栲树微卫星分子标记的开发

采用基因组DNA富集法FIASCO对我国典型常绿阔叶林建群种栲树(Castanopsis fargesii Franch.)进行了微卫星分子标记的开发。从栲树基因组中分离和筛选了15个微卫星位点,并对江西九连山栲树自然分布居群的遗传多样性进行了分析。结果表明,栲树具有较高水平的遗传多样性,每个位点在28株栲树个体上的平均等位基因数(A)为6.7(4～8个),平均观察杂合度(HO)为0.690(0.250～1.000),平均预期杂合度(HE)为0.698(0.293～0.867)。每个位点的第一排除概率值Pr(Ex1)为0.043～0.527,位点综合值为0.9972。单个位点的第二排除概率Pr(EX2)为0.159～0.694,位点综合值为0.9999。这些微卫星标记可为研究栲树的遗传多样性及居群遗传结构提供有效的遗传工具。     

栲属(壳斗科)植物的现代和地史分布

根据文献资料和标本馆及化石记录,讨论了壳斗科栲属植物的现代分布和地史分布。现代栲属植物有110～134种,主要分布在东亚及东南亚,其中印度支那地区有82种栲属植物,是世界栲属植物分布最集中的地区,马来西亚地区是栲属特有种最丰富的事实是支持马来西亚地区与其它地区的区系交流十分有限的论据。中国栲属植物最丰富的地区是滇黔桂地区（29种）。栲属植物现代多样化中心在马来西亚和中南半岛。排除Chrysolepis后,栲属的分布类型应属热带亚洲分布。栲属在地质历史上有着比现在广泛的分布,最早、最可靠的栲属化石记录发现于北美始新世地层,欧洲和日本始新世也有栲属的化石记录,化石记录表明栲属起源的时间不晚于古新世,所有的壳斗科及栲属的化石都发现于北半球,现代分布也主要在北半球,壳斗科及栲属起源于北半球可以确认,由于化石证据与现代植物学的研究结果有较大差异以及关键地区化石证据的不足,具体的起源地尚不能肯定。     

Chloroplast diversity and population differentiation of Castanopsis fargesii (Fagaceae): a dominant tree species in evergreen broad-leaved forest of subtropical China

Subtropical forests in China constitute the major expanse of evergreen broad-leaved forest in East Asia. The significant genetic divergence of the keystone tree species should be expected due to the huge geomorphological and environmental changes from west to east in subtropical China. In this study, a total of 652 individuals from 27 populations of Castanopsis fargesii throughout its natural range in mainland China were genotyped with eight chloroplast microsatellite markers to investigate genetic diversity, population differentiation, and demographic history of C. fargesii. Phylogeographic structure among populations of C. fargesii was evidenced by the permutation test, revealing that N_ST was significantly higher than G_ST . The strong genetic differentiation found among populations was well in accordance with isolation-by-distance model. In addition, significant isolation by elevation was detected among populations. Significant genetic differentiations were revealed among the west, center, and east regions by approximate Bayesian computations (ABC). The genetic divergence might reflect the regional responses to the fast and dramatic uplift of Yunnan-Guizhou Plateau and Wuyi mountain range in the Pleistocene. In the present study, contraction-expansion process was detected in the west, center, and east regions, indicating that geomorphological remodeling together with climatic changes in the Pleistocene had strong impact on genetic structure of C. fargesii.     

The Transferability of Nuclear Microsatellite Markers in Four Castanopsis Species to Castanopsis tibetana (Fagaceae)

Castanopsis tibetana is a typical and dominant component in subtropical evergreen broad leaved forests of China. However, its genetic diversity and long term persistence have been jeopardized by habitat fragmentation. To examine its genetic diversity and genetic structure, cross species amplification of 51 microsatellite loci which are derived from four congeneric species, ie., Castanopsis chinensis, Csclerophylla, Ccuspidata and Csieboldii, were tested in Ctibetana.Thirty five loci were successfully amplified in Ctibetana, among them 11 were polymorphic across four wild populations of Ctibetana (24 individuals in total). Genetic diversity of four Ctibetana populations (Jiangxi) was relatively low. The number of alleles (NA) ranged from 2 to 7 (average 45) and the ranges of observed (HO) and expected (HE) heterozygosities were 0505 and 0471,respectively. The results will facilitate the study and conservation of genetic diversity of Ctibetana.     

