Population Genetic Diversity And Ecology Suitability Regions Of Juniperus Przewalskii In Qinghai Province

Genetic diversity determines the survival,development and evolution of a species,and research on it is helpful to the conservation and utilization of this species.Juniperus przewalskii is a unique dominant tree species in the northeastern part of the Qinghai-Tibet Plateau,which has great ecological functions of water and soil conservation.At the same time,it has medicinal and material value.In the case of global warming,alpine species would be particularly vulnerable.As one of the fine native tree species in Qinghai Province,the current suitable area for J.przewalskii was still unclear.In order to fully grasp the genetic variation of J.przewalskii in Qinghai Province,reveal the correlation between J.przewalskii population genetic diversity and environmental factors,and better understand the ecological adaptability of J.przewalskii population.In this study,7 J.przewalskii populations in Qinghai Province were used as the research object,using SSR and SRAP two molecular marker techniques to analyze the genetic diversity characteristics of J.przewalskii and discuss the correlation between genetic diversity index and topographical climate factors.Simultaneously,the potential geographic distribution of J.przewalskii was simulated via Maxent model and Arc GIS spatial analysis technology in Qinghai Province under different climate scenarios.The research analyzed dominant factors affecting the potential distribution of J.przewalskii and discussed the changes in suitable distribution areas under future climate scenarios.It was expected to provide theoretical guidance for the selection of excellent germplasm of J.przewalskii and the protection,development and utilization of germplasm resources.1.20 pairs of SSR polymorphic primers and 22 pairs of SRAP polymorphic primers were screened out,and the average percentage of polymorphic were 100% and 99.58% respectively.Both molecular markers can be effectively amplified in J.przewalskii.Based on the genetic diversity index,the genetic diversity of J.przewalskii population was relatively rich.Population MX(Maixiu Forest Farm)and population DLX(Xiangride in Dulan County)had a higher level of genetic diversity,and population QL(Qilian County)had the lowest level of genetic diversity.The genetic differentiation of J.przewalskii was at a moderate level,which mainly occured within the population,and there is a certain degree of gene exchange between the populations.2.Based on the cluster analysis results of SSR and SRAP two molecular markers,the 7 J.przewalskii populations could be divided into two categories.The first category included MX(Maixiu Forest Farm in Zeku County),DLH(Delingha),DL(Dulan Forest Farm in Dulan County)and DLX(Xiangride in Dulan County);the second group included QL(Qilian)and HZ(Beishan Forest Farm in Huzhu County).The clustering results of the WL(Wulan)population was slightly different due to the different primers of the two markers.There was no significant correlation between the genetic distance and the actual geographic distance between populations of J.przewalskii.3.Environmental factors have varying degrees of influence on genetic diversity and geographic distribution.Altitude was the most important environmental factor,followed by precipitation and temperature,which affected the genetic diversity and geographic distribution of J.przewalskii.4.Under current climatic conditions,the suitable distribution area of J.przewalskii was mainly located in the eastern part of Qinghai Province,and the total suitable area accounted for 11.2%.The core suitable areas were mainly distributed in Qilian,Menyuan,Datong,Huzhu,Ledu,Minhe,Hualong,Pingan,Huangzhong,Huangyuan,Haiyan,Gangcha,Gonghe,Guinan,Guide,Jianzha,Xunhua,Tongren,Zeku,Henan,Tongde,Maqin,Xinghai,Wulan,Dulan,Maduo,and Delingha counties.After analysis,the dominant factors affecting the geographical distribution of J.przewalskii were altitude,annual precipitation,min temperature of coldest month,and slope,with a cumulative contribution rate of 85.9%.5.The three future climate scenarios had different effects on suitable areas of J.przewalskii.The suitable areas would shrink under the SSP245 scenario.The suitable areas would expand between the SSP126 and SSP585 scenarios.The suitable area of J.przewalskii had the most obvious expansion under the SSP126 climate situation,and its expanding areas were mainly located in Zeku County,the north-central part of Henan Mongolian Autonomous County,and the southeast of Qilian County.Under three climatic scenarios in the future,the suitable area of J.przewalskii gradually migrates to high altitude areas,but there is no clear shift in the latitude and longitude direction,which were generally stable.