Abstract: Plant Flower diversity is largely thought to be subject to pollinator-mediated natural selection. This study aimed to explore adaptation of floral traits and possible selective mechanisms of Iris lactea by detecting the correlations between floral traits and reproductive fitness in a natural population in the alpine grasslands in Tianzhu County. The results showed that the coefficients of variation for stamen-to-stigma distance and stigma height were the largest among the I. lactea flower traits,with 44% and 29%,respectively,while the degree of variation for inflorescence height and flower size was intermediate,and the degree of variation for exoperigon size was the smallest. There were highly significant positive correlations (P < 0.001) between inflorescence height,flower size,exoperigon size and stigma height and seed number and seed set;significant positive non-linear relationships (P<0.05) between stamen-to-stigma distance and seed set and significant negative non-linear relationship (P<0.05) between stigma height and seed set;there was a and significant positive correlation (P < 0.05) between the two combinations of the traits of stigma height and exoperigon size and both seed number and seed set. The analyses showed that there was a significant effect of floral trait variability in I. lactea on its reproductive fitness,and its floral structural trait combinations had specific fitness contributions,so there was a tendency towards functional integration to improve its pollination efficiency and reproductive success.

Key words: Iris lactea, Floral traits, Variability, Reproductive fitness

摘要： 植物花的多样性在很大程度上被认为是由传粉者介导的自然选择而导致的。本研究以天祝高寒草地马蔺(Iris lactea)为实验材料，通过检测其花性状与繁殖适合度之间的相关关系，探究了马蔺花性状的适应性及可能的选择机制。结果表明：在马蔺花性状中，雄蕊到柱头的距离和柱头高度两性状的变异系数最大，分别为44%和29%，花序高度和花大小的变异程度居中，垂瓣大小变异程度最小。马蔺的花序高度、花大小、垂瓣大小和柱头高度与其个体种子数和结籽率之间均存在极显著的正相关关系(P<0.001)；结籽率与雄蕊到柱头的距离之间存在显著的正非线性关系(P<0.05)；柱头高度与结籽率之间存在显著的负非线性关系(P<0.05)；柱头高度与垂瓣大小两性状组合对个体种子数和结籽率均存在显著影响(P<0.05)。分析表明，马蔺花性状变异对适合度具有显著影响，其花结构性状组合具有特殊的适合度贡献，故而存在功能整合的趋势以提高其传粉效率和繁殖成功。

关键词: 马蔺, 花性状, 变异性, 繁殖适合度