栲树种群生态位动态研究

用Levins生态位宽度及重叠、Feinsing等生态位宽度和Petraitis生态位重叠计测方法,处理缙云山森林群落演替系列取样,分析栲树种群的生态位特征及动态.结果表明,栲树种群为缙云山森林群落演替顶极群落常绿阔叶林的优势种群,其生态位宽度随群落演替过程基本呈增长趋势,而资源利用程度却呈“∧”形;对于栲树种群和缙云山森林群落其它14个优势种群间在所有5类群落中的生态位重叠,仅栲树种群与典型针阔混交林中的小叶栲、光叶灰木、川灰木、薯豆、白毛新木姜子、广东山胡椒、大头茶、虎皮楠、杉木、马尾松种群上和针叶林中小叶栲、光叶灰木、杉木种群上,表现出显著完全特定重叠.     

Divergence maintained by climatic selection despite recurrent gene flow: a case study of Castanopsis carlesii (Fagaceae)

Local adaptation to different environments has the potential to maintain divergence between populations despite recurrent gene flow and is an important driver for generating biological diversity. In this study, we investigate the role of adaptation in the maintenance of two parapatric varieties of a forest tree. We used sequence variation of chloroplastic DNA and restriction site‐associated DNA to investigate the genetic structure of two varieties of Castanopsis carlesii in subtropical China and relate it to climatic variation. We used niche reconstruction methods to investigate niche differentiation between the two varieties and to estimate the past distribution of this species. A deep divergence was observed between the two varieties, but evidence of introgression and genetic admixture was detected in two phenotypically and geographically intermediate populations. Niche reconstruction suggests that the distribution of the two varieties was disjunct during periods of global cooling and that the two varieties occupy significantly different niches. The genetic structure was mainly driven by environmental factors, and 13 outlier loci under divergent selection were correlated with climatic variation. These results suggest that the two varieties evolved in allopatry and came back into secondary contact after the last glacial maximum and that they are an evolutionary example of divergence maintained by climatic selection despite recurrent gene flow.     

Allozyme variation of populations of Castanopsis carlesii (Fagaceae) revealing the diversity centres and areas of the greatest divergence in Taiwan

• Background and Aims The genetic variation and divergence estimated by allozyme analysis were used to reveal the evolutionary history of Castanopsis carlesii in Taiwan. Two major questions were discussed concerning evolutionary issues: where are the diversity centres, and where are the most genetically divergent sites in Taiwan?• Methods Twenty-two populations of C. carlesii were sampled throughout Taiwan. Starch gel electrophoresis was used to assay allozyme variation. Genetic parameters and mean F_ST values of each population were analysed using the BIOSYS-2 program. Mean F_ST values of each population against the remaining populations, considered as genetic divergence, were estimated using the FSTAT program.• Key Results Average values of genetic parameters describing the within-population variation, the average number of alleles per locus (A = 2·5), the effective number of alleles per locus (A_e = 1·38), the allelic richness (A_r = 2·38), the percentage of polymorphic loci (P = 69 %), and the expected heterozygosity (H_e = 0·270) were estimated. High levels of genetic diversity were found for C. carlesii compared with other local plant species. Genetic differentiation between populations was generally low.• Conclusions From the data of expected heterozygosity, one major diversity centre was situated in central Taiwan corroborating previous reports for other plant species. According to the mean F_ST value of each population, the most divergent populations were situated in two places. One includes populations located in north central Taiwan between 24·80°N and 24·20°N. The other is located in south-eastern Taiwan between 22·40°N and 23·10°N. These two regions are approximately convergent with the most divergent locations determined for several other plant species using chloroplast DNA markers published previously. An important finding obtained from this study is that unordered markers like allozymes can be used to infer past population histories as well as chloroplast DNA markers do.     

栲树种群生态位动态研究

用Levins生态位宽度及重叠、Feinsing等生态位宽度和Petraitis生态位重叠计测方法 ,处理缙云山森林群落演替系列取样 ,分析栲树种群的生态位特征及动态 .结果表明 ,栲树种群为缙云山森林群落演替顶极群落常绿阔叶林的优势种群 ,其生态位宽度随群落演替过程基本呈增长趋势 ,而资源利用程度却呈“∧”形 ;对于栲树种群和缙云山森林群落其它 1 4个优势种群间在所有 5类群落中的生态位重叠 ,仅栲树种群与典型针阔混交林中的小叶栲、光叶灰木、川灰木、薯豆、白毛新木姜子、广东山胡椒、大头茶、虎皮楠、杉木、马尾松种群上和针叶林中小叶栲、光叶灰木、杉木种群上 ,表现出显著完全特定重叠 .     

