Allozyme variation within and between populations inLolium (Poaceae)

Isozyme analysis was used to determine genetic variation within and between populations of sevenLolium species. All populations from the inbreeding species (L. temulentum, L. remotum, L. loliaceum, andL. persicum) were completely fixed for all enzymes scored. They also contained, for four of the five enzyme systems studied, exactly the same allelic variant. The three cross-breeding species showed large within-population variation and much less between-population variation. The great similarity of the allozymic variants found in all species, made the division of the genusLolium into species on basis of allozymic data difficult. It was not possible to separate the different inbreeding species from each other. Within the cross-breeding groupL. multiflorum andL. rigidum could be distinguished fromL. perenne. L. multiflorum, andL. rigidum could, with more difficulty, also be separated from each other. Allelic variation could have more relation with the provenance of the populations than with taxonomic classification.Genetic variation inLolium spp. II. For first part see Pl. Syst. Evol. 188: 87–99.     

Ribosomal DNA variation within and among individuals ofLisianthius (Gentianaceae) populations

Restriction endonuclease fragment analysis of nuclear ribosomal DNA (rDNA) was completed on 25 individuals each from seven populations of theLisianthius skinneri (Gentianaceae) species complex in Panama. Seven restriction enzymes were used to determine the amount and type of rDNA variation within and among individuals of the populations. No restriction site variation was seen within populations or individuals although site differences were seen among populations. Spacer length variation within and among individuals of populations was mapped to the internal transcribed spacer (ITS) region between the 18S and 5.8S rRNA genes, a region inLisianthius rDNA that previously was shown to exhibit length differences among populations. This is the first reported case of such variation within and among individuals of populations for the ITS region. Presence or absence of ITS spacer length variation is not correlated with levels of isozymic heterozygosity within populations. No detectable length variation within individuals or populations was seen in the larger intergenic spacer (IGS). Although populations varied with respect to IGS length, all individuals of a given population had a single and equivalent IGS length.     

The relationship between population means and variances of reproductive success differs between local populations of white stork (Ciconia ciconia)

We studied the size and productivity of white stork (Ciconia ciconia) populations in eight study sites in Poland. The number of nesting pairs and the average number of chicks fledged per pair fluctuated over time, and the studied populations differed in the variance of both breeding success and number of breeding pairs. The variance of breeding success (both for the mean number of chicks and the proportion of successful nests) and the variance of the number of breeding pairs was not correlated with the extent of stable habitats (pastures, meadows, wetlands), other habitats (farmland), or with local population trends over time. We found a non-linear symmetrical relationship between annual mean reproductive success and its variance but only when considered as the proportion of successful nests (i.e., when individual nests are coded as a binary value: 0, no success; 1, success). No such relationship existed when success was expressed as the number of fledged chicks. Although a positive significant correlation occurred between fledgling numbers (discrete data) and the proportion of successful nests (binary data), we believe that the use of only binary data will be inadequate in more detailed analyses, such as population viability analysis.     

Genetic variation of blood proteins within and between local populations of grivet monkey (Cercopithecus aethiops aethiops) in central Ethiopia

A population genetic study by blood protein electrophoresis revealed that populations of wild grivet monkeys in central Ethiopia show a comparatively low level of variability and less differentiation among local populations over broad geographical areas. This is evaluated by comparison with other wild primate studies using the same electrophoretic technique. A total of 196 blood samples, collected from 10 local populations comprising 11 troops distributed along approximately 600 km of the Awash River, were examined for 33 genetic loci. The low level of variability was indicated by the proportion of polymorphic loci (P_poly), which was on average 11% with an average heterozygosity (H) of 3%. A tendency for lower genetic differentiation among local populations was shown by theG _ST value of 0.09, an averageF _ST of 0.08, andNei's genetic distance; ranging from 0.002 to 0.023. Considering paleoclimatological studies of the area and ecological traits of this species, these findings can be explained as a consequence of a comparatively recent and repeated series of rapid habitat expansions following severe climatic conditions.     

