Integral evaluation of phenotypic and genotypic variability of morphologic and psychophysiologic human traits

The paper demonstrates the expedience of the developed populational-genetic approach to studying the genetic bases of a complex of quantitative characters pertaining to different levels of human organization: anthropometry, neurodynamics and psychodynamics. The studies were carried out in eight human populations of different degree of isolation and ethnical background. It is shown that correlation phenotypic variability is higher for these characters, as compared to genotypic variability, the number of general genes responsible for this variability being decreased, respectively.     

The adaptedness of the floral phenotype in a relict endemic, hawkmoth-pollinated violet. 2. Patterns of variation among disjunct populations

This study examines patterns of variation in quantitative floral traits among 18 disjunct populations of Viola cazorlensis (Violaceae), a relict endemic violet of south-eastern Spain. At all sites, the species is almost exclusively pollinated by a single species of day-flying hawkmoth. Differences between populations were significant for all traits examined, and population means exhibit a broad range of variation. When all characters are considered together, each population displays a unique combination of characters. Despite interpopulation differences in character means, local populations retain most of the variability of the entire species. Floral traits do not vary in unison among flowers, and at least four different subsets of independently varying traits are identifiable. Floral similarity between populations of V. cazorlensis was largely unrelated to geographic proximity, as revealed by analyses at both large and small geographic scales. The geographic pattern of floral variation among populations represents a random patchwork, with unique combinations of character means occurring randomly across the study region. Marked population differences in quantitative floral traits in spite of spatial constancy in the identity of pollinators, a disintegrated floral phenotype, and prevailingly random geographic variation among populations, suggest low adaptedness of the floral phenotype of V. cazorlensis to its current hawkmoth pollinators.     

Leaf epidermal characteristics and genetic variability in Central European populations of broad-leaved Festuca L. taxa

Leaf epidermal (micromorphological and micromorphometric) features of the leaf blade were examined with light and scanning electron microscopy in 49 Central European natural populations of species belonging to subgenera Schedonorus and Drymanthele within the genus Festuca L. In addition, molecular biological (random amplified polymorphic DNA) studies were conducted on selected populations. The goal of the study was to reveal the degree of anatomical and genetic variability at the taxon and population level, as well as to determine the most important characters that allow differentiation of the taxa in these two subgenera. The anatomical variation was compared with the genetic distance between taxa. Investigated taxa exhibited great anatomic variability in terms of both qualitative (presence or absence, shape and appearance of various cell types) and quantitative characters (frequency and size of cells). Strong correlation was found between the genetic distance of populations and the frequency and size of silica cells in the costal zone of the epidermis, which indicates that silica cells are largely determined by the genetic background, regardless of varying environmental conditions. Our studies highlight that despite the high level of variability in anatomical features and genetic polymorphism, these fescue populations clearly segregate both in terms of epidermal structure and genetic constitution.     

Changes in the variability of quantitative characters in M2 induced in einkorn wheat by N-nitroso-N-methylurea and X-rays

Changes in the variability of quantitative characters (number of fertile stems, length of the stem and of the spike, number of spikelets in the spike, number of seeds in the spike and in the spikelet) in M₂ induced with 0·1 mM, 0·2 mM and 0·3 mM N-nitroso-N-methylurea (MNH) and with 5000r and 10 000 r of X-rays inTriticum monococcum L. var.sofianum Körn. were evaluated. The mean of the populations remained practically unchanged by the mutagens whereas the variability increased considerably with increasing concentration or dose. Changes in the variability were more pronounced in the values for the first stem than in the values for the first three stems. When changes in the population mean were found (with some of the most elevated concentrations and doses), these changes were shown to be mostly due to a repetition of the cultivation, whereas the changes in the variability were mostly due to the action of the mutagens. In all experimental populations, mutations in quantitative characters were successfully induced.     

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.     

