Absence of population genetic differentiation in the New Zealand greenshell mussel Perna canaliculus (Gmelin 1791) as assessed by allozyme variation

Genetic variation in the endemic New Zealand greenshell mussel, Perna canaliculus (Gmelin 1791), was examined using starch-gel electrophoresis at seven protein-coding loci (Idh; Acon-1; Acon-2; Gpd; Pgi; Pgm; Pgd) in 35 populations (N=1038 mussels). For all loci and all populations, Fisher's exact tests indicated highly significant departures from Hardy-Weinberg equilibrium (HWE), but this overall result was caused by significant heterozygote deficiencies at only two loci (Pgm and Pgd), and in only three northern populations (Kuaotunu, Te Haumi and Days Bay). Allelic and genotypic differentiation between population pairs at individual loci and across all loci were nonsignificant, and genotypic disequilibrium at each locus pair was also nonsignificant for all populations. Genetic variation in all populations was high (mean heterozygosity, 0.210+/-0.113), while Nei's D among populations was very low (0.002+/-0.002). Low population subdivision (θ=-0.001+/-0.002) and high levels of gene flow (Nm(p)=10.18; Nm(θ)=infinity) also indicated that the single panmictic unit model best explains population genetic homogeneity in P. canaliculus over a north-south distance >2000 km. Lack of genetic subdivision in this species is discussed in light of two previous allozyme studies, with differing results: one suggested that a north-south division exists between greenshell mussel stocks, and the other suggested that population structure in this species can be explained through isolation by distance model modified by local hydrology.     

Genetic structure of endangered Emmenopterys henryi Oliv. based on ISSR polymorphism and implications for its conservation

Inter-simple sequence repeat (ISSR) markers were used to determine the genetic variation and genetic differentiation of nine populations of Emmenopterys henryi Oliv., an endangered plant endemic to China. Relatively low genetic diversity was detected at population level (the percentage of polymorphic loci P=22.56%, the number of alleles per locus A=1.183+/-0.045, the effective number of alleles per locus A(E)=1.007+/-0.345, Nei's gene diversity h=0.071+/-0.017, Shannon information index I=0.104+/-0.025). However, the genetic diversity at species level was relatively high (P=56.05%; A=1.561+/-0.498, A(E)=1.325+/-0.371, h=0.191+/-0.199, I=0.287+/-0.284). Analysis of molecular variance showed that most of the ISSR variation (68.03%) in E. henryi occurred among populations. The estimated Nm from F (ST )was 0.235. It indicated that the fragmentation and isolation of populations might result from specific evolutionary history and anthropogenic activity. Consequently, genetic drift might play an important role in determining the genetic structure of E. henryi. Conservation strategies for this endangered species are proposed based on the genetic data.     

Genetic divergence between three sea urchin species of the genus Strongylocentrotus from the Sea of Japan

Intraspecific allozymic variation and interspecific genetic divergence were studied in three sea urchin species of the genus Strongylocentrotus (S. intermedius, S. nudus, S. pallidus) from the Sea of Japan. S. pallidus and S. intermedius showed high mean values of expected heterozygosity, H(e)=0.223+/-0.072 (17loci) and H(e)=0.230+/-0.065 (19loci), respectively. This estimate was somewhat lower in S. nudus, H(e)=0.126+/-0.043 (17loci). Estimates of Nei's genetic distance between S. nudus/S. intermedius (D=1.578, 17loci) and S. nudus/S. pallidus (D=1.327, 15loci) were considerably higher than that between S. intermedius/S. pallidus (D=0.269, 17loci). Invoking the protein clock hypothesis and using Panamanian geminate sea urchins for protein clock calibration, the time of divergence between S. intermedius and S. pallidus was estimated as 2.7MY. The results obtained for S. intermedius and S. nudus by us differ considerably from results obtained for these species by Norimasa Matsuoka and coworkers. The revealed discrepancies are discussed and the conclusion made that Matsuoka and coworkers' data on echinoderm biochemical genetics and systematics should be used with caution.     