Unique pattern of <Emphasis Type="Italic">R-</Emphasis>gene variation within populations in Arabidopsis

An understanding of the variation pattern in disease resistance (R) genes is essential for its use in breeding programs aimed at neutralizing the threat of pathogens. Although the variation between populations is well known, there is little research about R-gene variation patterns within populations. Here, we investigate the polymorphism at three R-gene loci of 39 individual plants from nine populations of Arabidopsis thaliana. Our data suggest that alleles of each locus from individuals within a local population were either nearly identical, or highly diverse as ones between populations. The vast majority (92.5%) of within-population variation was shared globally, with high levels of allelic diversity (up to 11.7%) and abundant diverse-alleles. This unique pattern of within-population variation at R-loci suggests that individual plants within a population had the great potential to maintain a high level of globally-shared polymorphisms, and that the diversifying selection was the major force maintaining such polymorphisms. Consequently, the shared-polymorphism became recyclable for new R-genes, as the corresponding avirulence re-emerges in pathogen populations. Nucleotide sequence data reported are available in the GenBank databases under the accession numbers EF368054-EF368158.     

Diversity within and between populations of two sympatrically distributed Hordeum species in Jordan

Summary The diversity of two sympatrically distributed barley species (Hordeum vulgare L. and Hordeum spontaneum C. Koch.) has been assessed for 7 morphometric and 13 qualitative traits. Phenotypically, Hordeum vulgare was more stable than Hordeum spontaneum for all morphometric traits; this is a reflection of domestication and selection. The overall diversity indexes were 0.546±0.125 and 0.502±0.113 for Hordeum vulgare and Hordeum spontaneum, respectively (P=0.095). However, Hordeum spontaneum expressed a higher level of diversity for most qualitative traits. The observed similarity for a number of diversity indexes is probably due to gene flow between the two species.     

High variability of genetic pattern in giant clam (Tridacna maxima) populations within French Polynesia

Nine populations of giant clams, Tridacna maxima, from six islands of French Polynesia were screened for allozyme variation at ten polymorphic loci. The genetic structure of populations of T. maxima were studied at different spatial scales: within an island, between islands of the same archipelago and between archipelagos. Significant genetic differences were observed only between populations from different archipelagos, and genetic differentiation was correlated with geographical separation. However, these results were only supported by a single locus, PEP * and all other loci were homogeneous between studied populations. According to Lewontin & Krakauer's model, the genetic structure can be explained by selection. The selective factors most likely depend on the respective habitat of each archipelago. We also studied genotype–phenotype correlation using the colour of the clam mantle, and did not find any relationship between the mantle colour and the genetic structure of the individuals.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 221–231.     

内蒙古中东部不同草原地带羊草种群遗传分化

运用 RAPD技术对内蒙古不同草原地带分布的 5个羊草种群 (共 10 0个个体 )的遗传多样性进行分析。 31个随机引物(10 nt)在 5个羊草种群中共检测到 4 96个扩增片断 ,其中多态性片断 4 89个 ,总的多态位点百分率达 98.6 %。利用 Nei指数和Shannon指数估算了 5个种群的遗传多样性 ,并计算种群相似系数和遗传距离运用 UPGMA法进行聚类分析。结果表明 :无论是种群内还是种群间 ,羊草均存在较高的遗传变异 ,大部分的遗传变异存在于种群内 (Nei指数和 Shannon指数估算结果分别为 85 .4 %和 72 .5 % ) ,只有少部分的遗传变异存在于种群间 ;不同种群的遗传多样性存在差异 ,各种群的遗传多样性与其所处的地理位置具有显著的相关性 ;5个种群的平均遗传距离为 0 .5 0 95 ,变异范围为 0 .4 6 84～ 0 .5 4 76 ;聚类分析结果显示地理距离较近的种群遗传距离较小 ,首先聚在一起 ,而地理距离较远的种群遗传距离较大 ,说明羊草种群间的遗传分化与地理距离存在一定相关性 ;但地理距离最近的两个种群并未最先聚集 ,说明羊草种群间的分化还与其生境的异质性有关     

Comparative bionomics of four populations of Meccus longipennis (Hemiptera: Reduviidae: Triatominae) under laboratory conditions

The values of biological parameters related to the life cycles of four populations of Meccus longipennis (Reduviidae: Triatominae) were evaluated. Cohorts of each of the four studied populations from different geographical areas of Mexico were maintained under similar laboratory conditions and then compared. The population from El Saucito de Araujo was different from the other three studied populations, which could help explain the secondary importance of M. longipennis in the state of Chihuahua. This paper also supports the proposition that biological traits are important criteria for determining relationships between populations.     

