Stress In Natural Populations Research Articles

The effects of temperature on plasticity, shape symmetry and seasonal variation in the freshwater benthic green microalga Micrasterias thomasiana

AbstractDesmids are usually abundant in shallow peatland pools. In these localities, water temperature is closely linked to seasonal fluctuations in air temperature, so with increasing temperature extremes in temperate ecosystems, these microalgae are exposed to conditions of high-temperature stress. We investigated whether the shape, size, and growth rates of Micrasterias thomasiana, a frequently occurring species, are associated with varying temperatures in cultures and natural populations. The research was based on parallel analysis of clonal populations in temperature levels from 13 to 33 °C as well as cells from natural populations collected during the season. The effects of high temperature on morphological plasticity and fluctuating asymmetry in the shape of cellular parts were investigated by the landmark-based geometric morphometrics. The results showed that variation among individuals and fluctuating asymmetry between the lateral lobes of Micrasterias cells increased at 29 °C and in natural samples taken in July and October. In parallel, the size of semicells growing at temperatures above 25 °C decreased compared to those grown at lower temperatures. However, the temperature effects on shape and size were not directly related to the growth rates. The overall bilateral asymmetry between semicell halves did not change in relation to varying temperatures. In general, the results showed that morphological variation in natural populations of M. thomasiana reflected seasonal cycles and corresponded to plasticity associated with temperature changes in clonal cultures. It might therefore be possible to use these phenotypic markers as indicators of thermal stress in natural populations inhabiting shallow pools in peatlands.

Fluctuating Asymmetry as a Measure of Stress in Natural Populations of Woody Plants: Influence of Ecological and Geographical Factors on Developmental Stability

Fluctuating asymmetry is a sensitive indicator of favorable conditions during the period of individual development. The influence of climatic factors, biotopic conditions, latitude, altitude, and age of plants from the natural populations of the silver birch Betula pendula Roth was analyzed. The material consisted of 13,000 leaves of the silver birch from 11 regions of north-eastern Siberia. The influence of 23 climatic factors and six integrated coefficients characterizing the general suitability of the climate, as well as summer, winter, spring, and autumn was analyzed. The developmental stability of woody plants and, consequently, the level of the FA of the lamina in natural biotopes can vary in a wide range. We found that climatic factors, mainly conditions in the warm season, have a significant impact. We also noted the influence of the age, biotope, and light conditions. For Betula pendula, an increase in FA was registered on the ecological periphery of its range, i.e., on the edge of the forest belt in the north and in the mountains. The data obtained demonstrate the high influence of natural stress-inducing factors on development stability in plants.

Role of HSP and Leptin in Dairy Animals during Thermal Stress: A Review

Thermal stress is a unique and complex process which alters the normal physiological mechanisms. Heat shock proteins (HSPs) are known to be highly conserved and ubiquitous proteins synthesized in response to several stimuli. The HSP inducers have been categorized as environmental (heat shock, UV radiation, heavy metals, amino acids, oxidative stress, etc.) pathological (bacterial or parasitic infections, fever, inflammation, etc.) and physiological (growth factors, cell differentiation, hormonal stimulation or tissue development, caloric restriction, etc.). The HSPs play an important role for maintaining cellular functioning under environmental challenges and protein denaturation conditions. There is a great potential for using HSP72 expression to detect natural adaptation and exposure to stress in natural populations. Leptin is a 16 kDa polypeptide hormone secreted primarily from the cells of white adipose tissue. Leptin acts through both central and peripheral mechanisms to affect feeding behaviour, lipid and glucose metabolism, thermogenesis, reproductive and endocrine functions. Leptin also plays an important role in the regulation of body weight and composition, e.g. reduction in feed intake and increase in energy expenditure. Bovine lymphocytes express Ob-Rb gene (leptin receptor) and also express leptin. There are ample information on the central role of leptin in brain and neural tissue regulation. In dairy cattle, the increase in milk yield has been associated with a negative energy balance and a decrease in fertility during early lactation. The hormone leptin is involved in regulation of nutritional status and reproductive function.

