Evidence Of Environmental Effects Research Articles

Do housing-induced changes in brain activity cause stereotypic behaviours in laboratory mice?

Abnormal repetitive stereotypic behaviours (SBs) (e.g. pacing, body-rocking) are common in animals with poor welfare (e.g. socially isolated/in barren housing). But how (or even whether) poor housing alters animals’ brains to induce SBs remains uncertain. To date, there is little evidence for environmental effects on the brain that also correlate with individual SB performance. Using female mice from two strains (SB-prone DBA/2s; SB-resistant C57/BL/6s), displaying two forms of SB (route-tracing; bar-mouthing), we investigated how housing (conventional laboratory conditions vs. well-resourced ‘enriched’ cages) affects long-term neuronal activity as assessed via cytochrome oxidase histochemistry in 13 regions of interest (across cortex, striatum, basal ganglia and thalamus). Conventional housing reduced activity in the cortex and striatum. However, DBA mice had no cortical or striatal differences from C57 mice (just greater basal ganglia output activity, independent of housing). Neural correlates for individual levels of bar-mouthing (positive correlations in the substantia nigra and thalamus) were also independent of housing; while route-tracing levels had no clear neural correlates at all. Thus conventional laboratory housing can suppress cortico-striatal activity, but such changes are unrelated to SB (since not mirrored by congruent individual and strain differences). Furthermore, the neural correlates of SB at individual and strain levels seem to reflect underlying predispositions, not housing-mediated changes. To aid further work, hypothesis-generating model fit analyses highlighted this unexplained housing effect, and also suggested several regions of interest across cortex, striatum, thalamus and substantia nigra for future investigation (ideally with improved power to reduce risks of Type II error).

Sex expression and genotypic sex ratio vary with region and environment in the wetland moss Drepanocladus lycopodioides

Abstract Sex ratio variation is common among organisms with separate sexes. In bryophytes, sex chromosome segregation at meiosis suggests a balanced progeny sex ratio. However, most bryophyte populations exhibit female-biased phenotypic sex ratios based on the presence of reproductive structures on gametophytes. Many bryophyte populations do not form sexual organs, and genotypic sex ratio variation in such populations is mostly unknown. We tested sex expression, and phenotypic and genotypic sex ratios against environmental parameters in natural populations of the unisexual wetland moss Drepanocladus lycopodiodes at 11 sites in each of three regions in southern Sweden. We identified sex in 660 individual ramets, based on sexual structures, when present, or with a specifically designed molecular marker, when absent. All regions exhibited a female bias in phenotypic and genotypic sex ratios. Sex ratio biases and sex expression differed between regions. Sex ratios were less female-biased in larger patches. Wetter patches exhibited a stronger female bias in genotypic sex ratio and lower sex expression. This is the first evidence of environmental effects on genotypic sex ratio in mosses. A higher frequency of females in wet patches could be due to higher female resource demands for sporophyte production or higher male sensitivity to wetness. A higher incidence of females than males in moister sites aligns with female flowering plants, but differs from reproductive bryophytes in drier environments. Taken together with previous results, our data indicate that sex ratio variation and its drivers differ among species, their life histories and environments.

Differential Responses of Taxonomic, Structural, and Functional Diversity to Local-Scale Environmental Variation in Afromontane Forests in South Africa

Exploring taxonomic, functional, and structural diversity can provide additional insights into our understanding of diversity responses to environment. Using altitude, slope, and relative radiation index as well as floristic and functional data from a South Africa Afromontane forest, we examined how taxonomic, structural, and functional diversity varied with local environmental variation. Taxonomic and structural diversity were quantified through species richness- and diameter class-based Shannon index and evenness, respectively. Skewness and coefficient of variation of diameter distribution were additionally computed for structural diversity. As for functional diversity, we used functional richness, evenness, divergence, and dispersion based on functional traits. Data were analyzed using multimodel inference and subset regression. We found little evidence of environmental effects on local-scale taxonomic diversity patterns. In contrast, structural and functional diversity metrics varied significantly along environmental gradients. Accordingly, diameter class-based Shannon evenness declined with increasing slope while skewness and coefficient of variation of diameter distribution increased with increasing slope. Functional evenness and divergence decreased with increasing altitude and radiation, respectively, while functional richness and dispersion increased with increasing slope. The results showed that taxonomic diversity patterns were less responsive to local-scale topographical variation than structural and functional diversity. Lower functional diversity on lower slope sites suggests weak environmental filtering effect promoting competitive exclusion and dominance of species with acquisitive traits. On higher slope sites, environmental filtering associated with slope gradient seems to favor coexistence of species with conservative traits and adapted to harsh conditions.

