植物边缘种群遗传多样性研究进展

边缘种群指地理分布边缘可检测到的一定数量的同种个体集合, 准确评价其遗传多样性对于理解第四纪冰期后气候变化对物种边缘扩展或收缩、遗传资源保护与利用以及物种形成等有重要意义。该文探讨了维持植物边缘种群遗传多样性的进化机制, 分析交配系统对物种边缘及其遗传多样性的影响, 比较了边缘与中心种群遗传多样性的差异及其形成的生态与进化过程, 并探讨了边缘种群遗传多样性与其所在的群落物种多样性的关系及理论基础。该文提出今后研究的重点是应用全基因组序列或转录组基因序列研究前缘-后缘种群之间或边缘-中心种群之间的适应性差异, 边缘种群与所在群落其他物种之间相互作用的分子机制, 深入解析边缘种群对环境的适应及边缘种群遗传多样性与群落物种多样性关系的生态与进化过程。     

黄渤海海域口虾蛄野生资源的种群遗传学研究

本研究通过扩增测序共获得了148条口虾蛄线粒体COⅠ基因序列,定义了52个单元型,其中存在63个变异位点。在黄渤海海域中,盐城口虾蛄种群的遗传多样性最高;渤海与黄海海域口虾蛄群体间遗传分化指数(Fst)为0.006 12。经MEGA 4.0软件计算得知11个种群间的遗传距离为0.0009~0.0057,而渤海与黄海两大海域间的遗传距离为0.0043。系统发生关系显示,渤海与黄海海域的单倍型呈交错聚集状态,说明两大海域间不存在显著的遗传分化。本次研究初步评估了两个海域的口虾蛄种群的遗传多样性水平,为渤海海域与黄海海域口虾蛄种质资源保护提供了基础资料。     

陕西实生板栗居群遗传多样性研究

利用超薄平板聚丙烯酰胺等电聚焦技术对陕西板栗4个实生居群,8个酶系统的20个位点进行了遗传多样性及遗传结构分析,结果表明：4个居群中以宝鸡居群遗传多样性最高,其P为80．0％,Ho,He分别为0．478和0．343,4个居群的居群遗传分化度Gst为6．2％,平均总遗传多样性为0．3372,总遗传多样性的93．8％属于居群内的遗传变异,聚类分析结果表明,以秦岭为界可以分为秦岭以南与秦岭以北2个略有差异的板栗自然亚分布区。     

Genetic variation and population structure ofCarex breviculmis (Cyperaceae) in Korea

We determined the genetic diversity and population structures ofCarex breviculmis (Cyperaceae) populations in Korea, using genetic variations at 23 allozyme loci.C. breviculmis is a long-lived herbaceous species that is widely distributed in eastern Asia. A high level of genetic variation was found in 15 populations. Twelve enzymes revealed 23 loci, of which 11 were polymorphic (47.8%). Genetic diversity at the speciesand population levels were 0.174 and 0.146, respectively. Total genetic diversity (H_T = 0.363) and within-population genetic diversity (H_s = 0.346) were high, whereas the extent of the population divergence was relatively low (G_ST = 0.063). Deviation from random mating (Fis) within the 15 populations was 0.206. An indirect estimate of the number of migrants per generation(Nm = 3.69) indicated that gene flow was extensive among Korean populations of this species. Analysis of fixation indices revealed a substantial heterozygote deficiency in some populations and at some loci. Genetic identity between popu-lations was high, exceeding 0.956.     

冷蒿种群在放牧干扰下遗传多样性的变化

通过随机扩增多态性 DNA(RAPD)方法检测了放牧干扰下冷蒿种群遗传多样性的变化。 17条 (组 )引物进行 RAPD分析 ,扩增共产生 2 5 4条带 ,其中 2 4 0条为多态性带 ,多态位点百分率达 94 .4 9%。随着放牧强度的增加 ,冷蒿种群多态位点百分数 ,Nei遗传多样性指数、Shannon信息指数均下降 ,种群内个体平均遗传一致度增加。放牧梯度上 4个冷蒿种群 H t=0 .2 116 ,Hs=0 .170 0 ,Dst=0 .0 4 16 ,种群间基因分化系数 Gst=0 .196 5 ,基因流 N*m=2 .0 4 5 1;同时随着放牧强度的增加 ,种群间的 Dst、Gst增加 ,N*m 降低。说明放牧限制了种群间的基因交流 ,使种群发生遗传分化。放牧梯度上的 4个冷蒿种群的遗传距离很小 ,但是随着放牧强度的增加 ,遗传距离在缓慢的增加 ,种群间的遗传一致度降低。根据遗传距离所构建的 U PGMA聚类图中冷蒿 4个种群随着牧压的增加 ,逐级聚在一起。这表明冷蒿种群的遗传分化与放牧强度的关系     