Development of microsatellites for the genus Salamandrina: A tool to discriminate between northern and southern spectacled salamanders (Salamandrina perspicillata and Salamandrina terdigitata) and their hybrids

Ten microsatellite loci were developed for the northern spectacled salamander, Salamandrina perspicillata, and cross-amplification was obtained for the southern spectacled salamander, Salamandrina terdigitata. These two species are the sole representative of the genus Salamandrina, a threatened amphibian endemic to the Italian peninsula. The two salamanders show a parapatric distribution with a contact zone in Central Italy. All but one locus were polymorphic and six microsatellites were found diagnostic for species discrimination. We genotyped a total of 169 individuals. Allelic diversity was 5.1 ± 1.5 SE in S. perspicillata and 1.9 ± 0.31 SE in S. terdigitata. Mean observed and expected heterozygosity were 0.51 ± 0.06 SE and 0.61 ± 0.07 SE, respectively in the northern spectacled salamander and 0.35 ± 0.15 SE and 0.35 ± 0.09 SE, respectively in the southern spectacled salamander. These new markers will provide an excellent tool to assess population structure and genetic diversity in Salamandrina and will be used to investigate natural hybridization events between northern and southern spectacled salamanders.     

四种松毛虫不同地理种群遗传多样性的等位酶分析

【目的】采用等位酶电泳技术对中国松毛虫属Dendrolimus 4种共9个地理种群进行遗传多样性和遗传分化研究。【方法】对6种等位酶系统乳酸脱氢酶（LDH）、苹果酸脱氢酶（MDH）、苹果酸酶（ME）、乙醇脱氢酶（ADH）、甲酸脱氢酶（FDH）、谷氨酸脱氢酶（GDH）进行聚丙烯酰胺凝胶电泳分析。【结果】在4种松毛虫9个地理居群中共检测到10个基因位点,其中4个位点为多态位点,检测到17个等位基因; 种群总体水平多态位点比率P=40%,平均有效基因数A=1.700,平均期望杂合度He=0.151,种群平均遗传距离为0.001～0.285; 其中马尾松毛虫指名亚种Dendrolimu punctatus Walker 6个居群的遗传分化度Fst=0.265,基因流Nm=0.692。4种松毛虫之间遗传关系最近的是落叶松毛虫D. superans Butler和马尾松毛虫的地理亚种赤松毛虫D. punctatus spectabilis Butler,遗传关系最远的是落叶松毛虫D. superans Butler和云南松毛虫D. houi Lajonquiere。【结论】 马尾松毛虫居群间遗传分化程度较大,基因交流较少,遗传漂变已经成为导致该物种种群分化的主要原因之一;遗传距离与地理距离存在一定相关性。     

Genetic variation in island populations of tuatara (<Emphasis Type="Italic">Sphenodon</Emphasis> spp) inferred from microsatellite markers

Tuatara (Sphenodon spp) populations are restricted to 35 offshore islands in the Hauraki Gulf, Bay of Plenty and Cook Strait of New Zealand. Low levels of genetic variation have previously been revealed by allozyme and mtDNA analyses. In this new study, we show that six polymorphic microsatellite loci display high levels of genetic variation in 14 populations across the geographic range of tuatara. These populations are characterised by disjunct allele frequency spectra with high numbers of private alleles. High F _ST (0.26) values indicate marked population structure and assignment tests allocate 96% of all individuals to their source populations. These genetic data confirm that islands support genetically distinct populations. Principal component analysis and allelic sequence data supplied information about genetic relationships between populations. Low numbers of rare alleles and low allelic richness identified populations with reduced genetic diversity. Little Barrier Island has very low numbers of old tuatara which have retained some relictual diversity. North Brother Island’s tuatara population is inbred with fixed alleles at 5 of the 6 loci.     

