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.     

Estimate of cytogenetic homeostasis in natural populations of some small murid rodents]

Cytogenetic homeostasis in natural populations under natural conditions and anthropogenic stress was estimated according to the frequency of chromosome aberrations in somatic cells for six species of small mammals. Cytogenetic homeostasis was disturbed under the stress effect of increased density during population cycles, at the ecological periphery, and in the case of environmental chemical and radiation contamination. Cytogenetic homeostasis disturbances were related to changes in other indices of homeostasis, such as developmental stability and immune status, suggesting the use of the cytogenetic approach for estimating the general state of individuals in natural populations.     

Estimate of Cytogenetic Homeostasis in Natural Populations of Some Small Murid Rodents

Cytogenetic homeostasis in natural populations under natural conditions and anthropogenic stress was estimated according to the frequency of chromosome aberrations in somatic cells for six species of small mammals. Cytogenetic homeostasis was disturbed under the stress effect of increased density during population cycles, at the ecological periphery, and in the case of environmental chemical and radiation contamination. Cytogenetic homeostasis disturbances were related to changes in other indices of homeostasis, such as developmental stability and immune status, suggesting the use of the cytogenetic approach for estimating the general state of individuals in natural populations.     

Morphogenetic approach to estimation of health of environment: Study of developmental stability

The study of the developmental stability in natural populations is a promising direction of population developmental biology, which opens new possibilities for estimation of the nature of the observed phenotypic diversity and understanding the mechanisms of population dynamics and microevolutionary transformations. This direction of the studies allows one to approach the estimation of the condition of natural populations. A special analysis of possible changes in the developmental stability indicators under different anthropogenic effects allows one to characterize this approach as one of the main within the methodology of the health of environment estimation based on the organism condition characteristics by the developmental homeostasis. The approach seems promising for the estimation and monitoring of the condition of natural populations of different species as well as for the environmental quality estimation.     

Lizards from Urban Areas Are More Asymmetric: Using Fluctuating Asymmetry to Evaluate Environmental Disturbance

The increase in human activities that leads to wildlife decline and species extinction poses an urgent need for simple indicators of environmental stress in animal populations. Several studies have suggested that fluctuating asymmetry (FA) can be an easy, direct measure of developmental instability because it is associated to environmental stress and, as such, it can be a useful indicator of population disturbance. We examined three different morphological traits in urban and rural populations of the common wall lizard (Podarcis muralis) to test whether anthropogenic disturbance causes an increase in FA. Compared to rural populations, urban ones showed higher levels of FA in all analyzed traits, thus providing evidence that FA can respond to anthropogenic disturbance. However, we also found significant differences in FA among traits, where femoral pores and subdigital lamellae, traits with a functional relevance, were more stable developmentally compared to supracilliar granules which have no evident function. Unsigned FA [abs(right-left)] exhibited significant, but weak, positive correlations among traits, indicating that developmental noise does not have a uniform effect across characters and thus questioning the view of developmental stability as an organism-wide property. The degree of signed FA (right-left) was more similar between structurally associated traits, possibly as an outcome of morphological integration. In conclusion, our results demonstrate that FA can be a reliable indicator of disturbance provided that it is analyzed on multiple traits simultaneously and examined at the population level.     

Bio-monitoring the genotoxicity of populations of Scots pine in the vicinity of a radioactive waste storage facility

Results of a long-term (1997-2002) study of the Scots pine populations growing in the vicinity of the radioactive waste storage facility ('Radon' LWPE) are presented. Cytogenetic disturbances in reproductive (seeds) and vegetative (needles) tissues sampled from Scots pine populations were studied to examine whether Scots pine trees have experienced environmental stress in areas with relatively low levels of pollution. The data clearly indicate the presence of mutagenic contaminants in the environment of the pine trees. An increased number of mitotic abnormalities, especially multipolar mitoses was found in the pine tree populations submitted to man-made exposure, which suggests that the cytogenetic damage is mainly caused by chemical contamination. A higher radioresistance of the Scots pine seeds from the impacted populations was shown by use of acute gamma-irradiation. During the observation period 1997-2002, pine trees exposed to anthropogenic pollution showed a steady increase of cytogenetic alterations in the root meristem cells.     

