Population genetics of Dagestan highlanders

Subdivision of some isolates and heterogenic populations in Daghestan is analysed by human gene and phen frequencies. Comparative population study of phenotypic variability of quantitative characters (anthropometric, neurodynamic and psychodynamic) is carried out. Common hierarchy of variability for all populations as well as an effect of inbreeding and panmixis on variability of the above-mentioned quantitative characters in different populations is demonstrated.     

Heritability of neurodynamics and psychodynamics in human populations

A component analysis of human neurodynamic and psychodynamic characters in the norm was carried out in 8 human populations characterized by different degrees of isolation and ethnic origin. An increase in phenotypic variability and a decrease in heritability with increasing complexity of organization of the characters under study were demonstrated for all these populations. The additive effect plays the major role in genetic determination of neurodynamic and psychodynamic characters studied. For a number of neurodynamic parameters the effect of intralocus dominance indicative of the oligogenic determination system was observed. Data in favour of real contribution of the factors linked to X-chromosome were obtained for simple sensomotor reactions.     

激光诱变小麦生育期性状和穗部性状的生物学效应研究

本试验采用N2激光和He—Ne激光辐照“绵阳21号”等四个小麦材料的干种子,采用随机区组设计,重复三次,利用生物统计和数量遗传学的方法,对L。和L：两代的抽穗期、开花期等4个生育期性状及穗长、小穗粒数等10个穗部性状的遗传变异进行研究。结果表明：辐射材料不同,诱变后代的变异差异明显;激光种类不同,后代变异差异不大;抽穗期穗长、小穗粒数的遗传力较高,早代单株选择的效果较好。     

Genetic analysis of ecologically relevant morphological variability in Plantago lanceolata L.

Summary Morphological variability was studied in two populations of Plantago lanceolata using diallel analysis. In each population, reciprocal crosses between all possible pairs of ten plants were made. In the greenhouse, six members of each family were grown and many characters were measured. Using the model of Cockerham and Weir, the contributions of the different genetic variance components were calculated. From earlier papers it was postulated in advance to what extent and by which effect the characters in both populations were genetically determined. The populations had been differentiated for life history and morphological characters, and varied also in the relative contribution of genetic components to variability. In the Merrevliet (Me) population, where strong biotic selection was assumed, low levels of additive-genetic variability were present and the relative dominance appeared to be high. The contrasting population, Westduinen (Wd), which is abiotically controlled and shows strong environmental variability, possessed higher levels of additive-genetic variability and lower levels of relative dominance. It is possible that differential natural selection has diminished additive-genetic variability to different extents in both populations: plasticity and environmental heterogeneity prevented the loss of additive-genetic variability in Wd, whereas in the stable population, Me, natural selection had the opportunity of not only changing the means of the characters but also of diminishing additive-genetic variability to a great extent.Grassland Species Research Group Publication No. 146     

The composition of a population of cloned cultures of revertant Vibrio cholerae L forms

The process of L-transformation and L-transformed state duration have been studied for their effect on variability of main characters of revertant cultures of choleric vibrions L-forms at the population level with the use of cloned cultures of the choleric vibrions. The study was conducted on two strains of the choleric vibrion of the eltor biovar in different periods of storage in the L-transformed state (1, 3, 6 months). It has been revealed that characters of the species and biovar remained stable despite the influence of L-transforming agents. The characters of clone cultures characterizing virulence (sensitivity to KhDF phages, hemolytic activity, toxin production and virulence for sucking rabbits proved to be subjected to variability to the greatest extent with simultaneous preservation of the toxin-production gene. A resistant change of the serovar (from Inaba to Ogava) is observed only in one revertant-subculture of the virulent strain.     

Genetic variability in two West Indian anoles (Reptilia, Iguanidae): relation to field thermal biology

Meristic and electrophoretic characters were used as independent estimators of genetic variability within populations of two West Indian Anolis lizard species. The species which uses flexible regulatory behaviours to maintain thermal homeostasis, A. roquet on Martinique, exhibited much less within-population electrophoretic variability than did the species which is behaviourally passive to changes in the thermal environment, A. gundlachi on Puerto Rico. The data suggest that the high genetic variability in A. gundlachi may be an adaptation to its coarse-grained perception of seasonal variation in the thermal environment, whereas A. roquet's low genetic variability may be adaptive because its flexible regulatory behaviours provide a temporally fine-grained perception of the thermal environment. Meristic characters did not demonstrate any interspecific difference in the amount of within-population genetic variability. Discordance in the results of the meristic and electrophoretic analyses suggest either that the two character sets sample dramatically different genetic phenomena or that environmental effects on the development of meristic characters render them unreliable as indicators of the genetic variability within geographically proximate populations.     

