Dynamics Analysis Of Pollen Flow Of The Treeline Species Abies Georgei At Different Elevations

High altitude tree lines are sensitive to climate change and are key areas for studying biological responses to global changes.In the past,the interpretation of the formation mechanism of alpine tree line mainly considers the limitation of the environment in terms of non-biological factors.In recent years,the model analysis results showed that the gene flow as a factor of antagonism of natural selection,have important influence to species distribution to form stable boundary,however at present very few research on tree line area of gene flow.This paper choose the treeline trees meili snow mountain Abies georgei as materials,from different altitude populations(treeline high altitude 4150-4250m;distribution of the core area of middle altitude 3800-3900m,distribution of the lower limit of low altitude 3500-3600m)in the family as a unit for sampling,using 7 SSR primers of fluorescent markers in 40 half-siblings family of 480 children and their potential parent SSR parting,using GenAlex,Cervus and STRUCTURE of genetic analysis software,at the same time the endosperm genotype,offspring genotype and maternal genotype data comparison,concluded that the potential paternal of seed.The results are as follows:(1)At different altitudes,there is a high genetic diversity in the family department and low genetic differentiation.7 pairs of Abies georgei microsatellite primers were calculated.The number of alleles(Na)in the 7 loci ranges from 9 to 24,and the number of effective alleles(Ne)ranges from 2.001 to 9.026,observed heterozygosity ranges from0.279-0.8052,expected heterozygosity ranges from 0.500-0.889,and diversity index(I)ranges from 0.981 to 2.469.from these numbers,AMOVA analysis of three offspring population.Long bract fir progeny populations in different altitude variation between low,only about 6%,and accounted for 26%of the differences among individuals,and intra-individual variation is very big,accounted for 68%.we can see that makers have high polymorphism and the genetic diversity of Abies georgei is fairly high and there is little difference in 3 offspring populations.(2)The dynamic of pollen flow between the three altitude populations were discussed,using the microsatellite markers to analyze the 480 offspring(144 tree line high altitude offspring,168 core distribution middle altitude offspring,168 low altitude offspring)of 40 families from three different altitude of Abies georgei.Under the confidence level of 80%with Cervus software can infer the treeline high altitude offspring population and the treeline high altitude male parent matching rate was 35%,the treeline high altitude offspring population and the core distribution middle altitude male parent matching rate was 10%,the treeline high altitude offspring population and the low altitude male parent matching rate was 19%.Of these 480 free pollinators:144 treeline offspring has 105 match possible male parent,of which 44 from high altitude male parent,42 from core distribution male parent,19 offspring from low altitude male parent.168 core distribution on middle altitude.There are 140 offspring matching possible male parent,of which 26 from high altitude male parent,63 from the core distribution middle altitude,53 offspring from low altitude male parent.168 low altitude of offspring.There are 120 offspring matching in possible male parent,which 30 from the treeline high altitude male parent,39 from core distribution of male parent,51 offspring from low altitude male parent.(3)Using the endosperm genotype,the analysis of the distribution ratio of the potential paternal(pollen donor)to the three altitude of the free pollination offspring of the fir.For high altitude treeline pollen donor offspring population,41%of the pollen from treeline high altitude candidate male parent population,31%of the pollen from core distribution altitude candidate male population,28%of the pollen from low altitude candidate male parent population.The probability of potential paternal at each altitude is very similar.Meanwhile,through the USEPOPINFO model in the Structure the offspring populations were clustered with the known parent information to obtain the probability that the three offspring populations were assigned to the three parent populations.The probability that the three offspring populations were assigned to the three candidate parent populations were close to each about 30%.The relationship between the three progeny populations and the three candidate male parent populations were very close.The populations between the three altitudes was inseparable and the gene flow was very frequently because of the genetic swamping effect,The gene flow mainly spreads from the distribution core to the edge,this amount of gene flow could form a swamping effect lead to the edge of the distribution area favorable allele spread in the population with difficulty and hinder the local adaptation.