Transcriptomic response of the intertidal limpet Patella vulgata to temperature extremes

Global warming is challenging wild species in land and water. In the intertidal zone, species are already living at their thermal limits, being vulnerable even to small increases in maximum habitat temperatures. Knowledge of the mechanisms by which many intertidal zone species cope with elevated temperatures is limited. We analysed the molecular thermal stress response of the limpet Patella vulgata under slight and frequent (one-day), and extreme and rare (three-day) warming events. Using RNA-seq to assess differential gene expression among treatments, differing molecular responses were obtained in the two treatments, with more changes in gene expression after the three-day event; with one-third of the differentially expressed transcripts being down-regulated. However, across treatments we observed shifts in gene expression for common aspects of the heat stress response including intra-cellular communication, protein chaperoning, proteolysis and cell cycle arrest. Of the 71,675 transcripts obtained, only 259 were differentially expressed after both heating events. From these, 218 defined the core group (i.e. genes induced by thermal stress with similar expression patterns irrespective of the magnitude of the warming event). The core group was composed of already well-studied genes in heat stress responses in intertidal organisms (e.g. heat shock proteins), but also genes from less explored metabolic pathways, e.g. the ubiquitin system, which were also fundamental regardless of the magnitude of the imposed warming. Moreover, we have also identified 41 signaling genes (i.e. a set of genes responding to both events and with expression patterns specific to the intensity of thermal stress), principally including genes involved in the maintenance of extracellular structure that have previously not been identified as part of the response to thermal stress in intertidal zone organisms. These signaling genes will be useful heat stress molecular biomarkers for monitoring heat stress in natural populations.

Molecular and morphological characterization related to salt stress in natural populations of the Medicago polymorpha species

Legumes are important crops due to their nutritional benefits as well as their utility in agriculture rotation. The morphological and molecular markers can elucidate plant response to stresses. In the present study, we investigated indicators of molecular polymorphism related to salt stress tolerance in natural populations of Medicago polymorpha species. The plant samples were collected from different geographical sites in western Algeria. Morphological growth parameters such as root length stem length of plant and T/R ratio were examined under four NaCl concentration levels (0, 68, 102 and 137 mM). The molecular study was carried out using SSR molecular markers on all the studied populations. Significant differences were observed in mean squares of analysis of variance, indicating relation between geographical origins and populations. This analysis showed the existence of two contrasted populations (DZ221 and DZ312). DZ221 is a relatively salt tolerant, and DZ312 is sensitive. The Principal Component Analysis (PCA) was calculated using the PCA function, revealing a high correlation between the morphological traits and the geographical distribution of populations. It divided populations into four distinguished groups respecting their origin geographical sites. The molecular results of the polymorphism degree showed that the natural populations of M. Polymorpha species were strictly homozygous (100%). The PIC index of the three microsatellites was very informative (0.77). Additionally, the results showed that both microsatellites (FMT11 and MTIC297) revealed some alleles detected in the tolerant population (DZ221) suggesting that they can be used as indicators of saline stress tolerance adaptation.

Measuring the Inter and Intraspecific Sexual Shape Dimorphism and Body Shape Variation in Generalist Ground Beetles in Russia.

Ground beetles in multiple species vary greatly in the expression of the shape on sexual traits, resulting in a sexual shape dimorphism as a consequence of sexual selection differences. The present research focuses on the study of inter and intrasexual sexual shape dimorphism of two generalist genera of ground beetles Pterostichus and Carabus. Geometric morphometric methods were applied to five generalist species of ground beetles Carabus exaratus, C. granulatus, Pterostichus melanarius, P. niger, and P. oblongopunctatus and several multivariate analyses were applied for two different traits, abdomen and elytra. Three of the five species analyzed showed high levels of sex-based shape dimorphism. However, the most generalist species, P. melanarius and P. oblongopunctatus, did not evidence shape-based sexual dimorphism differentiation in both of the analyzed traits, as statistically confirmed based on the permutation of pairwise comparison of the Mahalanobis distances of a sex–species classifier. It is generally known that environmental stress in natural populations can affect the fitness expression, principally related to sexual fecundity, being that this pattern is more evident in non-generalist species. In our results, the contrary pattern was found, with the absence of sexual shape dimorphism for two of the three generalist species analyzed. On the other hand, the interspecies shape variation was clearly identified using principal component analysis of both of the analyzed traits. Finally, this research is the first to analyze the relationship between sexual shape dimorphism in Russian ground beetles, evidencing the lack of understanding of the mechanism underlying the sexual dimorphism, especially in species living in extreme environments.

