新疆野苹果林的群落谱系结构与优先保护区确定

Malus sieversii is recognized as a major progenitor species to the cultivated apple, M. × domestica. It has been listed as the national endangered and second-class protected plants of China. Chinese part of M. sieversii forest distributes in the mountainous regions of Yili Prefecture and Tacheng Prefecture, the area of which likes island. It is suffered the range reduction and biodiversity loss from human activities, diseases and insect pests. At present, nature reserve has not been established for M. sieversii forest. Then, the primary task is to determine the priority conservation areas. Our previous researches showed that it was hard to identify the priority conservation areas of M. sieversii based only on population genetic structure. In this study, we will further investigate the population characteristics and the community composition of M. sieversii forest from six different locations, and then analyze the phylogenetic diversity and the phylogenetic structure of plant community in each location using the approach of phylogenetic community ecology. Based on these data, we aim to: 1) understand the variation of community stability between different locations based on phylogenetic diversity of plant community; 2) reveal the mechanism of biodiversity maintenance for M. sieversii forest based on phylogenetic community structure; 3) propose some priority conservation areas based on the variations of population characteristics, population genetic structure, phylogenetic diversity and phylogenetic structure of plant community. These results can help to choose priority conservation areas during the establishment of nature reserves for this important germplasm resource. At the same time, they will provide theoretical foundations to maintain the ecosystem health of M. sieversii forest.

新疆野苹果是栽培苹果的主要祖先来源，已被列为国家濒危二级保护植物。新疆野苹果林在我国呈岛屿状分布于伊犁和塔城的山地地区，并面临着严重的人为破坏和病虫危害。目前，新疆野苹果林的自然保护区尚未建立。而确定优先保护区是设置自然保护区的首要任务。前期研究发现仅从种群遗传结构的角度不易确定新疆野苹果的优先保护区。本项目将通过深入调查新疆野苹果林6个分布地的种群特征和群落组成，运用系统发育群落生态学的方法来获得不同分布地群落的系统发育多样性和群落谱系结构特征。其目的在于：①利用群落的系统发育多样性来探讨不同分布地群落稳定性差异；②运用群落谱系结构来揭示新疆野苹果林群落的生物多样性维持机制；③结合种群特征、种群遗传结构、群落的系统发育多样性和群落谱系结构来确定优先保护区。预期成果将为建立新疆野苹果林自然保护区时提供选择优先保护区的佐证，并为维持新疆野苹果林生态系统的健康提供理论依据。

新疆野苹果已被列为国家二级保护植物、具有生物多样性国际意义的优先保护物种及濒危重点保护植物。它与现代栽培苹果具有最近的亲缘关系，是栽培苹果的主要祖先来源。在我国，新疆野苹果林主要呈岛屿状残存分布于新疆伊犁和塔城地区。近些年来，由于人为破坏的影响以及多种病虫害的危害，新疆野苹果资源正面临着前所未有的生存危机。目前，新疆野苹果林的自然保护区尚未建立。而确定优先保护区是设置自然保护区的首要任务。本项目将通过深入调查对比新疆野苹果林6个分布地的种群特征和群落的物种多样性、群落的系统发育多样性以及群落的谱系结构。结果发现：①中国境内新疆野苹果存在三个不同的有效进化保护单元。他们之间存在着显著的谱系分化、地理隔离和环境适应性差异。②目前病虫害等导致新疆野苹果树木死亡未对种群遗传结构和多样性造成重要损失。存活和死亡植株间的遗传结构尚没有显著的遗传分化，一些低频度分布的等位基因伴随着植株死亡已经发生丢失。③人工复壮对新疆野苹果树种群遗传结构和多样性会造成一定影响。自然生长种群的遗传多样性低于人工复壮种群，且自然生长种群与人工复壮种群间存在显著的遗传结构分化。④伊犁野果林分布区是天山植物的冰期避难所。野果林重要植物成分都表现出西部居群具有更高的遗传分化；冰期时，天山野果林重要成分植物向西迁移到伊犁河谷避难，而间冰期时又向东发生扩张。⑤古今环境条件对野苹果林主要分布区的植物群落组成与群落谱系结构特征产生了一定影响。野苹果林分布的冰期避难所具有高的物种丰富度，且与环境因子显著相关。相比而言，两个群落结构指数与冰期避难所和环境变量无关；不同群落之间的相似度指数随着空间地理距离增加反而减小。冰期避难所和环境因子显著影响了天山及野果林地区群落的多样性格局，而并未影响群落谱系格局。本项目研究成果为建立新疆野苹果林自然保护区时提供选择优先保护区的佐证，并解析了新疆野苹果林生态系统的维持机制。