Knowledge Resource Center for Ecological Environment in Arid Area
| 亚洲中部荒漠区特有植物的地理分布格局研究 | |
| 其他题名 | Distribution Patterns of Endemic plants in Central Asian Desert |
| 马松梅 | |
| 出版年 | 2011 |
| 学位类型 | 博士 |
| 导师 | 陈曦 ; 张明理 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 物种的地理分布格局作为物种重要的空间特征，对研究物种起源、进化和保护均有重要的意义。亚洲中部荒漠区的13个植物特有或近特有属（连蕊芥属、合头藜属、戈壁藜属、河西菊属、沙冬青属、四合木属、绵刺属、钝基草属、革苞菊属、百花蒿属、喀什菊属、霸王属和紊蒿属，表1.1）都是单种或双种属。这些属的已知分布记录范围（8-109）代表了荒漠区大多数荒漠植物所能获得的分布记录个数，而且它们具有明显不同的地理分布特点。十三个特有属的地理分布区和潜在分布资料缺乏。本文选择三种预测原理和能力不同的物种分布模型：最大熵（Maxent）、预测规则集算法（GARP）和Domain模拟了13个属的潜在地理分布格局。研究结果比较了三种模型不同的预测特点和能力；模拟了每一个分类群所有的适生区和潜在地理分布界限；揭示了13个特有属的地理分布格局；解释了地理分布和环境因子之间的关系。在此基础上，提出了保护十三个特有属的合理策略。\n裸果木是第三纪孑遗稀有植物，分布区主要局限在西北荒漠区。本文利用Maxent和GARP模型模拟并分析了裸果木的潜在分布格局。青藏高原隆升显著影响了中国西部及边缘地区的陆地生态系统，中亚气候经历了若干次强烈的干旱化，这对裸果木的地理分布和谱系地理结构造成了怎样的影响，为了回答这些问题，选择了两个叶绿体DNA序列psbA–trnH和ycf6–psbM，从居群、个体到分子的层次对裸果木进行了谱系地理学研究。研究结果揭示了裸果木群体的遗传多样性水平；探讨了影响居群遗传结构的可能因素；分析了居群的动态历史和谱系地理结构；并推测了在第四纪西北气候急剧干旱化背景下，影响裸果木进化历史的主要事件。在此基础上，提出了保护和长期管理裸果木居群的具体策略和措施。以上三个方面的主要研究结果如下：\n1. 三种模型方法不同的模拟特点和能力\n对已知分布数据大于25的类群，AUC评价表明Maxent和Domain的预测准确性相似，都明显高于GARP。模型可视化的预测结果表明Domain模拟的最适合物种分布的分布区，主要围绕用于预测的已知分布点分布。GARP对模拟的特有属产生了大且连续的适生区，及一些不现实的破碎的潜在分布。而Maxent模型不仅在研究区域内为每一个测试的类群预测到了一定的适生区，而且排除了大多数不合理的空间预测。\n对分布记录小于25的类群，留一法评价结果发现Maxent基于8个已知分布点就产生了准确率较高的预测；GARP获得的预测成功率和预测到的面积比例和Maxent相似；但Domain模型基于有限的分布数据没有产生合理的预测。\n2. 特有属的地理分布格局\n特有属的丰富度和叠加的潜在分布都表明东阿拉善是它们的地理分布中心。丰富度分析表明，所有特有属的地理分布，一是主要围绕内蒙古阿拉善高原东部呈同心圆分布，二是集中分布在塔里木盆地的西北部和北部。叠加的潜在分布揭示的格局与丰富度的估计结果基本一致，但阿拉善高原西北部即中央戈壁的环境条件，被基于生态位原理的模型表明不适合这些特有属生态位的建立或是适生性较低。\n3. 裸果木的潜在地理分布研究 \n利用Maxent和GARP模拟了裸果木的潜在地理分布，主要得到两方面结论：（1）裸果木的潜在适生区全部集中在西北荒漠区，其中最佳适生区集中在三个区域，一是河西走廊中部和玉门以西、宁夏北部及内蒙古乌拉特后旗；二是塔里木盆地西北缘；三是柴达木盆地西北缘两片极小的高度适生区。裸果木的生态位被确定在一个较广的干旱环境空间：适生区极端最高气温基本上在29.2-36.8 °C之间，极端最低气温在-18.3至-13.4 °C之间；年平均降水量为40-200 mm；潜在蒸发率在3-15之间。（2）Maxent和GARP模型都较好地预测了裸果木的潜在分布，但Maxent的预测结果更直观地展示了裸果木的潜在分布格局和生态位要求。\n4. 裸果木的谱系地理学研究\n两序列拼接后共得到25个单倍型，其中有14个来自于塔里木盆地西北缘的居群。裸果木被发现存在较高的总的居群遗传多样性和平均居群内遗传多样性（hT = 0.849; hS = 0.350）。居群分化指数NST（0.791）显著高于GST (0.588) (P < 0.01)，表明裸果木居群存在显著的谱系地理结构。所有单倍型中，五个为共享单倍型，其中有两个最广布的单倍型：一个主要分布在甘肃省玉门以西、哈密盆地和内蒙古乌拉特后旗的居群，另一个则分布在新疆塔里木盆地的居群；剩余的20个为各自居群特有的单倍型。\n叶绿体单倍型的嵌套分支结构表明存在三个谱系地理支。估计裸果木单倍型谱系支之间的分化开始的时间大概在2.5–0.83 Ma (早更新世)，刚好落入了西北地区干旱化加剧的时间段。因此，认为气候导致的生境破碎化可能主要影响了裸果木当前的谱系地理结构。此外，Mantel检测和错配分布的结果也支持谱系推断，表明有些裸果木居群可能还发生了受限制的基因流，距离隔离效应和邻近范围内的居群扩张。根据以上研究结果，对裸果木提出了合理的保护策略。 |
| 英文摘要 | Geographic distribution pattern as an important spatial characteristic of a species is critical to study the origin, evolution and conservation. Thirteen endemic or near-endemic genera of eastern Central Asian desert (Synstemon, Sympegma, Iljinia, Zollikoferia, Ammopiptanthus, Tetraena, Potaninia, Timouria, Tugarinovia, Stilpnolepis, Kaschgaria, Sarcozygium, Elachanthemum; Table 1.1) are monotypic or bitypic genera. Thirteen genera have a range of distribution localities (8-109) that represent the data available for the most of desert plants, and also they have contrasting biogeographical distributions. Information about distribution areas and the potential distributions of 13 genera is unknown. This paper employed three species