植物在不同湿地环境条件下的繁殖策略及其响应机制

Flexible reproduction strategies that govern the diverse reproduction process in plants are today one of the new fields in plant life history and evolutionary ecology studies. Wetland ecosystem is significantly different from other ecosystems when comparing their environmental factors, so survival and reproduction of plants in the wetland are strongly affected by fluctuated water level, soil nutrition characteristic and pollinators. Meanwhile, plants adopt diverse strategies to adapt to the changed environmental conditions in the wetland. We'd like to establish study sites at 3 wetlands throughout Longwan National Nature Reserve that differed in successive characteristics, of which two wetlands with Lilium megalanthum, Lychnis Wilfordii distributed and all of them with Iris laevigata distributed. As we have found their reproduction process is related to the environmental conditions，We found Lilium megalanthum are under a transitional phase that its sexual system is changing from monomorphism to dimorphism, a breeding system where individuals produce hermaphrodite and male flowers. Another species Iris laevigata are also under such a transitional phase, but individuals produce hermaphrodite and female flowers. Furthermore, Lychnis wilfordii shows a distinctive reproductive strategy, that is the 10 stamens, five in each batch, mature day by day, occupying the optimal pollination position for about 10 hours before lying on the petals, while all of the pistil simultaneously elevate to the optimal pollination position at the third day of anthesis after the second batch of stamens lie on the petals. Through the investigation to features of plant sexual system(i.e., Monomorphism or dimorphism, monoecism or andromonoecy, monoecism or gynodioecy), sexual expression procedure(i.e., The changing function of vegetal organ via its changing spatial location), breeding system(i.e., Self-compatible, self-incompatible) and pollinator behavior, environmental factors of wetland, combined with artificial simulation experiment which control water level and Nitrogen gradient, we explored the relationship between plant reproduction strategies and environmental characteristics in this project. Our study on the variation of reproductive strategies of plants in different conditions of the wetland would provide new insights into the selective mechanisms, and evolutionary mechanisms for major transitions between reproductive strategies in wetland in Longwan National Nature Reserve. Moreover, this work can provide references for the biological conservation of the wetland plant.

植物繁殖过程和繁殖策略多样化是近年来植物生活史和进化生态学研究关注的新领域之一。湿地生态系统的环境要素与其他生态系统有较大区别，其水位波动、土壤营养和传粉媒介等因素强烈影响着湿地植物的生存和繁殖；而植物也同时会采取不同的策略以适应多变的湿地环境条件。本项目拟选取位于我国吉林省龙湾湿地保护区范围内3块具有不同演替特征的天然湿地为研究地点，以其中2块湿地中分布的大花百合、丝瓣剪秋萝和3块湿地中均分布的燕子花这3种植物为研究对象，通过对植物的性系统特征、性表达过程、繁育系统特征与传粉者和湿地环境因子的野外调查研究，结合人工模拟控制试验，在精确控制水位和氮元素梯度的试验条件下，验证燕子花对这2个因子及交互作用的繁殖响应过程。本项目的研究结果可以揭示吉林龙湾地区湿地植物在不同湿地条件下繁殖策略的变异规律及其对湿地环境因子的响应机制；同时研究结论可为湿地植物的保护工作提供一定的借鉴。

研究植物的繁殖策略可以更好的理解生物多样性的本质，同时这个问题也是植物生活史和进化生态学理论研究的热点问题之一。影响植物生长和繁殖过程的因素有很多，有的来自于植物本身的特征，有的则是环境条件的变化引起。湿地生态系统因其重要的生态功能，以及较高的生物多样性而受到人们的关注。湿地中环境因子的变化较为频繁，植物将采取不同的策略以适应这种变化的湿地环境条件。本项目以我国吉林省龙湾湿地保护区范围内分布的大花百合、浅裂剪秋萝、丝瓣剪秋萝和燕子花为研究对象，研究了它们的性系统特征、性表达过程、繁育系统特征及其传粉生物学，并结合人工控制试验，研究了植物生长、生理和繁殖的响应过程。研究结果发现大花百合种群中除了两性花个体外，还有雄性个体以及处于过渡阶段的柱头退化而失去功能的个体存在。大花百合具有自交不亲和的特点，只有两性花可以结种，过渡花虽然处于柱头退化阶段，仍然保留有缩短的雌蕊，但已经完全丧失了雌性功能，在功能上已经是雄花。浅裂剪秋萝和丝瓣剪秋萝均为雌雄异熟，而且在开花过程中，两种剪秋萝的雄蕊均分两批呈现花粉，每一批呈现5枚雄蕊，第1批散粉完毕第2批再进行呈现，而且不同批次的花粉和柱头的活性存在着明显的时间上的分离机制。这种繁殖策略有效的增加了花粉的输出，并且避免了性别功能之间的干扰。燕子花的有性繁殖和无性繁殖存在着权衡，并且不同分株之间存在着物种传递和共享的机制。当有性分株开花成功授粉后，与之相连的无性分株可以将光合物质传递给有性分株以供果实和种子的发育。水位影响着燕子花的繁殖策略，燕子花在水位较高的条件下，植株的资源分配更加倾向于维持繁殖分配不变，当面临自身所不适应的干旱胁迫环境时不开花，将资源全部分配给生长用以维持存活。本项目为认识植物繁殖策略的进化提供了一定的数据支持，具有一定的理论意义。