【作者】 孟金柳；

【导师】 杜国祯；

【作者基本信息】 兰州大学 ， 生态学， 2010， 博士

【摘要】 繁殖对策,尤其资源分配问题是植物生活史研究的核心。海拔等生长环境条件对植物的繁殖有很大影响,不同海拔地区生长的植株可能会采取不同的繁殖策略。在虫媒植物的传粉中,很多昆虫的访花行为是受视觉线索的吸引,那么如何把生长中所能获得的有限的资源在营养生长和繁殖,以及花器官内部分配是很重要的问题。青藏高原东部高寒草甸的植被类型包含了许多独特的植物类群。这些植物如何适应青藏高原特殊的环境条件,表现出什么样的繁殖对策,为繁殖生态学家、进化生物学家提供了独一无二的研究契机。因此,我们选择在青藏高原东部的高寒草甸,以比较原始的植物类群—毛茛科植物为研究对象,选择矮金莲花,钝裂银莲花和露蕊乌头3个常见物种,探讨其繁殖对策,如资源如何在花器官内部分配问题,试图揭示这些植物如何适应环境条件达到繁殖成功的,最后的结果表明：(1)花葶长度和植株对两性功能的资源投入之间的关系随物种和海拔不同而不同。在研究区域的所有海拔(2200m,3400m,3700m和3900m)种群中,自交不亲和的矮金莲花雄蕊数／雌蕊数和花葶长度都负相关。在合作这个较低海拔地区(2200m)的种群中,花葶长和雄蕊重／雌蕊重正相关；而对3个高海拔地区：3400m,3700m和3900m的种群,雄蕊重／雌蕊重和花葶长负相关。对于兼性自交的钝裂银莲花,在海拔2200m和2900m,雄蕊数／雌蕊数和花葶长度负相关,而在3400m却是负相关。雄蕊重／雌蕊重与花葶长度的关系刚好与雄蕊数／雌蕊数与花葶长度的关系呈现完全相反的变化趋势；矮金莲花和钝裂银莲花这两个交配系统不同的物种,花葶长度和雌雄两性功能的关系是不同的,也说明花葶对繁殖的影响不仅受海拔等生境的影响,也受到物种交配系统的影响。(2)对金莲花这种异交虫媒植物来说,高海拔植株受到花粉限制的程度要大于低海拔地区的植株。高海拔地区昆虫数目少,活动受限,植株为了得到受访的机会,增加了对萼片这种从视觉上展示花的结构的资源投入；而低海拔地区的植株则增加了对退化花瓣这种产蜜结构的生物量分配。控制实验表明花的展示结构对雌性繁殖成功的贡献要大于传粉报酬对雌性繁殖成功的贡献。这也是植物对待不同花粉限制程度,获得繁殖成功的策略；(3)露蕊乌头这个物种的雌蕊数在不同资源限制条件下和花位置之间是一个稳定的性状,而且不受基因型的控制；单粒种子大小也是一个较为稳定的种子性状,在家系和果实位置间没有变化,只受资源可利用性(即资源的相对充足或缺乏)的影响；花序内从基部—顶部的开花顺序,花的性分配偏雄,饱满的种子数和结籽率依次减小,而这种花序内的模式是“资源限制”和“位置效应”两方面原因造成的,顶部花的雄蕊数及花粉数更多,心皮数及胚珠数更少；同去叶这种开花前期受到资源限制处理的植株相比,遮阴(苗期即光合受限)植株表现出了极强的可塑性,通过减少营养生长,减少花数,降低对雄性资源的投入和增大花萼片和花瓣的展示面积等策略获得繁殖成功；(4)露蕊乌头花序内沿从基部—顶部的开花顺序,花寿命和雄蕊期都在逐渐延长,而雌蕊期没有变化,这与花序内性分配的变化相关；遮阴处理使植株的花期和雄蕊期缩短,也可能同样是受性分配的影响,遮阴减小了花的性分配。通过这些研究发现,这几种进化上属于比较原始的毛茛科物种物种,在对不同繁殖功能的资源分配(花展示,花报酬,雄性功能,雌性功能)之间互相关联,并且随着交配系统,海拔和花在花序中的位置变化而变化,构成了一个复杂的繁育系统,显示出了对高山极端环境的良好适应。更多还原

