| Acer mono var. mono is an important accompanied tree species with many functions such as economical, ecological and ornamental in the temperate mixed-broadleaved Korean pine forests in Northeast China. Because the forest in Northeast China has been severely disturbed since the late19th century by wars, fires, deforestation, overexploitation and changes in land use to agriculture field and grazing land, many tree species including Acer mono becoming threatened. In order to conserve and restore of forest or tree species in a region, it is necessary to understand the biological and genetic features of the tree species in the region. We therefore conducted the study using nuclear SSR markers and cpDNA sequencing, aimed to reveal the genetic diversity and genetic structure of A. mono, understand the existential state and then provide suggestion for conserving and restoring the threatened species. We also expected that our results might be helpful for conservation and management of the Northeast forest region. In addition, we studied the genetic relationships among sympatric variaties of Acer mono Maximum in Japan by using nSSR markers and cpDNA sequencing. At last, we try to clarify the phylogenetic relationships of all variaties of Acer mono Maximum we sampled. Our main results are as follows:(1) Acer mono maintained high level of genetic diversity (HE=0.738, AR=7.605) in nuclear genome overall56populations with higher genetic diversity among the48northeastern populations than that among the8southern populations (AR=8.593and7.910, p=0.119; HE=0.746and0.694,p=0.025); genetic differentiation among all population was medium with FST=0.073and G’ST-0.278, however, the differentiation among southern populations (FST=0.201, G’ST=0.722) was much higher than that among northeastern populations (FST=0.029, G’ST=0.114); genetic diversity decreased in northeastern populations along with latitude, which might be a common trend for tree species in Northeast China; Acer mono has experienced genetic bottleneck extensively, which might occur during the recent decades caused by unreasonable management and human activities;(2) The56populations were clustered into Northeastern populations (Popl), Southern populations (Pop3) and admixture population (Pop2), which appeared admixture feature of Popl and Pop3; divergence time were obtained by DIYABC analysis:Pop3diverged from ancestral population at88,800a BP, because of uplift of Qinling Mountains and blocking of fault zone of Taihang Mountains; Pop1diverged from Pop2at20,430a BP, because of blocking of Northeast Plain;(3) The total haplotype diversity for cpDNA of Acer mono var. mono was high (HT=0.857), but extremely low within population (HS=0.056), which indicated that the variances existed among populations mainly; differentiation among populations was extremely high (NST=0.960> GST=0.935; P>0.05) but no significant phylogeographic distribution of the haplotypes were detected; the current distributed pattern of cpDNA haplotyped in China might cause by allopatric fragmentation overall regions, but populations in Northeast China and in north of North China expanded their habitat during postglacial;(4) The two sympatric variaties in Hokkaido derived from one lineage but differentiated significantly from each other, reproductive isolation might be existent between the two variations; genetic relationships among the three sympatric variaties in Chichibu were closer compared to that in Hokkaido, hybridization and/or introgression existed among variaties; the higher genetic diversity of variaties in Chichibu than that in Hokkaido might be caused by hybridization and/or introgression; Japanese variations of Acer mono Maximum derived from China, eustatic fluctuation of sea level caused by climatic fluctuation during Quaternary resulted in eastward colonization of Acer mono via continental shelf of Yellow Sea, and the alternately separated and connected distributions formed current richness of variations of the species in Japan (8variaties);(5) Large genetic differentiation occurred between Acer mono var. macropterum that sampled from Yunnan Province and other variations, it is necessary to redefine its taxonomic status; Acer mono var. tricuspis that sampled from Emei Mountains appeared closer relationships with Acer mono var. mono;(6) Multiple separated refugia for Acer mono existed in China according to nSSR markers and cpDNA sequencing analysis, such as in south section of Changbai Mountains, north of North China, the junction of Taihang Mountains and Zhongtiaoshan Mountains, middle section of Qinling Mountains, Emei Mountains, Tianmushan Mountains and so on;(7) Different recommendation were proposed for conservation and silviculture contrapose different populations:for northeastern populations, selection and breeding of specific-functional variaty is impotant; for southern populations, an strategy for ex situ conservation should be conducted urgently and for the adjacent populations, the use of local seeds and nursery stocks for reforestation and an increase in reserve areas is necessary;... |
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