福建地区小叶买麻藤遗传多样性ISSR分析

采用13条ISSR引物对福建地区小叶买麻藤11个种群共211个样本进行了种群遗传多样性检测。结果表明:(1)小叶买麻藤在物种水平上遗传多样性较高而在种群水平上较低,揭示该物种具有较强的生存、适应、发展潜力,但其种群遗传多样性已经受到生境片段化及人为活动的影响;(2)小叶买麻藤的遗传分化在裸子植物中处于中等水平,选择和基因流对种群遗传分化的作用大于遗传漂变的作用;(3)小叶买麻藤种群退化主要受人类活动影响,影响的时间较短,尚未表现出种群遗传结构的改变。     

欧洲刺槐种源群体遗传结构和多样性

对来自欧洲和美国的 18个刺槐种源子代进行了等位酶分析。可进行遗传分析的 7个酶系统 (Amy,Fe,L ap,Idh,Mdh,6 Pgd,Skd)中有 14个基因位点 ,其中 12个位点具有多态性。每个多态位点平均等位基因数 (A/L )变化在 1.5 6～ 3.6 7之间 ,平均基因型数 (G/L)变化在 1.6 1～ 7.11之间 ,平均等位基因有效数目 (Ae)变化在 1.0 2～ 2 .5 0之间 ,预期杂合度 (H e)变化在0 .0 2～ 0 .5 6之间。不同种源群体之间也存在较大的遗传差异 ,在 8个德国种源中 ,各群体的 A、Ae、和 H e等相对较小 ,但不同群体间差异较大。各位点等位基因频率在不同种源群体间变化也较大 ,表明德国各种源群体内遗传变异相对较小 ,但群体间差异较大。来自匈牙利和斯洛伐克的 8个种源群则相反 ,各群体的 A、Ae、和 H e等相对较大 ,而不同种源群体间差异则较小 ,各位点等位基因频率在种源群体间变化相对一致 ,表明这两个国家的种源群体内变异较大 ,但不同种源群体间差异较小。欧洲的刺槐种源并未形成明显的地理变异模式 ,而且欧洲的种源和来自原产地的美国种源相比 ,没有发现明显的差异。经过 Hardy-Weinberg平衡检测证明 ,88.4 1%位点符合 H- W遗传平衡 ,表明各群体基因频率和基因型频率保持较高的稳定性 ,且种源内的变异大于种源间变异 ,94 .     

多叶重楼遗传多样性的RAPD分析

应用RAPD技术检测了多叶重楼(Paris polyphyfzo)2个变种4个居群的遗传多样性,并与1个凌云重楼(P．cronquistii)居群进行了比较。选择的16个随机引物在5个居群中共检测到246个多态位点。在居群水平上,滇重楼2个居群的多态位点百分比(PP鳓分别为57．43％和54．67%,Shannon指数分别为0．3080和0．2830;七叶一枝花2个居群的PPB分别为56．33％和57．75%,Shannon指数分别为0、3080和0．3293。在变种水平上,滇重楼的PPB为75．14％,Shannon指数为0．3922,遗传分化系数(Gst)为0．3085;七叶一枝花的PPB为80．31％,Shannon指数为0．3992,遗传分化系数(Gst)为0．3726;在种的水平PPB达92．05%,遗传分化系数Gst达0．5151。聚类分析显示滇重楼和七叶一枝花有较近的亲缘关系,而与凌云重楼遗传距离较远。此结果从分子水平上支持了过去将滇重楼和七叶一枝花划分为1个种下2个变种的形态分类观点。     

Genetic viability and population history of the giant panda, putting an end to the "evolutionary dead end"?