Contrasting evolutionary forces driving population structure at expressed sequence tag polymorphisms, allozymes and quantitative traits in white spruce

Patterns of variation in quantitative characters and genetic markers were compared among six regional populations of white spruce [Picea glauca (Moench) Voss]. Although some phenotypic characters were correlated with latitude (r = 0.791), longitude (r = -0.796) and precipitation during the growing season (r = 0.789), variability at genetic markers was not correlated with geographical or bioclimatic variables, and followed neutral expectations. Estimates of genetic diversity and population differentiation for 14 allozymes (translated regions of coding genes) were essentially indistinguishable from those observed for 11 expressed sequence tag polymorphisms (ESTPs) from untranslated regions of coding genes. Variation among populations for quantitative traits such as eighth year height (Q(ST) = 0.082), thirteenth year height (Q(ST) = 0.069), total wood density (Q(ST) = 0.102) and date of budset (Q(ST) = 0.246), was greater than for allozymes (G(ST) = 0.014) and ESTPs (G(ST) = 0.019). These trends suggest a strong adaptive response in quantitative traits, contrasting to allozymes and ESTPs where no selective response could be detected and where populations appeared to be essentially in a migration-drift equilibrium.     

Genetic Markers and Quantitative Genetic Variation in Medicago Truncatula (Leguminosae): A Comparative Analysis of Population Structure

Two populations of the selfing annual Medicago truncatula Gaertn. (Leguminoseae), each subdivided into three subpopulations, were studied for both metric traits (quantitative characters) and genetic markers (random amplified polymorphic DNA and one morphological, single-locus marker). Hierarchical analyses of variance components show that (1) populations are more differentiated for quantitative characters than for marker loci, (2) the contribution of both within and among subpopulations components of variance to overall genetic variance of these characters is reduced as compared to markers, and (3) at the population level, within population structure is slightly but not significantly larger for markers than for quantitative traits. Under the hypothesis that most markers are neutral, such comparisons may be used to make hypotheses about the strength and heterogeneity of natural selection in the face of genetic drift and gene flow. We thus suggest that in these populations, quantitative characters are under strong divergent selection among populations, and that gene flow is restricted among populations and subpopulations.     

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     

Variation patterns of bilateral characters: variation among characters and among populations in the White Sea herring, Clupea pallasi marisalbi (Berg) (Clupeidae, Teleosti)

Phenotypic variation in two populations of the White Sea herring Clupea pallasi marisalbi (Berg) (spring spawners and summer spawners), based on 21 meristic and 21 morphometric bilateral characters, has been studied. Total phenotypic variance was partitioned into a within-individual or stochastic component (fluctuating asymmetry) and an among-individual or factorial component, reflecting heterogeneity among individuals and resulting from the diversity of genotypes and environments. Both standardized stochastic and factorial components show clear negative correlations with means across characters. Negative correlation of the factorial components with means is in contradiction to the commonly accepted explanation of negative means-standardized variances association. Slopes of regression of standardized stochastic variances on means in meristic characters was significantly higher in summer spawners than in spring spawners, and results in discordance of stochastic variance across characters: it is higher in spring spawners for low and average variability characters and does not differ for both populations for high variability characters. The populations do not show notable differences in variation of morphometric characters. Consideration of other available data on these populations, such as spawning behaviour and salinity resistance of larvae, suggests that the lower slope of regression of stochastic variances on means is associated with the reduced viability of spring spawners     

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.     

Morphological and microsatellite diversity associated with ecological factors in natural populations of Medicago laciniata Mill. (Fabaceae)

Genetic variability in 10 natural Tunisian populations of Medicago laciniata were analysed using 19 quantitative traits and 12 polymorphic microsatellite loci. A large degree of genetic variability within-populations and among-populations was detected for both quantitative characters and molecular markers. High genetic differentiation among populations for quantitative traits was seen, with Q _ST = 0.47, and F _ST = 0.47 for microsatellite markers. Several quantitative traits displayed no statistical difference in the levels of Q _ST and F _ST . Further, significant correlations between quantitative traits and eco-geographical factors suggest that divergence in the traits among populations may track environmental differences. There was no significant correlation between genetic variability at quantitative traits and microsatellite markers within populations. The site-of-origin of eco-geographical factors explain between 18.13% and 23.40% of genetic variance among populations at quantitative traits and microsatellite markers, respectively. The environmental factors that most influence variation in measured traits among populations are assimilated phosphorus (P₂0₅) and mean annual rainfall, followed by climate and soil texture, altitude and organic matter. Significant associations between eco-geographical factors and gene diversity, H _e , were established in five-microsatellite loci suggesting that these simple sequence repeats (SSRs) are not necessarily biologically neutral.     