Peculiarities of Leukocytic Formula of Peripheral Blood of Green Frogs under Conditions of Anthropogenic Load

Changes of the total number of leucocytes and the leucocytic formula of peripheral blood were studied and stability of development was evaluated by the indicator of fluctuating asymmetry of populations of green frogs Rana lessonae Cam. and Rana ridibunda Pall. inhabiting city reservoirs of Nizhni Novgorod and the Nizhegorodskaya Province. The revealed changes in the amphibians white blood depending on the degree of anthropogenic effects in the studied reservoirs can be divided into two types. In the first type (the level of stability of development of populations is 2 scores according to Zakharov) there were revealed neutropenia, increased content of eosinophils, and total leucopenia. In the second type, a more intensive anthropogenic effect and deviation of the organism state from normal conditions, estimated by 3 scores (Zakharov), the leucograms of frogs were characterized by more pronounced negative alterations. Leucocytosis accompanied by neutropenia, eosinophilia, basophilia, and a decrease of the total number of lymphocytes has been established. In the absence of deviations of the stability of development from the conditionally normal state, there was revealed the balance of leucogram indicators, close to norm. An increase of the number of lymphocytes and young forms of neutrophils in the amphibian peripheral blood indicates stimulation of the processes providing the organism protective reaction. Cross-correlation between the integral indicator of stability of development, the content of eosinophils and lymphocytes has been established in individuals from populations of green frogs inhabiting the studied reservoirs.     

Study of developmental homeostasis: From population developmental biology and the health of environment concept to the sustainable development concept

The study of the indices of developmental homeostasis in natural populations leads to the definition of the fundamentals of population developmental biology, which is associated with the assessment of the nature of phenotypic diversity and the mechanisms of population dynamics and microevolutionary changes. Characterization of environmental quality based on the assessment of population status by developmental homeostasis determines the fundamentals of the health of environment concept. The use of the ideas of developmental homeostasis and the health of environment in the studies of homeostatic mechanisms of biological systems of different levels (from the organism and population to the community and ecosystem) is promising. This gives new opportunities for understanding the mechanisms that provide sustainability and their ratio at different levels as well as for the characterization of ontogenetic stability significance. The notion of developmental homeostasis, or homeorhesis, is promising for the elaboration of the ecological and biological basics of sustainable development.     

Effects of crossing distance on offspring fitness and developmental stability in Dalechampia scandens (Euphorbiaceae)

Crosses between genetically close and distant populations of Dalechampia scandens (Euphorbiaceae) were made to test whether the responses of various fitness components and measurements of developmental stability were affected by the outcrossing distance (level of outbreeding). Two fecundity traits, seed set and seed mass, decreased consistently with increasing level of outbreeding, and hybrids between the most divergent populations were sterile. Effects of the genetic distance between parental populations on viability traits, survival and vigor at 1 month of age, were highly idiosyncratic. Hybrids of one long-distance combination had no reduction in survival and vigor, while both traits were greatly reduced in the other long-distance combination. The expression of outbreeding depression on fecundity traits differed between reciprocal crosses in some hybrids but not others; thus, hybrid breakdown may have been due to cytoplasmic-by-nuclear gene interactions, reduced endosperm formation, or an interaction between progeny and maternal genotype. None of the measures of developmental stability had a consistent relationship with either genetic distance between parental populations or seedling vigor. These results suggest that fecundity and viability traits may be differentially affected by hybridization, probably due to differences in genetic architecture among populations. This study also confirms that developmental stability, as measured by the level of fluctuating asymmetry, is not a reliable index of genetic stress.     