Behavioural response to combined insecticide and temperature stress in natural populations of Drosophila melanogaster.

Insecticide resistance evolves extremely rapidly, providing an illuminating model for the study of adaptation. With climate change reshaping species distribution, pest and disease vector control needs rethinking to include the effects of environmental variation and insect stress physiology. Here, we assessed how both long-term adaptation of populations to temperature and immediate temperature variation affect the genetic architecture of DDT insecticide response in Drosophila melanogaster. Mortality assays and behavioural assays based on continuous activity monitoring were used to assess the interaction between DDT and temperature on three field-derived populations from climate extremes (Raleigh for warm temperate, Tasmania for cold oceanic and Queensland for hot tropical). The Raleigh population showed the highest mortality to DDT, whereas the Queensland population, epicentre for derived alleles of the resistance gene Cyp6g1, showed the lowest. Interaction between insecticide and temperature strongly affected mortality, particularly for the Tasmanian population. Activity profiles analysed using self-organizing maps show that the insecticide promoted an early response, whereas elevated temperature promoted a later response. These distinctive early or later activity phases revealed similar responses to temperature and DDT dose alone but with more or less genetic variance depending on the population. This change in genetic variance among populations suggests that selection particularly depleted genetic variance for DDT response in the Queensland population. Finally, despite similar (co)variation between traits in benign conditions, the genetic responses across population differed under stressful conditions. This showed how stress-responsive genetic variation only reveals itself in specific conditions and thereby escapes potential trade-offs in benign environments.

The transposable element Bari‐Jheh mediates oxidative stress response in Drosophila

Elucidating the fitness effects of natural genetic variants is one of the current major challenges in evolutionary biology. Understanding the interplay between genotype, phenotype and environment is necessary to make accurate predictions of important biological outcomes such as stress resistance or yield in economically important plants and animals, and disease in humans. Based on population frequency patterns and footprints of selection at the DNA level, the transposable element Bari-Jheh, inserted in the intergenic region of Juvenile Hormone Epoxy Hydrolase (Jheh) genes, was previously identified as putatively adaptive. However, the adaptive effect of this mutation remained elusive. In this work, we integrate information on transcription factor binding sites, available ChIP-Seq data, gene expression analyses and phenotypic assays to identify the functional and the mechanistic underpinnings of Bari-Jheh. We show that Bari-Jheh adds extra antioxidant response elements upstream of Jheh1 and Jheh2 genes. Accordingly, we find that Bari-Jheh is associated with upregulation of Jheh1 and Jheh2 and with resistance to oxidative stress induced by two different compounds relevant for natural D. melanogaster populations. We further show that TEs other than Bari-Jheh might be playing a role in the D. melanogaster response to oxidative stress. Overall our results contribute to the understanding of resistance to oxidative stress in natural populations and highlight the role of transposable elements in environmental adaptation. The replicability of fitness effects on different genetic backgrounds also suggests that epistatic interactions do not seem to dominate the genetic architecture of oxidative stress resistance.

The ecology of stress: a marriage of disciplines

The ecology of stress: a marriage of disciplines

Assessment of reproductive stress in natural populations of the fish Aphanius fasciatus using quantitative mRNA markers

