Evaluation of developmental stability and cytogenetic homeostasis in populations of European green frogs (Rana esculenta-complex) under natural and anthropogenic conditions]

The status of amphibians in populations subjected to anthropogenic influence of various natures has been evaluated. We studied the effect of complex anthropogenic influences as well as chemical and radiation pollution. The status of the specimens in populations was evaluated by morphological (developmental stability as the level of fluctuating asymmetry) and cytogenetic (micronucleus test) methods. Disturbed developmental stability and cytogenetic homeostasis have been observed in populations affected by anthropogenic factors, which indicates the changed status of the organism.     

Cytogenetic approach to estimation of developmental stability of the natural population of coregonid fishes

A comparative cytogenetic analysis of coregonid fish was carried out in the river and lake ecosystems of the northern Tyumen' District. The occurrence of chromosomal aberrations in embryonic cells of fish steadily increased during the period from 1989 until 2001. Possible causes of this dynamic are discussed.     

Possible application of the indices of developmental stability and photosynthetic activity for studying the states of natural plant populations using the weeping birch as an example]

We have generalized the materials of population-phenogenetic studies of the weeping birch in different environmental conditions using developmental stability analysis and photosynthetic activity measurements.     

Comparative evaluation of stability of benzylpenicillin in acid media of natural solutions and in culture fluid]

Inactivation of benzylpenicillin in real media i.e. fermentation broths and their filtrates was studied in comparison with the published data on inactivation of commercial benzylpenicillin in aqueous solutions as dependent on the medium pH and temperature. The lowest constant of benzylpenicillin inactivation was shown to be in the fermentation broths.     

Morphological polyvariance of ontogeny in natural plant populations]

The main patterns of expression of the morphological polyvariance of plants are discussed: diversity of biomorphs, pathways of ontogeny, and disturbances of morphogenesis. The diversity of biomorphs of tap root plants in different ecological conditions has been analyzed in detail. Promising directions of future studies have been formulated.     

Study of developmental homeostasis in natural populations. Health of environment concept: Methodology and practice of estimation

Increasing anthropogenic impact on the natural environment determines the urgency and significance of provision of the all-round estimation and monitoring of its consequences. The methodology of the health of environment estimation based on characteristics of the condition of different species of living beings by the developmental homeostasis is proposed as an operational approach for this problem solution. The elaborated methodology approbation during the execution of a number of the projects on the estimation of the environmental quality under different types of the anthropogenic impact allows one to characterize the possibilities of used approaches for estimation of the environment’s auspiciousness for living beings and humans. This also opens up the possibility to estimate the range of possible changes of the developmental homeostasis in real natural conditions.     

Ontogenetic approach to studying natural avian populations]

The asymmetry of digit folidosis and the correlation of exterior characteristics have been studied in 20 passerine species. The level of the characteristic asymmetry depends on the phylopatry level and regularly increases in the species disposed to annual change of the nesting site. We assume that the revealed variability reflects interpopulation flow of genes. Age-, sex-, and biotope-related changes associated with urbanization have been revealed in the correlation of characteristics. Older birds have more pronounced correlation of characteristics; it is also more specific for males than females. Correlation of characteristics is less pronounced in the urban avian populations. These differences are interpreted in terms of stabilizing selection within intraspecific groups.     

Estimation of the developmental stability of small-leafed lime on natural reserves and in urbanized territories

The developmental stability of small-leaved lime (Tina cordata Mill.) was estimated in populations on territories of the Kerzhenskii State Nature Reserve, Nizhni Novgorod District, and in an industrial region of Nizhni Novgorod. The developmental stability was estimated according to the fluctuating asymmetry of the leaf measurements. The results obtained suggest that, in the urbanized territory, the homeostatic developmental mechanisms are weakened, as expressed in the increased degree of leaf asymmetry.     

Effective population size of natural populations of Drosophila buzzatii, with a comparative evaluation of nine methods of estimation

Allozyme and microsatellite data from numerous populations of Drosophila buzzatii have been used (i) to determine to what degree N(e) varies among generations within populations, and among populations, and (ii) to evaluate the congruence of four temporal and five single-sample estimators of N(e) . Effective size of different populations varied over two orders of magnitude, most populations are not temporally stable in genetic composition, and N(e) showed large variation over generations in some populations. Short-term N(e) estimates from the temporal methods were highly correlated, but the smallest estimates were the most precise for all four methods, and the most consistent across methods. Except for one population, N(e) estimates were lower when assuming gene flow than when assuming populations that were closed. However, attempts to jointly estimate N(e) and immigration rate were of little value because the source of migrants was unknown. Correlations among the estimates from the single-sample methods generally were not significant although, as for the temporal methods, estimates were most consistent when they were small. These single-sample estimates of current N(e) are generally smaller than the short-term temporal estimates. Nevertheless, population genetic variation is not being depleted, presumably because of past or ongoing migration. A clearer picture of current and short-term effective population sizes will only follow with better knowledge of migration rates between populations. Different methods are not necessarily estimating the same N(e) , they are subject to different bias, and the biology, demography and history of the population(s) may affect different estimators differently.     

