Knowledge Resource Center for Ecological Environment in Arid Area
| 亚洲中部干旱区荒漠建群种红砂遗传结构及种群历史动态演化的研究 | |
| 其他题名 | The study on genetic structure and population historical dynamics of desert constructive species Reaumuria soongarica in Arid Central Asian |
| 殷恒霞 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 导师 | 王让会 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 亚洲中部干旱区（Arid central Asia，ACA）的形成和演化是第三纪以来最重要的地质事件之一，被认为与青藏高原隆升及现代亚洲季风系统的形成和发展密切相关，也是目前地学领域研究热点之一，但是ACA以及东亚季风系统的时空演化对荒漠植物的遗传结构和地理分布模式的影响远未清楚。本文对广泛分布于ACA的老第三纪（古近纪）孑遗植物红砂(Reaumuria soongarica)的现存分布区进行了全面调查，并采集了包括腾格里沙漠、巴丹吉林沙漠、塔克拉玛干沙漠、古尔班通古特沙漠、库姆塔格沙漠和柴达木盆地等荒漠区域的34个群体共272个个体，利用母系遗传的叶绿体基因（cpDNA）和双亲遗传的核糖体内部转录间隔区片段（nrITS）的序列变异式样，构建了红砂的谱系遗传结构，并反演其群体动态进化历史和模拟历史分布区变化，探讨了第三纪以来亚洲中部干旱化过程和东亚季风系统对该物种地理分布格局和遗传结构的影响，从分子谱系地理学角度为ACA区域的干旱化时空演化历史增添佐证。此外，采用磁珠富集法构建了高丰度的红砂基因组微卫星富集文库，并进行了特性分析，为理解红砂基因组的适应性进化奠定基础。本文主要结果：(1) cpDNA和nrITS的单倍型地理分布及组内遗传多态性分析表明，红砂叶绿体基因遗传多样性存在明显的谱系地理结构（Nst ＞ Gst, Nst = 0.386 p = 0.034; Gst = 0.279 p = 0.021），单倍型网状拓扑结构分为东-西部两大支系，且东部支系最先分化出来。基于被子植物叶绿体基因的突变速率和分子钟估算其分化时间约为2.96 百万年前（Million years ago, Mya），推测上新世末期青藏高原东北部的剧烈隆升引起红砂种群内东西部支系的分化，而东亚冬季风的加强则推动了东西两大支系进一步分化。同时发现东西部支系红砂群体发生了异步分化，东部支系群体分化时间较早为大约1.72Mya，西部支系群体分化的时间为大约1.26Mya，这种现象说明局域季风气候波动对荒漠建群植物的非平衡支系分化也有深远作用。(2)通过cpDNA和nrITS单倍型拓扑结构和有效群体大小分析，发现古尔班通古特沙漠区域分布的红砂种群为后衍群体，且该地区可能存在双向迁移定植；根据分化时间估算发现该地区红砂群体发生双向迁移定植时间在0.37Mya以后，结合古地质气候研究数据推测，东亚夏季风在这一时期的加强带动红砂种子从东部地区向古尔班通古特沙漠区域迁移扩散。另外，结合黄土地层学对古尔班通古特沙漠区域荒漠化的研究，我们推测该区域干旱化大约于0.4Mya发生，从而为红砂群体的迁移定植提供了适宜的生境。(3)通过对红砂群体动态历史分析，发现整个红砂群体的有效群体大小具有显著增加的趋势，而且处于亚洲夏、冬季风交界带的东部红砂群体的有效群体大小增长最为显著，说明东亚季风系统可显著加快该区域物种进化速率。分布区生态位模型结果揭示，东部群体潜在分布区受气候驱动显著变迁；而西部群体一直呈现稳定缓慢增长趋势，与该区域地理相对隔离封闭而受到季风气候波动的影响较小，而东部区域受到东亚季风的影响比较频繁导致生境片段化较为严重。(4)柴达木盆地通道区域的红砂群体除了具有来自东部支系单倍型，而且还具有来自西部支系的祖先单倍型；经检测发现东亚冬季风方向母系基因流显著加强，推测柴达木盆地的遗传混杂可能是由于这一时期的东亚冬季风加强的驱动力下带动红砂种子迁移扩散所致。(5)通过构建红砂基因组微卫星富集文库及特性分析发现，所获得的13922条微卫星序列中完美型占88%，非完美型10%，混合型2%，并且微卫星重复基元显示5种类型，以三碱基基元(GGT)n、(TGG) n、(ACC) n最多，高达60.7%；其次为二碱基基元，主要是 (AC) n、(GT) n、(CA) n，占38.6%；这可能与其所处极端生境，耐受干旱、低温及盐碱特性有关。另外，通过对随机挑选的100条微卫星序列设计引物，并以遗传距离和地理距离相距较远个体的基因组为模板进行扩增筛选，获得了12对有效的多态性微卫星引物。这将为研究红砂的遗传多样性及适应性进化提供新的借鉴思路。 |
| 英文摘要 | The formation and evolution of Arid Central Asia (ACA), being one of the most important geological events since Tertiary, is thought to be closely correlated with the uplift of the Qinghai-Tibet Plateau (QTP), as well as the evolution of the modern Asian monsoon, and is becoming a hot topic in the geological research. However, the effect of the tempo-spatial evolution of the ACA and East Asian monsoon system (EAMS) on the genetic structure and geographically distribution patterns of desert plants has rarely been reported. In overall survey of the distributed regions of Reaumuria soongarica, an old Tertiary (Paleogene) relict plant and desert constructive species，and widespread distributed in ACA, in the present study, we collected 272 individuals in 34 populations from desert regions including the Tengger Desert, Badan Jaran Desert, Taklimakan Desert, Gurbantonggut Desert, Kumtag and Qaidam Basin. Two molecular marker, maternally inherited chloroplast DNA (cpDNA) and the parental genetic ribosomal internal transcribed spacer region fragment (nrITS), had been used to reconstruct genetic genealogical structure, explore population dynamics history and simulate the changes of the historical potential distribution areas, and consequently we deciphered the effect of the aridity of ACA and the evolution of EAMS on the geographical distribution pattern and genetic structure of R. soongarica, which provides a new evidence for the tempo-spatial evolutionary history from the viewpoint of molecular phylogeography. In addition, to well understand the adaptive evolution of R. soongarica, we used the method of magnetic beads enrichment to build enriched microsatellite sequence library and analyzed the characteristics of library through sequencing results. The main conclusions revealed from the present study were as follows:(1) Based on the haplotype geographic distribution of cp DNA and ITS and in-group genetic polymorphism analysis, there existed significant geographical structure in the chloroplast genetic diversity (Nst＞Gst, Nst = 0.386 p = 0.034; Gst = 0.279 p = 0.021), and two lineages, Eastern and Western clades, were