中国沙棘(Hippophae rhamnoides subsp. sinensis)天然群体的遗传变异分析

近十年，植物群体遗传学的研究飞速发展，然而与海拔相关的植物群体遗传结构和遗传变异研究却相对较少。到目前为止，还不清楚遗传变异与海拔之间是否有一个通用的格局。在山区，各种生态因子，如温度、降水、降雪、紫外线辐射强度以及土壤成分都随海拔梯度急剧变化，造成了即使在一个小的空间区域，植被类型变化显著，这种高山环境的异质性和复杂性为我们研究植物群体遗传结构和分化提供了方便。沙棘(Hippophea)属于胡颓子科(Elaeagnaceae)为多年生落叶灌木或乔木，雌雄异株，天然种群分布极为广泛。中国沙棘(H. rhamnoides subsp. sinensis)是沙棘属植物中分布较广的一个亚种，种内形态变异非常丰富，加之其具有独特的繁育系统和广泛的生态地理分布，是研究沙棘属植物遗传变异和系统分化的理想材料。本文从1,800 m 到3,400 m 分5 个海拔梯度进行取样，用RAPD 和cpSSR 分子标记研究了卧龙自然保护区中国沙棘天然群体的遗传结构和遗传变异。5 个取样群体依次标记为A、B、C、D 和E，它们分别代表分布在海拔1,800，2,200，2,600，3,000 和3,400 m 的5 个天然群体。RAPD实验用11 条寡核苷酸引物，扩增得到151 个重复性好的位点，其中143 个多态位点，多态率达94.7%。在5 个沙棘群体中，总遗传多样性值(HT)为0.289，B群体内的遗传多样性值为0.315，这完全符合沙棘这种多年生、远交的木本植物具有高遗传变异的特性。5 个群体内遗传多样性随海拔升高呈低－高－低变异趋势，在2,200 m海拔处的B群体遗传多样性达最大值0.315，3,400 m海拔处的E群体则表现最小仅0.098。5 个群体间的遗传分化值GST＝0.406，也即是说有40.6%的遗传变异存在于群体间，1,800 m海拔处的A群体与其它群体的明显分离是造成群体间遗传分化大的原因。UPGMA聚类图和PCoA散点图进一步确证了5 个群体间的关系和所有个体间的关系。最后，经过Mantel检测，遗传距离与海拔表现了明显的相关性(r = 0.646, P = 0.011)。cpSSR 实验中，经过对24 对cpSSR 通用引物筛选，11 对引物能扩增出特异性条带，只有2 对引物(ccmp2 和ARCP4)呈现多态性。4 个等位基因共组合出4 种单倍型，单倍型Ⅰ出现在A 群体的所有个体和B 群体的8 个个体中，C、D、E 三个群体均不含有，而单倍型Ⅱ出现在C、D、E 三个群体的所有个体及B 群体的18 个个体中，A 群体不含有。另外两种单倍型Ⅲ和Ⅳ为稀有类型，仅B 群体中的4 个个体拥有。这种单倍型分布模式和TFPGA 群体聚类图揭示了，C、D、E 群体可能来源于同一祖先种，而A 群体却是由另一祖先种发展起来的，B 群体则兼具了这两种起源种的信息，这可能是因为在历史上的某一时期，在中国沙棘群体高山分化的过程中，B 群体处某个或者某些个体发生了基因突变，具备了适应高海拔环境的能力，产生了高海拔沙棘群体的祖先种。 In recent ten years, studies about population genetics of plants developed rapidly,whereas their genetic structure and genetic variation along altitudinal gradients have beenstudied relatively little. So far, it is uncleared whether there is a common pattern betweengenetic variation and altitudinal gradients. In the mountain environments, importantecological factors, e.g., temperature, rainfall, snowfall, ultraviolet radiation and soil substratesetc., change rapidly with altitudes, which cause the vegetation distribution varying typically,even on a small spatial scale. The mountain environments, which are heterogeneous andcomplex, facilitate and offer a good opportunity to characterize population genetic structureand population differentiation.The species of the genus Hippophae L. (Elaeagnaceae) are perennial deciduous shrubs ortrees, which are dioecious, wind-pollinated pioneer plants. The natural genus has a widedistribution extending from Northern Europe through Central Europe and Central Asia toChina. According to the latest taxonomy, the genus Hippophae is divided into six species and12 subspecies. The subspecies H. rhamnoides ssp. sinensis shows significant morphologicalvariations, large geographic range and dominantly outcrossing mating system. Thesecharacteristics of the subspecies are favourable to elucidate genetic variation and systemevolution. To estimate