广西栲树林分类的研究

以栲树为主的常绿阔叶林,在广西广泛分布于东部中亚热带地区海拔700 m以下红、黄壤丘陵山地,而且是这个区域最有代表性的地带性群落类型;在南亚热带和北热带山地也有小片分布。本文描述了广西常见的13个群丛,扼要地阐述了它们的地理分布、生境特点和种类组成。所有这些材料可作为其保护和科学管理的基础。     

Potential refugia in Taiwan revealed by the phylogeographical study of Castanopsis carlesii Hayata (Fagaceae)

In this study, we examined spatial patterns of chloroplast DNA (cpDNA) variation in a total of 30 populations of Castanopsis carlesii Hayata (Fagaceae), a subtropical and temperate tree species, including 201 individuals sampled throughout Taiwan. By sequencing two cpDNA fragments using universal primers (the trnL intron and the trnV-trnM intergenic spacer), we found a total of 1663 bp and 21 polymorphic sites. These gave rise to a total of 28 cpDNA haplotypes. The level of differentiation among the populations studied was relatively high (GST = 0.723). Two ancestral haplotypes are widely distributed. The Central Mountain Ridge (CMR) of Taiwan represents an insurmountable barrier to the east-west gene flow of C. carlesii. Among the populations studied, three separated populations, at Lienhuachih, Fushan and Lichia, have high nucleotide diversity. Estimates of NST-GST for populations on both sides of the CMR indicate that no phylogeographical structure exists. According to the genealogical tree, number of rare haplotype and population genetic divergence, this study suggests that two potential refugia existed during the last glaciation: the first refugium was located in a region to the north of Hsuehshan Range (HR) and west of the CMR; the second refugium was located in south, especially southeastern Taiwan. In fact, the second refugium happens to be the same as that reported for Quercus glauca. A 'star-like' genealogy is characteristic when all haplotypes rapidly coalesce and is a general outcome of population expansion. The neutrality test and mismatch distribution also suggest demographic expansion recovering from a bottleneck.     

广西栲树林分类的研究

以栲树为主的常绿阔叶林,在广西广泛分布于东部中亚热带地区海拔700 m以下红、黄壤丘陵山地,而且是这个区域最有代表性的地带性群落类型;在南亚热带和北热带山地也有小片分布。本文描述了广西常见的13个群丛,扼要地阐述了它们的地理分布、生境特点和种类组成。所有这些材料可作为其保护和科学管理的基础。     

广西栲树林分类的研究

以栲树为主的常绿阔叶林,在广西广泛分布于东部中亚热带地区海拔700 m以下红、黄壤丘陵山地,而且是这个区域最有代表性的地带性群落类型;在南亚热带和北热带山地也有小片分布。描述了广西常见的13个群丛,扼要地阐述了它们的地理分布、生境特点和种类组成。所有这些材料可作为其保护和科学管理的基础。     

广西栲树林分类的研究

以栲树为主的常绿阔叶林,在广西广泛分布于东部中亚热带地区海拔700 m以下红、黄壤丘陵山地,而且是这个区域最有代表性的地带性群落类型;在南亚热带和北热带山地也有小片分布。本文描述了广西常见的13个群丛,扼要地阐述了它们的地理分布、生境特点和种类组成。所有这些材料可作为其保护和科学管理的基础。     

Footprints of natural and artificial selection for photoperiod pathway genes in Oryza

Asian rice, Oryza sativa, consists of two major subspecies, indica and japonica, which are physiologically differentiated and adapted to different latitudes. Genes for photoperiod sensitivity are likely targets of selection along latitude. We examined the footprints of natural and artificial selections for four major genes of the photoperiod pathway, namely PHYTOCHROME B (PhyB), HEADING DATE 1 (Hd1), HEADING DATE 3a (Hd3a), and EARLY HEADING DATE 1 (Ehd1), by investigation of the patterns of nucleotide polymorphisms in cultivated and wild rice. Geographical subdivision between tropical and subtropical O. rufipogon was found for all of the photoperiod genes in plants divided by the Tropic of Cancer (TOC). All of these genes, except for PhyB, were characterized by the existence of clades that split a long time ago and that corresponded to latitudinal subdivisions, and revealed a likely diversifying selection. Ssp. indica showed close affinity to tropical O. rufipogon for all genes, while ssp. japonica, which has a much wider range of distribution, displayed complex patterns of differentiation from O. rufipogon, which reflected various agricultural needs in relation to crop yield. In japonica, all genes, except Hd3a, were genetically differentiated at the TOC, while geographical subdivision occurred at 31°N in Hd3a, probably the result of varying photoperiods. Many other features of the photoperiod genes revealed domestication signatures, which included high linkage disequilibrium (LD) within genes, the occurrence of frequent and recurrent non‐functional Hd1 mutants in cultivated rice, crossovers between subtropical and tropical alleles of Hd1, and significant LD between Hd1 and Hd3a in japonica and indica.     