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 17:285-293 (2012) - DOI: https://doi.org/10.3354/ab00482 Assessment of reproductive stress in natural populations of the fish Aphanius fasciatus using quantitative mRNA markers Ali Annabi1, Kaouthar Kessabi1, Anna Navarro2, Khaled Saïd1, Imed Messaoudi1, Benjamin Piña2,* 1Institut Supérieur de Biotechnologie, Université de Monastir, Monastir 5000, Tunisia 2Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona, 18, 08034 Barcelona, Spain *Email: bpcbmc@cid.csic.es ABSTRACT: Four populations of the Mediterranean killifish Aphanius fasciatus were studied to evaluate the biological effects of environmental pollution. These effects were measured using RNA quantification-based markers in the gonads and liver. Metallothionein genes in both testes and ovaries showed elevated expression in males and females from the more contaminated areas. In addition, males from these areas showed elevated levels of vitellogenin synthesis in the liver. These results were correlated with heavy metals and polycyclic aromatic hydrocarbon levels in water and sediment samples from the sampling sites. They represent the first evidence of an incipient feminization of marine fish along the coast of Tunisia and confirm the utility of RNA quantification-based markers for monitoring environmental impact on small animals and in species for which very little biological information is available. KEY WORDS: Environmental pollution · Brackish water · Coastal pollution · Endocrine disruption · Quantitative real-time polymerase chain reaction · qRT-PCR Full text in pdf format Supplementary material PreviousNextCite this article as: Annabi A, Kessabi K, Navarro A, Saïd K, Messaoudi I, Piña B (2012) Assessment of reproductive stress in natural populations of the fish Aphanius fasciatus using quantitative mRNA markers. Aquat Biol 17:285-293. https://doi.org/10.3354/ab00482 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 17, No. 3. Online publication date: December 13, 2012 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2012 Inter-Research.

Evaluating stress in natural populations of vertebrates: total CORT is not good enough

Summary Our goal in this review is to discuss how measures beyond simple quantification of total glucocorticoid levels are needed in comparative studies of stress. We need to measure corticosteroid binding globulin – CBG – and further downstream performance metrics to properly evaluate the significance and impact of stress in wild populations. We briefly cover the current literature, discuss methods that may enable detection of chronic stress and point to directions for future research to continue to clarify this field. CBG may regulate access of hormones to tissues, but disagreement remains as to the functional importance of total vs. free vs. bound hormone in the plasma. Here we focus on recent studies providing solid evidence supporting the free hormone hypothesis. These studies unequivocally indicate that the biologically active fraction consists only of the portion that is free (not total levels in the blood). We also present the ‘reservoir hormone hypothesis’, indicating the relevance of CBG‐bound hormone in the plasma. The vast majority of physiological studies on stress in natural populations only measure blood corticosterone or its faecal metabolites. However, downstream metrics (e.g. immune function, oxidative stress and body mass changes) can assess the physiological impact of the changes in corticosterone and CBG and ultimately of the adaptiveness of these changes. Here we will discuss some of the most promising factors that can be measured downstream of the plasma and the rationale for their measurement, how to do it, and an introduction to the evidence. Although we draw on biomedical findings for some of this insight, we recognized that findings from a few mammalian laboratory species (primarily rats and mice) may not apply to the vast diversity of vertebrate species from fish to birds. In large measure we are still in the natural history phase of the accumulation of fundamental knowledge in terms of trying to extract general principles in the stress biology of natural populations. Our review outlines what is needed to lay the foundation for these principles.

Surplus Photosynthetic Antennae Complexes Underlie Diagnostics of Iron Limitation in a Cyanobacterium

Chlorophyll fluorescence from phytoplankton provides a tool to assess iron limitation in the oceans, but the physiological mechanism underlying the fluorescence response is not understood. We examined fluorescence properties of the model cyanobacterium Synechocystis PCC6803 and a ΔisiA knock-out mutant of the same species grown under three culture conditions which simulate nutrient conditions found in the open ocean: (1) nitrate and iron replete, (2) limiting-iron and high-nitrate, representative of natural high-nitrate, low-chlorophyll regions, and (3) iron and nitrogen co-limiting. We show that low variable fluorescence, a key diagnostic of iron limitation, results from synthesis of antennae complexes far in excess of what can be accommodated by the iron-restricted pool of photosynthetic reaction centers. Under iron and nitrogen co-limiting conditions, there are no excess antennae complexes and variable fluorescence is high. These results help to explain the well-established fluorescence characteristics of phytoplankton in high-nutrient, low-chlorophyll ocean regions, while also accounting for the lack of these properties in low-iron, low-nitrogen regions. Importantly, our results complete the link between unique molecular consequences of iron stress in phytoplankton and global detection of iron stress in natural populations from space.