Genetic patterns and conservation of the Scarlet Macaw (<Emphasis Type="Italic">Ara macao</Emphasis>) in Costa Rica

Once widely distributed throughout the lowland forests of Costa Rica, scarlet macaws (Ara macao) have been reduced to two major, geographically separated, populations along the Pacific slope. Past demographic declines raise conservation concerns regarding the detrimental effects of population fragmentation. This investigation aimed to evaluate the current status of scarlet macaws along the Pacific slope by examining levels of genetic variation and patterns of genetic structure within and among remnant populations. Statistical analyses using multilocus genotypes revealed strong differentiation between Central and South Pacific populations, suggesting local geographic barriers have historically restricted gene flow between these localities. High genetic diversity suggests neither population suffers from genetic erosion, likely resulting from relatively large population sizes and high dispersal capacity and longevity. However, evidence of disequilibrium within the Central Pacific population infers anthropogenic threats have disrupted natural population dynamics. These results advocate on focusing available resources on habitat restoration and nest protection, as a means to assist in reestablishing demographic stability and maintain the genetic health of wild scarlet macaws in Costa Rica.     

Effects of anthropogenic disturbance on indri (Indri indri) health in Madagascar

Anthropogenic habitat disturbance impairs ecosystem health by fragmenting forested areas, introducing environmental contamination, and reducing the quality of habitat resources. The effect of this disturbance on wildlife health is of particular concern in Madagascar, one of the world's biodiversity hotspots, where anthropogenic pressures on the environment remain high. Despite the conservation importance of threatened lemur populations in Madagascar, few data exist on the effects of anthropogenic disturbance on lemur health. To examine these impacts, indri (Indri indri) populations were evaluated from two forest reserves that differ in their exposure to anthropogenic disturbance. We compared the health status of 36 indri individuals from two sites: one population from a protected, undisturbed area of lowland evergreen humid forest and the other population from a reserve exposed to frequent tourism and forest degradation. Comparison of indri health parameters between sites suggests an impact of anthropogenic disturbance, including significant differences in leukocyte count and differential, 12 serum parameters, 6 trace minerals, and a higher diversity of parasites, with a significant difference in the presence of the louse, Trichophilopterus babakotophilus. These data suggest that indri living in disturbed forests may experience physiological changes and increased susceptibility to parasitism, which may ultimately impair reproductive success and survival.     

Developmental stability covaries with genome-wide and single-locus heterozygosity in house sparrows

Fluctuating asymmetry (FA), a measure of developmental instability, has been hypothesized to increase with genetic stress. Despite numerous studies providing empirical evidence for associations between FA and genome-wide properties such as multi-locus heterozygosity, support for single-locus effects remains scant. Here we test if, and to what extent, FA co-varies with single- and multilocus markers of genetic diversity in house sparrow (Passer domesticus) populations along an urban gradient. In line with theoretical expectations, FA was inversely correlated with genetic diversity estimated at genome level. However, this relationship was largely driven by variation at a single key locus. Contrary to our expectations, relationships between FA and genetic diversity were not stronger in individuals from urban populations that experience higher nutritional stress. We conclude that loss of genetic diversity adversely affects developmental stability in P. domesticus, and more generally, that the molecular basis of developmental stability may involve complex interactions between local and genome-wide effects. Further study on the relative effects of single-locus and genome-wide effects on the developmental stability of populations with different genetic properties is therefore needed.     

