基于遗传标记研究水青冈对动物捕食和传播限制的生态适应机制

Fagus is a dominant tree genus in humid temperate forests in the Northern Hemisphere. A varying species in this genus distribute in China and China is also regarded as the distribution center of this genus. A few of the thirteen species in this genus are characterised by having a multi-stemmed form; for example F. engleriana in China, but other species are single-stemmed form, for F. pashanica. Chinese Fagus species occur in the humid mountains of southern China. F. engleriana mainly occurs in the northern part of the Chinese beech range and in the coolest climate. It has a multi-stemmed form at all sites of its range (except for Fanjingshan). While the single-stemmed trees are found in all habitats of F. pashanica's range. Seed predation and dispersal limitation plays a critical role in the spatial distribution and successional development of plant communities within many ecological systems. These may trigger regeneration from seeds and sprouting of some trees, and also cause resumption of growth in suppressed trees. The ecological adaptations and evolutionary origins of sprouting in general, however, remain to be fully understood and established. To explore the role of seed predation and dispersal limitation in the ecological adaptation of multi-stemmed form in F. engleriana, we will carry out the comparative study between F. engleriana and F. pashanica in Shennongjia Nature Reserve, using genetic analysis and field control experiments. The Janzen-Connell model will be used to analysis whether the occurrence of root-sprouting and multi-stemmed form is ecological adaptation strategy of Fagus recruitment. Condersing plant-animal interaction, this study is a new topic for sprouting reasech and the occurrence of multi-stemmed form in Fagus. Our results will help to elucidate the mechanism of Fagus recruitment and explore the ecological adaptation and evolutionary significance.

壳斗科水青冈属植物是北半球山地落叶阔叶林的主要优势种，我国是其种类最丰富国家和分布中心。前期基金项目研究表明啮齿动物是水青冈种子的主要捕食和传播者，萌生种类种子受捕食压力大，被传播距离远。但缺乏遗传标记分析，不能获得实际更新距离，难以明确萌生更新是否是对环境胁迫压力的生态适应现象。本研究拟在前期研究基础上，以同域分布具萌生更新的米心水青冈和非萌生的巴山水青冈为研究对象，通过遗传标记分析和野外控制实验，从萌生更新的生态适应角度分析动物在水青冈更新中的潜在影响，并利用Janzen-Connell 模型探究萌生更新是否是水青冈对动物高捕食压力和传播限制所采取的生态适应策略。本研究从动植物关系角度探究水青冈的更新机制及其萌生的生态适应意义，这不仅在萌生机制研究方面属新思路，且是水青冈更新研究的新内容。研究结果将有助于阐明水青冈的更新机制，揭示萌生更新的进化意义，为水青冈管理与保护提供依据。

壳斗科水青冈属植物是北半球山地落叶阔叶林的主要优势种，我国是其种类最丰富国家和分布中心。前期基金项目研究表明啮齿动物是水青冈种子的主要捕食和传播者，萌生种类种子受捕食压力大，被传播距离远。但缺乏遗传标记分析，不能获得实际更新距离，难以明确萌生更新是否是对环境胁迫压力的生态适应现象。本研究拟在前期研究基础上，以同域分布具萌生更新的米心水青冈和非萌生的巴山水青冈、长柄水青冈为研究对象，通过遗传标记分析和野外控制实验，从萌生更新的生态适应角度分析动物对水青冈更新中的潜在影响，并利用Janzen-Connell 模型探究萌生更新是否是水青冈对动物高捕食压力和传播限制所采取的生态适应策略，最终确定种子实际更新距离和格局。结果显示具有萌生更新的米心水青冈比仅有实生更新的巴山水青冈具有更远的种子扩散距离，而长柄水青冈因其种子较大，也有较远的种子扩散距离；具萌生更新的米心水青冈有最远的花粉扩散距离，非萌生更新的长柄水青冈和巴山水青冈次之。长柄水青冈的遗传多样性最高，米心次之，而巴山水青冈最低。这些结果表明动物高捕食压力诱导的负密度制约效应是米心水青冈萌生更新的驱动因子，而动物长距离传播是米心水青冈萌生更新的生态适应性因素，支持了生态“占位”假说。本研究从动植物关系角度探究水青冈的更新机制及其萌生的生态适应意义，在萌生机制研究方面属新思路，且是水青冈更新研究的新内容。研究结果不仅有助于阐明水青冈的更新机制，揭示萌生更新的进化意义，为水青冈林管理与保护提供依据；更可为揭示种群动态的机制，理解动物和植物之间互作关系的规律，了解生态系统演替及其组分之间的关系，认识动物对种子的捕食与传播在生态系统中的作用，进而为生态系统维持和生物多样性保护提供科学依据及有效措施。