Genetic diversity and genetic differentiation of natural Pinus koraiensis population

Genetic diversities and genetic differentiations of the four Pinus koraiensis populations （Gaofeng Forestry Farm at Tangwanghe in Yichun City, Erdaobaihe Town in the Changbai Mountains, Shcngshan Forestry Farm in Heihe City, in China, and the suburb of Vladivostok City in Russia） were analyzed by using ISSR PCR technique. The results of 15 primers amplification showed that the ratio of polymorphic site of P koralensis population was 60.7%. Euch primer had 3.6 polymorphic sites, The diversity levels of the four P. koraiensis populations were rather higher compared with those of other Pinaceae species. The genetic diversity levels of t： koraiensis populations grown in the center region were higher than those grown in the edge zone. The genetic diversity of r3 koraiensis mainly came from the interiot of the population, accounting for 73% of total genetic diversity. There were no positive correlation between genetic distances and geographical distances for the four P koraiensis populations. The gradual decrease of natural distribution region of P. koraiensis was due to anthropic destroy and environmental factors （i.e. fire and wind throw）, rather than the lower genetic diversity.     

天然红松种群遗传多样性和遗传分化的研究

ISSR是一种特异性较强、稳定性较高的分子标记方法。本研究采用ISSR-PCR技术,检测了红松(PinuskoraiensisSieb.etZucc)在伊春市汤旺河高峰林场、长白山二道白河、黑河胜山林场和俄罗斯海参崴市郊的四个种群的遗传多样性和遗传分化。15个引物的扩增结果表明:红松群体的多态位点比率是60.70%,平均每个引物3.6个多态位点,多样性水平在松科植物中是较高的;红松分布中心区的遗传多样性要高于边界区;和大多数木本植物一致,红松群体的基因多样性主要来自种群内部,占总基因多样性的73%;红松四个种群的遗传距离和地理距离之间无正相关性。根据研究结果推测,天然红松分布区逐渐缩小的原因不是由于遗传多样性水平过低引起的,而是由于人类的破坏作用,再加上火灾和风倒等因素造成的。     

Genetic diversity and population structure of Robinia pseudoacacia from six improved variety bases in China as revealed by simple sequence repeat markers

Robinia pseudoacacia is an important afforesta-tion tree introduced to China in 1878. In the present study, we examined the genetic diversity among 687 strains ...     

昆虫遗传多样性与种群分化的研究进展

阐述了不同地理,不同寄主,及其他环境因素影响下昆虫种群的遗传多样性的研究,并讨论了现在昆虫遗传分化的研究热点和发展趋势。     

Genetic diversity and population structure in wild stands of cacao trees (Theobroma cacao L.) in French Guiana

The native cacao trees (Theobroma cacao L.) in south-eastern French Guiana represent a noteworthy fraction of the genetic diversity of this species. Several scientific surveys have led to the collection of numerous accessions, which provides an opportunity for investigating the pattern of genetic diversity in natural populations. Using a capillary electrophoresis genotyping system, we fingerprinted 189 wild trees in 18 natural populations. Based on the 15 loci SSR profiles, we analyzed the intra- and inter-population variation and their relationship with control clones. The global allelic richness was 4.87 alleles per locus, but was 2.4 on average within individual populations; gene diversity was 0.368 and observed heterozygosity was low (0.160). Major structuring was discovered in the metapopulation of French Guianan wild cacao trees (Fst = 0.20), which could be explained by the biological characteristics of the cacao tree and the climatic events that affected the Guianan forests in the Quaternary period.     

Genetic diversity and population structure analysis of Pistacia species revealed by phenylalanine ammonia-lyase gene markers and implications for conservation

