基于腊叶标本分析的木姜叶柯表型性状变异及地理分化研究

Phenotypic Variation and Geographical Differentiation of Lithocarpus Litseifolius Based on Herbarium-Specimen Analysis

【目的】从木姜叶柯[Lithocarpus litseifolius(Hance)Chun]叶片表型性状上分析其变异特征及地理分化特性,为资源利用提供实践指导。【方法】以全分布区内62个居群469份腊叶标本的叶长(LL)、叶宽(LW)、叶片长宽比(LL/LW)、叶尖长(TL)、叶尖夹角(TA)、叶柄长(PL)、一级侧脉对数(PLV)、叶基夹角(BA)和叶面积(LA)等9个表型性状为对象,采用方差分析、主成分分析(PCA)及聚类分析,研究各居群叶片表型性状变异、地理分化模式及其与主要地理-气候因子的相关性。【结果】①叶片表型性状变异较大,变异系数9.79%(TA)~42.57%(TL),平均22.59%。不同居群间叶片表型性状达到极显著变异(P<0.01),LL、LW、LL/LW、TL、TA、BA及LA变异主要来自居群间,PL和PLV变异来自居群间及居群内。②叶片表型性状间达到显著或极显著相关,且LL、LW及LA与经度达到极显著负相关,BA与纬度达到极显著负相关,LL与LA与年降水呈显著负相关,BA与极端最低温度呈现极显著正相关。叶片表型性状变异呈现经纬双向变异模式,年降水量和极端最低温度为主要驱动因子。③主成分分析获知9个性状可用3个主成分表示(累计贡献率为81.45%),主成分的居群聚类将62个居群聚为4个大类。从大的景观尺度来看,居群未严格按照地理距离而聚类,在较小的区域尺度,地理距离较近的居群则聚为一大类。【结论】木姜叶柯叶片表型性状存在着丰富的变异,且呈现出经纬双向变异的模式。62个居群的叶片可分为长披针形、宽披针形、长椭圆形和宽椭圆形等4大类。

[Objective]This study aims to determine the variations of leaf phenotypic traits and geographical differentiation patterns of Lithocarpus litseifolius(Hance)Chun,thus providing the practical guidance for its resource utilization.[Method]Taking 469 herbarium-specimen in 62 populations in the whole area as research objects,variance analysis,principal component analysis(PCA)and cluster analysis were used to study the variations of leaf phenotypic traits,geographical differentiation patterns and their correlation with major geographic-climate factors.The leaf phenotypic traits include leaf length(LL),leaf width(LW),leaf length-to-width ratio(LL/LW),leaf tip length(TL),leaf tip angle(TA),petiole length(PL),primary lateral veins(PLV),leaf base angle(BA)and leaf area(LA).[Result]①The variations of leaf phenotypic traits were significant;the variation coefficient ranged from 9.79%(TA)to 42.57%(TL),and averaged at 22.59%.Leaf phenotypic traits showed significant variations across different populations(P<0.01).The variations of LL,LW,LL/LW,TL,TA,BA and LA were mainly exhibited across the population,while the variations of PL and PLV were exhibited both across and within the population.②There were significant or extremely significant correlations among leaf phenotypic traits;LL,LW and LA showed highly significant negative correlations with longitude;BA showed a highly significant negative correlation with latitude;LL and LA showed significant negative correlations with annual precipitation;BA showed a highly significant correlation with extreme minimum temperature.The variations of leaf phenotypic traits showed a pattern of double variation in latitude and longitude,while annual precipitation and extreme minimum temperature were the main driving factor.③From principal component analysis(PCA),it was learned that 9 characteristics could be represented by 3 principal components(The cumulative contribution rate was 81.45%),and 62 populations could be classified into 4 categories according to the cluster class of principle components.On a large landscape scale,populations did not cluster strictly based on geographical distance;On a smaller regional scale,populations that were closer in geographical distance clustered into a large group.[Conclusion]There were significant variations in the leaf phenotypic of L.litseifolius and had given priority to both longitude and latitude.The leaves of 62 populations could be divided into four categories:long lanceolate,wide lanceolate,long elliptic and wide elliptic.