Zinc and cadmium hyperaccumulation by Thlaspi caerulescens from metalliferous and nonmetalliferous sites in the Mediterranean area: implications for phytoremediation

Growth, tolerance and zinc and cadmium hyperaccumulation of Thlaspi caerulescens populations from three metal contaminated soils and three normal soils were compared under controlled conditions. Individuals of six populations were cultivated on five soils with increasing concentrations of zinc (50–25000 μg g⁻¹) and cadmium (1–170 μg g⁻¹). There was no mortality of normal soil populations in the four metal-contaminated soils, but plant growth was reduced to half that of populations from metal-contaminated soils. However, in noncontaminated soil, the growth of individuals from normal soils was greater than that of individuals from metal-contaminated soils. Individuals from normal soils concentrated three times more zinc in the aboveground biomass than those from metal-contaminated soils, but the latter accumulated twice as much cadmium. We conclude that populations of T. caerulescens from both normal and metal-contaminated soils are interesting material for phytoextraction of zinc and cadmium, but to optimize the process of phytoextraction it is necessary to combine the extraction potentials of both type of populations.     

广东高州普通野生稻(Oryza rufipogon Griff)的遗传多样性和居群遗传分化研究

利用30对SSR引物对广东高州普通野生稻3个群体进行了遗传多样性分析和居群遗传分化研究.结果表明,30对引物中只有20对表现出多态,多态位点比率P为66.7%;在20个多态位点中共检测出81个等位变异,平均等位变异数(Ap)为4.05 个;3个群体总的遗传多样性(Ht)为0.61,其中,居群内的遗传多样性为居群间的遗传多样性的3倍多,说明总的遗传多样性主要来自居群内;虽然居群间的遗传分化系数(G ST)较低,仅为0.2427,但当遗传相似系数临界值增加时,3个群体在聚类图上相对独立 ,说明3个群体既存在着高度的遗传相似性,又具有一定程度的遗传分化,可以作为3个居群进行原生境保护.     

Variation in pollen limitation and floral parasitism across a mating system transition in a Pacific coastal dune plant: evolutionary causes or ecological consequences?

Background and Aims Evolutionary transitions from outcrossing to self-fertilization are thought to occur because selfing provides reproductive assurance when pollinators or mates are scarce, but they could also occur via selection to reduce floral vulnerability to herbivores. This study investigated geographic covariation between floral morphology, fruit set, pollen limitation and florivory across the geographic range of Camissoniopsis cheiranthifolia, a Pacific coastal dune endemic that varies strikingly in flower size and mating system.Methods Fruit set was quantified in 75 populations, and in 41 of these floral herbivory by larvae of a specialized moth (Mompha sp.) that consumes anthers in developing buds was also quantified. Experimental pollen supplementation was performed to quantify pollen limitation in three large-flowered, outcrossing and two small-flowered, selfing populations. These parameters were also compared between large- and small-flowered phenotypes within three mixed populations.Key Results Fruit set was much lower in large-flowered populations, and also much lower among large- than small-flowered plants within populations. Pollen supplementation increased per flower seed production in large-flowered but not small-flowered populations, but fruit set was not pollen limited. Hence inadequate pollination cannot account for the low fruit set of large-flowered plants. Floral herbivory was much more frequent in large-flowered populations and correlated negatively with fruit set. However, florivores did not preferentially attack large-flowered plants in three large-flowered populations or in two of three mixed populations.Conclusions Selfing alleviated pollen limitation of seeds per fruit, but florivory better explains the marked variation in fruit set. Although florivory was more frequent in large-flowered populations, large-flowered individuals were not generally more vulnerable within populations. Rather than a causative selective factor, reduced florivory in small-flowered, selfing populations is probably an ecological consequence of mating system differentiation, with potentially significant effects on population demography and biotic interactions.     