Geographic differentiation in the house fly estimated by microsatellite and mitochondrial variation

Gene flow over very large geographic scales has been investigated in few species. Examples include Drosophila melanogaster, Drosophila subobscura, Drosophila simulans, and the Mediterranean fruit fly (Ceratitis capitata). The cosmopolitan house fly, a highly vagile, fecund, colonizing species offers an additional exemplar. Genotypes at seven microsatellite loci were scored in 14 widely separated natural house fly populations from the Nearctic, neotropics, Afrotropics, Palearctic, and Asia. Allelic diversities and heterozygosities differed significantly among populations. Averaged over all populations, Weir and Cockerham's theta = 0.13 and RST = 0.20. Pairwise genetic distance measures were uncorrelated with geographic distance. Microsatellite frequencies were compared with mitochondrial data from 13 of the same populations in which theta = 0.35 and Nei's GST = 0.72. Mitochondrial variation indicated up to threefold greater indices of genetic differentiation than the microsatellites. We were unable to draw any biogeographical inferences from these results or from tree or network topologies constructed from the genetic data. It is likely that high microsatellite diversities, mutation rates, and homoplasy greatly compromised their usefulness in estimating gene flow. House fly colonization dynamics include a large number of primary and secondary colonizations coupled with substantial genetic drift, but no detectable bottlenecks.     

Differentiation of four Indian aboriginal cattle populations revealed by STR markers

Cattle are the most important livestock in India and play a pivotal role in agrarian economy. There are 34 recognized breeds of cattle and number of unexplored lesser known populations. The present study is a contribution towards determining genetic variation and understanding the relationship among four lesser known populations. A total of 194 unrelated DNA samples from three cattle populations of Orissa (Binjharpuri, Ghumsuri, Motu) and Hill cattle of Kumaun (Kumauni) were collected from respective breeding tracts. Genotyping was done with 23 bovine microsatellite markers as suggested by International Society for Animal Genetics (ISAG) and FAO (DAD-IS) on automated sequencer. The average observed heterozygosity in the four populations lie within the narrow range of 0.623 +/- 0.04 in Binjharpuri to 0.664 +/- 0.03 in Kumauni. Mean estimates of observed and expected heterozygosity over all loci and breeds were 0.651 +/- 0.02 and 0.720 +/- 0.01, respectively. In the overall population, the homozygote excess (F(IT)) of 0.132 +/- 0.03, was partly due to the genetic differentiation among breeds (F(ST) = 0.044 +/- 0.01) and, to a larger extent, to a significant homozygote excess within breeds (F(IS) = 0.094 +/- 0.03). The phylogenetic reconstruction from a UPGMA clustering based on Nei's Standard genetic distance yielded a tree with Binjharpuri and Ghumsuri on a single node and Motu and Kumauni on separate nodes. The most probable clustering detected by STRUCTURE in population was three. Binjharpuri and Ghumsuri animals were assigned to one cluster with high proportion of membership.     

雌雄异株稀有植物伞花木(Eurycorymbus caraleriei)自然居群的等位酶遗传多样性研究

伞花木（Eurycorymbus caraleriei）为中国特有的第三纪孑遗单种属植物,雌雄异株。采用超薄平板微型聚丙烯酰胺等电聚焦电泳方法对其5个自然居群和1个人工迁地保护居群的等位酶变异进行了初步研究。对7个酶系统中14个位点的等位酶居群遗传多样性及遗传结构分析结果表明：伞花木具有较高水平的遗传多样性,其每位点平均等位基因数A=1．6,平均多态位点比率P=42．9％,平均预期遗传杂合度Hr=0．216;各居群的遗传多样性无显著性差异,但都表现为严重偏离Hardy-Weinberg平衡的杂合子过量;其遗传变异主要发生在居群内（93．1％）,居群间分化较小（Gst=0．069）,居群问遗传一致度较高（I=0．965～1．000）。推断这可能是由于其古老孑遗性、雌雄异株、混和传粉方式的生物学特性以及其长寿命的生活史等原因所导致;同时,居群间的较高基因流（Nm=3．128）也可能起到很大的作用。还使用UPGMA聚类方法推断了武汉植物园迁地保护的野外居群来源,在对迁地保护居群的评价中发现迁地保护居群仅保存了该物种基因型多样性的16％,在此基础上提出了今后进一步的保育策略。     

