Ecological Divergence And Population Genetics Of Picea Mongolica And Its Related Species

Picea mongolica as an endemic species only distributes in the eastern edge of Hunshandake Sandy Land in Inner Mongolia,China.The spruce exerts some important roles on preventing land desertification in Inner Mongolia and barring sand moved to Peking from Inner Mongolia by the wind;meanwhile,it benefits to local residents in ecology,economics,and social values.However,the taxonomic status of P.mongolica has been discussing by many experts.Therefore,18 natural populations of P.mongolica and its related species Picea koraiensis and Picea meyeri were researched in the study.To analysis the genetic diversity,genetic structure,population dynamic history,phenotypic diversity,phenotypic differentiation and ecological divergence of three spruces using phenotypic traits,SNPs and bioclimatic variables.The classification status of P.mongolica has important strategic significance to provide some reliable evidence for the next research on species prevention and reasonable utilization.The results are as follows:(1)Precipitation of wettest quarter(Bio 16),Precipitation of warmest quarter(Bio 18),Mean temperature of driest quarter(Bio 9)and Mean temperature of coldest quarter(Bio 11)as main factors caused the niche differentiation of three spruces through quantitative analysis of the niche difference based on climate variable from 217 distribution record points of three sprues.Besides,the niche simulation experiment shows that distribution range of the three spruces in potential distribution area in LGM was larger than that in LIG,and the best distribution range of the three sprues in the 2080s will be shrinking compared to today.(2)P.koraiensis has two resin canals accounting for 62.07%of observed slices,P.meyeri has one resin canal accounting for 60.42%of observed slices and resin canal was not found in the P.mongolica tissue slices accounting for 92.8%of observed slices via observing 162 needle cross-sections of the three spruces under a microscope.(3)16 traits of the three spruces has significant different(P<0.01)in among and whthin populations through analyzing 16 quantitative traits of 540 individuals from 18 populations of the three spruces.And the coefficient of variation(CV)of the P.mongolica was the largest for 17.90%,the CV of the P.koraiensis was ranked second for 14.79%,and CV of the P.meyeri was the smallest for 13.93%,while the CV of needles and cone's traits was rather larger than others.The CV of all shape index(length/width)in the different traits were larger than their single trait.In addition,the needle and cone traits have an index of rich diversity information.The average phenotypic differentiation coefficients(VST)of 16 phenotypic traits of P.mongolica,P.meyeri,and P.koraiensis were 32.371%,29.890%,29.809%,respectively.Thus,the variation within populations acts as a leading position as the VST among populations was less than compared to within populations.(4)The correlation analysis of 16 quantitative traits about climatic and geographic factors shows that latitude,longitude,and altitude had markedly effects on needles,cones,seeds shapes of sprues.The temperature had significant(r>0.45)or extremely significant(r>0.6)correlation with CW,SL,SSW,CLW and SSLW of sprues;SSL SSW,SWL,and QSW are crucial traits of the sprues via researching 16 quantitative traits of the sprues using correlation analysis,PCA and cluster analysis,and P.mongolica has similar morphological trait with P.meyeri.(5)316.29 Gb Clean Data was gained from 152 samples of 18 populations of three spruces based on GSB,and Q20?97.24%,Q30?92.61%,average content of GC for 40.77%.The results showed that GBS had some reliable characteristic of premium sequencing quality and good quality distribution.Finally,a total of 3,104,341 SNPs was found based on Picea abies as a reference genome by SNPs calling.(6)The genetic diversity of the three spruces were evaluated based on 3,104,341 SNPs,the results showed that P.mongolica has the highest genetic diversity(He=0.1548,Ho=0.1248,Pi=0.1936)than P.meyeri(He=0.1464,Ho=0.1123,Pi=0.1775)and P.koraiensis(He=0.1307,Ho=0.1213,Pi=0.1775).Among population of three sprues has the smallest genetic differentiation coefficient(FST),the genetic variation basically come from within population.The genetic differentiation of three spruces also had a small value,the FST value wass 0.0612 and 0.1360 between P.mongolica and P.meyeri,P.mongolica and P.koraiensis.(7)Three spruces could be clearly distinguished as well as the relationship of P.mongolica is closer with P.meyeri through analyzing their structure,PCA and phylogenetic tree based on 3,101,341 SNPs loci.Besides,the results of the population history dynamic of three spruces showed that they had one time of population shrinking event between in LIG and LGM;and the effective population size of P.mongolica and P.meyeri had significantly different about 22,000 years ago,which more and more dramatically different as over time.(8)35 of significant related SNPs loci were found by Compressed mixed linear model(CMLM)in 3,104,341 of SNPs and 5 important phenotypic traits of three sprue.18 SNPs were significantly related with SSL,8 SNPs loci were related with CL,7 loci were related with the QSW,2 of SNPs were related with NL,and 1 SNP were related with SL.Meanwhile,the genotype of P.mongolica and P.meyeri have significant relevant SNP loci.(9)P.mongolica could be classified for a special species according to niche differentiation,phenotypic differentiation and genetic differentiation.In LGM,the effective population size of the P.mongolica was expanded compared to in LIG.At the same time,species formation of sprues is closely associated with the Quaternary glacial period based on population expansion,expansion time and time reflection in LGM of the Quaternary.