genetic variation and genetic structure of H. rhamnoides ssp. sinensisat different altitudes, we surveyed five natural populations in the Wolong Natural Reserve at altitudes ranging from 1,800 to 3,400 m above sea level (a.s.l.) using random amplifiedpolymorphic DNA markers (RAPDs) and cpSSR molecular methods. The five populations A,B, C, D, and E correspond to the altitudes 1,800, 2,200, 2,600, 3,000 and 3,400 m,respectively.Based on 11 decamer primers, a total of 151 reproducible DNA loci were yielded, ofwhich 143 were polymorphic and the percentage of polymorphic loci equaled 94.7%. Amongthe five populations investigated, the total gene diversity (HT) and gene diversity within population B equaled 0.289 and 0.315, respectively, which are modest for a subspecies of H.rhamnoides, which is an outcrossing, long-lived, woody plant. The amount of geneticvariation within populations varied from 0.098 within population E (3,400 m a.s.l.) to 0.315within population B (2,200 m a.s.l.). The coefficient of gene differentiation (GST) amongpopulations equaled 0.406 and revealed that 40.6% of the genetic variance existed amongpopulations and 59.4% within populations. The population A (1,800 m a.s.l.) differed greatlyfrom the other four populations, which contributes to high genetic differentiation. A UPGMAcluster analysis and principal coordinate analyses based on Nei's genetic distances furthercorroborated the relationships among the five populations and all the sampling individuals,respectively. Mantel tests detected a significant correlation between genetic distances andaltitudinal gradients (r = 0.646, P = 0.011).Eleven of the original 24 cpSSR primer pairs tested produced good PCR products, onlytwo (ccmp2 and ARCP4) of which were polymorphic. Four total length variants (alleles) werecombined resulting in 4 haplotypes. The haplotype was present in all individuals of Ⅰpopulation A and 8 individuals of populations B, the other three populations (C, D and Epopulations) did not share. The haplotype was present in all individuals of populations C, D Ⅱand E and 18 individuals of populations B, population A did not share. The other twohaplotypes and were rare haplotypes, which were only shared in 4 individuals of Ⅲ Ⅳpopulation B. The distribution of haplotypes and TFPGA population clustering map showedthat the populations C, D and E might be origined from one ancestor seed and population Amight be from another, whereas population B owned information of the two ancestor seeds. Itwas because that gene mutation within some individual or seed in the location of population Bwas likely to happen in the history of H. rhamnoides, which was the original ancestor of thehigh-altitude populations.