Behavioural responses to predator chemical cues and local variation in antipredator performance in Rana temporaria tadpoles

Antipredator behaviour is an important factor influencing survival probability of prey animals, and it may evolve rapidly as a response to changes in predator regime. I studied antipredator behaviour of common frog ( Rana temporaria ) tadpoles from three populations that differ in predator regimes. In the first experiment, tadpoles obtained from four natural matings in each population were subjected to chemical cues from either European perch ( Perca fluviatilis ) or from larvae of the dragonfly Aeshna juncea . Tadpoles decreased their activity in response to both predators, but the spatial behaviour of tadpoles differed between the two predator treatments. In general, there were no differences in behaviours among the populations, but in three out of four studied behaviours there were differences between parentages within the populations suggesting that these behaviours may be genetically determined. The lack of a significant Predator×Population interaction suggests no differences in plastic antipredator behaviour among the populations, while the lack of significant Predator×Parentage interaction suggests no genetic variance within the populations for plastic antipredator behaviour. In the second experiment, tadpoles from the three populations were exposed to predation by a free-ranging A. juncea . In line with the first experiment, there were no differences in survival rate between the populations. R. temporaria tadpoles seem to rely heavily on plastic antipredator behaviour as their main response to predator chemical cues. There was very little indication of local behavioural differentiation and the possible reasons for the lack of divergence among populations are discussed.     

茶尺蠖和灰茶尺蠖内共生菌Wolbachia的分子检测及序列分析

【目的】对茶尺蠖Ectropis obliqua及其近缘种灰茶尺蠖E.grisescens体内共生菌Wolbachia进行分子鉴定,确定两者体内Wolbachia的感染率及其进化地位,为进一步探讨其对茶尺蠖和灰茶尺蠖的潜在影响提供科学依据。【方法】采用Wolbachia的16S r RNA、fts Z和wsp基因特异性引物,通过PCR扩增法检测了我国3个茶尺蠖地理种群(浙江杭州、余杭和江苏无锡)和3个灰茶尺蠖地理种群(浙江新昌、湖北浠水和江西南昌)中Wolbachia的感染情况,并进行测序和序列分析。【结果】茶尺蠖和灰茶尺蠖都感染了Wolbachia,灰茶尺蠖的Wolbachia感染率为100%,但茶尺蠖的Wolbachia感染率在22%~95%,且PCR产物电泳得到的条带微弱。wsp序列在茶尺蠖和灰茶尺蠖种间、种内无差异;但16S r RNA序列在茶尺蠖和灰茶尺蠖种间、种内差异为0.362%~0.727%之间;茶尺蠖样本未成功扩增出fts Z序列,灰茶尺蠖样本获得2条fts Z基因序列差异为1.647%。基于Wolbachia的16S r RNA和wsp基因构建的系统发育树表明,本研究中茶尺蠖和灰茶尺蠖种群所感染的Wolbachia全部属于B组的Pip亚组。【结论】茶尺蠖和灰茶尺蠖均被B组Pip亚组的Wolbachia感染,但感染率相差很大,这为研究Wolbachia对茶尺蠖和灰茶尺蠖生物学及生态学的影响奠定了基础。     

Evolution of the Selfing Syndrome in Arabis alpina (Brassicaceae)

Introduction

The transition from cross-fertilisation (outcrossing) to self-fertilisation (selfing) frequently coincides with changes towards a floral morphology that optimises self-pollination, the selfing syndrome. Population genetic studies have reported the existence of both outcrossing and selfing populations in Arabis alpina (Brassicaceae), which is an emerging model species for studying the molecular basis of perenniality and local adaptation. It is unknown whether its selfing populations have evolved a selfing syndrome.

Methods

Using macro-photography, microscopy and automated cell counting, we compared floral syndromes (size, herkogamy, pollen and ovule numbers) between three outcrossing populations from the Apuan Alps and three selfing populations from the Western and Central Alps (Maritime Alps and Dolomites). In addition, we genotyped the plants for 12 microsatellite loci to confirm previous measures of diversity and inbreeding coefficients based on allozymes, and performed Bayesian clustering.