【Abstract】 Reproductive strategies, especially resource allocation are central of study of plant life history. In the pollinating process, many pollinators are attracted by visual cues. Outcrossers at different altitudes can obtain more visitations through different strategies to release the absence of pollinators. Increasing the resources investment to their attractants and rewards of insect-pollinated plants in high arctic and alpine areas is regarded as an adaption to low pollinator abundance and consequent pollen limitation. There are a lot of unique plants in Alpine Meadow at Eastern QinghaiTibetan Plateau. How to adapt the especial environment of Alpine, and what reproductive strategies appear for these species, which provide a special chance for ecologists and evolutionists. Therefore, we selected 3 common species of Ranunculaceae, comparative primordial plants in Alpine Meadow at Eastern QinghaiTibetan Plateau, and studied the reproductive strategies, such as reproductive allocation, especially sex allocation, to understand how the plants adapt the environmental conditions. The results showed:(1) The results showed that relationship between scape length and male, female function vared with speices with different mating systems and with attitudes, In Trollius ranunculoides Hemsl. (self-incompatible) plants, the relationship between scape length and stamina:pistils number (the ratio of stamina number to pistils number of a flower) and stamina:pistils weight (the ratio of stamina weight to pistils weight of a flower) vried with altitude. Stamina:pistils number was negatively related to scape length at all attitudes (2900m,3400m,3700m and 3900m). Stamina:pistils weight was positively related with scape length at the lowest elevation (2900m) but negatively related at the other three higher elevations (3400m,3700m and 3900m). In Anemone obtusiloba D. Don (facultatively self-pollinated), stamina:pistils number was positively related to scape length at two lower elevations (2200m and 2900m), but negatively related to scape length at a higher elevation (3400m). In contrast, stamina:pistils weight was negatively at the two lower elevations (2200m and 2900m) but positively related at the higher elevation (3400m) with scape length. (2) In Trollius ranunculoides plants, conspicuous yellow sepals is a visual attractive structure of this species) while degenerate petals can be evaluated as reward to pollinators i.e. nectar output, because each petal has a nectary at the base and the number of petals has a positive relationship with visiting maintenance Pollen limitation and resources allocation to sepals and petals was studied in Trollius ranunculoides at four altitudes. Female fitness was more pollen limited at the higher altitudes. The plants invested more resources to sepals and less to petals at higher than at the lower altitues.(3) Both the number of pistil and seed size of Aconitum gymnandrum plants did not vary with flower position within inflorescence or with different genotypes. The seed size, but not the number of pistil was affected by different resource availability. From bottom to top flower within inflorescence floral sex allocation tends to be male-biased: more anther number and pollen, less carpel number and ovule, lower seed set at top flower. It was caused by "constructure effect" and "resource limitation"(4) Floral longevity and male phase duration of Aconitum gymnandrum increased and the female phase duration was invariable from bottom to top flowers. Shading plants starting from the seedling stage maintained reproduction success, which was attributable to strategies like less investment to vegetative growth and male function; less flowers and larger flower display size. Shaded plants also had shorter floral longevity and male phase duration.In summary, our studies showed that, generally alpine plant species were pollen limited. To overcme pollen limitatation, resources allocation to different parts of reproduction functions (floral display, floral longivtiy and male and femal function) was related with each other. They also varied with many interal and external factors related to reproduction, such as mating system, altitudes and flowers postions within inflorescence. The alpine plant species at high altitudes would increase floral display to increase the opportunity of pollinators’ visitation. These results indicated the three species had evolved complex reproduction systems to well adapt to the alpine envionments.更多还原