Phylogenetic relationship of the populations within and around Japan using 105 short tandem repeat polymorphic loci

We have analyzed 105 autosomal polymorphic short tandem repeat (STR) loci for nine East and South-eastern Asian populations (two Japanese, five Han Chinese, Thai, and Burmese populations) and a Caucasian population using a multiplex PCR typing system. All the STR loci are genomewide tetranucleotide repeat markers of which the total number of observed alleles and the observed heterozygosity were 756 and 0.743, respectively, for Japanese populations. Phylogenetic analysis for these allele frequency data suggested that the Japanese populations are more closely related with southern Chinese populations than central and/or northern ones. STRUCTURE program analysis revealed the almost clearly divided and accountable population structure at K=2–6, that the two Japanese populations always formed one group separated from the other populations and never belong to different groups at K≥3. Furthermore, our new allele frequency data for 91 loci were analyzed with those for 52 worldwide populations published by previous studies. Phylogenetic and multidimensional scaling (MDS) analyses indicated that Asian populations with large population size (six Han Chinese, three Japanese, two Southeast Asia) formed one distinct cluster and are closer to each other than other ethnic minorities in east and Southeast Asia. This pattern may be the caviar of comparing populations with greatly differing population sizes when STR loci were analyzed.     

Distribution of genetic diversity within and between Western Mediterranean island populations of the black rat Rattus rattus (L. 1758)

Genetic diversity was estimated by allozyme analysis at 26 loci in black rat populations (Rattus rattus) from 15 western Mediterranean islands (Hyéres, Corsica, Sardinia and related islets). Although overall variability levels were low (H = 0.025), the mean heterozygosity values for the islands were similar to those for three reference mainland populations. Within the islands, however, genetic diversity varied in relation to island size and geographic isolation. In particular, most small insular populations were significantly more variable than those on both large and isolated islands. The generic relationships between island populations were established by F_ST analyses indicating possible geographic origins and patterns of colonization. The maintenance of unexpectedly high levels of variability in the small island populations is discussed in relation to changes in the demographic and social structure observed in these populations. These island populations of black rat illustrate how genetic diversity may be efficiently maintained in a series of interconnected spatially fragmented populations.     

Evolutionary relationship between Enterobacteriaceae: comparison of the ATP synthases (F1F0) of Escherichia coli and Klebsiella pneumoniae

The ATP synthase complex of Klebsiella pneumoniae (KF₁F₀) has been purified and characterized. SDS-gel electrophoresis of the purified F₁F₀ complexes revealed an identical subunit pattern for E. coli (EF₁F₀) and K. pneumoniae. Antibodies raised against EF₁ complex and purified EF₀ subunits recognized the corresponding polypeptides of EF₁F₀ and KF₁F₀ in immunoblot analysis. Protease digestion of the individual subunits generated an identical cleavage pattern for subunits , , , , a, and c of both enzymes. Only for subunit different cleavage products were obtained. The isolated subunit c of both organisms showed only a slight deviation in the amino acid composition. These data suggest that extensive homologies exist in primary and secondary structure of both ATP synthase complexes reflecting a close phylogenetic relationship between the two enterobacteric tribes.Abbreviations ACMA 9-amino-6-chloro-2-methoxyacridine - DCCD N,N-dicyclohexylcarbodiimide - FITC fluorescein isothiocyanate - SDS sodium dodecyl sulfate - TTFB 4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazole     

Parasitic systems and the structure of parasite populations

 The analysis of population systems is carried out on the basis of the spatial and functional classification of populations developed by V.N. Beklemishev. The population system is a functional part of a particular community. Steady interrelationships between population systems of different species within the community (referred to as ”community links”) appear to be a prerequisite for the formation of a complex of population systems. A prominent example of this is the parasitic system. The parasitic system is the population system of a parasite with all the connected populations of its hosts. The complexity of a parasitic system depends on: (1) peculiarities of the life cycle of the parasite, since its population system is the organizing component of the parasitic system and (2) subdivision of the environment for the parasites. The first trait is discussed from the standpoint of the phase structure of populations, which is clearly seen in parasites. The second one comprises the organization of the parasites’ environment according to the scale of variability (interspecies, interpopulation or intrapopulation) of hosts. These make it possible to recognize spatial and functional parts in the framework of the parasitic system. A critical review of the terminology is presented together with a list of the pertaining vocabulary. Received: 15 January 1998 / Accepted: 15 October 1998     

