中国梭梭和白梭梭的比较谱系地理研究

Haloxylon genus in China only including: endangered Haloxylon ammodendron and H.Persicum (Amaranthaceae), which all have important ecology function to prevent windstorms and fasten sand. However, in the context of Quaternary climate oscillations, the genetic diversity, phylogeographical pattern, evolutionary pattern, ecological niche divergence, potential distribution and its environmental forces of Haloxylon ammodendron and H.Persicum, and how the future climate change would influence their distribution and intraspecific genetic diversity? These problems are still unknown and became to the bottleneck to scientifically protect the two species. This study based on cpDNA, ITS and SSR gene data, employs various population genetic analyses and phylogeographical analysis to reveal relations and divergence of their phylogeographical lineages, to detect gene introgression and hybridization between different lineages, to illuminate phylogeographical patterns and its forming process, and to clarify the relative impact of the same environmental change(e.g.,aridification, snady desert formation and expansion) to the evolution pattern of two species. Using ecological niche model MAXENT and GIS tool to analyze the suitable distribution range, pattern and the environmental forces under the Quaternary last glacial maximum climate, at reference climate and during future climate, quantize and compare the similarity of ecological niches, and then to clarify the role of ecological factors to species speciation, distribution and evolution. This project would help to thoroughly understand the phylogeographical pattern, evolution pattern and distribution pattern of Haloxylon genus in China, and to guide the management and conservation of the existing populations and genetic diversity.

中国梭梭属植物仅包括濒危梭梭和白梭梭，都具有防风固阻沙的重要生态功能。然而，在第四纪气候波动下，两种梭梭的遗传多样性、谱系格局、进化格局、生态位分化、潜在分布及其环境驱动力，以及未来气候变化又将如何影响它们的分布及种内遗传多样性，这些问题尚不可知，成为科学保护两物种的瓶颈。本研究基于cpDNA、ITS和SSR数据，利用各种居群遗传分析和谱系地理分析，揭示它们的谱系关系和谱系分化，检测谱系间的基因渐渗、杂交，阐明谱系格局及其形成过程，探明相同的环境变化如干旱化、沙漠形成、扩张等对它们进化格局的相对影响。利用生态位模型MAXENT和GIS工具分析第四纪最大冰期气候、基准气候及未来气候条件下两物种的适宜分布范围、格局及其环境驱动力，量化生态位的相似性，阐明生态因素对物种形成、分布与进化的影响。本项目将助于深入理解两种梭梭的谱系格局、进化格局及分布格局，指导现有居群和遗传多样性的科学管理和保护。

中国梭梭属植物仅包括梭梭和白梭梭，具有防风固沙的重要生态功能。第四纪气候波动对两种梭梭的遗传多样性、谱系格局、进化格局及潜在分布造成了怎样的影响，成为了科学保护两物种的瓶颈。本研究基于cpDNA和ITS数据，利用各种居群遗传分析和谱系地理分析研究了中国梭梭和白梭梭植物的遗传多样性和谱系地理结构。研究结果表明：1) 研究区梭梭和白梭梭居群均具有较高的遗传多样性，居群间遗传分化显著，两种植物呈两个独立的谱系，谱系间未检测到基因渐渗，干旱化、沙漠形成、扩张及天山隆升主要影响了梭梭与白梭梭的谱系地理结构，冰后期广泛发展的干旱生境和相对适宜的气候可能为梭梭和白梭梭的范围扩张提供了有利的条件；基于2 个nrDNA 序列(ITS2、ITS1-ITS4) 和3 个cpDNA非编码区序列(trnS-trnG、rps4 和trnV) 序列组合均可以作为鉴定梭梭和白梭梭的DNA 条形码序列；2)西北地区荒漠植物梭梭居群呈两个谱系支：新疆的居群和青海、甘肃、内蒙的居群各为一支，种内谱系分化约发生于第四纪早更新世，检测到的两条地理障碍：星星峡和祁连山很可能造成了梭梭的种内异域分化，分布模型、扩散路径分析和错配分布分析均支持梭梭经历了冰后期范围扩张；3) 未来气候情景下，梭梭的适宜分布范围将显著增加，仅在塔里木盆地西端的分布将破碎、减少；分布范围可能将向西北和东北方向迁移。梭梭和白梭梭的生态位分化不明显，说明生态因素很可能对2 种植物的分化与进化没有起到明显的作用，2种植物很可能也具有相近的进化历史。本项目的研究结果助于深入理解两种梭梭的谱系格局和分布格局，指导现有居群和遗传多样性的管理和保护。