Evaluation of genetic differentiation in Bos indicus cattle breeds from Marathwada region of India using microsatellite polymorphism

Elucidation of genetic variability and genetic relationship among breeds has direct relevance with the issues of sustainable use of domestic animal genetic resources. In the present study, genetic polymorphism was evaluated using 22 microsatellite loci in unrelated samples of Red Kandhari and Deoni cattle breeds inhabiting the same geographical area of Marathwada region in Maharashtra state (western India). This work was mainly aimed at assessing the current genetic diversity to understand whether the two zebu populations in question are genetically differentiated. A total of 164 alleles were detected with an average of 5.82 and 5.86 alleles per locus (MNA) in Red Kandhari and Deoni breeds, respectively. The estimated mean observed (Ho) and expected (He) heterozygosity were 0.47 and 0.64 in Red Kandhari vs. 0.57 and 0.69 in Deoni cattle, respectively, demonstrating considerable level of genetic variation in both the populations. Mean estimates of F statistics were: F (FIT) = 0.315 +/- 0.035, f(FIS) = 0.231 +/- 0.031, theta(FST) = 0.110 +/- 0.022, with both the breeds exhibiting significant deficit of heterozygotes (FIS = 0.179 in Deoni; 0.278 in Red Kandhari). The multilocus FST values implied that 11.0% of the total genetic variation corresponds to breed and were statistically greater than zero for the two populations, suggesting population division. The evaluation of exact test also indicated that allele frequencies across all the loci differed significantly (P < 0.001) between two zebu breeds, further supporting population differentiation. Different genetic distance measures showed considerable levels of distances between the two cattle breeds (0.318 = Nei's standard DS; 0.250 = Nei's DA; 0.416 = Cavalli-Sforza and Edwards's Dc; 0.164 = Reynold's, and 2.64 = Delta mu square (dmicro)2. Bayesian statistical approach to assign each individual to the population also supported considerable differentiation between the two cattle breeds, possibly reflecting the limited gene flow between the two Marthwada cattle populations. The existence of cohesive breeding structure of both the breeds was further substantiated by allele-sharing distance measures (DAS) among individual animals. The results of this study thus revealed that the two Bos indicus breeds sharing the common breeding tracts are genetically differentiated enough as separate breeds.     

云南金钱槭 等位酶 遗传多样性 生境片段化 保育策略

云南金钱槭（Dipteronia dyeriana）是我国特有的国家Ⅱ级重点保护珍稀濒危植物,仅分布于云南的文山、屏边和蒙自三县交界地区。采用水平切片淀粉凝胶电泳等位酶分析方法,对采自三个县的天然居群的63个样品进行了遗传多样性检测。8个酶系统的13个等位基因位点分析表明,云南金钱槭的遗传多样性水平低,其平均多态位点百分率P=15.4%,每位点平均等位基因数A=1.2,平均预期杂合度He=0.064,各居群都偏离Hardy-Weinberg平衡,杂合子过量,居群间的基因分化系数GST=0.099,遗传变异主要发生在居群内（90.1%）,居群间分化较小,居群间遗传一致度较高（I=0.985～1）,具有一定的基因流（Nm=2.669）。不加权对平均法（UPGMA）聚类可将4个居群分为两支,水头箐居群和马家寨居群亲缘关系最近,聚类后与黑洞居群形成一支再和中槽子居群聚类,这与其地理分布格局大致吻合。据此提出了关于云南金钱槭保育策略的建议。     

Genetic diversity of north-east Asian cattle based on microsatellite data

In order to assess the genetic variability and population structure of north-east Asian cattle, 13 microsatellite loci were analysed for a total of 200 individuals including Korean, Chinese, Japanese Black and European Holstein cattle. Observed and expected heterozygosity, two estimators (F(ST) and G(ST)) of gene differentiation, and Nei's DA distance were evaluated. Based on expected mean heterozygosity, the lowest genetic diversity was exhibited in Japanese Black cattle (H(E)=0.471), and the highest in Chinese cattle (H(E)=0.744). Korean cattle revealed a relatively high degree of genetic diversity (H(E)=0.728). Average proportion of genetic variation because of interpopulation subdivision among north-east Asian cattle varied between 10.9 and 9.9%, depending on the estimator used. N-J tree based on Nei's DA genetic distance showed that Korean and Chinese cattle are closely related, whereas Japanese Black cattle are clearly distinct from the other two populations, forming a north-east Asian outgroup.     

