华中地区珍稀木本植物迁地保护种群动态与维持机制

Understanding population dynamics and the underlying maintenance mechanisms of endangered plants under ex situ conservation is a central question in conservation biology. Transplanted individuals at ex situ conservation sites probably have low survival rate and recruitment limitation, because of poor adaptation, low genetic variation, or both. However, a remarkable number of studies currently focused on whether ex situ populations capture genetic variation of their wild original populations, but it is still lack of a comprehensive study concerning not only genetic diversity, but also traits characteristics of both leaf and seed. Especially for woody plants, because of their long life-history, risks such as reduction in performance of reproductive traits and fitness decline of seedling have rarely been addressed so far. In this project, our study species are several rare or endangered woody species endemic to China or East Asia. In 1980s, several conservation biologists transplanted seedlings of these species from their wild populations within and around central China to Jiugongshan National Natural Reserve, Hubei Province. First, we will study population dynamics of these species under ex situ conservation by investigating their survival, reproduction, and recruitment characteristics after transplantation for more than 30 years. Second, we will compare traits of both leaf (morphological and nutrient) and seed (morphological and germination) between their ex situ conservation populations and wild source populations. Third, we will test whether ex situ conservation populations capture enough genetic variation from their wild source populations by doing a worldwide meta-analysis and also by using our study species as a case study. Additionally, we will also compare genetic variation between adult and seedling individuals in both ex situ populations and wild source populations. In general, this project aims to investigate population dynamics and the underlying maintenance mechanisms of several rare or endangered woody plants under ex situ conservation for more than 30 years.

迁地保护植物的种群动态及维持机制是保护生物学的核心问题之一。迁地保护植物多面临存活困难或更新限制，这可归因于移栽对象对新环境的不适应、遗传涵盖度不足、或二者的共同作用。然而，当前对迁地保护植物遗传涵盖度的研究相对较多，整合种群动态、性状特征和遗传涵盖度的全方位研究尚较少。尤其是木本植物，由于其生活史周期较长，针对其迁地保护种群的繁殖特征和后代适合度的研究当前仍为难点。本项目拟选取迁地移栽30余年的多个亚热带山地珍稀木本植物及其野生来源种群为研究对象，通过比对分析，研究其迁地保护种群的存活、繁殖和更新现状，分析迁地保护种群的种群动态；同时结合性状特征（叶片和种子）和种群遗传学特征（Meta分析和案例研究）分析揭示种群动态的维持机制。该项目的开展不仅可以促进植物保护生物学理论的完善和发展，也可以为全方位评估我国珍稀植物迁地保护实施策略的合理性提供案例研究，为更加全面有效的保护提供新的科学依据。

迁地保护植物的种群动态及其维持机制是保护生物学的核心问题之一。本项目以华中地区迁地移栽30余年的多个珍稀木本植物及其野生来源种群为研究对象，整合种群动态、性状特征和遗传涵盖度尝试从多个角度揭示迁地保护种群动态的维持机制。研究内容如下：（1）亚热带山地珍稀植物迁地保护种群动态；（2）迁地保护种群与野生来源种群的性状特征；（3）迁地保护种群与野生来源种群的种群遗传学特征。.研究结果：（1）5种代表性濒危植物（珙桐、金钱槭、白辛、银鹊树和水青树）在迁地种群均能够正常生长，当前的存活率分别为43%、74%、56%、67%和56%，大多数物种还能够开花结实。（2）叶片性状的均值在迁地和野生种群中存在差异，表明迁地种群的适应策略与野生种群有所不同。在迁地种群中，某些物种叶片功能性状的种内变异程度比野生种群显著降低，这可能会减小迁地种群的稳定性。（3）迁地种群的虫食率显著低于野生种群。与野生种群相比，迁地种群的防御化学物质总体含量较低，但营养物质含量较高。（4）5种木本珍稀植物的迁地种群与野生种群的遗传多样水平相似，迁地种群表现出较高的遗传涵盖度。（5）目前全球范围的迁地保护普遍面临遗传涵盖度低的问题。迁地保护种群的低遗传涵盖度可以归因于不完善的取样策略和迁地保护过程中的遗传侵蚀。.本研究结果表明，虽然迁地保护种群具有较高的遗传涵盖度，并且能够正常生长且大部分可以开花结实，但是通过叶片功能性状和虫食情况分析可以看出，迁地保护种群的生长策略和应对天敌昆虫的策略都发生了一定程度的改变，不利于将来进行野外回归。此外，全球范围内的迁地保护面临遗传涵盖度较低的问题，我们针对性的提出了3个提高迁地保护种群遗传涵盖度的建议。因此，本研究被认为在提高迁地保护有效性方面具有重要的实践意义。