Information on population genetic structure and crop genetic diversity is important for genetically improving crop species and conserving threatened species.The PAL gene sequence is part of a multigene family that can be utilized to design DNA marker systems for genetic diversity and population structure investigation.In the current study, genetic diversity and population structure of100 accessions of wild Pistacia species were investigated with 78 PAL markers.A protocol for using PAL sequences as DNA markers was developed.A total of 313 PAL loci were recognized, showing 100% polymorphism for PAL markers.The PAL markers produced relatively more observed and effective alleles in Pistacia falcata and Pistacia atlantica, with a higher Shannon's information index and expected heterozygosity in P.atlantica, Pistacia vera and Pistacia mutica.Pairwise assessment of Nei's genetic distance and genetic identity between populations revealed a close association between geographically isolated populations of Pistacia khinjuk and Pistacia chinensis.The accessions of wild Pistacia species had more genetic relationship among studied groups of species.Analysis of molecular variance indicated 19% amongpopulation variation and 81% within-population variation for the PAL gene based DNA marker.Population structure analysis based on PAL revealed four groups with high genetic admixture among populations.The results establish PAL markers as a functional DNA marker system and provide important genetic information about accessions from wild populations of Pistacia species.     

斑背大尾莺汉口亚种(Locustella pryeri sinensis)遗传多样性及种群结构研究

采用线粒体控制区（807bp）序列分析对中国境内斑背大尾驾3个繁殖种群及1个越冬种群的遗传多样性及种群遗传结构,结果表明：斑背大尾莺的单倍型歧义度（Hd）为0.759±0.056,核苷酸多样性较（π）为0.002。三个地理种群的FST值以及繁殖种群同越冬种群之间的ΦST值表明不同地理单元之间无显著遗传分化。对不同单倍型的聚类分析（UPGMA）结果以及网络图（Network picture）结果也支持不同种群之间无显著分化。分子变异分析 （AMOVA）显示斑背大尾莺汉口亚种不同地理种群间遗传差异不大,98.5%的差异源自种群内部,仅1.5%源自种群间。中性检验结果Fu’sFS值为负值,错配分布分析结果呈单峰,表明斑背大尾驾在我国的进化史经历了种群扩张。这一假设也得到Tajima’D检验和Fu’s检验结果的支持（D=-1.80,p=0.02;Fs=-22.11,p=0.001）,该扩张大约发生在28,700年前。     

Genetic diversity and population structure of Raffaelea quercus‐mongolicae,a fungus associated with oak mortality in South Korea

Raffaelea quercus‐mongolicae is a fungus associated with oak wilt and deemed to cause extensive oak mortality in South Korea. Since the discovery of this fungus on a dead Mongolian oak (Quercus mongolica) in 2004, the mortality continued to spread southwards in South Korea. Despite continued expansion of the disease and associated significant impacts on forest ecosystems, information is lacking about the origin and genetic diversity of R. quercus‐mongolicae. Restriction‐site‐associated DNA (RAD) sequencing was used to assess genetic diversity and population structure among five populations (provinces) of R. quercus‐mongolicae in South Korea. In total, 179 single nucleotide polymorphisms (SNPs) were identified among 2,639 RAD loci across the nuclear genome of the 54 R. quercus‐mongolicae isolates (0.0012 SNPs per bp), which displayed an overall low expected heterozygosity and no apparent population structure. The low genetic diversity and no apparent population structure among South Korean populations of this ambrosia beetle‐vectored fungus support the hypothesis that this fungus was introduced to South Korea.     

Genetic diversity and structure of Drimys brasiliensis in southern Brazil:insights for conservation

Population genetics studies are widely recognized for generating useful knowledge for biodiversity conservation.To date,however,little is known about the levels and distribution of genetic diversity of Drymis brasiliensis(Miers LC),a tree species from the Atlantic Rainforest.Therefore,in this study,we investigated how genetic diversity is distributed within and among populations of D.brasiliensis from southern Brazil using allozyme markers to genotype reproductive trees(8 populations) and seedlings(3 populations).Furthermore,in two populations,we established two permanent plots(5.1 and 1 ha) to analyze fine-scale genetic structure(FSGS).Studied populations presented low levels of genetic diversity(reproductive=0.085;seedlings=0.054) and high fixation indexes(reproductive=0.396;seedlings=0.231).Genetic divergence among populations was equal to 0.05,which is significant,signaling that few populations can conserve large portions of the species total genetic diversity.FSGS was only detected for one population,when reproductive individuals were separated by less than40 m.Low genetic diversity combined with high fixation indexes clearly signal a risk of losing diversity.Therefore,conservation efforts should be aimed at enhancing gene flow within the studied populations.     

