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1.
Fossil wood is both abundant and ubiquitous through geological time and space. During growth the parent plant was directly influenced by the biotic and abiotic (including climatic-) factors in the surrounding environment. The climate affects wood production in a number of ways and it is the resulting physiognomic and chemical characters that can help retrodict palaeoclimate. Physiognomic characters include those morphological and anatomical characters that in turn have enabled the use of wood characters, tree ring characters and statistical parameters (Mean Sensitivity) to determine seasonality, length and favourability of growing season, growth rates and forest productivity. Potential chemical characters discussed include (i)␣the preservation of wood-derived compounds (e.g. guaiacyl, syringyl p-hydroxyphenyl and resins); (ii)␣degree of lignin degradation to determine climate induced environmental changes; and (iii) stable isotopes (δD, δ13C and δ18O) to help determine aspects of past climates as derived from environmental changes. The feasibility and methodology of these characters, in both angiosperm and conifer wood, are reviewed in order to establish certain safe guards, or prerequisites, such that interpretations of palaeoclimate can be as unbiased, and thus as reliable, as possible.  相似文献   

2.
We have studied the genetic properties of five S. aureus strains (serotypes 18 and III) isolated in France during a recent outbreak and carrying two new resistance characters (tobramycin and streptogramin). After transfer by transduction of these resistances, recipient cells were found in each case to harbor a single multicopy plasmid carrying the two resistance characters plus resistance to cadmium salts and/or resistance to tetracycline. The five Sgr-Tmr plasmids recovered by transduction are related epidemiologically; all five belong to the same incompatibility group and they share from 50 to 100% base sequence homology. Three of the five have similar restriction endonuclease patterns.  相似文献   

3.
The stability of complex patterns of geographic variation was investigated by assessing the congruence between multivariate ordinations derived from randomly chosen real characters. Two series of populations were analysed representing two situations with complex patterns of geographic variation. The first, a ‘Eurasian’ series of populations, showed a strongly structured hierarchical pattern, the second, an ‘eastern’ series of populations, showed a more subtle complex pattern of smooth clines and steps. The characters were selected from a total of 81 (Eurasian) or 61 (eastern) within-population independent characters from six different systems. The congruence between ordinations of the geographical populations was measured by the rotational fit statistic, R2. Three procedures were used to compare ordinations based on from two to up to 80 characters randomly chosen to give: A, completely independent character sets; B, subsets compared to the total set; and C, potentially overlapping sets. All three procedures showed that congruence between the ordinations was asymptotic in relation to character number. This relationship was described by one of two mathematical models (procedure B did not result in a hyperbolic model as found with simple patterns of geographic variation). Generally speaking, once a sufficient number of characters are used, the complex patterns of geographic variation are stable, reliable and predictive and not substantially influenced by character choice. The strongly structured hierarchical pattern required 15 or so characters to achieve reliability whilst the more subtle patterns required 20 or so characters. However, the addition of further characters does improve reliability in both cases. The greater percentage of variance portrayed by three-dimensional ordinations compared to two-dimensional ordinations is achieved at the cost of lower congruence when a sufficient number of characters are used. If case studies of geographic variation were to adopt these procedures (preferably using completely independent character sets; procedure A) the reliability of their results would be indicated).  相似文献   

4.
杜鹃花属种类繁多,广泛分布于欧亚大陆和北美大陆,由于种间变异大、过渡特征丰富,其分类鉴定一直存在较多争议。该研究通过扫描电镜对常绿杜鹃亚属(subgen. Hymenanthes)麻花杜鹃亚组(subsect. Maculifera)的11种3变种植物的叶表皮微形态特征进行观察,为麻花亚组的分类与鉴定提供新的依据。结果显示:麻花杜鹃亚组植物上表皮表面平滑或粗糙、无表皮毛,具有条状、分枝状或短杆状初级蜡质纹饰;下表皮表面有或无分枝状蜡质纹饰,少部分具有表皮毛,不具有指状或乳状突起、亦无腺体;气孔器形状为圆形或椭圆形,内外拱盖表面粗糙或光滑,周围无间断的条形突起环绕。研究表明,麻花杜鹃亚组植物叶片微形态特征表现出一定的共性与多样性,可为麻花杜鹃亚组植物的分类和进化研究补充形态学依据。依据本研究观察结果对麻花杜鹃亚组进行了分类检索,并讨论了叶表皮微形态特征在该亚组近缘物种和种下类群研究中的分类学意义。  相似文献   

