入侵植物刺萼龙葵花部性状的表型变异及其对繁殖适合度的影响

Phenotypic variation in floral traits of an invasive plant(Solanum rostratum)and its impact on reproductive fitness

入侵植物花部性状的表型变异及其与繁殖适合度的关系是入侵生态学研究中的基本问题之一.为明确入侵植物刺萼龙葵(Solanum rostratum)种群间和种群内花部性状的表型变异程度和变异规律,并探讨刺萼龙葵花部表型变异对繁殖适合度的影响,采用巢式方差分析、变异系数分析、相关分析、主成分分析及多元线性回归等分析方法,对中国京冀地区的6个刺萼龙葵自然种群的10个花部表型性状和果实种子数量进行了研究.结果表明,(ⅰ)刺萼龙葵花部表型性状在种群间和种群内均存在极显著的变异,种群间的变异(27.26%)大于种群内的变异(3.55%),种群间平均表型分化系数为82.31%,种群间变异是刺萼龙葵表型变异的主要来源,表明刺萼龙葵具有较强的环境适应能力;(ⅱ)各花部表型性状的平均变异系数(coefficient of variation,CV)为13.13%,变异幅度为7.45%~29.79%,柱头与最近喂食雄蕊顶端的距离(distance between the stigma and the closest feeding stamen,DSF)的变异系数最大,传粉雄蕊长(length of the pollinating stamen,LP)的变异系数最小.结合主成分分析的结果,柱头与DSF和柱头与传粉雄蕊顶端的距离(distance between the stigma and the pollinating stamen,DSP)是花部表型性状变异的主要方向;(ⅲ)花部表型性状主要受经度的影响,其次为海拔、纬度、种群大小和种群密度;(ⅳ)刺萼龙葵花部表型性状对植株的结实数量具有显著影响,而且柱头与最近喂食雄蕊顶端的距离越近,植株的结实数量越多.

Solanum rostratum is an invasive plant in China.Our objectives were to determine the phenotypic variations in flowers of Solanum rostratum populations and their effect on reproductive fitness.The number of fruits and seeds of 174 individuals and 10 phenotypic traits of 522 flowers were recorded in 6 natural Solanum rostratum populations.The results were analyzed using nested analysis of variance,coefficient of variation,correlation analysis,principal component analysis,and multiple regression analysis.Significant differences in phenotypic variations were observed among and within the Solanum rostratum populations.The variation was greater among populations(27.26%)than within populations(3.55%).The mean phenotypic differentiation coefficient was 82.31%,indicating that the variance among populations was the main source of the phenotypic variation and that S.rostratum has a strong ability to adapt to a changing environment.The average coefficient of variation(CV)was 13.13%,ranging from 7.45% to 29.79%.The CV of the distance between the stigma and the closest feeding stamen(DSF)was the highest,and the CV of the length of the pollinating stamen(LP)was the lowest.Combined with the results of the principal component analysis,DSF and the distance between the stigma and the pollinating stamen(DSP)were the main directions of phenotypic variation.Longitude had a greater effect on phenotypic variation than altitude,latitude,population size,or density.The floral traits of Solanum rostratum had a significant effect on the number of fruits,and the closer the distance between the stigma and the closest feeding stamen,the more fruits were produced.