Craniometrical variability and developmental stability. Two useful tools for assessing the population viability of Eurasian otter (Lutra lutra) populations in Europe.

Morphometrical univariate analyses of otter skulls collected over the past hundred years in European countries from presumed healthy populations were compared with skulls from presumed endangered populations. The average degree of sexual dimorphism of die European populations was found to be directly correlated to die skull size of die male otters. Fluctuating asymmetry (FA) in metric skull traits was analysed as an estimator of developmental stability. There was evidence for increased FA in different traits over time in some of the presumed endangered populations, and for a reduction in size of skull traits. In contrast, the healthy populations did not show any significant changes in the same traits during the same period. The reduced sexual dimorphism of the endangered populations is suggested to be a product of relaxed sexual selection and deteriorated habitat conditions. Environmental and genetic forces that may have shaped these patterns are discussed.     

Life history and population dynamics of the western mosquitofish: a comparison of natural and introduced populations

Life history and population dynamic patterns of Gambusia affinis in southeastern Louisiana varied spatially and temporally in 1990 and 1991, but were consistent with previous reports of this species in the southern regions of its natural range. Several differences exist among populations in different geographic regions within the United States, as reported in the literature, which do not follow a' native v . introduced' dichotomy: (1) brood size decreases and offspring size increases from north to south; (2) large overwintered females in northern areas produce more broods within a season than those in southern populations, while the reverse is true for young-of–year females; (3) minimum size at first reproduction follows a seasonal pattern within populations, but tends to be smaller in southern and larger in northern and Hawaiian populations; (4) synchronous reproduction early in the season is characteristic of northern populations, but does not occur in southern areas; and (5) mosquitofish reproduce year–round in Hawaii, while 'southern' populations within the continental U.S. cease reproduction during winter.     

Distribution and stability of supernumerary microchromosomes in natural populations of the Amazon molly, Poecilia formosa

In animals, supernumerary chromosomes and their evolution have mostly been studied in sexual reproducing species. In the present study, for the first time, the natural distribution and stability of supernumerary microchromosomes were investigated in the unisexual fish species Poecilia formosa. Natural habitats throughout the range of P. formosa were screened for the presence of microchromosomes over several years. A high frequency of microchromosomes was found in the Río Purificación river system. Evidence points to the presence of the same microchromosome lineage over many generations. No supernumerary chromosomes were found elsewhere than in the Río Purificación representing a significant difference in the distribution of microchromosome-bearing individuals between the Río Purificación and all other collection sites.     

Spatial-temporal stratifications in natural populations and how they affect understanding and estimation of effective population size

The concept of effective population size (N(e) ) is based on an elegantly simple idea which, however, rapidly becomes very complex when applied to most real-world situations. In natural populations, spatial and temporal stratifications create different classes of individuals with different vital rates, and this in turn affects (generally reduces) N(e) in complex ways. I consider how these natural stratifications influence our understanding of effective size and how to estimate it, and what the consequences are for conservation and management of natural populations. Important points that emerge include the following: 1 The relative influences of local vs metapopulation N(e) depend on a variety of factors, including the time frame of interest. 2 Levels of diversity in local populations are strongly influenced by even low levels of migration, so these measures are not reliable indicators of local N(e) . 3 For long-term effective size, obtaining a reliable estimate of mutation rate is the most important consideration; unless this is accomplished, estimates can be biased by orders of magnitude. 4 At least some estimators of contemporary N(e) appear to be robust to relatively high (approximately 10%) equilibrium levels of migration, so under many realistic scenarios they might yield reliable estimates of local N(e) . 5 Age structure probably has little effect on long-term estimators of N(e) but can strongly influence contemporary estimates. 6 More research is needed in several key areas: (i) to disentangle effects of selection and drift in metapopulations connected by intermediate levels of migration; (ii) to elucidate the relationship between N(b) (effective number of breeders per year) and N(e) per generation in age-structured populations; (iii) to perform rigorous sensitivity analyses of new likelihood and coalescent-based methods for estimating demographic and evolutionary histories.     