Population structure and genetic diversity of four Henan pig populations

To investigate the population structure and genetic diversity of Henan indigenous pig breeds, samples from a total of 78 pigs of 11 breeds were collected, including four pig populations from Henan Province, three Western commercial breeds, three Chinese native pig breeds from other provinces and one Asian wild boar. The genotyping datasets were obtained by genotyping‐by‐sequencing technology. We found a high degree of polymorphism and rapid linkage disequilibrium decay in Henan pigs. A neighbor‐joining tree, principal component analysis and structure analysis revealed that the Huainan and Erhualian pigs were clustered together and that the Queshan black pigs were clearly grouped together but that the Nanyang and Yuxi pigs were extensively admixed with Western pigs. In addition, heterozygosity values might indicate that Henan indigenous pigs, especially the Queshan black and Huainan pigs, were subjected to little selection during domestication. The results presented here indicate that Henan pig breeds were admixed from Western breeds, especially Nanyang and Yuxi pigs. Therefore, establishment of purification and rejuvenation systems to implement conservation strategies is urgent. In addition, it is also necessary to accelerate genetic resources improvement and utilization using modern breeding technologies, such as genomic selection and genome‐wide association studies.     

The relationship between reproductive success and demographic structure in remnant populations of Primula veris

Plants often suffer reductions in fecundity due to fragmentation, degradation and destruction of populations and their sites. Whether this decrease in seed production has population-level consequences is generally unknown. Here, we aimed to determine the current status of remnant populations in the perennial herb Primula veris in Belgium. Furthermore, we investigated the effects of reduced population size and morph bias on reproductive success and explored if changes in demographic structure could be associated with population fecundity. We studied 69 populations that differed in population size from three to nearly 1500 flowering plants. Three different population types could be distinguished: (a) “dynamic” populations, characterized by high densities of 1 year old juveniles, (b) “normal” populations with adult age-stages prevailing, but still a considerable number of juveniles, and (c) “regressive” populations, in which only flowering adults dominate and rejuvenation hardly occurs. The three population types differed with respect to population size and morph frequency. Dynamic populations were significantly larger and showed a weaker morph bias compared to the intermediate normal and the small regressive populations. Reproductive success, studied the previous year in 26 populations, decreased significantly with decreasing population size and was significantly associated with the demographic structure of the populations. Coefficients of variation for the proportion of flowers setting fruit, the number of seeds per fruit and the total number of seeds per plant decreased significantly with increasing population size. Hence, the observed variability in seed set may be one of the causal factors affecting the observed types of population demographic structure.     

Quantitative resistance differences between and within natural populations of Solanum chilense against the oomycete pathogen Phytophthora infestans

The wild tomato species Solanum chilense is divided into geographically and genetically distinct populations that show signs of defense gene selection and differential phenotypes when challenged with several phytopathogens, including the oomycete causal agent of late blight Phytophthora infestans. To better understand the phenotypic diversity of this disease resistance in S. chilense and to assess the effect of plant genotype versus pathogen isolate, respectively, we evaluated infection frequency in a systematic approach and with large sample sizes. We studied 85 genetically distinct individuals representing nine geographically separated populations of S. chilense. This showed that differences in quantitative resistance can be observed between but also within populations at the level of individual plants. Our data also did not reveal complete immunity in any of the genotypes. We further evaluated the resistance of a subset of the plants against P. infestans isolates with diverse virulence properties. This confirmed that the relative differences in resistance phenotypes between individuals were mainly determined by the plant genotype under consideration with modest effects of pathogen isolate used in the study. Thus, our report suggests that the observed quantitative resistance against P. infestans in natural populations of a wild tomato species S. chilense is the result of basal defense responses that depend on the host genotype and are pathogen isolate‐unspecific.