5.
Growth of Japanese macaques during their first year was analyzed longitudinally, using body measurements. Measurements of 44 somatometrical characters were taken on seven animals. Work with the newborn data produced a formula which fits well. The formula is: y=a (x+b) n (y=size, x=age). At first, growth was analyzed, character by character, using birth sizes and incremental increases. The results show a major growth pattern for many characters: increments vary inversely with birth size. Application of the growth formula produced two further insights: (1) growth pattern is not so simple as imagined from the birth size-increment pattern; and (2) the characters which deviate from the birth size-increment pattern have large growth only at the earliest period (in few months), in spite of their small size. Sex differences were clear within the first year, especially for characters which differ greatly between adults.  相似文献   

6.
Summary Electrofocusing and agarose electrophoresis techniques both reveal polymorphism of ESD 2, which may be subdivided into two different proteins, coded for by genes allelic to ESD *1. After agarose electrophoresis, ESD 2 is slightly more anodally located than ESD 5, while the latter is considerably more acidic as revealed by electrofocusing in polyacrylamide gel slabs. Family studies have confirmed that each of the allele products behave as Mendelian characters: and the gene frequencies in a Norwegian population material are about 0.08 and 0.02 for the ESD *2 and ESD *5 alleles, respectively.  相似文献   

7.
Summary Twenty characters were measured on 60 tomato varieties cultivated in the open-air and in polyethylene plastic-house. Data were analyzed by means of principal components, factorial discriminant methods, Mahalanobis D2 distances and principal coordinate techniques. Factorial discriminant and Mahalanobis D2 distances methods, both of which require collecting data plant by plant, lead to similar conclusions as the principal components method that only requires taking data by plots. Characters that make up the principal components in both environments studied are the same, although the relative importance of each one of them varies within the principal components. By combining information supplied by multivariate analysis with the inheritance mode of characters, crossings among cultivars can be experimented with that will produce heterotic hybrids showing characters within previously established limits.  相似文献   

8.
Synopsis Examination of more than 2,000 alewives (Alosa pseudoharengus) and blueback herring (A. aestivalis) from various areas in the Saint John River, N.B., showed differences in their morphometric and meristic characters. They differed also in length and age, compositions, spawning time, length and age at maturity, back-calculated lengths, and growth parameters. Within each species, between-area comparisons showed significant differences in some of their meristic characteristics.To test a homing hypothesis for alewives, a multivariate analysis was performed on eight meristic characters. Two discriminant function programs, discriminant analysis for two groups and a multiple group stepwise discriminant analyses were used. Values of the generalized Mahalanobis D2 and percent overlap in frequency distributions of meristic characters suggest that considerable straying of fish, especially between adjacent areas occurs during upstream spawning migration.This article is one of several papers presented at the Second European Ichthyological Congress, Paris, 8–15 September 1976, to be published in Environmental Biology of Fishes.  相似文献   