Results and Discussion

Plants from the three selfing populations had markedly smaller flowers, less herkogamy and lower pollen production than plants from the three outcrossing populations, whereas pistil length and ovule number have remained constant. Compared to allozymes, microsatellite variation was higher, but revealed similar patterns of low diversity and high Fis in selfing populations. Bayesian clustering revealed two clusters. The first cluster contained the three outcrossing populations from the Apuan Alps, the second contained the three selfing populations from the Maritime Alps and Dolomites.

Conclusion

We conclude that in comparison to three outcrossing populations, three populations with high selfing rates are characterised by a flower morphology that is closer to the selfing syndrome. The presence of outcrossing and selfing floral syndromes within a single species will facilitate unravelling the genetic basis of the selfing syndrome, and addressing which selective forces drive its evolution.     

Differences in parasite susceptibility and costs of resistance between naturally exposed and unexposed host populations

It is generally assumed that resistance to parasitism entails costs. Consequently, hosts evolving in the absence of parasites are predicted to invest less in costly resistance mechanisms than hosts consistently exposed to parasites. This prediction has, however, rarely been tested in natural populations. We studied the susceptibility of three naïve, three parasitized and one recently isolated Asellus aquaticus isopod populations to an acanthocephalan parasite. We found that parasitized populations, with the exception of the isopod population sympatric with the parasite strain used, were less susceptible to the parasite than the naïve populations. Exposed but uninfected (resistant) isopods from naïve populations, but not from parasitized populations, exhibited greater mortality than controls, implying that resistance entails survival costs primarily for naïve isopods. These results suggest that parasites can drive the evolution of host resistance in the wild, and that co‐existence with parasites may increase the cost‐effectiveness of defence mechanisms.     

东方雏蝗不同地理种群雄性鸣声结构的比较研究

比较分析了东方雏蝗Chorthippus intermedius B.-Bienko的竞争鸣叫声和3个不同地理种群的召唤声。研究结果表明,东方雏蝗3个不同地理种群召唤声时域特征大致相同,在脉冲组持续时间与频域特征上,山西中条山种群与吉林松花湖种群较相似,黑龙江镜泊湖种群与前二者差异稍明显。黑龙江镜泊湖种群的竞争声由2~4个脉冲组组成的脉冲序列组成,其脉冲组的基本结构与召唤声相同,但脉冲组持续时间相对较短。     

Evolutionary increases in defense during a biological invasion

Invasive plants generally escape from specialist herbivores of their native ranges but may experience serious damage from generalists. As a result, invasive plants may evolve increased resistance to generalists and tolerance to damage. To test these hypotheses, we carried out a common garden experiment comparing 15 invasive populations with 13 native populations of Chromolaena odorata, including putative source populations identified with molecular methods and binary choice feeding experiments using three generalist herbivores. Plants from invasive populations of C. odorata had both higher resistance to three generalists and higher tolerance to simulated herbivory (shoot removal) than plants from native populations. The higher resistance of plants from invasive populations was associated with higher leaf C content and densities of leaf trichomes and glandular scales, and lower leaf N and water contents. Growth costs were detected for tolerance but not for resistance, and plants from invasive populations of C. odorata showed lower growth costs of tolerance. Our results suggest that invasive plants may evolve to increase both resistance to generalists and tolerance to damage in introduced ranges, especially when the defense traits have low or no fitness costs. Greater defenses in invasive populations may facilitate invasion by C. odorata by reducing generalist impacts and increasing compensatory growth after damage has occurred.     