落叶松杂种F1代群体遗传多样性的RAPD、SSR分析

为给落叶松杂种F1代进化潜力的研究提供资料,利用RAPD、SSR标记分析了日本落叶松×兴安落叶松杂种F1代147个个体的遗传多样性。RAPD遗传多样性分析结果为,有效等位基因数平均值1.669 1,Nei遗传多样度平均值为0.395 5,Shannon多样性指数平均值为0.583 1;SSR遗传多样性分析结果为,有效等位基因数平均值1.689 2,Nei遗传多样度平均值为0.399 8,SSR标记的Shannon多样性指数平均值0.587 0。SSR标记和RAPD标记所揭示的杂种F1群体遗传多样性水平各指数值基本一致,且都表明与日本落叶松杂交后,杂种F1群体在遗传多样性上高出兴安落叶松。     

Genetic monitoring of traditional chestnut orchards reveals a complex genetic structure

Key message

This study presents the results of a systematic genetic analysis between wild and cultivated chestnuts in an orchard in southern Spain, highlighting a complex structure and considerable genetic diversity and opening the possibility to generalize this approach to other Mediterranean orchards.

Context

Tree genetic monitoring offers a good opportunity to evaluate populations and preserve their long-term adaptive evolutionary potential. Chestnut is a multipurpose species of high economic importance in the Mediterranean basin and considered an example of integration between natural and man-driven distribution of diversity under changing environmental and historical conditions. Due to its multipurpose characteristics, man influenced its populations (grafting/sexual propagation) and a complex genetic structure is expected.

Aims

We monitored the trees of a chestnut orchard for studying the genetic diversity and relationship in grafts and rootstocks and detecting possible response in its adaptive potential.

Methods

For this, morphological traits and genomic and genic microsatellite markers were used.

Results

Chestnut trees showed considerable genetic structure, with high level of clonality in the varieties and genetic diversity in rootstocks. The similarity analysis revealed a different clustering pattern for varieties, detecting higher variability for genomic microsatellite markers. Rootstocks harboured a high level of diversity, not previously described, and not contained in the genetic information from populations and varieties from the same region.

Conclusion

Results contribute to understanding the human role in the management of chestnut and demonstrate that rootstocks constitute an unexploited reservoir of variation valuable for conservation strategies against stress factors and future and unpredictable environmental changes.

     

Genetic diversity of pine‐parasitic nematodes Bursaphelenchus xylophilus and Bursaphelenchus mucronatus in China

The internal transcribed spacer (ITS) regions of rDNA have been routinely employed for identification and phylogenetic analysis of many nematode species. In this study, the intra‐ and interspecies ITS genetic diversity of Bursaphelenchus xylophilus and Bursaphelenchus mucronatus was evaluated. Ninety‐one isolates of the two nematode species collected from 14 Chinese provinces, Japan and Korea were used for ITS‐PCR and sequencing. An unweighted pair group cluster analysis dendrogram clustered them as two B. mucronatus and one B. xylophilus independent clades. Principal component analysis showed the phylogenetic relationship of the two nematode species more clearly; B. mucronatus isolates were separated into more than four groups, whereas B. xylophilus isolates still clustered into a group. The results of the Mantel test indicated the correlation of genetic distance matrices and geographic distance matrices was significant for both nematode species. The genetic differentiation coefficient (G_st) and gene flow (N_m) of B. mucronatus were 0.341 and 1.091, respectively, suggesting the importance of landscape heterogeneity and considerable obstacles for genetic exchange among B. mucronatus isolates in China. However, G_st and N_m of B. xylophilus were 0.188 and 2.151, respectively, very different compared to B. mucronatus. This could be owing to the short‐term introduction of B. xylophilus into China and a rapid spread through anthropogenic pathways. Our work adds to the understanding of the genetic diversity and genetic relationship of the two pine‐parasitic nematode species, and will aid in controlling them in the future.     

