| The origin of P. densata.mast is hot spot in botany.It has been proved that P. densata originate the hybrid of P. tabuliformis and P. yunnanensis from the study about nuclear DNA, chloroplast DNA and mitochondrion DNA. P. densata is the first homoploid hybrid speciation as a tree,but the evidence of reproductive biology has not been reported.We conducted a comparative analysis on cone and seed morphometric traits and reproductive traits in P. densata, P. yunnanensis and P. tabuliformis by Variance analysis, Principal component analysis and Hierarchical cluster analysis. Based on the direct cross(P.tabuliformis×P.yunnanensis) and reciprocal cross(P.yunnanensis X P. tabuliformis) between P. yunnanensis and P. tabuliformis, compare filial generation and natural generation by 21 characters,test the crossability,provide new information and evidence for P. densata hybrid speciation.The main results are followings: (1)The variance of Cone and seed morphometric characters are obvious in three species; (2)The variability in these traits was bigger in P. densata than in the other two pine species;(3)Cone and seed morphometric characters of P. densatais in the middle of P. tabuliformis and P. yunnanensis.It show the characteristic of hybrid speciation;(4)There are some difference between filial generation and natural generation in morphometric traits and reproductive traits, but ,it is no doubt that we can get the generation that have reproductive capacity.All of above is the evidence to the origin of P. densata.Compared with parents species, P. densata has the hybrid characters and proved the molecular surveillance result which consider both . P. tabuliformis and P. yunnanensis could be the parent The difference of population in species crossability and the different habitat provided the evolutional evidence for the form of P. densata. Compared with parents, P. densata still be heterozygosity.In the future study the backcross, ecological genetic should be studied. |
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