9.
Identification of alleles responsible for various agro-morphological characters is a major concern to further improve the finger millet germplasm. Forty-six genomic SSRs were used for genetic analysis and population structure analysis of a global collection of 190 finger millet genotypes and fifteen agro-morphological characters were evaluated. The overall results showed that Asian genotypes were smaller in height, smaller flag leaf length, less basal tiller number, early flowering and early maturity nature, small ear head length, and smaller in length of longest finger. The 46 SSRs yielded 90 scorable alleles and the polymorphism information content values varied from 0.292 to 0.703 at an average of 0.442. The gene diversity was in the range of 0.355 to 0.750 with an average value of 0.528. The 46 genomic SSR loci grouped the 190 finger millet genotypes into two major clusters based on their geographical origin by the both phylogenetic clustering and population structure analysis by STRUCTURE software. Association mapping of QTLs for 15 agro-morphological characters with 46 genomic SSRs resulted in identification of five markers were linked to QTLs of four traits at a significant threshold (P) level of ≤0.01 and ≤0.001. The QTL for basal tiller number was strongly associated with the locus UGEP81 at a P value of 0.001 by explaining the phenotypic variance (R 2) of 10.8 %. The QTL for days to 50 % flowering was linked by two SSR loci UGEP77 and UGEP90, explained 10 and 8.7 % of R 2 respectively at a P value of 0.01. The SSR marker, FM9 found to have strong association to two agro-morphological traits, flag leaf width (P—0.001, R 2—14.1 %) and plant height (P—0.001, R 2—11.2 %). The markers linked to the QTLs for above agro-morphological characters found in the present study can be further used for cloning of the full length gene, fine mapping and their further use in the marker assisted breeding programmes for introgression of alleles into locally well adapted germplasm.  相似文献   

10.
Asymmetry has been used as a measure of developmental stability for bilaterally symmetrical organisms. Most studies have failed to partition the genetic and environmental contributions to the asymmetry phenotype due to the limitations of the systems used or the shortcomings in experimental design. The Notch mutants of Drosophila melanogaster were used to study the genetic contribution to asymmetry for six different bristle characters. Asymmetry response was character specific for the mutants examined. For N spl, N Co, N 264–47, Ax 71d, Ax 9B2, Ax E2, l(1)N B and nd 2 significant asymmetry responses, relative to wildtype Canton‐S, were observed for some characters. N 60g11 and nd 1 did not exhibit significant asymmetry for any of the characters examined. All of the mutants except N 60g11 and nd 1 showed thoracic bristle asymmetry. However, when asymmetry scores were pooled over the five bristle characters which individually exhibited fluctuating asymmetry, no significant differences were found between any genotypes. Therefore pooling asymmetry values across characters obscures the significant character specific asymmetry values observed. Thus caution is necessary when using the asymmetry phenotype of specific characters to draw organism wide conclusions about developmental stability. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

11.
In the recent years using non-traditional sources, i.e. saline water in irrigation becomes essential. Overcoming the toxic effects of salinity stress and improving salt tolerance is consider one of the challenges for enhancing germination, seedling characters and biochemical analysis. Therefore, a laboratory experiment was conducted to study the response of seven Egyptian flax cultivars i.e. (Giza 9, Giza 10, Giza 11, Giza 12, Sakha 2, Sakha 5 and Sakha 6) germinated under five salinity stress i.e. (control, 3, 6, 9 and 12?dS?m?1) at Research Institute of Nyiregyhaza using Factorial Experimental in Randomized Complete Block Design (RCBD) with four replications. The following results were recorded: Tested Egyptian flax cultivars significantly varied for germination characters, seedling properties and chemical analysis. Giza 11 exceeded recorded the maximum values of germination and seedling characters, potassium and proline content compared with the other studied cultivars. Increasing salinity stress up to 12?dS?m?1 significantly affected germination characters, seedlings parameters and chemical analysis. In general, Giza 11 cultivar substantiated best at high level of salinity stress compared with other studied cultivars. Furthermore, produced the lowest values of Na+ content.  相似文献   

