【作者】 关保华；

【导师】 常杰； 葛滢；

【作者基本信息】 浙江大学 ， 植物学， 2004， 博士

【摘要】 在变化的环境条件下，相同的基因型产生多个表现型的特性被称为表型可塑性。物种之间表型可塑性的区别具有重要的生态学和进化学意义。本文比较研究了濒危植物杭州石荠苧（Mosla hangchowensis Matsuda）与同属三种非濒危植物：华荠苧（Mosla．chinensis Maxim．）、石荠苧（Moslascabra（Thunb．）C．Y．Wu et H．W．Li）和小鱼仙草（Mosla dianthera（Buch．-Ham．）Maxim．）响应土壤水分状态的表型可塑性。研究的内容包括四种植物在三个生活史阶段的生长、形态、生理生态和生殖等方面的表型可塑性差异。我们希望通过分析石荠苧属四种植物响应不同土壤水分的表型可塑性的差别，探索可塑性与野外分布和进化分歧之间的关系，并进一步找出杭州石荠苧的濒危机制。土壤水分共分成五个处理，以相对土壤含水量（Relative water content，RWC）来表示：持续饱和（Constant Saturation，CS；模拟湿润生境）、80％～100％田间持水量（Water HoldingCapacity，WHC）、60％～100％田间持水量、400％～100％田间持水量以及20％～100％田间持水量（分别模拟不同的降雨间隔期），各处理在文中分别简称为CS、W₈₀、W₆₀、W₄₀和W₂₀处理。结果表明： 1、在7月份营养生长盛期，杭州石荠苧的表型可塑性最低，石荠苧最高；到9月份开花初期，则是小鱼仙草可塑性最高，华荠苧最低；11月份生殖期结束前，也是小鱼仙草最高，但最低的是石荠苧；整个生活史阶段的表型可塑性从高到低的顺序是：小鱼仙草＞石荠苧＞杭州石荠苧＞华荠苧。石荠苧和华荠苧的表型可塑性在生长过程中会逐渐减小，而杭州石荠苧和小鱼仙草则有增加趋势。 2、在响应土壤水分变化时，石荠苧和小鱼仙草能够在较短的时间内迅速做出形态可塑性调整，杭州石荠苧比较迟缓，华荠苧最迟缓。 3、杭州石荠苧的理想水分生态位是从40％～80％田间持水量，理想水分生态位是与实际水分生态位相矛盾，野外分布在胁迫的水分环境，采用K-策略进行繁殖，生产出数量少的大种子，但由于后代的生存条件恶劣，竞争能力差，不利于野外种群的维持；华荠苧的理想水分生态位是40％～80％田间持水量，野外分布在适宜水分生态位的边缘，它能够加强生殖投入，产生数最多的小种子，生活史采用r-策略，但由于苗期大量死亡，成年植株对光的竞争能力差，所以在野外群落中的数量也较少；石荠苧的理想水分生态位也是从40％～80％田间持水量，营养生长发达，植株高，对光的竞争能力比较强；小鱼仙草的理想水分生态位是40％～100％田间持水量，野外在各种水分条件下都能分布，在高水分条件下具有很强的光竞争能力，在低水分条件下能够简化营养生长，保证生殖成功。 4、杭州石荠苧的濒危是由于它的表型可塑性发展的方向是不利的，没有朝高的竞争能力和高的耐受能力方向发展；华荠苧的表型可塑性虽然很小，但具有适应干旱和耐受低光环境的特征，适应性比杭州石荠苧高；石荠苧和小鱼仙草的高的表型可塑性使它们在高水分条件下具有很强的竞争能力，在低水分条件下则具有很强的耐受能力。 通过本文的研究，我们得出了以下结论：比较原始的物种（如华荠苧）表型可塑性比较低，进化速度快的物种（如小鱼仙草）则具有高的表型可塑性；杂草化程度较高、在野外群落中能够成为优势物种的植物（如石荠苧和小鱼仙草）的表型可塑性也高于稀少化和濒危的物种（如华荠苧与杭州石荠苧）。更多还原

【Abstract】 Phenotypic plasticity is defined as the property of a genotype to produce different phenotypes when exposed to different environments. Plasticity differences between species have important implications in terms of ecological and evolutional consequence. The phenotypic plasticity of an endangered plant, Mosla hangchowensis Matsuda response to soil water statuses was compared in this paper with three widely distributed plants, M. chinensis Maxim, Mosla scabra (Thunb.) C. Y. Wu et H. W. Li and Mosla dianthera (Buch.-Ham.) Maxim. The growth, architectural, physioecological and reproductive plasticity across three history period of four Mosla species were studied. We present the comparative study to probe into phenotypic plasticity patterns of these four Mosla species in response to different soil water content, aiming to find out the relationship between the phenotypic plasticity and field abundance and evolutional divergence, and then to find out the endangered mechanism of M. hangchowensis. The five treatments were interpreted in terms of relative soil water content (RWC) and measured in terms of soil water holding capacity (WHC). For the 1st treatment, soil water was maintained as constant saturation (CS, simulate the wet habitat); For the 2nd treatment, plants were not watered unless the RWC dropped to 80% WHC. Similarly, distilled water was added to saturation whenever WHC dropped to 60%, 40%, and 20% in the 3rd, 4th and 5th treatment, respectively. The five treatments were defined as constant saturation (CS), W80, W60, W4o and W2o, respectively. And the results indicated:1. At the vigorous vegetative growth period in July, M. hangchowensis had the lowest phenotypic plasticity while M. scabra had the highest. At the early blooming period in September, M. dianthera had the highest phenotypic plasticity while M. chinensis had the lowest. Before the end of the reproductive growth in November, it was also M. dianthera which had the highest phenotypic plasticity and M. chinensis which had the lowest. Viewed from the whole history period that the phenotypic plasticity orders were: M. dianthera > M. scabra > M. hangchowensis > M. chinensis. In the growing process, the phenotypic plasticity of M. scabra and M. chinensis decreased gradually, while the phenotypic plasticity of M hangchowensis and M. dianthera increased.2. M. scabra and M. dianthera can rapidly adjust their architectural traits in response to soil water statuses, while M. hangchowensis responded more sluggishly, and M. chinensis responded most sluggishly.3. The optimum water niches (OWN) of M. hangchowensis was from 40% soil water holding capacity (WHC) to 80% WHC, but M. hangchowensis distributes in drought environment in the field, so the actual water niches (AWN) separated from OWN in M. hangchowensis. M. hangchowensisadopted K-strategy to produce less bigger seeds, that is disadvantage to maintain the population in the field because of the severely condition and less competition of the offspring. The OWN of M chinensis was also from 40% WHC to 80% WHC, and M. chinensis distributes in relatively dry environment which is the edge of its OWN, while M. chinensis allocated more mass to produce more smaller seeds adopting the r-strategy. However, M chinensis couldn’t be dominant species because of the high mortality of the seedlings and the less competition for light. The OWN of M. scabra was from 40% WHC to 80% WHC too. M. scabra was competitive because of its better vegetative growth and taller growth than M. hangchowensis and M. chinensis. The OWN of M. dianthera was from 40% WHC to 100% WHC, it can distribute from dry environment to wet environment in the field. And it had very competitive superiority in the wet water condition because of the higher apical, but high endurance in dry condition with simply vegetative growth but more reproductive growth.4. The reason that M hangchowensis being endangered is that it has disadvantage phenotypic plasticity orientation; the phenotypic plasticity can’t make it more competitive and endurant. Thoug更多还原