QUANTITATIVE GENETICS AND POPULATION DYNAMICS

This study examines the dynamics of a competition and a host-parasite model in which the interactions are determined by quantitative characters. Both models are extensions of one-dimensional difference equations that can exhibit complicated dynamics. Compared to these basic models, the phenotypic variability given by the quantitative characters reduces the size of the density fluctuations in asexual populations. With sexual reproduction, which is described by modeling the genetics of the quantitative character explicitly with many haploid loci that determine the character additively, this reduction in fitness variance is magnified. Moreover, quantitative genetics can induce simple dynamics. For example, the sexual population can have a two-cycle when the asexual system is chaotic. This paper discusses the consequences for the evolution of sex. The higher mean growth rate implied by the lower fitness variance in sexual populations is an advantage that can overcome a twofold intrinsic growth rate of asexuals. The advantage is bigger when the asexual population contains only a subset of the phenotypes present in the sexual population, which conforms with the tangled bank theory for the evolution of sex and shows that tangled bank effects also occur in host-parasite systems. The results suggest that explicitly describing the genetics of a quantitative character leads to more flexible models than the usual assumption of normal character distributions, and therefore to a better understanding of the character's impact on population dynamics.     

Variability of nonmetric traits of musk deer <Emphasis Type="Italic">Moschus moschiferus</Emphasis> L. (Moschidae,Cetartiodactyla) craniums

Variation in 15 phenotypic traits is investigated in 349 craniums of seven geographic populations. Differences between geographic populations are ascertained, and phenotypic peculiarities of the subspecies are determined by principal component analysis and cluster analysis using the measure of the contribution to variability of populations and of subspecies similarity. Variations in populations of the Siberian and Himalayan subspecies in nonmetric characters are established. Differences between the craniums from populations are shown to be manifested to a greater degree than between the craniums of subspecies. The analysis of nonmetric characters showed the lack of a rare phene as a diagnostic feature of the musk deer.     

Morphological variability of Tragopogon pterodes Pančić ex Petrović achenes: taxonomic evaluation of heterocarpy

This study presents the carpological heterogeneity of Tragopogon pterodes, an endemic plant species from Balkan Peninsula. The goal of this paper was to determine the variability of morphological characters of achenes and assess the degree of their morphological differentiation relative to the position they occupy in the receptacle. Analysis included four different populations of T. pterodes and examination of 18 (8 qualitative and 10 quantitative) characters of achenes in total. Data analysis employed basic statistic, univariate (ANOVA, Tukey HSD) and multivariate (CDA, CA) analyses to check the level of heterocarpy in this species. The results indicate possible morphological differentiation of three groups of achenes (outer, median and inner achenes), depending of their position on the receptacle. The members of all three types were described, illustrated and compared. The variability of investigated carpological characters in this species is providing important information prior to their further taxonomic treatment.     

Morpho-anatomical differentiation of the balkan populations of the species Teucrium flavum L. (Lamiaceae)

Ecological plasticity, i.e., inter-population differentiation of the species Teucrium flavum was analyzed on the basis of morpho-anatomical variability of its five populations from the maquis (Cisto-Ericetea and Cisto-Micromerietea), rocky grounds (Festuco-Brometea) and rocky crevices (Asplenietea rupestris) in the Eumediterranean and sub-Mediterranean region. Univariate statistic analysis included 22 quantitative characters related to the leaf and stem anatomy and morphology. In order to establish the variability and significance of morpho-anatomical differentiation, principal component analyses (PCA), multivariate analyses of variances (MANOVA), discriminant components analysis (DCA) and clustering, according to the UPMGA method based on Mahalanobius’ distances, have been done.The morpho-anatomical analysis of plants from the five distant populations confirmed that the species T. flavum belongs to malacophyllous xeromorphic species. It was established that the plants from all the five populations analyzed are distinguished by stable conservative xeromorphic characteristics. There is a difference between the pronounced xeromorphic plants belonging to Eumediterranean populations and the subxeromorphic sub-Mediterranean ones.     