12.
Missing data are commonly thought to impede a resolved or accurate reconstruction of phylogenetic relationships, and probabilistic analysis techniques are increasingly viewed as less vulnerable to the negative effects of data incompleteness than parsimony analyses. We test both assumptions empirically by conducting parsimony and Bayesian analyses on an approximately 1.5 × 106‐cell (27 965 characters × 52 species) mustelid–procyonid molecular supermatrix with 62.7% missing entries. Contrary to the first assumption, phylogenetic relationships inferred from our analyses are fully (Bayesian) or almost fully (parsimony) resolved topologically with mostly strong support and also largely in accord with prior molecular estimations of mustelid and procyonid phylogeny derived with parsimony, Bayesian, and other probabilistic analysis techniques from smaller but complete or nearly complete data sets. Contrary to the second assumption, we found no compelling evidence in support of a relationship between the inferior performance of parsimony and taxon incompleteness (i.e. the proportion of missing character data for a taxon), although we found evidence for a connection between the inferior performance of parsimony and character incompleteness (i.e. no overlap in character data between some taxa). The relatively good performance of our analyses may be related to the large number of sampled characters, so that most taxa (even highly incomplete ones) are represented by a sufficient number of characters allowing both approaches to resolve their relationships. © The Willi Hennig Society 2009.  相似文献   

13.
Inheritance of morphological characters related to male and female genitalia was examined in Archips podanaScop. The position and number of aedeagus prongs had a monogenic diallelic mode of inheritance. The gene determining this character is autosomal. Homozygous and heterozygous males have respectively one and two prongs. In contrast to homozygous for P 1(prong A) and heterozygous (prong A+B) males, males homozygous for P 2(prong B) were characterized by much more active courtship. The gene correlates with a set of characters controlling individual ecology, exploring behavior of females, and feeding on different cultures. Morphological adult type 0 is an extremely weak form of phenotype B. Exploring activity of adults having phenotype B is the highest at the ratio of cis-11-tetradecenol to the other components of the female sex pheromone that leads to a somewhat lower activity of males of other phenotypes. In females, no regularities in inheritance of phenotypic characters were revealed. A hypothesis on a mechanism for maintenance of population stability for the given phenotypes is advanced and a possible mechanism for microevolution of a polymorphic species is proposed.  相似文献   

14.
Leaf growth patterns were investigated in 11 evergreen (with leaf life-spans of just more than 1 year) and 15 deciduous species, occurring along an elevational gradient of 600–2200 m elevation in the Central Himalaya. Records were made of the leaf initiation period, leaf population dynamics, leaf expansion, leaf mass changes, leaf longevity and related parameters. Species of both groups produced leaves at similar rates during March to April, the driest period of the year. Species of both groups had approximately fully developed foliage during the warm, wet period (mid-June to mid-September) of the monsoon. However, significant differences were found at group level in other characters: shoot length (19.5 cm per shoot for deciduous and 11.7 cm for evergreen species); leaf population per 10 cm shoot length (4.7 vs 15.0); leaf area (107.9 vs 41.4 cm2/ leaf); specific leaf mass (106.9 vs 191.3 g/m2); and leaf mass loss after the monsoon period, being rapid and higher (31.6%) in deciduous species and slow and limited in the evergreens (26.2%). However, species of the two groups showed considerable overlaps in the values of above characters. The evergreen species of the Central Himalaya resembled the deciduous species of the region more than the multi-year leaves of clearly evergreen species. The evergreens bear leaves throughout the year, but like deciduous species bear the cost of annual replacement of old leaves by new leaves. They seem to outcompete deciduous species by producing annually a greater mass of leaves of low-carbon cost (per unit leaf mass), which is capable of conducting photosynthesis all year round. A situation of less marked contrast between favourable and nonfavourable periods, with respect to temperature, seems to favour the leaf characters of the evergreens.  相似文献   