Population Genetic Structure of a Centipede Species with High Levels of Developmental Instability

European populations of the geophilomorph centipede Haplophilus subterraneus show a high proportion of individuals with morphological anomalies, suggesting high levels of developmental instability. The broad geographic distribution of this phenomenon seems to exclude local environmental causes, but the source of instability is still to be identified. The goal of the present study was to collect quantitative data on the occurrence of phenodeviants in different populations, along with data on the patterns of genetic variation within and between populations, in order to investigate possible association between developmental instability and genetic features. In a sample of 11 populations of H. subterraneus, distributed in western and central Europe, we looked for phenodeviants, in particular with respect to trunk morphology, and studied genetic variation through the genotyping of microsatellite loci. Overall, no support was found to the idea that developmental instability in H. subterraneus is related to a specific patterns of genetic variation, including inbreeding estimates. We identified a major genetic partition that subdivides French populations from the others, and a low divergence among northwestern areas, which are possibly related to the post-glacial recolonization from southern refugia and/or to recent anthropogenic soil displacements. A weak correlation between individual number of leg bearing segments and the occurrence of trunk anomalies seems to support a trade-off between these two developmental traits. These results, complemented by preliminary data on developmental stability in two related species, suggest that the phenomenon has not a simple taxonomic distribution, while it exhibits an apparent localization in central and eastern Europe.     

Genetic variation in remnant populations of Dalbergia nigra (Papilionoideae), an endangered tree from the Brazilian Atlantic Forest

BACKGROUND AND AIMS: Dalbergia nigra, known as Brazilian rosewood, is an endangered tree species restricted to the Brazilian Atlantic Forest and has been intensively logged for five centuries due to its high-quality wood. The objective of the present study was to assess the genetic variation and structure in adults and saplings of the species from a large reserve of the Atlantic Forest, the Rio Doce State Park, and from two small surrounding fragments, one better preserved and another with a high degree of anthropogenic disturbance. METHODS: Analyses of genetic variation and structure were conducted by studying allozyme markers. Seven putative enzymatic loci were resolved, five of them being polymorphic. KEY RESULTS: The mean numbers of alleles per locus (A) were 1.93 and 1.73, while the percentages of polymorphic loci (P) were 93 and 73 % for adults and saplings, respectively. Saplings from the fragment with high anthropogenic disturbance exhibited the lowest values of A and P. The fragment that constitutes a conservation area exhibited genetic variation similar to the population from the large reserve. The observed (H(o)) and expected (H(e)) heterozygosities were not significantly different among the three populations. Only sapling populations showed F(ST) values (divergence among populations) significantly different from zero over all studied loci. The fragment with high anthropogenic disturbance exhibited considerable genetic divergence in relation to the above-cited populations. CONCLUSIONS: The evaluated populations displayed mean levels of genetic variation intermediate to those expected for narrow and widespread species. The results suggest that fragments with similar area and geographical distance from a large protected reserve can exhibit different levels of genetic variation, depending on the degree of anthropogenic disturbance. The considerable genetic variation in the protected fragment points to the importance of adequate conservation of small fragments for the preservation of genetic variation in D. nigra.     

Drosophila suzukii wing spot size is robust to developmental temperature

Phenotypic plasticity is an important mechanism allowing adaptation to new environments and as such it has been suggested to facilitate biological invasions. Under this assumption, invasive populations are predicted to exhibit stronger plastic responses than native populations. Drosophila suzukii is an invasive species whose males harbor a spot on the wing tip. In this study, by manipulating developmental temperature, we compare the phenotypic plasticity of wing spot size of two invasive populations with that of a native population. We then compare the results with data obtained from wild‐caught flies from different natural populations. While both wing size and spot size are plastic to temperature, no difference in plasticity was detected between native and invasive populations, rejecting the hypothesis of a role of the wing‐spot plasticity in the invasion success. In contrast, we observed a remarkable stability in the spot‐to‐wing ratio across temperatures, as well as among geographic populations. This stability suggests either that the spot relative size is under stabilizing selection, or that its variation might be constrained by a tight developmental correlation between spot size and wing size. Our data show that this correlation was lost at high temperature, leading to an increased variation in the relative spot size, particularly marked in the two invasive populations. This suggests: (a) that D. suzukii's development is impaired by hot temperatures, in agreement with the cold‐adapted status of this species; (b) that the spot size can be decoupled from wing size, rejecting the hypothesis of an absolute constraint and suggesting that the wing color pattern might be under stabilizing (sexual) selection; and (c) that such sexual selection might be relaxed in the invasive populations. Finally, a subtle but consistent directional asymmetry in spot size was detected in favor of the right side in all populations and temperatures, possibly indicative of a lateralized sexual behavior.     