Population genetics of introduced and native populations of the green mussel, Perna viridis: determining patterns of introduction

Genetic variation can be used to determine routes of introduction of non-native species and whether introduced populations lost variation during establishment. The present study sought to determine whether multiple, geographically isolated non-native populations of the green mussel, Perna viridis, were the product of a stepping stone expansion of a single introduction or from multiple independent introductions from the native range. Measurements of genetic variation were compared among five introduced populations and three populations from within the native range. We sequenced 650 bp of the mitochondrial gene cytochrome oxidase I from 280 samples from five introduced populations and another 190 samples from three native populations. Haplotype frequencies of all introduced populations were not significantly different from each other, but virtually all populations differed from samples taken from the native range. Measurements of genetic variation tended to suggest that introduced populations had less variation than most native populations and there was no evidence for admixture in any of the introduced populations. The genetic data and Monte Carlo simulations both provide compelling evidence of a stepping-stone pattern of introduction of P. viridis from the native range to Trinidad, and from Trinidad to other locations in the Caribbean and United States. The lack of genetic variation in introduced populations suggests that the initial introduction was relatively small and the lack of admixture suggests a single original source population.     

企鹅珍珠贝不同地理群体遗传多样性的fAFLP 分析

为阐明企鹅珍珠贝(Pteria penguin)不同地理种群的遗传多样性机制, 采用荧光标记扩增片段长度多态性(fAFLP)技术分析了企鹅珍珠贝广西涠洲岛、广东流沙湾和海南黎安3 个不同地理群体的遗传多样性。选取7 对引物组合对90 个个体(每个群体30 个)进行fAFLP 扩增, 结果发现每个个体均能扩增出清晰的、可重复的扩增条带, 每对引物的扩增位点数在100—163 之间, 共得到895 个扩增位点, 多态位点数为865 个; 涠洲岛、流沙湾和黎安群体的多态位点比例分别为70.73%、63.13%、66.82%。Nei 遗传多样性指数为0.1634、0.1558、0.1783, Shannon 遗传多样性指数为0.2635、0.2474、0.2932。3 个群体间遗传相似度在0.9722—0.9824之间, 遗传距离在0.0177—0.0282 之间。根据遗传距离绘制UPGMA 聚类图, 但Mantel 检验结果显示企鹅珍珠贝三群体间的遗传距离与地理距离之间无显著相关。Shannon 遗传多样性指数和AMOVA 分析, 结果均显示企鹅珍珠贝的遗传变异主要来源于群体内个体间, 7.91%的遗传变异来自群体间, 92.09%的遗传变异来自群体内。分析群体的显性基因型频率分布和基因流Nm 发现3 个群体有基本相同的遗传结构, 有明显的基因交流。研究结果表明北海涠洲岛群体、湛江流沙湾群体和海南黎安群体的企鹅珍珠贝种质有较高的多态位点比例, 但未发生显著地理分化。这一结果为我国企鹅珍珠贝的良种选育以及种质资源保护措施的制定提供了参考依据。       

Adaptation to salinity inHordeum jubatum L. populations studied using reciprocal transplants

Tillers and seedlings ofHordeum jubatum L. from three sites with contrasting salinity regimes in central Saskatchewan, Canada were reciprocally transplanted in order to examine the tolerance of populations of this species to salinity and related habitat factors. Survival, growth and fecundity of the three populations were controlled more by transplant site characteristics than by genetic differences, i.e. differences among populations at a site tended to be smaller than differences among sites. Survival, growth and reproduction of all three populations were best at the non-saline site. The population originating at the non-saline site showed the poorest growth in the two saline habitats, but still had substantial salt tolerance. Fecundity was greatest when the populations were grow at their site of origin.     

Genetic and morphological variation of three freshwater lake populations of Coilia ectenes (Engraulidae)

Population structure of the important commercial fish, Coilia ectenes was investigated in samples from three freshwater lakes in the Eastern China using a multivariate approach of morphometries and mitochondrial DNA control region sequencing. A total of eighteen morphological distances of truss method and eight morphometric variables were taken from each fish. Multivariate analyses of the morphometric data revealed significant morphological differences among the three lake populations, especially for those samples from Taihu Lake. Discriminant functions were used to compare sites, and these permitted an 83% success rate in distinguishing fish from the three sites. However, no obviously geographical differentiation was found among those populations of C. ectenes based on the genetic data. In the AMOVA analysis, only 2.2% genetic variability came from different populations, and most of them were present within the sub-populations. Experience a recent population expansion and some movement of fish among those areas, quite possibly enough to bring about relative genetic homogeneity, but there is insufficient to prevent the three populations from differing phenotypically. The diversified environmental factors may be playing an important role in shaping morphological variations among those populations.     