Association between individual genetic diversity of two oak host species and canopy arthropod community structure

Numerous oak species have wide geographical distribution and canopy dominance and they may influence the structure and functioning of the community. Therefore, they can be considered as foundation species. In the present study, we tested the potential association between individual genetic diversity of the host plant (microsatellites), host tree species (Quercus castanea and Q. crassipes), and seasonality (dry vs. rainy) with their arthropod community structure [diversity (H′), density, biomass and composition]. Forty individual oak canopies were fogged (10 individuals per species per season) in the Parque Ecológico Ciudad de México. We identified 338 arthropod morphospecies belonging to 21 orders. NMDS showed a separation of host tree species during both seasons, suggesting a different community structure between host tree species. Q. crassipes showed the highest values for H′, richness, and density in comparison with Q. castanea. In contrast, Q. castanea showed the highest values for arthropod biomass. Homozygosity by locus index (HL), a measure of individual diversity, showed that the more genetically diverse host individuals registered more H′ and density of arthropods, independently of the season. On the contrary, arthropod biomass registered an inverse pattern. This study suggests that genetic diversity of foundation species is an important element in the structuring of the canopy arthropod community.     

Analysis of genetic diversity and prediction of Larix species distribution in the Qinghai-Tibet Plateau,China

Larix resources in the Qinghai-Tibet Plateau have important ecological and economic values.However,the lack of genetic diversity background and related research hinders the development of conservation strategies.In this study,genetic diversity and distribution of five Larix species were investigated.Using 19 polymorphic microsatellite markers to study 272 representative individuals from13 populations,the results show low genetic diversity at the population level,with variation explained mainly b...     

Molecular markers reveal low genetic diversity in Casuarina equisetifolia clonal plantations in South China

New Forests - Casuarina equisetifolia is planted extensively in clonally-established coastal shelterbelts in South China. During the last decade, the plantations have been severely attacked by...     

Analysis of genetic diversity for wild and captive green peafowl populations by random amplified polymorphic DNA technique

The genetic diversity of the populations for 14 wild green peafowls (Pavo muticus) and 18 captive green peafowls was investigated by using the technology of random amplified polymorphic DNA (RAPD). Totally 161 and 166 amplified bands were obtained by using 23 arbitrary primers to amplify the genomic DNA of wild and captive green peafowls respectively. The results showed that the average relative genetic distance of the wild and captive green peafowls populations was 0.0555 and 0.1355, respectively, and difference of the average relative genetic distances between the two populations was 0.1635. The Shannon diversity index for the wild and captive green peafowl populations was 0.4348 and 1.0163, respectively, which means that there exists significant difference in genetic diversity between the two populations, and the genetic diversity of wild green peafowl was low. The two populations originated from two different families according to analysis by the UPGMA method. This research can provide the theoretical basis for supervising genealogies management of peafowl populations.     

Genetic diversity of Populus euphratica populations in northwestern China determined by RAPD DNA analysis

Five Populus euphratica Oliver populations in northwestern China were analyzed using RAPD DNA markers to determine genetic diversity among and within populations. One hundred-and-five polymorphic bands were observed, ranging in size from 250 bp to 1700 bp, using 10 primers. Only one population on the north side of the Tianshern Range had a unique band common to all individuals that was not found in individuals from populations in the Tarim River valley. Intra-population genetic diversity was high in two populations along the Tarim River and low in the other three populations. There was no significant correlation between genetic distances and geographic distances. The result of correspondence analysis shows that the individuals from the three populations with low genetic diversity are isolated from each other. The result of cluster analysis based on genetic distance shows that the population in the Tianshern Range is genetically distant from the other populations. These results suggest that the Tianshern Range population was genetically isolated from the other populations.     

Managing biological and genetic diversity in tropical agroforestry

Agroforestry Systems - The issues of biological and genetic diversity management in agroforestry are extremely complex. This paper focuses on genetic diversity management and its implications for...     

昆虫遗传多样性研究及展望

遗传多样性研究层次主要有细胞、蛋白质和DNA。介绍了遗传多样性的基本含义和现状。从3个层次对昆虫遗传多样性的研究方法和研究内容进行了评述,其中着重讨论遗传多样性的研究进展,并提出了DNA序列变异尺度将成为今后遗传多样性的研究重点。     

Plant diversity, population structure, and regeneration status in disturbed tropical forests in Assam, northeast India

We investigated the plant population structure and the phy-tosociological and regeneration status in two disturbed tropical forests in Assam Province, the Hojai Reserve Forest and Kumorakata Reserve Fo...