云南穗花杉的遗传多样性研究

采用随机扩增多态DNA(RAPD)方法对云南穗花杉(Amentotaxus yunnanensis)4个居群和台湾穗花杉似(Amentotaxus for9rmosana)1个居群共104个个体进行了遗传多样性分析。9个随机引物共扩增出清晰谱带143条。云南穗花杉在物种水平上遗传多样性较高(多态位点百分率P为79．0％,基因多样性指数He为0．2718),但云南穗花杉和台湾穗花杉居群内遗传多样性均较低(P为18．0％、6．9％;He为0．0688、0．0198)。云南穗花杉居群间遗传分化强烈(AMOVA,GST和Shannon多样性指数分别为0．7611,0．7503和0．7526)。据推测,第四纪冰川引起的瓶颈效应,小规模居群引起的遗传漂变及幼苗成活率低等因素都加剧了居群间的遗传分化。建议对所研究的云南穗花杉全部居群予以保护,特别是对云南西畴和贵州兴义市七舍两个具有相对较高遗传多样性的居群应该优先建立就地保护点,以达到最大限度保存云南穗花杉遗传多样性的目的。     

天然红松林等位酶研究

利用红松种子的单倍体胚乳,采用水平切片淀粉凝胶电泳技术,对采自三个地区的天然红松林的材料进行了１０种酶系统的等位酶实验,共获得了１８个等位基因位点,对这１８个位点等位基因的统计分析表明：红松种群的多态位点百分数为Ｐ＝７７．７８％,等位基因平均数为Ａ＝２．０,预期杂合度为Ｈｅ＝０．１６４８。红松种群间遗传分化程度在松属于较低水平。在红松１８个等位基因位点的变异中,绝大部分变异９４．２％来自种群内部,     

濒危灌木长叶红砂遗传多样性的RAPD分析

应用RAPD分子标记对濒危灌木长叶红砂(Reaumuria trigyna)种群遗传多样性进行了分析.应用18条随机引物对长叶红砂5个种群的95个个体进行扩增,检测到118个位点,其中多态位点105个.结果表明:长叶红砂种群的多态位点比率(P)为88.98%,显示出长叶红砂种群存在较高的遗传多样性.Shannon多样性指数(0.4966)、Nei基因多样性指数(0.3303)和基因分化系数(Gst=0.1425)的分析结果显示,长叶红砂种群遗传变异大多存在于种群内,种群间的遗传分化占14.25%.聚类分析表明,长叶红砂种群遗传距离与地理距离之间无直接相关关系.遗传多样性水平与物种特性和所处不同群落有关,濒危植物并不一定表现为遗传变异水平的降低.     

异色瓢虫不同地理种群的ISSR种群多样性分析

异色瓢虫Harmonia axyridis(Pallas)在亚洲地区是一种重要的捕食性天敌昆虫,但是当引入到欧美后,对当地的物种产生了威胁.本文用ISSR技术对两个中国本地种群和一个引入美国的种群进行了种群多样性以及种群分化的分析.8条ISSR引物共扩增出105条带,其中多态性条带比率为96.19%.Nei's多样性指数、Shannon信息指数、多态性条带比率,在中国种群与美国种群中均非常接近,种群分化不明显(G_(st)=0.042).AMOVA分析显示种群多样性主要来源于种群内部,种群问的基因流非常强(N_m=5.537).基于Nei's多样性构建的聚类结果显示ISSR是一种快速有效的研究异色瓢虫种群多样性关系的技术.     