A fresh approach reveals how dispersal shapes metacommunity structure in a human‐altered landscape

Summary To understand species losses from disturbed landscapes, it is important to distinguish the effects of degraded environmental conditions from those caused by barriers to dispersal between habitat patches. To assess the relative importance of these effects, we developed a new approach using permutation and association tests applied to rank abundance data, using the invertebrate fauna of two rivers in two seasons. Our study streams were Hughes Creek and Seven Creeks, in south‐eastern Australia, which have both been degraded by agriculture in downstream sections. We collected benthic invertebrates and also dispersing individuals (drift, terrestrial adults) during two seasons in 2007–2008. Study sites spanned strong environmental gradients as well as the main dispersal route (up‐ and down‐channel). Environmental data were analysed to set up permutation tests on rank abundances. Survey and disperser data were contrasted using contingency table analyses. The results suggest dispersal plays a strong role in community structure. Environmental effects were evident and strongest upstream, but evidence of environmental effects was weak over much of the gradient. Many species had different distributions in different data sets or dispersers that were abundant at locations distant from centres of benthic distribution. Our results differ from many studies, but few have been able to evaluate dispersal effects directly. Our method provides a practical approach for evaluating the role dispersal plays in driving species abundance patterns across landscapes, thus bridging a gap between theory and practice. Synthesis and applications. Managers typically use indices of ecosystem health that assume environmental conditions largely determine species diversity and abundance. Dispersal between habitat patches is known to be important, but there are no reliable methods to assess the role dispersal may play. We provide an approach that allows both dispersal and environmental effects on species distributions to be evaluated from survey data. This may open the way for dispersal information to be incorporated into management actions. Additionally, the approach should allow improved siting of restoration projects that depend greatly on successful dispersal of individuals for successful outcomes.

Temporal trends in age and size at maturation of four North Sea gadid species: cod, haddock, whiting and Norway pout

Younger ages and smaller sizes at maturation have been observed in commercial fish stocks over the last century. We establish that age and length at 50% proportion mature (i.e. the proportion of mature individuals in a population or the probability that an individual is mature) decreased from the 1970s to the 2000s in North Sea cod Gadus morhua, haddock Melanogrammus aeglefinus and whiting Merlangius merlangus, but not in Norway pout Trisopterus esmarkii. The potential contributions of demography, phenotypic plasticity and evolution to these trends were assessed. First, maturation trends were extricated from demographic effects and growth-dependent plasticity by estimating probabilistic maturation reaction norms (PMRNs). PMRN midpoints have significantly shifted downwards at most ages for cod, haddock and whiting, but not for Norway pout. Second, increased temperature and food abundance, loosened trophic competition and relaxed social pressure may also trigger growth-independent plasticity in maturation. Principal component regression of PMRN midpoints on annual estimates of relevant environmental vari- ables exhibiting a temporal trend suggest that, despite some evidence of environmental effects, PMRN trends were mostly independent of growth-independent plasticity in haddock, whiting and male cod, but not in female cod. According to these findings, evolution of maturation, potentially in response to fishing, is plausible in haddock, whiting and male cod, but unlikely for Norway pout, and does not explain trends in female cod maturation. In agreement with life-history theory, the maturation response was larger in fast-growing, late- and large-maturing species exhibiting moderate reproductive effort.

Description of the air quality in the Navarro Dumpsite area of influence, in Cali, Colombia.

Background: This study evaluated emissions from the municipal open dump in Cali, the Navarro dump (ND), and their effects in air quality of an area defined as exposed (< 3 km distance and downwind) as compared with a control zone (>3 km and upwind). Methods: Sample collection was carried out with semiautomatic equipments following approved international procedures accepted by local environmental laws. Sampling was carried out simultaneously in the study zones during three climatologic periods: dry, rainy and inter-season periods. Ten samples were taken during each period, for a total of 30 samples per zone. Particulate matter below 10 micras, SO2, methane and volatile organic compounds: benzene, toluene and xilene were measured in each sample. Results: Results showed sources of methane and benzene are mainly inside the ND and are carried by wind dispersion to the exposed zone of the study. There is evidence of a gradient in benzene concentrations starting in the ND (p< 0.01). Benzene concentrations were high in the exposed zone (median=2.92 µg/m3) and 48% of samples collected there were above the maximum level of air quality norm. These measurements were higher that those made in the control zone (median=1.54 µg/m3) where only 22% of the samples were above the maximum levels. Methane also showed decreasing concentrations from exposed to control zone, and there was also a higher concentration of particle matter < 5 micras in the exposed area. Conclusions: Our study gives evidence of environmental effects in areas < 3 km distant of a dump site. This distance should be considered when defining the perimeter of a non inhabited area around municipal solid waste disposals.