Anthropometric multivariate structure and dermatoglyphic peculiarities in biochemically and morphologically different heterozygous groups

Multivariate analysis of the relationship between degree of heterozygosity at four blood group loci and the morphological variability in a human population was carried out. Additionally, the possibility that dermatoglyphic patterns correlate with biochemical and anthropometric variables was also investigated. A strong and significant increase in the frequency of morphologically multimodal individuals was observed, which paralleled the heterozygosity level. Discriminant analysis, by quantitative characters, of the closest pair of biochemically different samples yielded a satisfactory discrimination. Multiple correlations of each variable with all the others (18 traits), the communality of characters, the index of integration, and the Mahalanobis distances of the factor scores for each individual (all extracted from principal component analysis) were all indicative of the different multivariate structures of homo- and heterozygous individuals and thus supported the hypothesis that heterozygotes tend to cluster near the center of the joint multivariate distribution. The dermatoglyphic patterns showed a certain relationship with the morphological makeup of individuals. Correlations between biochemical heterozygosity at blood group loci and patterns of digital dermatoglyphics were rather irregular.     

Phenotypic and genetic differentiation of human populations with respect to morphologic and psychophysiological traits

Four groups of human characters (mendelian markers, anthropometry, neurodynamics and psychodynamics) were studied in eight human populations characterized by different degrees of isolation and different ethnic backgrounds, and located in different ecological conditions. The populations examined were proved to display phenotypic and genetic differentiation for the studied groups of characters which were compared with linguistic and geographical distances. The role of genetic factors and that of environmental factors was shown to diminish and to increase, respectively, as the degree of complexity of expression of the group of characters under study (from anthropometry to psychodynamics) goes up.     

Immune response to parasitic attack: evolution of a pulsed character

Pulsed characters are temporary biochemical, cellular, or structural changes produced in response to environmental or biotic challenge. For example, response to parasitic attack develops as a pulse of defensive chemicals or cells that typically decay after the parasite has been controlled. Almost all theories for the genetic variability of characters assume measurements on static characters. This paper presents theoretical tools to examine optimal control variables for pulsed characters and the expected level of genetic variability in those control variables. The example of host immune response to parasitic attack is used to develop the theory.     

Numerical classification of species of Vibrio and related genera

Data from 1091 strains of the family Vibrionaceae collected in five different studies have been merged into a single data matrix and analysed in a taxonomic study. A set of 142 characters was selected to compare these data. Seventy-nine characters were common to all studies, but data for the other 63 characters were incomplete. Cultures of 90 strains, examined in more than one of the original studies, were used to estimate test error and inter-study variability. The data from these replicate strains also allowed the problem of merging data from different studies to be assessed. Taxonomic resemblance was estimated on the basis of 111 characters using the S_SM coefficient and UPGMA clustering. A taxonomic analysis based on 999 strains, which included most of the major species of the family Vibrionaceae, gave 59 clusters and 44 unclustered strains. A table of properties of these phenons was produced. The results showed that data obtained from studies carried out at different times and in different locations, but using standard techniques, could be combined and used to provide useful taxonomic information.     

Liquid nitrogen storage of yeast cultures. II. Stability of characteristics of stored strains

Nineteen strains of yeasts possessing different characteristics were stored in liquid nitrogen and after 5 years phenotypic characters were evaluated and compared with equivalent strains preserved under paraffin oil. All qualitative characters tested remained stable, and quantitative characters varied only within the range of natural variability.     

On Temporal Dynamics of Morphological Variations in the Black Sea Mussel Mytilus galloprovincialis Lam.

Temporal variations in morphological characters of the shells were studied in 12 samples of mussels M. galloprovincialis Lam. from the Black Sea commercial collectors that belong to different generations. The samples were shown to be diverse in every studied character and the degree of characters' variability in the samples was different. The morphological diversity of samples diminished with age. Different generations from the same habitat had specific features of age-related variability expressed as different rates of age-related changes and direction and degree of variability. This effect is considered as an index of the influence of ecological conditions on the shell growth and formation.     

Detection of invasive and cryptic species in marine mussels (Bivalvia,Mytilidae): A chromosomal perspective

Marine mussels illustrate a stunning variability in shape and color. Such variability, added to the scarcity of reliable morphological characters for their identification, can mislead recognition prompting the assignation of specimens of a single species to different ones or incorporate specimens belonging to different taxa into a single one. DNA barcoding is widely used for species identification; however, as this method relies on the previous morphological identification of the specimens, some of the DNA sequences stored in DNA databases are incorrectly assigned to a given species. In view of this uncertainty, further criteria beyond morphological characters and DNA sequences in databases are required to more reliably and accurately identify marine mussels. In this work we mapped ribosomal RNA and histone gene clusters to chromosomes of four species of marine mussels and compared them with those from another eight marine mussel taxa. Specimens of these twelve taxa were also DNA barcoded. Our results clearly demonstrated that the chromosomal analysis of marine mussels could shed light on their identification and, therefore, solve contradictions posed by morphological and molecular data.     