The giant panda (Ailuropoda melanoleuca) is currently threatened by habitat loss, fragmentation, and human persecution. Its dietary specialization, habitat isolation, and reproductive constraints have led to a perception that this is a species at an "evolutionary dead end," destined for deterministic extinction in the modern world. Here we examine this perception by a comprehensive investigation of its genetic diversity, population structure, and demographic history across its geographic range. We present analysis of 655 base pairs of mitochondrial (mt) control region (CR) DNA and 10 microsatellite loci for samples from its 5 extant mountain populations (Qinling, Minshan, Qionglai, Liangshan, and Lesser Xiangling). Surprisingly, extant populations display average to high levels of CR and microsatellite diversity compared with other bear species. Genetic differentiation among populations was significant in most cases but was markedly higher between Qinling and the other mountain ranges, suggesting, minimally, that the Qinling population should comprise a separate management unit for conservation purposes. Recent demographic inference using microsatellite markers demonstrated a clear genetic signature for population decline starting several thousands years ago or even further back in the past, and being accelerated and enhanced by the expansion of human populations. Importantly, these data suggest that the panda is not a species at an evolutionary "dead end," but in common with other large carnivores, has suffered demographically at the hands of human pressure. Conservation strategies should therefore focus on the restoration and protection of wild habitat and the maintenance of the currently substantial regional genetic diversity, through active management of disconnected populations.     

中国水青冈种内种间遗传多样性的初步研究

本文利用凝胶电泳法研究了亮叶水青冈(Fagus lucida)、巴山水青冈(F. pashanica)和米心水青冈(F. engleriana)的遗传多样性。所测定的酶系统包括：过氧化物酶(PX₁和PX₂)、磷酸葡萄糖脱氢酶(PGD)、超氧化物歧化酶(SOD)、谷氨酸草酰乙酸转氨酶(GOT₁和GOT₂)、异柠檬酸脱氢酶(IDH)、甲基萘醌还原酶(MNR)、葡萄糖磷酸变位酶(PGM₁和PGM₂)和苹果酸脱氢酶(MDH₂)8种酶系统,测定和分析了3种水青冈的等位基因频率和遗传距离指标,为进一步研究水青冈属各种间的亲缘关系和进化提供了科学依据。     

Development and Characterization of 15 Polymorphic Micro satellite Markers for a Highly Adaptive and Wide-range Frog （Microhyla fissipes）

In order to analyze population genetic structure at multiple spatial scales, microsatellite loci were developed for the ornamented pygmy flog （Microhylafissipes）, and 15 polymorphic microsatellite loci were successfully screened from 105 individuals, of which 82 from four populations distributed in the Sichuan Basin and 23 from the Sangzhi population in western Hunan. Five loci were found to deviate significantly from Hardy-Weinberg equilibrium in one to three popu lations, probably due to small sample size or null alleles. The average number of alleles in all loci was 8.5, ranging from 4 to 13, and the observed and expected heterozygosity ranged from 0.26 to 0.90 and 0.63 to 0.90, respectively. The Sangzhi population and the remaining four populations can be clearly separated using Bayesian clustering methods, showing that the genetic structure of M. fissipes was probably affected by the topography, especially mountain barriers. These polymorphic microsatellite loci could be used for further study on the landscape genetics of this highly adaptive and widely distributed species.     

Assessment of the population structure of five Finnish dog breeds with microsatellites

Genetic variabilities within and between Finnish populations of Golden Retrievers, German Shepherds, Wirehaired Dachshunds, Pembroke Welsh Corgis and Bedlington Terriers were quantified with microsatellite allele numbers, observed heterozygosities, expected heterozygosities, FIS estimates, FST estimates and DS distances. In a sample of 50 individuals from each, breed and ten polymorphic loci, the highest genetic diversity was exhibited in the Wirehaired Dachshunds and lowest in the Bedlington Terriers. Although statistically significant deviations from the Hardy-Weinberg (H-W) equilibrium were observed, they occurred at an unexpectedly low frequency. Most strikingly, the extremely small Bedlington Terrier population displayed genotypes in H-W proportions in all investigated loci. The H-W deviations always occurred with positive FIS estimates, which, on average, were not larger than values reported for free-living canids. Genetic differentiation between the breeds was very large. As a comparison, present estimates were, on average, over two times higher than previously observed between breeds of sheep, and over two times higher than the highest estimates reported between human populations. Moreover, the highest DS distances were only slightly lower than the lowest values inferred between humans and chimpanzees. Severe bottlenecks in the recent past of the examined breeds were not statistically supported. The presented data imply genetic isolation and intense artificial selection in the history of these breeds of dogs.