喀斯特耐阴灌木淡黄金花茶的精细空间遗传结构与基因流

摘要

Camellia flavida,a golden Camellia with yellow petals,is a typical shade-tolerant shrub in karst regions.The aim of this study was to explore whether karst habitat heterogeneity contributes to the fine-scale spatial genetic structure (SGS),gene flow,and genetic differentiation of C.flavida at the small scale within a 15hm2 plot of northern tropical karst seasonal rain forest in Nonggang,based on 13 microsatellites.The results indicated that there was a significant SGS in C.flavida within a distance of 50 m,the intensity of which is moderate (Sp =0.0248) among shrub and gravity-dispersed species.The mean seed and pollen dispersal distances of C.flavida were short at 12.47 m and 29.03 m,respectively,with 72.2％ of pollen and 81.0％ of seed being mainly spread within 20 m.In addition,there was significant genetic differentiation among four populations at the small scale (distance between populations ＜ 1 km),and even between two patches separated by a distance of only 100 m.It is concluded that karst habitat heterogeneity significantly influences the gene flow of C.flavida,leading to comparatively strong SGS and genetic differentiation at the small scale.%淡黄金花茶(Camelia flavida)是一种具有淡黄色花瓣的金花茶植物,为喀斯特典型的耐阴灌木.基于广西弄岗喀斯特季节性雨林15 hm2(300 m×500 m)监测样地,利用13对微卫星(SSR)标记,探讨喀斯特地貌对淡黄金花茶的精细空间遗传结构(SGS)、基因流和小尺度范围遗传分化的影响.结果表明:(1)淡黄金花茶在50 m距离内产生显著的SGS,在灌木类型和依赖种子传播的物种中具有中等程度的SGS强度(Sp=0.0248);(2)淡黄金花茶种子和花粉传播平均距离较短,分别为12.47 m和29.03 m,72.2％花粉和81.0％种子的传播距离均主要是在20m内;(3)淡黄金花茶在小尺度范围(种群间距离＜1 km)的4个种群,甚至相距100 m的两个斑块产生了显著的遗传分化.喀斯特生境地貌对淡黄金花茶的基因流产生阻碍作用,从而导致淡黄金花茶在小尺度范围产生遗传分化.