| The genus Abies is the second largest genus in the family Pinaceae,disjunctly distributed in high altitude or high latitude of Asia,Europe and North America with China as its diversification center.Because of the complexity of morphological variation and the limitation of sampling and molecular markers,the subgenus division and species classification of Abies have always been controversial,especially in the Himalayas and Hengduan Mountains of China.Firs,as evergreen trees with strong cold and shade tolerance,they often grow in rainy and cool alpine,sub alpine regions and are sensitive to climate change.For such a group with both ecological and economic value,it is of great theoretical significance and application value to carry out systematic classification and pedigree geography research.In this study,on the one hand,we analyzed morphological traits and genetic differentiation of Abies delavayi complex distributed in Himalayas and Hengduan Mountains of China by integrating data from morphology and population genetics,using principal component analysis and phylogeographical analyses to provide a basis for species delineation of this complex.On the other hand,based on integrating phylogeographical analyses and species distribution modeling,we explored how Abies delavayi complex responded to the Quaternary climate changes.The main research content and conclusions are as follows:(1)In order of clear species delimitation in the complex,21 morphological characters of 71 herbarium specimens were collected to conduct the multivariate analyses.The results of morphological and phylogeographical analyses are consistent.The four species are highly overlapped and can be regarded as one species.The complex were divided into three varieties(A.delavayi var.delavayi Franch,A.delavayi var.fabri(Mast.)D.R.Hunt and A.delavayi var.nukiangensis(W.C.Cheng & L.K.Fu)Farjon & Silba)and one subspecies(A.delavayi subsp.fansipanensis(Q.P.Xiang,L.K.Fu & Nan Li)).(2)In phylogeographical analyses,we collected 4 species,15 populations and 163 individuals.Mitochondrial genes nad1-2 and nad5-4 and chloroplast gene trn S-trn G were selected in the analysis of gene lineage.In species distribution modeling,we performed analyses based on 105 environmental variables at five different time points.The mismatch distribution analyses based on cp DNA indicates that only Abies fabri detected notable range expansions event of estimatly 64.9-42.9kya.The results of species distribution modeling over different time periods showed that the optimal distribution area of Abies delavayi complex was significantly broader during the glacial period(the LGM)than during the interglacial periods(the LIG,present,2050 and 2080),consistent with the results of mismatch distribution analysis.Combined with the genetic diversity pattern,it was revealed that Abies delavayi complex experienced glacial expansion and interglacial contraction as documented in the “elevation shift” hypothesis. |