distribution models (SDMs): the maximum entropy (Maxent), the Genetic Algorithm for Rule-set Prediction (GARP), and Domain to model the potential distribution for each taxon. We compared the different predictivities of three methods; identified all the suitable areas and potential distribution limit for each taxon; analysized the distribution patters of 13 genera, and also explained the relationship between taxa geographical distributions and environmental variables. Finally, the conservation strategies for endemic genera tested were discussed based on the above results. \nGymnocarpos przewalskii (Maxim.) is a rare and relic plant, and mainly restricted to the northwestern China desert. This paper predicted and analyzed the potential distribution patterns of G. przewalskii using the Maxent and GARP. The uplift of the Tibetan Plateau dramatically affects the terrestrial ecosystems in western China. The climate in the northwestern China experienced several episodes of rapid aridification, and how is the climate-induced phylogenetical structure of G. przewalskii? Therefore, a phylogeographical study was conducted using two chloroplast regions (psbA–trnH and ycf6–psbM) in 160 individuals representing 16 populations, sampled across most of the species range. This study examined the level and structure of cpDNA variation in G. przewalskii and factors affecting them. The demographic history and phylogeographic structure of G. przewalskii were investigated, and the possible historic process was clarified. The main results are summarized as follows:\n1. Different predictivities of three modelling methods \nFor species with occurrence localities over 25, AUC evaluation shown that Maxent and Domain performed similarly, and both obtained significantly higher scores than GARP did. However, the visual predictions produced by Domain were found to be closely matched to or surrounded the observed localities. GARP predicted large and continuously suitable habitats around the species’ localities, and also produced some isolated or fragmented spatial predictions. In contrast, Maxent successfully removed most of the unlikely spatial distributions, and still correctly predicted a reasonable proportion of the study area for each taxon tested.\nFor species with localities fewer than 25, the results of jackknife tests indicated that Maxent generated predictions with high success rate based on eight localities. The produced predictions of GARP are similar to Maxent. Domain did not produce reasonable predictions based on limited localities. \n2. Potential distribution patterns of 13 endemic genera \nThe estimated richness of 13 genera and the superimposed potential distributions indicated that the eastern Alashan of Inner Mongolia was the most noticeable endemic area. The richness indicated that endemic genera showed a concentric distribution around the Alashan Plateau, or concentrated in the northwestern and northern Tarim Basin. The superimposed potential distributions generally demonstrated similar patterns to these identified by the richness. However, the superimposed