Genetic variability in natural populations of Arabidopsis thaliana in northern Europe

Ten populations of the model plant Arabidopsis thaliana were collected along a north-south gradient in Norway and screened for microsatellite polymorphisms in 25 loci and variability in quantitative traits. Overall, the average levels of genetic diversity were found to be relatively high in these populations, compared to previously published surveys of within population variability. Six of the populations were polymorphic at microsatellite loci, resulting in an overall proportion of polymorphic loci of 18%, and a relatively high gene diversity for a selfing species (HE = 0.06). Of the overall variability, 12% was found within populations. Two of six polymorphic populations contained heterozygous individuals. Both FST and phylogenetic analyses showed no correlation between geographical and genetic distances. Haplotypic diversity patterns suggested postglacial colonization of Scandinavia from a number of different sources. Heritable variation was observed for many of the studied quantitative traits, with all populations showing variability in at least some traits, even populations with no microsatellite variability. There was a positive association between variability in quantitative traits and microsatellites within populations. Several quantitative traits exhibited QST values significantly less than FST, suggesting that selection may be acting to retard differentiation for these traits.     

Morphological variation in populations of Bletia purpurea (Orchidaceae) and description of the new species B. riparia

Bletia purpurea is the most widespread species in its genus. Morphological variation has been recognized throughout the range of its distribution. In this paper, the morphological variation from 63 populations (583 individuals) ofBletia purpurea is assessed to determine whether more than one species were present. Forty-four quantitative and qualitative characters were examined by univariate analyses and exploratory multivariate analyses. Univariate analyses indicate that quantitative characters such as lateral sepal width, petal. width, lip length, and lip width are significantly different for populations from Acazónica, Mexico. Floral parts in the populations from Acazónica are the smallest among all populations. Qualitative characters such as petals covering the lip midlobe and horizontal lip position are found exclusively in the same populations. We concluded that these populations should be described as a new species,B. riparia. Multivariate analyses indicated that morphological variation among the other populations cannot be ascribed to geographic distribution or ecological factors.     

不同种群中海南粗榧(Cephalotaxus mannii)形态变异研究

通过变异系数和性状差异显著性检验,研究了海南粗榧在坝王岭等５个种群内和种群间不同形态变异以及形态总体变异。结果表明：①海南粗榧营养器官性状比生殖器官性状变异大;枝性状组中,分枝角度变异较小;叶性状组中,叶数量变异较大;球果、种子生物量变异都大于它们的其它性状。②在５个种群内,同一性状变异幅度基本相同。③同一性状在种群间和种群内的变异基本接近。④不同性状在种群间存在差异,有的显著,有的不显著,但种群间形态总体差异都不显著     

Molecular and Quantitative Genetic Differentiation in Sitobion avenae Populations from Both Sides of the Qinling Mountains

Quantitative trait differences are often assumed to be correlated with molecular variation, but the relationship is not certain, and empirical evidence is still scarce. To address this issue, we sampled six populations of the cereal aphid Sitobion avenae from areas north and south of the Qinling Mountains, and characterized their molecular variation at seven microsatellite loci and quantitative variation at nine life-history traits. Our results demonstrated that southern populations had slightly longer developmental times of nymphs but much higher lifetime fecundity, compared to northern populations. Of the nine tested quantitative characters, eight differed significantly among populations within regions, as well as between northern and southern regions. Genetic differentiation in neutral markers was likely to have been caused by founder events and drift. Increased subdivision for quantitative characters was found in northern populations, but reduced in southern populations. This phenomenon was not found for molecular characters, suggesting the decoupling between molecular and quantitative variation. The pattern of relationships between F_ST and Q_ST indicated divergent selection and suggested that local adaptation play a role in the differentiation of life-history traits in tested S. avenae populations, particularly in those traits closely related to reproduction. The main role of natural selection over genetic drift was also supported by strong structural differences in G-matrices among S. avenae populations. However, cluster analyses did not result in two groups corresponding to northern and southern regions. Genetic differentiation between northern and southern populations in neutral markers was low, indicating considerable gene flow between them. The relationship between molecular and quantitative variation, as well as its implications for differentiation and evolution of S. avenae populations, was discussed.