetic diversity and structure in 10 populations of P. persica using SCoT molecular markers. We determined a significant genetic diversity in the genomic DNA using AMOVA, which mainly to diversity among populations. Moreover, high levels of genetic differentiation (Gst), total genetic variation (Ht), and a low rate of gene flow were recorded between populations. In some populations, high levels of genetic polymorphism resulted from frequent mutations in their members. The Mantel test showed a significant correlation between genetic diversity and geographic distance. We found three genotype groups among the populations using STRUCTURE and clustering analyses. These genotypes did not conform to specific distribution patterns. Our results indicated that fragmented and small-sized populations, a flat rate of gene flow, a low rate of mutations, and the breeding system in Parrotia led to high levels of population differentiation along with a nearly uniform genetic structure in most populations. Three main diversity centers exist for Parrotia in Hyrcanian forests, which are of importance for conservation strategies. A comparison with previously published population genetic patterns in Hyrcanian relict tree species ( Zelkova Spach and Pterocarya Nutt . ex Moq .) suggests that these have different genetic structures with higher rates of gene flow between populations. The detected genotypes can be used to generate new genotypes by cross pollination, and also they can cultivate as avenue trees and parks in urban areas around each genotype to conserve biodiversity in this species.