Application of heat shock protein expression for detecting natural adaptation and exposure to stress in natural populations

Abstract Heat-shock proteins (HSPs) play an undisputed role for maintaining cellular functioning under environmental challenges and protein denaturing conditions. Compelling evidence points to an evolutionary important role of HSPs and a strict evolutionary control of these proteins as a balance between benefits and costs. While there is a great potential for using HSP expression for detecting natural adaptation and exposure to stress in natural populations, some obstacles and key issues await investigation. From an ecological perspective these key issues needs to be resolved in order to fully appreciate the complex responses and adaptations to stress and to increase our understanding of HSPs and other molecular chaperones for stress adaptation and potential use as biomarkers. Here, the current knowledge and understanding of HSPs is reviewed and a number of key issues including the interpretation of elevated HSP levels, the complications of extrapolating between laboratory and field conditions, the effects of choice of traits and methodology and the larger intra-and extracellular networks of interactions that HSPs participate in are discussed.

Fluctuating Asymmetry as an Indicator of Environmental Stress From Off‐Highway Vehicles

Abstract: With human activities increasingly impacting natural resources in relatively remote locations, there is a need for simple and efficient methods to explore the ecological consequences of these activities. Little is understood about the influences of off‐highway vehicle (OHV) use on wildlife populations. We examined the effect of OHV activity on developmental instability in a phrynosomatid lizard (i.e., western fence lizard [Sceloporus occidentalis]) in the western Great Basin, USA. We measured fluctuating asymmetry (FA) of bilateral head‐scale patterns in populations of lizards at 3 OHV and 3 non‐OHV sites. Fluctuating asymmetry was higher at OHV sites relative to non‐OHV sites, supporting the idea that OHV activity can stress wildlife populations. We found FA to be a good tool for uncovering responses to stress in natural populations, and we recommend exploring FA as a means of uncovering developmental instability in other systems that merit conservation interest.

Decrease of fluctuating asymmetry among larval instars in an aquatic, holometabolous insect

The use of fluctuating asymmetry (FA) to reveal environmental stress in natural populations has been investigated extensively over the past decade. In aquatic ecosystems, many investigations involve amphibiotic insects with larval development stages in freshwater. To explain the important variability in study results, we investigated the FA level of a natural Hydropsyche exocellata (Insecta: Trichoptera) population at four different stages, from first larval instar to adult. The level of FA decreased between larval stages, but remained constant between the last larval instar and the adult. The presence of a compensational growth mechanism and the elimination of asymmetric individuals by natural selection are two hypotheses that could explain this observation. To cite this article: C. Piscart et al., C. R. Biologies 328 (2005).

Ecologically relevant stress resistance: from microarrays and quantitative trait loci to candidate genes — A research plan and preliminary results usingDrosophila as a model organism and climatic and genetic stress as model stresses

We aim at studying adaptation to genetic and environmental stress and its evolutionary implications at different levels of biological organization. Stress influences cellular processes, individual physiology, genetic variation at the population level, and the process of natural selection. To investigate these highly connected levels of stress effects, it is advisable - if not critical - to integrate approaches from ecology, evolution, physiology, molecular biology and genetics. To investigate the mechanisms of stress resistance, how resistance evolves, and what factors contribute to and constrain its evolution, we use the well-defined model systems of Drosophila species, representing both cosmopolitan species such as D. melanogaster with a known genome map, and more specialized and ecologically well described species such as the cactophilic D. buzzatii. Various climate-related stresses are used as model stresses including desiccation, starvation, cold and heat. Genetic stress or genetic load is modelled by studying the consequences of inbreeding, the accumulation of (slightly) deleterious mutations, hybridization or the loss of genetic variability. We present here a research plan and preliminary results combining various approaches: molecular techniques such as microarrays, quantitative trait loci (QTL) analyses, quantitative PCR, ELISA or Western blotting are combined with population studies of resistance to climatic and genetic stress in natural populations collected across climatic gradients as well as in selection lines maintained in the laboratory.

