Botanical Institute, Göteborg University, Box 461, SE 405 30 Göteborg, Sweden.
Am J Bot. 2002 Nov;89(11):1772-8. doi: 10.3732/ajb.89.11.1772.
In geonomoid palms floral scent is both an important pollinator attractant and an important factor in reproductive isolation. However, little is known about intraspecific variation in floral scent composition in these as well as in other plants. In this study the level of variation in floral scent composition found within and among five populations of Geonoma macrostachys var. macrostachys in the western Amazon is documented. Floral scent samples were collected using head-space adsorption and were analyzed by gas chromatography-mass spectrometry. Most of the 108 compounds recorded were of isoprenoid origin, but only 28 of the compounds were found in all 62 samples analyzed. No differentiation was found between the studied populations, confirming that G. macrostachys var. macrostachys is outbreeding and indicating that the individual populations are part of a metapopulation linked by sufficient gene flow to avoid local differentiation. However, a negative correlation between distance and similarity of floral scent chemistry indicates a case of clinal variation within the distribution area of G. macrostachys. Male euglossine bees are infrequent visitors to G. macrostachys, while other groups of insects are abundant. However, the level of variation and the chemical composition lend support to a suggested importance of male euglossine bees in long-distance pollen flow in G. macrostachys. Other insect groups are probably important in securing pollination of most flowers with pollen from nearby sources.
在地理型掌状叶科棕榈植物中，花的气味既是吸引传粉者的重要物质，也是生殖隔离的重要因素。然而，人们对这些植物以及其他植物中花的气味组成的种内变异知之甚少。在这项研究中，记录了在亚马逊西部的 5 个地理型掌状叶科掌状叶棕变种大穗棕种群内和种群间的花的气味组成的变异程度。使用顶空吸附法收集花的气味样本，并通过气相色谱-质谱法进行分析。记录的 108 种化合物中大多数为异戊二烯类化合物，但只有 28 种化合物在分析的 62 个样本中均有发现。研究的种群之间没有分化，这证实了大穗棕变种是异交的，并且表明各个种群是通过足够的基因流连接成一个集合种群的，以避免局部分化。然而，花的气味化学物质的距离和相似性之间的负相关表明，在大穗棕的分布区域内存在渐变现象。雄性绿宝石蜜蜂很少访问大穗棕，而其他昆虫群体则很丰富。然而，变异程度和化学成分表明，雄性绿宝石蜜蜂可能在大穗棕的长距离花粉流中具有重要作用。其他昆虫群体可能在确保大多数来自附近花粉源的花授粉方面起着重要作用。