Gonadal Dysgenesis Determinants in a Natural Population of DROSOPHILA MELANOGASTER

Three populations of Drosophila melanogaster from northern California were surveyed for the ability to produce and resist gonadal dysgenesis in the P-M system of hybrid dysgenesis. Males from all three populations produced low to moderate levels of gonadal dysgenesis in crosses to Oregon-R M females. Most females had the P cytotype, but the M cytotype occurred occasionally. The three populations could not be statistically differentiated from one another, but were easily distinguished from populations from Australia and Wisconsin on the basis of gonadal dysgenesis potential. The California populations had higher levels of M cytotype than did the Wisconsin population. Thirteen X chromosomes and 11 pairs of autosomes were extracted from one of the California populations, using a modification of the standard balancer chromosome technique to suppress hybrid dysgenesis during extraction. All lines produced strongly skewed sterility distributions in crosses to M-strain females, and mean levels of sterility were less than 50%. There was evidence of nonadditive interactions between the autosomes. Most extraction lines had the P cytotype, but M and intermediate cytotypes were observed. Some of the intermediate cytotypes were stable over time. Lines were tested at two different times after extraction. Some lines evolved higher sterility potential as they were kept in the laboratory, even in the presence of P cytotype. The results point out a number of deficiencies in current genetic and population genetic models of hybrid dysgenesis and imply that gonadal dysgenesis is unlikely to be an important evolutionary force in this population.     

The postglacial history of Scots pine (Pinus sylvestris L.) in western Europe: evidence from mitochondrial DNA variation

The geographical structure of mitochondrial (mt)DNA variants (mitotypes) was investigated in 38 western European populations of Scots pine Pinus sylvestris using restriction fragment length polymorphism (RFLP) analysis of total DNA and a homologous cox1 probe. Three major mitotypes (designated a, b and d ) were detected. Within Spain all three major mitotypes were found, gene diversity was high, H_T = 0.586, and this diversity was distributed predominantly among rather than within populations (F_ST(M) = 0.813 for the seven Spanish populations). Mitotype d was present only in the most southerly population from the Sierra Nevada . Elsewhere in Europe, populations showed little or no mtDNA diversity within regions, but there were marked differences between regions. Italian populations were fixed for mitotype b ; populations from northern France, Germany, Poland, Russia and southern Sweden were fixed for mitotype a ; while populations in northern Fennoscandia were fixed for mitotype b . The isolated Scottish populations were predominantly of mitotype a , but mitotype b was present in three of the 20 populations scored. In Scotland, UK gene diversity (H_T = 0.120) and genetic differentiation among populations (F_ST(M) = 0.37) was much lower than in Spain. When interpreted in the light of complementary data from pollen analysis and nuclear genetic markers, the results suggest that present-day populations of P. sylvestris in western Europe have been derived from at least three different sources after glaciation.     

Genomic variation in Pekin duck populations developed in three different countries as revealed by whole‐genome data

It is well known that both British and American Pekin ducks originated from China. However, the populations differ substantially in production performance, but the genetic changes involved are still poorly understood. Herein, we sequenced 24 individual Pekin ducks (eight from each population) with an average sequencing depth of more than 45× for each population (mean coverage of 6.29 per individual). Among these populations from three different countries, we identified a large number of SNPs and indels as well as many unique population variants, which can be used as population‐specific molecular markers. Genomic comparisons among the three duck populations revealed many candidate genes as well as pathways and Gene Ontology categories that are putatively associated with meat yield in the British population, growth in the American population and brain development in all three populations. These findings will enable a better understanding of the artificial selection history of Pekin ducks and provide a valuable resource for future research on the breeding of this species.     