Ontogenesis of rat immune system: Proteasome expression in different cell populations of the developing thymus

Immune proteasomes in thymus are involved in processing of self-antigens, which are presented by MHC class I molecules for rejection of autoreactive thymocytes in adults and probably in perinatal rats. The distribution of immune proteasome subunits LMP7 and LMP2 in thymic cells have been investigated during rat perinatal ontogenesis. Double immunofluorescent labeling revealed LMP7 and LMP2 in thymic epithelial and dendritic cells, as well as in CD68 positive cells - macrophages, monocytes - at all developmental stages. LMP2 and LMP7 were also detected by flow cytometry in almost all thymic CD90 lymphocytes through pre- and postnatal ontogenesis. Our results demonstrate that the immune proteasomes are expressed in all types of thymic antigen presenting cells during perinatal ontogenesis, suggesting the establishment of the negative selection in the thymus at the end of fetal life. The observation of the immune proteasome expression in T lymphocytes suggests their role in thymocyte differentiation besides antigen processing in thymus.     

Live animal radiography to measure developmental instability in populations of small mammals after a natural disaster

Stress placed on individuals in a population from natural and anthropogenic disturbances can elevate developmental instability. We studied the result of a natural disaster when one-third of a forested nature preserve was destroyed by an F3 tornado. Populations of two abundant species of small mammals, Peromyscus maniculatus and P. leucopus, were monitored in both disturbed and undisturbed habitats. We used an X-ray technique to measure developmental instability as indicated by fluctuating asymmetry (FA) in cranial and skeletal features of live animals. FA in femur length was higher in disturbed habitat for P. leucopus but was higher in undisturbed habitat for P. maniculatus. This difference in developmental instability mirrors differences in habitat preference between these species: P. leucopus prefers forest habitat and P. maniculatus prefers open, herbaceous habitat. These results were not explained by either food availability or body condition, both of which were higher in the disturbed habitat suggesting higher quality for this habitat. Thus, the FA response may be related to other indicators of habitat quality, e.g., vertical stratification, coarse-woody debris, or population density, which may differ between undisturbed and disturbed habitats.     

Genetic diversity in a seed production population vs. natural populations of Sitka Spruce

Isozyme analysis was applied to estimate the level of variation and the genetic structure of a seed-production population (i.e., seed orchard) and 10 range-wide natural populations of Sitka spruce (Picea sitchensis (Bong.) Carr.). Gene diversity and heterozygosity estimates were comparatively high in both the seed orchard and the natural populations studied. The seed orchard population showed a significantly higher number of alleles per locus and percentage of polymorphic loci. Though not significant, mean heterozygosity of the seed orchard was higher than that observed for all natural populations. Genetic distance analysis indicated that the seed-orchard population was genetically similar to three natural populations from which the parent trees were selected. Parent trees sampling breadth has been identified as the major cause for the observed increased level. The impact of recurrent selection and seed orchard biology and management on maintaining the genetic diversity is discussed.     

Viral infectious and chromosome aberrations in Bank Vole from natural and laboratory populations]

The frequency of chromosome damage was studied in the carriers of virus of the hemorrhagic fever with renal syndrome (Puumala virus) and in noninfected animals from two laboratory colonies and two natural populations of bank vole. In the laboratory colony, where Puumala virus persisted for three years, multiaberrant ("rogue") cells were found in the bone marrow; the mean frequencies of both structural and numeral chromosome abnormalities were significantly enhanced. In the other laboratory colony, no Puumala virus was detected during all 30 years of its existence, but the mean frequencies of structural chromosome damage were increased to the same degree probably due to the prolonged breeding under laboratory conditions, which resulted in suppression of immunity and DNA repair. The voles from the natural populations were more resistant to the clastogenic viral effect, but they also had multiaberrant cells which served as indicators of viral infection. The data obtained support the hypothesis that viral infections increase mutation rate, contributing thereby to the evolution process.     

Infanticide in microtines: Importance in natural populations

Summary To test the hypothesis that the incidence of infanticide should increase as population density increases in microtines (Mallory and Brooks, 1978), an index of pregnancy success was developed. There was no negative correlation between population density and pregnancy success in four species of Microtus and thus the hypothesis is refuted. There was a positive correlation between instantaneous growth rate and pregnancy success in M. pennsylvanicus and M. townsendii.