异子蓬和盐地碱蓬种群分布差异的生态机制：从种子性状变异的角度

As the only propagule for annual angiosperm plants, seeds can significantly influence population dynamics and the geographic distribution. Our study focuses on the heteromorphic seeds (oblate and brown; biconvex lenticular and black) of rare Suaeda aralocaspica and widespread Suaeda salsa. By using field survey, common garden experiments, pot experiments and lab analysis, seed traits and its variation of different populations of two Suaeda species will be investigated to test the trait variation trade-off hypothesis basing on the generalist/specialist trade-off: functional traits of widespread species have high variation and those of endemic species have low variation. The contents of this project include: 1) seed traits (ratio, size, dormancy and germination) comparison of inter- and intraspecific populations; 2) the analysis of seed traits variation; and 3) effects of environmental factors on seed traits variation. Therefore, by comparing various aspects of seed traits of S. aralocaspica and S. salsa, this study is designed to reveal the variation mechanism of seed traits regulated by environmental and maternal factors, establishing the concept model of seed traits variation, and illuminating the ecological mechanism of distribution difference btween the two. The results could enrich theory and methods in the field of rare and widespread species, and provide basis for the protection of plant species with extremely small populations and for adaption of populations to global climate change.

作为一年生被子植物唯一的繁殖体，种子深刻影响着种群动态和地理分布。本项目以碱蓬属稀有种异子蓬和广布种盐地碱蓬的异型种子（扁圆形棕色种子和双凸透镜形黑色种子）为研究对象，采用野外样带调查、同质园实验、盆栽实验和室内分析等手段，对两种碱蓬不同种群的种子性状及其变异进行研究，验证基于通才/专才权衡理论提出的性状变异权衡假说—广布种功能性状高变异/狭域种低变异。内容包括：1）种间和种内不同种群的种子性状（比例、大小、休眠和萌发等）对比；2）种子性状变异程度分析；3）环境因素对种子性状变异的影响。本研究通过比较异子蓬和盐地碱蓬种子性状的差异，旨在揭示环境和母体因素影响种子性状变异的规律，建立种子性状变异的概念模型，阐明两种碱蓬种群分布差异的种子生态机制。这将丰富稀有种和广布种研究的方法和理论，为探索极小种群物种保护和植物种群对全球气候变化的适应提供依据。

种子是绝大多数一年生植物唯一的繁殖体，深刻影响着种群分布和种群动态。进行稀有种和广布种的种子生态学比较研究，有助于深入了解造成稀有种局限分布的原因。表型可塑性是植物适应环境的表现，具有更高可塑性的植物可能具有更广的地理分布。种子异型性是植物一种特殊的表型可塑性，一般出现在干旱区、盐渍土地区等不稳定环境。异型种子在休眠和萌发等方面存在明显差异。本项目以碱蓬属稀有种异子蓬和广布种盐地碱蓬的异型种子（扁圆形棕色种子和双凸透镜形黑色种子）为研究对象，采用野外样带调查、盆栽实验和室内分析等手段，对两种碱蓬不同种群的种子性状及其变异进行研究，验证基于通才/专才权衡理论提出的性状变异权衡假说—广布种功能性状高变异/狭域种低变异。内容包括：1）种间和种内不同种群的种子性状（比例、大小、休眠和萌发等）对比；2）种子性状变异程度分析；3）环境因素对种子性状变异的影响。研究结果表明：不同居群间两种碱蓬棕色种子的萌发率没有显著差异，而异子蓬黑色种子的萌发率显著低于盐地碱蓬黑色种子的。异子蓬两种种子的长度都显著大于盐地碱蓬的。异子蓬两种种子的比例变化范围小于盐地碱蓬的。异子蓬黑色种子的萌发变异小于盐地碱蓬黑色种子的。异子蓬棕色种子大小的变异显著小于黑色种子的，而盐地碱蓬棕色种子大小的变异显著大于黑色种子的。从西北干旱区到东南湿润区，盐地碱蓬的萌发率、大小和比例没有表现出明显的地带性规律。本研究通过比较异子蓬和盐地碱蓬种子性状的差异，分析了环境和母体因素对种子性状变异的影响，部分验证了基于通才/专才权衡理论提出的性状变异权衡假说—广布种功能性状高变异/狭域种低变异，阐明了两种碱蓬种群分布差异的种子生态机制。这丰富了稀有种和广布种研究的方法和理论，为探索极小种群物种保护和植物种群对全球气候变化的适应提供了依据。