Evidence of environmental effects on reproductive characteristics of Nile tilapia ( Oreochromis niloticus) populations from man-made lakes of Ivory Coast

Large differences in reproductive traits were observed between populations of Oreochromis niloticus sampled in 9 manmade lakes of Ivory Coast. In order to assess whether these variations in reproductive characteristics resulted from short term adaptation or from a longer evolutionary process, living specimens were caught in the two most differentiated populations in term of life history traits, and placed in a common environment in culture conditions. Genetic analysis of fish from these two populations were performed using four microsatellite markers and revealed that both descended originally from the same strain (Bouaké station) which was constituted from broodfish initially caught in the Nile and Volta basins. Fish from the two populations were subjected to a common environment (pond and aquariums) for five months. Then, their reproductive characteristics were analysed and no significant differences were found in fecundity, egg size and spawning frequency. These results indicate that reproductive differences between the two populations, originally observed in the two reservoirs, mostly reflect the phenotypic plasticity of the species in facing different environmental conditions.

The origins of sex differences in depressive disorder: bridging the gap

The high prevalence of depressive disorder in women is well established. However, it has not been convincingly explained. This reflects a more general failure of research to provide a comprehensive aetiological account of depression. The examination of the sex difference can be used as a probe to evaluate how far we have gone in substantiating integrated models of depressive disorder. In this paper, I review several lines of investigation in order to assess the relative importance of social, psychological and biological influences on the sex difference in depression. These include the epidemiology of macrosocial variables and age effects, and the exploration of relevant psychological attributes, including temperament, personality, and attributional and coping styles. We must also consider the experience of psychosocial adversity, and in particular the possibility of an increased susceptibility of women to some forms of stress. Both the tendency to affiliation and the requirement for social support seem stronger in women. There is appreciable direct and indirect evidence that the particular strains of the roles available to women may increase their risk of depression. Biological explanations tend to be couched in hormonal terms. However, the most convincing hormonal correlates of depressive disorder relate not to sex hormones but to corticosteroids and their control mechanisms. These do not appear to differ by sex. However, the greatest problem for biological explanations of the sex difference lies in the failure of genetic models to account for it. It is hard to conceive of a biological substrate unaffected by genetic factors. Thus, while there seems no doubt that biological factors are involved in the emergence of depressive disorder, they do not appear to be responsible for the sex difference. All told, the evidence for environmental effects is much better for social than for physical factors, and a plausible case can be made for a developmental perspective involving the interaction of social experience and psychological attributes.

Electropolymerization of Cationic Amphiphilic Pyrrole Derivatives on Electrodes. Evidence for Environmental Effects on Redox Potentials of Trapped Anions

Electropolymerization of Cationic Amphiphilic Pyrrole Derivatives on Electrodes. Evidence for Environmental Effects on Redox Potentials of Trapped Anions

Evidence for environmental effects on early-type galaxy X-ray halos

Possible causes for the large dispersion in the X-ray luminosities (Lx) of early-type galaxies are discussed. It is shown that early-type galaxies with relatively low values of Lx for a given optical luminosity L(B) have about 50 percent more neighbors than galaxies with relatively high Lx, suggesting that low-Lx galaxies tend to be in denser environments. It is concluded that the large dispersion in X-ray luminosity, for a given L(B) might be caused either by ram-pressure stripping of the gaseous halos or by mergers.

Implicit Messages: A Review of "Bias in Mental Testing"Bias in Mental Testing. Arthur R. Jensen

A review of Jensen's impressive volume, Bias in Mental Testing, could either address the issues of bias that he considers, and thereby detail the virtues of this scholarly tome, or it could speak to the ghosts that haunt it. Because other reviewers in this series are likely to describe the major theses and lines of evidence in the book, I have chosen to confront the demonic implications in a rather brief ceremony. As a preface, let me say that I agree with Jensen's review of the literature on test construction, and I accept his major conclusions: that tests are not biased against blacks by the standards of test construction and validation, that the differences in performance between blacks and whites are really there, and that test differences have important implications for educational and occupational selection. If the racial differences in general ability are real and cannot be accounted for by biases in the tests, then what can be done about inequities in the distribution of social rewards? Not much, according to Jensen; the evidence for genetic differences in intelligence overwhelms any evidence for environmental effects, so that the reader is left with real differences, important consequences, and no remedies. Jensen's most important conclusions are never stated. By addressing so narrowly the scientific issues of test bias, Jensen has avoided an explicit statement of the conclusions that scream out from his pages: that blacks as a group will not succeed educationally and occupationally in this society, and their lack of success can be justified by their poor performance on tests that predict educational and occupational success. And there is the final, damning implication that the cause of their failures is the pervasive genetic difference in intelligence between the races. The apparition of racial genetic inferiority rises from this book. I will deal first with the ghost of racial genetic differences and then try a little exorcism through incantations about cultural differences in child rearing.

Ab initio UHF calculations. Part 7.—Possible evidence for environmental effects on the radicals BH–3, CH3and NH+3

The radicals BH–3, CH3 and NH+3 are compared using ab initio UHF calculations after annihilation of the contaminating quartet spin state. Although there is a consistency in the trends predicted for the properties, these are not in accord with those determined experimentally. Although the out-of-plane zero-point energy vibration has a dominating influence, it is concluded that the environment must determine the physical properties of BH–3.