栲树冠层光合生理特性的空间异质性

森林冠层在能量传输、光合有效辐射和微气象等方面的差异可导致冠层光合生产力空间分布的变化.叶片光合生理特性在空间上的差异对精确估算森林冠层的初级生产力十分重要.本文以亚热带常绿阔叶林优势种---栲树(Castanopsis fargesii)为对象,研究叶片光合生理特性在冠层空间上的变化.结果表明:1)在垂直方向上,冠层北向叶的饱和光合速率(Amax)、光饱和点(LSP)和CO2羧化效率(CCE)均表现为上部>中部>底部,且依次平均降低19.4%、18.1%和37.1%;光补偿点(LCP)、光下暗呼吸(Rd)以及冠层南向叶的饱和光合速率、光饱和点和CO2羧化效率均表现为上部>底部>中部,上部比中部和底部高出12.3%~71.4%;表观量子效率(AQY)表现为底部>上部>中部,底部分别是顶部和中部叶的1.2和1.3倍;2)在水平方向上,冠层上部和底部南向叶的饱和光合速率、光饱和点和CO2羧化效率比北向叶高0.9%~31.5%;冠层中部北向叶的饱和光合速率等6个参数比南向叶高9.6%~63.2%.因此,在冠层水平上模拟和估算植物生产力时,必须考虑冠层光合生理特性的空间差异.     

中国板栗EST-SSR分子标记在栲树中的通用性分析

简单重复序列也称为微卫星分子标记,不仅在同属近缘种间具有良好的通用性,甚至在近缘属间也具有一定的通用性。本研究利用壳斗科基因组信息数据库中公布的中国板栗124对多态的EST-SSR引物在栲树中进行跨属(栗属到栲属)通用性研究,结果显示中国板栗EST-SSR引物在栲树中通用性和多态性分别为42.7%和56.6%;使用19对多态的EST-SSR引物对4个栲树自然居群的遗传多样性进行初步分析,结果显示栲树自然居群具有较高的遗传多样性(Na=6.105,Ho=0.563,He=0.621)。这些引物为栲树群体遗传学的深入研究提供了有力工具。     

Footprints of selection in wild populations of Bicyclus anynana along a latitudinal cline

One of the major questions in ecology and evolutionary biology is how variation in the genome enables species to adapt to divergent environments. Here, we study footprints of thermal selection in candidate genes in six wild populations of the afrotropical butterfly Bicyclus anynana sampled along a c. 3000 km latitudinal cline. We sequenced coding regions of 31 selected genes with known functions in metabolism, pigment production, development and heat shock responses. These include genes for which we expect a priori a role in thermal adaptation and, thus, varying selection pressures along a latitudinal cline, and genes we do not expect to vary clinally and can be used as controls. We identified amino acid substitution polymorphisms in 13 genes and tested these for clinal variation by correlation analysis of allele frequencies with latitude. In addition, we used two F_ST‐based outlier methods to identify loci with higher population differentiation than expected under neutral evolution, while accounting for potentially confounding effects of population structure and demographic history. Two metabolic enzymes of the glycolytic pathway, UGP and Treh, showed clinal variation. The same loci showed elevated population differentiation and were identified as significant outliers. We found no evidence of clines in the pigmentation genes, heat shock proteins and developmental genes. However, we identified outlier loci in more localized parts of the range in the pigmentation genes yellow and black. We discuss that the observed clinal variation and elevated population divergence in UGP and Treh may reflect adaptation to a geographic thermal gradient.     

栲树种群的年龄结构及其生长特征

为了了解栲树的更新方式和更新动态,研究了栲树的生长特征和种群年龄结构.结果表明：栲树种群的年龄结构呈“间歇型”,经历了两个死亡高峰,并存在一个长达30年的断层;栲树的生长受光照的影响,具有很强的可塑性;由于林下光照弱且在垂直空间上不存在差异,栲树生长5～8年后进入生长的第1个抑制期,其年高生长速度可小于0.1 m,并可维持10年;栲树生长的第1个抑制期的起始时间对应着种群第1个死亡高峰期的结束时间,而其结束时间对应着种群第2个死亡高峰期的起始时间,表明栲树生长特征是影响其种群年龄结构的关键因素.     

Topographic effects on fine‐scale spatial genetic structure in Castanopsis chinensis Hance (Fagaceae)

Ecological study plots are usually treated as if they are flat. This does not hold for many situations such as mountains where topography is complex. In areas with complex topography individual relationships are not only determined by projection distance, but also by surface distance. To demonstrate this we compared projection and surface distances by analyzing spatial genetic autocorrelation for Castanopsis chinensis in two subplots (A and B) in the Dinghushan (DHS) national nature reserve in subtropical South China. We observed that the two types of distances generally result in similar fine‐scale spatial genetic structure (SGS) patterning for the spatially less structured subplot B, but not for the highly structured subplot A. The present study shows clearly that accounting for plot architecture in plant species on topographically complex areas enables a more accurate picture of the underlying spatial genetic structure to emerge.