Among‐ and within‐population variability in tolerance to cadmium stress in natural populations of Daphnia magna: Implications for ecological risk assessment

Previous attempts to test the hypothesis that laboratory selection of isogenetic populations can produce test organisms with a significantly increased mean tolerance to toxic substances have failed. One possible explanation for such failure is that the tolerance of laboratory populations is largely constrained by their origins (were the source populations composed of tolerant genotypes?). To address this question, among- and within-population variability in stress tolerance was assessed by calculating the variance in individual fitness and longevity across a cadmium gradient (0-10 microg/L). The study employed Daphnia magna clones from four geographically separate European populations. Results revealed significant differences in tolerance to lethal levels of toxic stress among populations. The distribution of tolerances within two of the studied populations showed high amounts of genetic variation in tolerance. Genetic relationships between tolerance traits and life history performance under nonstressful environments differed among the studied populations. One population showed significant but low costs associated with tolerance, whereas no costs were associated with tolerance in the other population. These results suggest that laboratory selection will favor individuals with high fitness or reproductive performance under optimal laboratory conditions resulting in laboratory populations with similar or lower tolerance to toxic stress than their original field populations. Given that populations can exhibit high levels of genetic variability in tolerance to toxic stress, minimizing genetic diversity in toxicity tests will increase the uncertainty attendant in extrapolating from the lab to the field.

Developmental stability and environmental stress in natural populations of Drosophila pachea

We examined the relationship between developmental stress and fluctuating asymmetry in a natural population of Drosophila pachea, a cactophilic fruitfly. Cactus host variation was found to exert significant influence on the size of legs and of wings of emerging adults, but stressors associated with reduced size did not show the predicted increase in fluctuating asymmetry for either leg or wing length. These findings underscore questions raised by other investigators as to the broad utility of fluctuating asymmetry as a measure of environmental stress

Flavodoxin as an in situ marker for iron stress in phytoplankton

A fundamental issue in marine science is the identification of the factors controlling biological uptake of CO2, in high-nitrate, low-chlorophyll regions. A recent in situ iron fertilization experiment demonstrated that iron limitation is responsible for low phytoplankton stocks in the equatorial Pacific4. Here we show that flavodoxin, a biochemical marker of iron limitation, can be used to map the degree of iron stress in natural populations. Flavodoxin assays along a 900-km east-west transect in the northeastern subarctic Pacific revealed a pronounced increase in iron stress in the region west of the 135° W meridian. Addition of dissolved iron alleviated this stress. Immunostaining of single cells from the most western station showed that flavodoxin is present specifically within the chloroplasts of diatoms. Our approach provides a rapid means of defining the extent of iron stress in the ocean5 and supports the hypothesis that diatoms are iron stressed in the northeast Pacific.

STRESS TOLERANCE IN INTERTIDAL SEAWEEDS

ABSTRACTIntertidal seaweeds are periodically exposed to air where they experience a variety of potentially stressful environmental conditions, including nutrient limitation, high light, high and low temperature, desiccation, and osmotic stress. This paper considers the current understanding of stress tolerance in intertidal seaweeds and discusses ways in which future research could increase our understanding of the role of environmental factors in the ecology and physiology of these algae. We believe research is required in at least three areas. 1) Laboratory physiological studies have established that correlations exist between stress tolerance and the vertical distribution of species. However, little information is available on the importance of stress in determining community structure in nature. Field experiments are essential to relate the impact of single or multiple stresses on the survival, growth, and reproductive output of macroalgae. In paticular, it is necessary to clarify the role of sublethal stress in determining the outcome of competitive interactions. 2) With the exception of obvious lethal effects or damage associated with extreme environmental conditions, such as unusually hot and dry weather, it is difficult to evaluate the occurrence and severity of stress in natural populations of seaweeds. There is a need to develop molecular and biochemical markers specific for individual stresses or groups of stresses to allow the unambiguous and direct determination of stress in situ. 3) Despite the apparent importance of stress in intertidal seaweeds, we are largely ignorant of the mechanistic basis of tolerance. The application of currently available tools of molecular and cell biology to the investigation of stress‐induced transcriptional and translational changes could enormously increase our understanding of both the sites of, and pathways involved in, stress tolerance. In summary, there are numerous unanswered fundamental questions about the stress tolerance of intertidal seaweeds, providing opportunities for research ranging from field ecology to molecular biology and biochemistry.