Pinus mugo (Pinaceae) in the Abruzzi Mountains: high morphological variation in isolated populations

Thirty-three individuals of Pinus mugo from the Abruzzian Apennines (Italy), the most isolated population of the species, were examined biometrically to verify the range of trait variation and compared with six other populations sampled in the north-eastern part of the species range. Ten needles and ten cones from each individual were measured and quantified on the basis of 31 traits. The interpopulation comparison revealed a close affinity of the Abruzzian population of P. mugo to three of the six other populations. The other three north-eastern populations, one from the Tatra Mountains and two from the Chornokhora Mountains, appeared to be different. This suggests that these populations originated from other Pleistocene centres of occurrence. The intrapopulation variation of the population from the Abruzzian Apennines is comparable with those of all six populations of P. mugo from the Sudety and Carpathian Mountains. These findings support the hypothesis that isolated but locally abundant plant populations do not necessarily show a reduction in variability resulting from isolation.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 309–316.     

Allozyme Variation in a Threatened Freshwater Fish, Spotted Murrel (Channa punctatus) in a South Indian River System

Samples of the spotted murrel (Channa punctatus) were collected from three rivers of Tamil Nadu and Kerala. The allozyme variation of C. punctatus was investigated by polyacrylamide gel electrophoresis. Eighteen enzymes were detected, but only 10 (EST, PGM, G3PDH, G6PDH, SOD, GPI, ODH, GDH, XDH, and CK) showed consistent phenotypic variations. Allele frequencies were estimated at the 18 polymorphic loci representing 10 enzymes. Two rare alleles, EST-4*C and G6PDH-2*C, were noted in the Tamirabarani and Kallada populations but were absent in the Siruvani population. The allele frequencies of the Tamirabarani and Kallada populations were similar, except for a few loci. Among the three populations, the maximum genetic distance (0.026) and FST (0.203) were found between the geographically distant Siruvani and Kallada populations. Overall the study showed that among the three populations, the Tamirabarani and Kallada have similar genetic structures.     

江苏Q型烟粉虱抗性监测及其靶标基因克隆

应用成虫浸叶生测法研究了江苏省扬州、无锡和东台3个地区Q型烟粉虱Bemisia tabaci(Gennadius)田间种群对5种杀虫剂的抗药性。结果表明,与相对敏感种群相比,Q型烟粉虱田间种群已对氯氰菊酯和吡虫啉产生了低到中等水平抗性,对阿维菌素仍然表现敏感。进一步通过RCR扩增获得了长度分别为287bp和184bp的烟粉虱乙酰胆碱酯酶ace1和para-同源钠离子通道基因片断。序列分析表明,江苏Q型烟粉虱存在与有机磷抗性相关的乙酰胆碱酯酶F331W突变和与拟除虫菊酯抗性相关的钠离子通道L925I和T929V突变。     

Low genetic differentiation among widely separated populations of the pearl oyster Pinctada fucata as revealed by AFLP

Genetic variation within and among five populations of the pearl oyster Pinctada fucata, from China (Daya Bay, Sanya Bay and Beibu Bay), Japan (Mie Prefecture) and Australia (Port Stephens) was studied using AFLP. Three primer pairs generated 184 loci among which 91.8-97.3% is polymorphic. An overall genetic diversity of 0.38 among populations and an average of 0.37 within populations (ranging from 0.35 in Japanese population to 0.39 in Beibu Bay population) were observed. Genetic differentiation among the five populations is low but significant as indicated by pairwise G_ST (0.0079-0.0404). AMOVA further shows that differentiation is significant among the five populations but is not significant at a broader geographical scale, among the three groups of Chinese, Japanese and Australian populations or among the two groups of Australian and north Pacific populations. The low level of genetic differentiation indicated that P. fucata populations in the west Pacific are genetically linked. Among the five populations, the Australian one is more differentiated from the others, based on both pairwise AMOVA and G_ST analyses, and is genetically isolated by distance as indicated by Mantel test. However, genetic differences among the three Chinese populations are not correlated with the geographic distances, suggesting that Hainan Island and Leizhou Peninsula may act as barriers blocking gene flow.