保护生物学的技术方法在极度濒危植物紫花杜鹃中的应用

	保护生物学的技术方法在极度濒危植物紫花杜鹃中的应用
	敖艺山
导师	马永鹏
关键词	ddRAD-seq、遗传多样性、群体遗传学、保护策略 ddRAD-seq、Genetic Diversity、Population genetics、Conservation Strategy
摘要	杜鹃花是杜鹃花科（Ericaceae）杜鹃属（Rhododendron L.）植物的统称。我国拥有大约 600 种杜鹃花，是世界上杜鹃花种类最多的国家。在《中国生物多样性红色名录——高等植物卷》中，我国极度濒危（Critically Endangered，CR）的杜鹃花有 12 种，而本课题的研究对象紫花杜鹃（R. amesiae）就属于其中之一。我国对杜鹃花的研究相较国外起步晚，大多数原生杜鹃种并未得到有效的保护，即使是列入极度濒危等级的紫花杜鹃，除标本记录外我们查不到其相关的文献记录。本文主要利用保护生物学的技术方法去探讨紫花杜鹃的濒危机制，提出合理的保护建议；同时，为珍惜濒危植物的濒危机制探索提供一套合理高效的方法。首先，通过查阅标本，确定野外的大概分布区后，进行野外综合调查，明确紫花杜鹃的野外分布现状和受威胁因素等；然后，基于 ddRAD-Seq 分析紫花杜鹃的遗传多样性（π）、群体分化指数（FST）和群体结构；最后，根据野外传粉试验和传粉昆虫的观察，分析其自然条件下的结实是否受到传粉限制。结果表明：（1）紫花杜鹃目前在野外有 8 个居群，均生长在道路两侧或靠近河流，受到较为严重的人为干扰和自然灾害，如道路修建、放牧、采矿、旅游和泥石流、塌方等；此外，紫花杜杜鹃自然条件下幼苗形态建成较为困难，只在分布区边缘有少量的幼苗生长，且生境破碎化严重，种群扩张也受限；根据 IUCN 物种红色名录濒危等级和标准 3.1 版，紫花杜鹃现存在成熟个体大于 250 株，但小于 1000 株的居群，因此可以考虑降低其濒危等级到易危（Vulnerable，VU）；（2）遗传多样性分析结果表明，紫花杜鹃遗传多样性（π）在 0.123~0.146 之间，比大多数濒危物种遗传多样性高（π<0.1）；群体结构分析表明，紫花杜鹃的 8 个居群可划分为 2 个遗传组分，老榆林（LYL）居群为单独一个遗传组分，木龙沟（ML）和四姑娘山（SG）居群为另一个遗传组分，其余 5 个居群个体是上述两个遗传组分的混合；（3）紫花杜鹃的主要传粉昆虫熊蜂、蝴蝶在野外的数目极其稀少，访花频率低（熊蜂： 1.53 朵·h-1，蝴蝶：0.20 朵·h-1），推测其繁育受到传粉昆虫限制；紫花杜鹃自然状态下的结实率为 38.10%，通过人工同株异花授粉和异株异花授粉，结实率显著提高到了 70.37%和 80.77%，表明紫花杜鹃自然状态下可能受到了花粉限制。尽管紫花杜鹃目前拥有较高的遗传多样性，但破碎化的生境、较严重的近交以及传粉昆虫的稀缺会进一步加剧其濒危情况。本文整合了野外资源分布调查、群体遗传和传粉生物学试验等保护生物学技术与方法，探明了紫花杜鹃濒危的机制，为该物种的有效保护奠定基础。; Rhododendron is the general name for plants of the genus Rhododendron L. in the Ericaceae. China has the largest number of rhododendron species in the world with about 600 species. However, most Chinese rhododendrons were not well explored in the field and rare conservation work was conducted towards this genus. Based on Threatened Species List of China’s Higher Plants, a total of 12 species, including R. amesiae, was evaluated to be the critically endangered (CR) in China. In this study, we mainly use the methods of conservation biology to explore the endangerment mechanism and formulate a reasonable conservation strategy for R. amesiae. Firstly, we checked the specimen records to determine the approximate distribution area in the field and conducted a comprehensive field survey to clarify the current distributions and threats of R. amesiae. Secondly, the genetic diversity (π), population genetic differentiation index (FST) and population structure of R. amesiae were analyzed based on Double Digest Restricted site-associated DNA sequencing (ddRAD-seq). Finally, to confirm whether seed was effectively produced in natural conditions, hand pollination experiments and observations of floral visitors were conducted in Laoyulin (LYL) natural population of R. amesiae. The results showed that: (1) Eight populations of R. amesiae were found at the road sides or near the river bank in the wild. They were suffered from severe human disturbances and natural disasters, such as road construction, grazing, mining, tourism, mudslides and landslides. Moreover, seedling morphogenesis are difficult under natural conditions, with only a small number of seedlings growing at the edge of the distribution area. R. amesiae suffered severe habitats fragmentation, thus limiting populations expansion. According to IUCN Red List Categories and Criteria: Version 3.1, there are populations with more than 250 mature individuals but less than 1000 mature individuals of R. amesiae. We therefore considered downgrade its threatened category from critically endangered (CR) to vulnerable (VU). (2) The genetic diversity analysis showed that the nucleotide diversity (π) of R. amesiae ranged from 0.123 to 0.146, which was higher than that of most endangered species (π < 0.1). Population structure analysis showed that eight populations of R. amesiae could be divided into two groups. One group included LYL with all individuals dominated by a single genetic component, the other group included ML and SG with all individuals dominated by a different genetic component, and the remaining 5 populations included individuals with both of these two genetic groups. (3) The reproduction of R. amesiae suffered from pollen limitation. Firstly, the effective pollinating insects like bumble bee, butterfly in the wild are rare, and the frequency of visiting flowers is low (bumble bee: 1.53 a flower·h-1, butterfly: 0.20 a flower·h-1). Secondly, the fruiting rate was 38.10% under natural conditions,
语种	中文
	2022-05
学位授予单位	中国科学院大学
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/75169
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	敖艺山. 保护生物学的技术方法在极度濒危植物紫花杜鹃中的应用[D]. 中国科学院大学,2022.

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