【作者】 齐威；

【导师】 杜国祯；

【作者基本信息】 兰州大学 ， 生态学， 2010， 博士

【摘要】 本文在对青藏高原东缘109科427属1268种被子植物种子大小的变异和进化模式进行了分析,着重研究了种子大小变异与环境因子(海拔、生境中的水和光梯度、土壤酸碱度和营养梯度)、植物的功能和生活史特征(种子传播形式、生活型、植株高度和比叶面积)、繁殖特征(性系统、传粉形式和花对称)、种子发育特征(每果种子数和种子发育时间)、生活史对策(植物的竞争能力和适应干扰能力)和分布区类型等17个因子间的相关性,并从不同角度分析了海拔对种子大小变异的影响,以期揭示青藏高原东缘植物种子大小变异的进化及生态适应和进化规律。结果如下：1,青藏高原东缘区系被子植物的种子大小分布从10-3mg到104mg相差约为6-7个数量级。种子大小主要集中在0.1-10.Omg范围之内,占到总种数的75.9%,属于小种子占优势的区系。2,青藏高原东缘区系中,分类学水平超目、科和属均显著影响种子大小,它们分别解释19.5%、48.9%和90.2%的种子大小变异,与影响和控制种子大小的其它因素相比,科和属所占的比例最高,因而系统发育是决定种子大小的一个关键因子。3,种子大小变异与除了花对称性外的16个因子都存在着明显的相关性,既使用独立对照法除去系统发育的影响,这些因子的影响也大多显著。其中,对种子大小变异影响最大是种子传播形式,其次是种子发育时间、每果种子数、植株高度和生活型。4,总体上,种子大小随海拔减小有一个先快后慢的趋势,其中,在温带区域下缘,种子大小呈现快速下降趋势；在温带区域上缘和亚高山区域,种子大小呈现缓慢下降趋势；而在高寒地区,种子大小倾向与海拔无关。与此相关的三段回归(分界点在海拔2200m和3450m)能解释8.8%的种子大小变异。5,水和光梯度、种子传播形式、生活型和生活史对策对种子大小的影响随海拔升高而减小,而每果种子数的影响却在增加。6、存在一个种子大小依赖的种子大小和海拔间的关系。依据属内的系统发育独立对照,属内种子大小对照值和属的种子大小平均值呈极明显的负关系,即当种子大小小于1mg时,种子大小倾向随海拔而增加,而当种子大小大于1mg时,种子大小倾向随海拔而减小。7、存在一个海拔依赖的种子大小和海拔间的关系。依据属内的系统发育独立对照,属内种子大小对照值和属的海拔平均值呈极明显的正关系,当海拔低于3000m时,种子大小倾向随海拔而减小,而当海拔高于3000m时,种子大小倾向随海拔而变大。8、植物分布区类型不同,种子大小变异存在较大的差异。一般来说,分布中心越靠近赤道的植物类群,其种子越大；而全球分布范围越广,种子就越小。更多还原

【Abstract】 In this paper,1268 angiosperm species, being derived from 427 genera and 109 families (Davies 2004), were gathered up from the eastern Qinghai-Tibetan flora to analyze the relationships between seed size and 17 related attributes, including altitude, microhabitat light, microhabitat moisture, soil PH, soil organic matter, seed dispersal mode, growth form, plant height, seed development time, seeds per fruit, specific leaf area, sexual system, floral symmetry, pollination pattern, competitive strategy, ruderal strategy and areal-types. Statistical methods included one-way and nested ANOVA, linear regression, regression tree, and phylogenetically independent contrast. The results showed:1. Seed size of the Qinghai-Tibetan flora ranged over 6-7 orders of magnitude, from 10-3mg to 104 mg. However, seed size of 75.9% species ranged from 10"1 mg to 101 mg, suggesting the flora was characterized by small seeds.2. Order, family and genus accounted for 19.5%,48.9%and 90.2%of total variation in seed size, respectively. Thus, it was evident that seed size was strongly related to phylogeny.3. The cross-species and evolutional relationships between seed size and most related attributes, except for floral symmetry, were significant. Seed dispersal mode was the main factor affecting seed size variation, following by seed development time, seeds per fruit, plant height and growth form.4. The optimal model about the cross-species relationship between seed size and altitude was a 3-step regression, which could account for 8.8%seed size variation. In the model, the slope of the relationship was steep in the altitudinal group< 2200 m asl., about 1.4-fold decrease in seed size with every 100 m increase in altitude, but was moderately steep in the altitudinal group from 2200 m to 3450 m asl., about 1.1-fold decrease in seed size with every 100 m increase in altitude. Moreover, there was no significant seed size-altitude relationship in the altitudinal group> 3450 m asl.5. The influences of microhabitat light, microhabitat moisture, seed dispersal mode, growth form and plant height on seed size decreased, but the influences of seeds per fruit increased, with increasing altitude.6. There was a size-dependent seed size variation along altitudinal gradients. Based on phylogenetically independent contrast (PIC), the relationship between seed size contrasts and generic seed size averages was significantly negative. If generic average seed size was less than 1mg, it would increase along altitudinal gradients, otherwise, would decrease along altitudinal gradients.7. There was an altitude-dependent seed size variation along altitudinal gradients. Based on PIC, the relationship between seed size contrasts and generic altitudinal averages was significantly positive. When generic average altitude was less than 3000m asl., seed size contrast would be less than zero, otherwise, would be more than zero.8. Seed size was tightly related with the areal-types of angiosperm. World widespread species had the smallest seeds, while the seeds of tropical species were biggest.更多还原