若尔盖高原花湖湖滨湿地甲烷排放研究

若尔盖高原湿地位于青藏高原东北部地区，平均海拔3,400-3,600m，是长江和黄河的自然分水区，区内发育了大面积的草本沼泽以及高寒沼泽化草甸、高寒湖泊。由于它所处的位置海拔高、气候波动较大，并处于我国三大自然区的交错过渡带，因而被认为是我国最为典型的脆弱湿地生态系统之一。由于地处偏远、自然环境条件恶劣等多方面的原因，针对若尔盖湿地的科学研究资料一直以来还非常缺乏。本文对国内外近年来在湿地生态系统甲烷排放过程、研究方法，以及关于湿地生态系统甲烷排放的影响因素进行了综述，并采用静态箱－气相色谱法，从湿地环境格局、湿地甲烷排放等方面，对若尔盖高原典型高寒湖泊湖滨不同类型湿地甲烷排放特征进行了研究，并进一步探讨了影响若尔盖高原高寒湖泊湖滨带甲烷排放的因素。得到如下结果：1．若尔盖高原花湖湖滨湿地在植物生长季（6 至8 月），甲烷排放平均速率为0.315 mg·m-2·h-1；不同月份间甲烷排放速率存在差异，分别为：-0.054、0.471、0.493 mg·m-2·h-1。不同类型湿地甲烷排放速率亦表现出差异，两栖蓼（Polygonum amphibium）湿地、滩涂和藏嵩草（Kobresia tibetica）草甸甲烷排放速率分别为：0.464、0.477、0.005mg·m-2·h-1。2．若尔盖高原花湖湖滨湿地甲烷排放速率与土壤10cm 温度显著相关。土壤温度是影响若尔盖高原花湖湖滨不同类型湿地甲烷排放的重要因素之一。随着土壤温度的升高，土壤微生物活性增强，使土壤中的氧消耗加快，氧化还原电位下降，有利于产甲烷菌的生长，从而增加土壤的甲烷产生量。3．地表水位与若尔盖高原花湖湖滨湿地甲烷排放速率相关性不显著。地表水覆盖，使得湿地土壤缺氧状况得到加强，增强了土壤中产甲烷菌的活性，促进甲烷形成，再通过植物、气泡或扩散的形式释放出土壤。但水层的加深，也使土壤中已产生的甲烷在通过气泡或扩散形式穿越水层时，被氧化的量增加，从而减少了甲烷向大气中的排放。4．植被高度以及植被地上生物量与若尔盖高原花湖湖滨带甲烷排放速率的相关性不显著。植物主要通过凋落物以及根系分泌物的输入为产甲烷菌提供基质，并作为土壤与大气之间的甲烷气体交换的传输途径；与其他环境因素共同影响湿地生态系统甲烷排放。The Zoige wetland on the eastern fringe of Qinghai-Tibetan Plateau, with averagealtitude between 3,400 and 3,600m, is the watershed of Yangtze River and YellowRiver. There are large area of peatland, subalpine meadow and lakes in this region.Due to its high elevation, transitional topology and high fluctuation of climate, theZoige wetlands represent one of the most fragile wetland ecosystems in China. And asa result of remote location and harsh environment conditions, the researches on theZoige wetland are relatively rare, especially the researches on the methane emissionfrom littoral zone of alpine lakes. Variations of methane emission rates as measuredby the method of static chamber – gas chromatography (GC) were detected fromlittoral zone of alpine lake on the Zoige Plateau. Relationships between methaneemission rates and environmental factors were analyzed. It is concluded that:1．The average methane emission rate in the littoral zone of Huahu Lake, ZoigePlateau is 0.315 mg·m-2·h-1, with evident spatial and temporal variations. The littoralzone has different methane effluxes with -0.054, 0.471, and 0.493 mg·CH4·m-2·h-1in June, July and August respectively. Different types of wetland have differentmethane emission rates, with value of 0.464, 0.477, and 0.005 mg·CH4·m-2·h-1 forPolygonum amphibium wetland ( PA ), Shoal ( S ) and Kobresi tibetica meadow ( KT ), respectively.2． The soil temperature at 10cm is significantly correlated with the methane effluxesin littoral zone of Huahu Lake, Zoige Plateau, and which is one of the most important factors influencing the methane emission from this region. The activities of soilmicroorganisms rise under higher soil temperature and increases oxygen consumptionand decreases Eh, which is in favor of the methanogensis, and enhances theproduction of methane in soil.3． The correlation between the standing water and methane effluxes from littoralzone of Huahu Lake is not significant. Because of the standing water, the anaerobicconditions of wetland soil have been enhanced, and are favor to the decomposition oforganic matter. And the anaerobic conditions strengthen the methanogensis’ activities,thus the methane production, which release to the atmosphere by diffusion, ebullitionand aerenchymal plants. With the water level’s increase, more methane produced insoil which is transferred by ebullitions or diffusion are oxidated, thus reduce themethane release to the atmosphere.4． The height and aboveground biomass of vegetation are not significant related tothe methane effluxes from littoral zone of Huahu Lake, Zoige Plateau. The vegetationprovides substrates for methanogensis by litter and root exudates; act as thetransportation way of methane between soil and atmosphere; influence the methaneemission of wetland ecosystems with other environment factors.

Geochemistry of rare earth elements in Permian coals from the Huaibei Coalfield；China

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delta C-13 variation of C-3 and C-4 plants across an Asian monsoon rainfall gradient in arid northwestern China

IEECAS SKLLQG