Genetic diversity and differentiation of dromedarian camel of India

Estimation of genetic variability and relationship among different livestock breeds is important for management of genetic resources for their sustainable utilization and conservation. This is more important when the livestock species, like camel, have shown a sharp decline in head count during the last decade. In the present study we estimated genetic variability and relationship among four camel breeds of India using 23 microsatellite loci. A total of 252 alleles were observed across all the four populations with mean number of alleles per locus as 8.04, 7.30, 6.39, and 7.43 for Bikaneri, Jaisalmeri, Kutchi, and Mewari breeds, respectively. The mean observed heterozygosity of the four breeds were 0.58, 0.57, 0.56, and 0.60 for Bikaneri, Jaisalmeri, Kutchi, and Mewari breeds, respectively and were lower than expected heterozygosity values. The mean estimates of F statistics were 0.227+/-0.044 (F(IT)), 0.157+/-0.038 (F(IS)), and 0.082+/-0.019 (F(ST)). The values were significantly different from zero for all the three measures and point towards the existence of population structure and moderate differentiation in four camel breeds. The exact test also indicated significant population differentiation (P < 0.001). The analysis of molecular variance revealed 12% of the variation attributed to among populations and 88% within populations. Sixty-nine percent of the individuals could be correctly assigned using "leave one out" procedure. All the individuals of Mewari and 42 out of 44 Jaisalmeri were correctly assigned. The existence of strong population structure in Jaisalmeri and Mewari camel was further substantiated by Nei's standard genetic distance as well as interindividual allele sharing distance. Thus these two breeds owing to selection for specific traits are distinct from other camel breeds.     

Genetic diversity and phylogenetic relatedness among six endemic Pterostylis species (Orchidaceae; series Grandiflorae) of Western Australia, as revealed by allozyme polymorphisms

Starch gel electrophoresis was employed to survey the allozyme polymorphism and phylogenetic relationships among 35 populations covering six closely related Western Australian endemic Pterostylis species (series Grandiflorae); viz P. rogersii, P. aspera, P. angusta, P. hamiltonii, P. scabra and P. aff. alata. The aim of this study was to determine intraspecific and interspecific genetic diversity and species relationships based on allozyme analysis. The frequencies of 56 alleles at 12 enzyme systems coded by 15 loci were determined along with a mean intraspecific genetic identity value. Allozyme markers clearly discriminated populations belonging to different species. Nei's genetic distance/identity co-efficient was used to measure the level of genetic differentiation among populations and species. Based on these values, a dendrogram was constructed which revealed that all the populations clustered into groups corresponding to the respective species. Gene diversity analysis among all the species revealed total genetic diversity H(t) of 0.23 with co-efficient of gene differentiation 10% (G(st)=0.10). Mean genetic variability (H(e)=0.136, P=40%) was also higher than for other outbreeding plant species. Mean genetic identity coefficient of populations of all species was 0.859 which increased to 0.877 upon exclusion of P. aff. alata, indicating a high degree of similarity among all species except P. aff. alata which segregated distinctively from the rest. Overall, the investigation provided independent support for the morphological segregation of these taxa.     

广东省五节芒遗传多样性的ISSR分析

采用ISSR分子标记技术,对广东省内分布的能源植物五节芒(Miscanthus floridulus)13个野生居群共215个个体的遗传多样性进行了研究.9个ISSR引物共扩增到了81个位点,其中76个是多态性位点.结果表明,广东五节芒的遗传多样性水平很高,物种水平上,多态位点百分率(PPB)为93.83％,Nei's...     

Genetic relationship among Japanese sentinel crabs (Decapoda: Ocypodidae: genus Macrophthalmus)

Seven species (eight populations) of sentinel crabs (genus Macrophthalmus) from the Japan coast and Uca vocans and Ocypode ceratophthalma, were examined electrophoretically for genetic variations in 13 enzymatic and one non-enzymatic protein comprising 17 loci. Most species were highly differentiated from each other (Nei's genetic distance, 0.29-1.63). The least genetic distance was found between M. japonicus and M. banzai, the genetic distinctiveness of the two taxa being supported by three divergent loci with no common allele. The genetic relationships among Macrophthalmus species differed greatly from those inferred from morphological features, with a UPGMA tree suggesting that the sub-genus Macrophthalmus is polyphyletic.     