15.
To discover whether the protoplast fusion method is useful or not for interspecific breeding, some methods were devised, and the appearance of various hybrids with different characters and the change of antibiotic activities in the recombinants obtained by the protoplast fusion were investigated. The purification of protoplasts, the choice of parental natural characters as selection markers, and the adoption of a replica method for selecting all types of recombinants were devised and used for these experiments. Protoplast fusion was done between S. griseus KCC S-0644 and each strain of 5 species that were clearly different species from S. griseus, in addition to being streptomycin sensitive (SMs) and capable of L-arabinose utilization for growth (Ara+). Recombinants (SMr, Ara+) obtained by protoplast fusion displayed a great variety of hybrids in their taxonomic characters, e.g., 21 recombinant strains obtained by the cross between S. griseus and S. griseoruber consisted of 14 types of hybrids. Antibiotic productivity was examined in all recombinants obtained. Although both parental species produced their respective antibiotics, 60% of the recombinants did not produce any antibiotic and 24% produced different antibiotics from those of their parents. Among those recombinants, it was also found that the distribution of the productivity of each antibiotic among the recombinants was entirely different from that of the allelo-character in each taxonomic feature.  相似文献   

16.
Summary Thirty okra genotypes of diverse eco-geographical origin were grown in single-row plots in a randomised complete block design. The data collected on 14 characters were subjected to analysis of variance. By multivariate analysis (Mahalanobis D2 technique), the genetic divergence among the genotypes were quantitatively measured. The genotypes were grouped into five clusters by this technique. There was no relationship between clustering pattern and eco-geographic distribution. The effects of genetic divergence on the choice of parental stock in hybridization was discussed.  相似文献   

17.
18.
A diallel cross was carried out among seven varieties of white clover to investigate the inheritance of some of those characters which affect potential seed yield. Peduncle length and number of seeds/floret have low narrow-sense heritabilities, while peduncle length displays the added complications of heterozygosity and non-allelic interactions. Consequently, improvements in these characters will be difficult. Seed number m-2 is a composite character which apparently exhibits heterozygosity. Higher seed yields will therefore be obtained by selection for its component characters, particularly floret number and floral density, both of which are apparently inherited in a comparatively straightforward manner. These results are discussed in the context of improving the potential seed yield of white clover.  相似文献   

19.
Summary A variety of conditions caused both, the f+ antigen and fr-receptor sites of E. coli strains to appear or disappear simultaneously: Both characters were lost after temperature-downshift, they were recovered after temperature-upshift; fr-refractory mutants failed to absorb f+ antibodies. Strains, genetically labelled with an Flac+ episome permitted the differentiation of an episomal and a chromosomal lesion, both of which affected the receptor site for fr, and at least one of which (episomal lesion) affected the formation of the f+ antigen as well. (In addition, strains lacking fr receptors had exhibited a significant reduction of their capacity to form recombinants.) The results provide strong correlative evidence for the identity of the f+ antigen and the cellular receptor for fr. The results provide additional evidence for the identity of the phage- and the mating-specific sites on E. coli.  相似文献   

20.
Results of experiments concerning comparison of tomato fruit properties which were collected from plants obtained in three manners are described. Control plants were received from seeds. Remaining plants were derived in vitro from leaf and shoot fragments on MS medium supplemented with IAA 0.2 mg·l−1 and BA 2 mg·l−1 (Górecka and Krzyżanowska 1991, Górecka et al. 1994) or with Fari’s et al. (1992) method of obtaining plants by decapitation of sterile seedlings and culture on MS medium without hormones. Evaluation of physical and chemical fruit characters was performed. In the spring experiment the biggest diameter (72 mm), weight (154 g) and volumne (151 ml) were characterized to fruits from plants obtained in vitro on MS medium with IAA and BA. Also fruits from plants received by Fari’s methods were significantly superior in these characters over fruits from the control plants. The fruits from the plants obtained in vitro on MS medium with IAA and BA had highest sugar content (2.95 % f.wt.) and fruits from in vitro plants after Fari’s method contained highest vit.C-13.4 mg·100 g−1 f.wt (significant differences in comparison to control fruits). In other characters fruits from in vitro did not differ as compared to control ones. In the autumn experiments significant differences among fruit groups and characters evaluated were not stated. Generally, yield quality was poorer in the all autumn treatments.  相似文献   

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