Studies On The Ulmus Pumila Spatial Distribution Pattern And The Genetic Diversity Of Ancient Wild Ulmus Pumila In Inner Mongolia

Ulmus pumila,also known as Ulmus,is mainly distributed in northeast,North and northwest China to the north of the Yellow River in China,with strong adaptability.In this study,the ecological niche model was used to explore the spatial distribution pattern of Ulmus pumila,and the macro changes of genetic structure of Ulmus pumila were preliminarily analyzed by genetic diversity analysis method,and the ecological distribution range of Ulmus pumila under climatic conditions were simulated.The aim of this study was to provide basic data and scientific basis for the investigation and regionalization of native tree resources of Ulmus pumila in China,and to provide theoretical guidance for the development and protection of germplasm resources of Ulmus pumila.1.MaxEnt and ArcGIS software were used to fit the dominant environmental factors affecting the distribution of Ulmus pumila and predict the potential spatial distribution of Ulmus pumila under climate scenarios of the contemporary,2050 s and 2070s(RCP2.6and RCP6.0).The results showed that the MaxEnt model had high accuracy in predicting the potential distribution of Ulmus pumila,and the AUC values of training set and test set were 0.921 and 0.911,respectively.The contribution rates of temperature seasonal variation(Bio4),annual precipitation(Bio12)and precipitation seasonal variation(Bio15)were up to 88.4%,indicating that temperature and precipitation were the main factors affecting the distribution of Ulmus pumila in seasons and years.2.Depends on the climate environment variables,Ulmus pumila predict potential distribution area,the current period,high suitable District mainly concentrated in China’s hebei province in north China,shaanxi,shanxi,shandong province,in central China’s xinjiang,Inner Mongolia,gansu,also have a large distribution in northwest China,jilin,liaoning and hulunbuir,northeast China.Under the background of global climate change,under different climate scenarios in the 2050 s and 2070s(RCP2.6 and RCP6.0),the area of high suitable area of Ulmus pumila decreased,while the area of middle and low suitable area increased,and new potential suitable area appeared.The distribution of Ulmus pumila showed a trend of migrating to high latitude and high altitude area.3.On the basis of niche software fitting suitable areas of wild Ulmus pumila in Inner Mongolia and combined with field investigation,9 regional sample sites in eastern,central and western Inner Mongolia were identified.105 samples from 9 populations were sequenced by GBS--SNP simplified genome sequencing,and 4366605 SNPS were reserved.The genetic diversity,genetic structure and environmental correlation of SNP dataset were analyzed.The results showed that at the population level,the hardy Weinberg balance test was higher to achieve population genetic equilibrium,while Tajimi’s D test was higher and T > 0,indicating that spatial shrinkage,bottleneck effect and balance selection were obvious in population genetic history.The nucleotide diversity π indicated that the genetic differences among the 9 populations of wild Ulmus pumila in Inner Mongolia were small and the genetic diversity level was low.4.Based on the STRUCTURE analysis of SNP data set,the genetic structure can be divided into three categories: CF,TL and ARS in eastern Inner Mongolia are divided into one category;The EL,HS and ALS in central Inner Mongolia were classified into one class.Western Inner Mongolia is divided into YSD,BT and BM.5.Through gradient forest analysis,the genetic data of Wild Ulmus pumila in Inner Mongolia were correlated with climate data,which were classified into eastern region,western region,central region and overall level according to the genetic structure.Average temperature in the hot season(bio10),seasonal variation of precipitation(bio15)and longitude(longtitude)had a significant impact on genetic variation,suggesting that genetic structure is related to environment.