Responses Of Two Endemic Roscoea Species With Contrasted Reproductive Traits In The Hengduan Mountains To Climate Changes

Climate change has important impacts on biodiversity.Adaptation,migration or extinction of species are closely associated with climate changes.Close associations between climate changes and biodiversity have been comprehensively studied,including the impact of climate changes on genetic divergence and genetic diversity.However,adaptive responses to climate changes were relatively rarely known.The Hengduan Mountains is one of the biodiversity hotspots in the world.To explore the adaptive potential of current genetic diversity to climate changes will be significant to understand the origin and maintenance of biodiversity in the Hengduan Mountains.This study employed genotyping-by-sequencing(GBS)based on next-generation sequencing,integrated principles of phylogeography and landscape genomics to do research on two endemic Roscoea species in the Hengduan Mountains.These two species are R.humeana and R.schneideriana with reproductive distinct prosperities of outcrossing and selfing respectively.The aim of this study is to explore the adaptive responses of these two herbs to climate changes.The main findings are as follows:(1)The 5902 single nucleotide polymorphisms(SNPs)of R.humeana and 7850 SNPs of R.schneideriana were produced to analysis genetic diversity,genetic structure and effective population changes through time.The results showed that the genetic differentiation coefficient,the genetic diversity and the heterozygosity within population of R.humeana were higher than those of R.schneideriana.After the Last Glacial Maximum(LGM),the effective population size of R.humeana increased while the effective population of R.schneideriana decreased.(2)Species distribution model(SDM)was used to predict the potential distribution area of species from past to future.The results showed that the potential distribution areas of R.schneideriana contracted from the past to the future,but the potential distribution areas of R.humeana is stable from the current to the future;And the optimal distribution areas of the six SDM models were overlapped.(3)Mantel test,partial mantel test and partial redundancy analyses were used to estimate the contribution of climate and geography to genetic variability.For R.humeana,isolation by distance or isolation by environment was significant under controlling of climate or geography.Contribution of climate to genetic variation was larger than the contribution of geography.For R.schneideriana,the results showed that the environmental distance was irrelevant,but it was correlated with the geographical distance.Redundancy analysis showed that for both species,the contribution of climate was greater than geography.(4)Using gradient forest(GF)models to explore the relationship between current and future climate and genetic variability through climate adaptability and genetic vulnerability,precipitation of the warmest season(BIO18)played pivotal role in the adaptivity to climate changes.Distribution area controlled by precipitation of the driest Quarter(BIO17),R.schneideriana has the most severe genetic vulnerability under future climatic conditions.These results suggested the current genetic diversity of R.humeana and R.schneideriana were shaped by the Quaternary climate fluctuations and persistence in microrefugia in the Hengudan Mountains and had the ability to track climate changes.R.humeana can survive in the future refugia within the area of the warmest season precipitation is higher than 560 mm,and R.schneideriana can survive in the future refugia within the area of the warmest season precipitation is higher than 580 mm.This study provided a case for exploring the formation and maintenance of biodiversity in the Hengduan Mountains.