Biosystematic studies of the Elymus hispidus (Poaceae: Triticeae) group in Iran

Biosystematic studies on the Elymus hispidus group included investigations on morphological characters and variability in cultivation, crossing experiments, hybrid fertility and meiotic configuration in hybrids. Elymus gentry! is a distinct species with a different altitudinal distribution from that of E. hispidus. Morphological characters which have been used to split E. hispidus into distinct species or subspecies are not constant in cultivation. The majority of the cultivated plants were morphologically similar to the maternal individuals from which seed was collected in the field. However, in some accessions the offspring represented different morphological variants when cultivated. Hybrids between different variants were fertile and showed regular meiosis. Different variants within the E. hispidus group tend to grow in different habitats and as characters to some extent show constancy in cultivation, three varieties, var. hispidus , var. podperae and var. villosus are recognized for E. hispidus in Iran.     

Some aspects of intraspecific variability of the closely related species of the Dermacentor marginatus complex (Acari: Ixodidae) as demonstration of microevolutionary process

Individual and geographical variability of male conscutum pattern in five closely related species of the Dermacentor marginatus complex (D. marginatus, D. ushakovae, D. niveus, D. silvarum, D. nuttalli) has been examined. The pattern has been examined in three to six geographical samples within each specific distribution range. It was established that the pattern of the conscutum central area is subjected to individual and geographical variability on an extreme degree and gives very few intraspecific differential characters, but it shows interspecific differences in some cases. However the dark patches of marginal flank (npkappadelta and 3deltakappa respectively, see Fig. 3) show statistically significant differences in length in all geographical samples of the first four species. Characteristic features of ixodid ticks morpogenesis rule out to a considerable extent the possibility to trace geographical variability of the same characters by all stages of ontogenesis. In these cases, when it is possible, the tendencies to variability on different stages do not always coincide. There is no coordination within the species in the degree of differences of examined geographical samples by pattern and morphological characters, i. e. very complex polymorphis is observed. In the context of the evolution that kind of polymorphism of the geographical samples has provided the species with high adaptive potential for conquest of the extensive range and maintaining large numbers. The question of allopatric speciation of the closely related D. marginatus-D. silvarum with small secondary area of transgression their ranges, and sympatric speciation of the D. ushakovae-D. niveus is postulated.     

Phenotypic variability and correlation between skinfold thickness and arterial pressure level]

Contribution of genetic and environmental factors in phenotypic variability of blood pressure level and skinfold thickness, and phenotypic correlation between these characters was calculated on the basis of familial correlations. It was shown that genetic determinant explains considerable portion of blood pressure level and skinfold thickness variability. Among common environmental effects, the factors affecting one generation are important with regard to variability of these characters. Maternal effect is expressed in the variability of systolic and diastolic blood pressure. Correlation between blood pressure level and triceps skinfold thickness is determined by genetic factors, whereas that between blood pressure level and subscapular skinfold thickness is mediated by environmental factors. The results obtained may be applied in populational prevention of cardiovascular disease.     

Pollen characteristics of New Zealand Gnaphalieae (Compositae) and their taxonomic significance II. Tem

Pollen ultrastructure has been investigated in 35 taxa of Gnaphalieae (Compositae), predominantly from New Zealand. Pollen grains of all taxa examined are tectate‐columellate and caveate. The characters regarded as particularly distinctive include variability of columellar form and internal organisation of the columellae. The importance of pollen characters in the classification of the New Zealand Gnaphalieae is discussed. The species of Haastia, characterised by senecioid pollen and internal tecta, do not belong to the Gnaphalieae. In the species with helianthoid pollen and sub‐columellae five different columellae types can be distinguished.     

Pleiotropic Stabilizing Selection Limits the Number of Polymorphic Loci to at Most the Number of Characters

We demonstrate that, in a model incorporating weak Gaussian stabilizing selection on n additively determined characters, at most n loci are polymorphic at a stable equilibrium. The number of characters is defined to be the number of independent components in the Gaussian selection scheme. We also assume linkage equilibrium, and that either the number of loci is large enough that the phenotypic distribution in the population can be approximated as multivariate Gaussian or that selection is weak enough that the mean fitness of the population can be approximated using only the mean and the variance of the characters in the population. Our results appear to rule out antagonistic pleiotropy without epistasis as a major force in maintaining additive genetic variation in a uniform environment. However, they are consistent with the maintenance of variability by genotype-environment interaction if a trait in different environments corresponds to different characters and the number of different environments exceeds the number of polymorphic loci that affect the trait.     

Statistical Genetics of an Annual Plant, Impatiens Capensis. I. Genetic Basis of Quantitative Variation

Analysis of quantitative genetics in natural populations has been hindered by computational and methodological problems in statistical analysis. We developed and validated a jackknife procedure to test for existence of broad sense heritabilities and dominance or maternal effects influencing quantitative characters in Impatiens capensis. Early life cycle characters showed evidence of dominance and/or maternal effects, while later characters exhibited predominantly environmental variation. Monte Carlo simulations demonstrate that these jackknife tests of variance components are extremely robust to heterogeneous error variances. Statistical methods from human genetics provide evidence for either a major locus influencing germination date, or genes that affect phenotypic variability per se. We urge explicit consideration of statistical behavior of estimation and testing procedures for proper biological interpretation of statistical results.