distributions indicated that the Central Gobi was ecologically of low suitability or unsuitable for the establishment of 13 genera. \n3. Potential distribution patterns of Gymnocarpos przewalskii\nUsing Maxent and GARP, we modeled the distribution patterns of Gymnocarpos przewalskii. The two main results are summarized as follows: (1) the highest environment suitable areas of G. przewalskii are predicted at first in the middle of Hexi corridor and the western Yumen of Gansu Province, the north of Ningxia-Hui Autonomous Region, the part of the Wulate Banner of Inner Mongolia, and the extremely minimal and isolated areas in northwestern Qaidam Basin. The ecological niche for G. przewalskii was defined in a widely arid environmental space: max temperature of warmest month almost during 29.2-36.8 °C, min temperature of coldest month ranging from -18.3 °C to -13.4°C, annual precipitation between 40-200 mm, and maximal potential evapotranspiration ratio between 3 and 15. (2) Both Maxent and GARP obtained good predictions for G. przewalskii. However, Maxent displayed the distribution patterns and ecological niches of the species more clearly, than GARP did.\n4. Phylogeography of Gymnocarpos przewalskii\nA total of 25 haplotypes were identified, and 14 of which were found in the northwestern Tarim Basin of southern Xinjiang. G. przewalskii presented high levels of total genetic diversity (hT = 0.849) and average gene diversity within populations (hS = 0.350). Total NST (0.791) was much higher than GST (0.588) (P < 0.01), indicating significant phylogeographic structure in G. przewalskii. There are only five shared haplotypes, and the remaining 20 ones are private to their particular populations. One of the most common haplotype, 1, widespread in populations of the Hami Basin of eastern Xinjiang, western Yumen of Gansu Province, and northernmost Wulate Banner of Inner Mongolia; and the other haplotype 12 was found in five populations of the northwestern Tarim Basin. \nThe haplotype networks identified three four-step nested clades. The occurred divergence of the three clades of G. przewalskii was estimated at 2.5–0.83 Ma, just falls into the period of aridity of the northwestern China. We therefore suggested that the phylogeographic structure of G. przewalskii has been heavily influenced by the climate-induced fragmentation. In addition, results of mantel tests and mismatch analyses agree well with nested clade phylogeographical analysis, in suggesting patterns of isolation by distance and contiguous range expansion in some populations. Finally, the conservation strategies for G. przewalskii were discussed based on our results. |
| 中文关键词 | 特有属 ; 物种分布模型 ; 潜在地理分布格局 ; 裸果木 ; 谱系地理学 |
| 英文关键词 | endemic genera species distribution models potential geographic distribution patterns Gymnocarpos przewalskii phylogeography |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 地图学与地理信息系统 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286990 |
| 推荐引用方式 GB/T 7714 | 马松梅. 亚洲中部荒漠区特有植物的地理分布格局研究[D]. 中国科学院大学,2011. |
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