presented, moreover, the Eastern clade was firstly differentiated. Besides, the divergence time between the two lineages was ca. 2.96 (Million years ago, Mya) evaluated by mutant rate of angiosperm chloroplast DNA and relaxed molecular clock, suggesting that the divergence in the late Pliocene was induced by the uplift of the eastern QTP, while the strengthening East Asian winter monsoon (EAWM) exacerbated the process. Meanwhile, the asynchronous divergence was observed, the divergence time of Eastern clade was earlier for ca. 1.72Mya, and the Western clade was for ca. 1.26Mya, which suggested a prominent effect of local monsoonal climate on non-balance lineage divergence of desert constructive species.(2) Based on the haplotype topology of cpDNA and ITS and effective population skyline plots, the R. soongarica populations distributed in Gurbantonggut Desert were posterior species, and generated due to the bi-directional migration and colonization, the time of which might be after 0.37 Mya according to the evaluated divergence time. Combining with paleo-geologic and –climatic records, we proposed that the East Asian summer monsoon (EASM) strengthening forced the seeds of R. soongarica to migrate from eastern regions to Gurbantonggut Desert region. Additionally, in combination with the stratigraphy of loess on the desertification of the Gurbantonggut Desert, we revealed that the region formed ca. 0.4 Mya，when the suitable habitats were offered for the migration and colonization of R. soongarica.(3) According to the population dynamics history analysis of R. soongarica, the effective population size of the entire population has the tendency of significant increasement, while the eastern population in the junction of EASM and EAWM increased most remarkablely, we inferred that the EAMS would significantly accelerate the evolution of species distributed in the regions. In addition, the ecological niche models (ENMs) showed that the potential distribution areas of the eastern population in monsoonal zone experienced strikingly contraction – expansion migration during the LIG period, while those of the western population were displaying with the stable and slow increasement. The discrepancy we proposed might be due to the little influence on western regions by the monsoonal fluctuation for the relative isolated and closed geographic locations, while the habitats fragment were more severe because of the frequent influence on the eastern regions by EASM.(4)The populations from the Qaidam Basin corridor not only beard haplotypes from the eastern lineage, but also the ancestral haplotype from the western lineage, moreover, the maternal gene flow was obviously promoted along the EAWM, we referred that the gene admixture in the Qaidam Basin might be induced by the strengthened EAWM driving the seeds of R. soongarica to spread at that time.(5) Based on the enriched microsatellite sequence library and characteristics analysis through sequencing results, 13922 microsatellite sequences were obtained with 88% perfect, 8% imperfect and 2% compound repeat motifs, and of these microsatellite loci, five type repeat primitives were presented, including prominent 60.7% three base primitive with (GGT)n, ( TGG) n and ( ACC)n, and 38.6% two base primitive with (AC) n, (GT) n and (CA) n, which might be correlated with their extreme habitats and characteristics of the tolerance with aridity, hypothermy and saline alkali. In addition, 12 pair effective microsatellite primers have been screened out by designing primers with the 100 random microsatellite sequences and PCR screening with templates in populations with distant genetic and physical distance. The investigation will provide useful information for studying the genetic diversity and adaptive evolution of R. soongarica. |
| 中文关键词 | 亚洲中部干旱区 ; 东亚季风系统 ; 青藏高原隆升 ; 红砂 ; 遗传结构 ; 群体动态历史 ; SSR富集文库 |
| 英文关键词 | Arid Central Asian East Asian monsoon system uplift of the Qinghai-Tibetan Plateau R. soongarica phylogeography population genetic structure population dynamics SSR enrichment library |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287683 |
| 推荐引用方式 GB/T 7714 | 殷恒霞. 亚洲中部干旱区荒漠建群种红砂遗传结构及种群历史动态演化的研究[D]. 中国科学院大学,2016. |
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