High level of genetic divergence between sympatric color morphs of the littoral sea anemone Anthopleura orientalis (Anthozoa: Actiniaria)

Using enzyme electrophoresis and nematocyst analysis, the sympatrically occurring "light" and "dark" color morphs of the sea anemone Anthopleura orientalis from the Sea of Japan were shown to be two valid species. The "light" morph was identified as A. orientalis (Averintsev, 1967 Issledovaniya fauny morei: Vyp. 5 (13). Nanka, Leningrad, pp. 62-77), while the "dark" morph was designated as Anthopleura sp. The analysis of 21 isozyme loci revealed high value of Nei's genetic distance (D=1.284) between the two species, which are indistinguishable in their external morphology. The mean values of observed and expected heterozygosities for A. orientalis and Anthopleura sp. are high (H(o)=0.252+/-0.061, H(e)=0.250+/-0.061 and H(o)=0.327+/-0.052, H(e)=0.351+/-0.054, respectively). The species differ significantly in the size of spirocysts and nematocysts, among which the atrichs from acrorhagi and the basitrichs from actinopharynx contribute most to the observed difference. Strong qualitative difference is revealed between distributions of nematocysts in mesenteric filaments of the two sea anemone species studied. The possible conspecificity of Anthopleura sp. with Anthopleura artemisia (Dana, 1848) is discussed and the conclusion made that these are two separate species.     

Breeding structure of Glossina pallidipes populations evaluated by mitochondrial variation

Mitochondrial DNA diversity was studied at four loci in six natural populations of the tsetse fly Glossina pallidipes from Zimbabwe, Mozambique, Kenya, and Ethiopia. Single-locus diversity varied from 0.39 at 12S to 0.65 at COII. A total of 32 haplotypes was found with a mean of 6.4 +/- 2.9 per locus. To study breeding structure, diversity at two loci, COII and 16S2, was evaluated in 18 populations sampled from an area of approximately 1,611,000 km2 and in three laboratory cultures. Twenty-six haplotypes were detected at the two loci and mean haplotype diversity over all natural populations was 0.63. A high degree of population subdivision was detected within and among the Ethiopian and Kenya populations. The Zimbabwe and Zambia populations showed much less variation and differentiation than the northern populations. A population in Mozambique showed high levels of haplotype variation and affinities closest to populations in eastern Kenya, some 1700 km to the north. Analysis of variance of haplotype frequencies showed that 51.5% of the total lay within populations, 13% among populations within five nested groups, and 35.5% among the five groups. Wright's FST was 0.485, Nei's GST was 0.33, and Weir and Cunningham's theta = 0.45. Ecological data show that G. pallidipes is highly vagile. The large amount of genetic differentiation may be explained by genetic drift that occurred in scattered, relict populations during the rinderpest panzootic of the late 19th and early 20th centuries.     

An electrophoretic investigation of populations of Atherina boyeri Risso, 1810 and A. presbyter Cuvier, 1829 (Teleostei: Atherinidae): genetic evidence in support of the two species

The data obtained using electrophoresis strongly support the specific status of Atherina boyeri Risso, 1810 and A. presbyfer Cuvier, 1829, and thuscontradict the recently proposedsynonymyof the two species. Four populations of A. boyeri and six populations of A. presbyter were assayed for 11 enzymes and general protein using muscle and liver extracts. Eight of the 11 enzymes were shown to be polymorphic at the 95% level. Sixteen loci, encoding 40 putative alleles were consistently resolved in all 10 populations.
The two species were fixed for different alleles at the EST-3 locus. At the G3PDH locus. with the exception of two heterozygotes, all individuals of each species were also homozygous for different alleles. At the PGM locus the common allele was unique to each species.
The mean Nei's genetic distance ( ), over all loci, calculated between populations of A. boyeri (= 0.10 ± 0.06); between populations of A. presbyter ( = 0.02 0.02) and between populations of A. boyeri and A. presbyter ( = 0.42 0.09) indicated the separateness of the two species.
UPGMA cluster analysis based on genetic distances produced a dendrogram whose principal dichotomy resulted in the formation of two clusters. The ordination of populations in the UPGMA cluster analysis strongly reflected the geographic distribution of populations in both species.