Model Of Endemic Plants Response To Geo-climatic Changes In The Qinling Mountains

The Qinling Mountains,a transitional zone between the subtropical zone and the warm temperate zone in central and western China,are the geographical dividing line between the north and south of China and the watershed between the Yellow River and the Yangtze River.Due to the unique geographical location of the Qinling Mountains,the region has bred a wealth of species resources.The Qinling Mountains is also one of the world's biodiversity hotspots,and is known as one of the rare "biological gene banks" in the world.However,for a long time,the origin and evolutionary history of the endemic plants in the Qinling Mountains in response to geological changes and the impact mechanism of global climate change on the endemic plants in the Qinling Mountains are still unclear.In this study,30 species of endemic plants naturally distributed in the Qinling Mountains of China were used as the research object.The chloroplast genome sequence was obtained through the second-generation sequencing technology,and the phylogenetic and divergence time were detected to explore the relationship between the chloroplast genomes and geological events.At the same time,based on the distribution data of these endemic plants in the Qinling Mountains and the climatic and environmental factors,the maximum entropy model combined with Arc GIS was used to simulate the population dynamics history of the endemic species in the Qinling Mountains in response to climate fluctuations.The specific research results are as follows:1.The second generation high-throughput sequencing technology was used to assemble and annotate the complete chloroplast genome sequence,and the chloroplast genome from Gen Bank public database was downloaded for comparative analysis.The results showed that the chloroplast genome structure of the 30 species of endemic plants to the Qinling Mountains sampled is relatively conservative and consists of tetrads.The chloroplast genome contains approximately 109-143 genes,including 70-93 protein-coding genes,29-42 t RNA genes and 4-8 r RNA genes.2.Based on the complete chloroplast genome data set,we examined the phylogenetic relationships and divergence histories of 30 endemic plants in Qinling Mountains.The phylogenetic relationship and divergence time of 30 species of unique plants in Qinling area were tested and it was found that the divergence time range of plant species in the unique tree group in Qinling area was 3.52-0.25 million years ago,gymnosperms differentiated earlier,which may be related to their long-term evolutionary history.The species of the shrubland group divergence time 21.86-0.92 million years ago.Some of the oldest families and genera,such as Biondia chinensis,originated 21.86 million years ago and Paeonia rockii subsp.taibaishanica,recently divergence time 0.92 million years ago.The divergence time of herbaceous species ranged from 23.74-0.27 million years ago.Among them,Arenaria giraldii originated earlier,and Ligularia dolichobotrys belonged to the recently differentiated species.The origin and divergence of these Qinling endemic plant groups coincide with the large-scale uplift events in different periods of Qinling area,which indicates that the geological change events in this area drive the origin and evolution of plant groups in the region.3.Max Ent Ecological niche models,the potential geographic distribution changes of 30 endemic plants in the Qinling Mountains are predicted in different historical periods.The results showed that among all the sampled species,only the herbaceous species Gypsophila huashanensis contracted in its potential distribution area during the Last Glacial Maximum(LGM),while the other species had the largest potential suitable distribution area during LGM.At the same time,it was also found that most of the endemic species in the Qinling Mountains shrank in the potential distribution area of species simulation during the last interglacial period and the next 2050 period.The possible reason for the change pattern of this distribution area is that the differences in the microenvironment in different historical periods in the Qinling Mountains have affected the changes in the geographic distribution of different plant groups.