Fluctuating asymmetry and allozymic heterozygosity among natural populations of pocket gophers (Thomomys bottae)

Fluctuating asymmetry, or random deviations from bilateral symmetry, has been widely used as a measure of developmental stability. The relationship between fluctuating asymmetry (FA) and allozymic heterozygosity was evaluated using 18 natural populations of pocket gophers ( Thomomys bottae ). Heterozygosity in local populations of pocket gophers ranges over more than an order of magnitude (1.5—18.4%), making this burrowing rodent particularly apt for such studies. Two measures of FA in mensural skull characters were examined: absolute deviations between left and right sides and the variance of signed differences. After log transformations, levels of FA among individuals and populations were not related to size. Repeated-measures analyses of variance showed that FA was significant relative to measurement error, both across populations and within them. Asymmetries of different characters were uncorrelated, despite positive significant correlations among the characters themselves. FA levels varied only slightly among populations of gophers, and this variation was not significant for most characters. FA levels of populations were not correlated with allozymic heterozygosity, and analyses of variance in FA employing heterozygosity were not significant. Heterozygosity levels in these rodents appear more strongly related to aspects of population history (especially effective size and gene flow) than to developmental stability. Because so many genomic and environmental factors can affect morphological variation, caution is needed in interpreting correlations between genetic and phenetic variation.     

GENOMIC COADAPTATION AND DEVELOPMENTAL STABILITY WITHIN INTROGRESSED POPULATIONS OF ENNEACANTHUS GLORIOSUS AND E. OBESUS (PISCES,CENTRARCHIDAE)

Using fluctuating bilateral asymmetry as a measure of developmental stability, we tested the hypothesis that genomic coadaptation mediates developmental stability in natural populations. Hybrid populations were more asymmetrical than populations of the parental species, and ranks of overall developmental instability were positively correlated with ranks of mean heterozygosity in these populations. The failure to find increased asymmetry in previous studies of natural hybrid populations (Jackson, 1973a, 1973b; Felley, 1980) suggests that such populations may have re-evolved coadapted genomes. Increased asymmetry in hybrid Enneacanthus populations may reflect the youthfulness of these populations.     

Shaping intraspecific variation: Development,ecology and the evolution of morphology and life history variation in tiger salamanders

The tiger salamander,Ambystoma tigrinum, is a geographically widespread, morphologically variable, polytipic species. It is among the most variable species of salamanders in morphology and life history with two larval morphs (typical and cannibal) and three adult morphs (metamorphosed, typical branchiate, cannibal branchiate) that vary in frequency between subspecies and between populations within subspecies. We report morphometric evidence suggesting that branchiate cannibals arose through intraspecific change in the onset or timing of development resulting in the wider head and hypertrophied tooth-bearing skull bones characteristic of this phenotype. We also quantified bilateral symmetry of gill raker counts and abnormalities, then evaluated fluctuating asymmetry as a measure of the developmental stability of each morph. There was a significant interaction between fluctuating asymmetry of developmental abnormalities in cannibals and typicals and the locality where they were collected, suggesting that relative stability of each phenotype could vary among populations. While altered timing of developmental events appears to have a role in the evolution and maintenance of morphs, novel phenotypes persist only under favorable ecological conditions. Predictability of the aquatic habitat, genetic variation, kinship, body size, intraspecific competition and predation all affect expression and survival of the morphs inA. tigrinum. This taxon provides an excellent model for understanding the diversity and complexity of developmental and ecological variables controlling the evolution and maintenance of novel phenotypes.