Heterogeneous Environmental Conditions Research Articles

Advanced integration of fluid dynamics and photosynthetic reaction kinetics for microalgae culture systems

BackgroundPhotosynthetic microalgae have been in the spotlight of biotechnological production (biofuels, lipids, etc), however, current barriers in mass cultivation of microalgae are limiting its successful industrialization. Therefore, a mathematical model integrating both the biological and hydrodynamical parts of the cultivation process may improve our understanding of relevant phenomena, leading to further optimization of the microalgae cultivation.ResultsWe introduce a unified multidisciplinary simulation tool for microalgae culture systems, particularly the photobioreactors. Our approach describes changes of cell growth determined by dynamics of heterogeneous environmental conditions such as irradiation and mixing of the culture. Presented framework consists of (i) a simplified model of microalgae growth in a culture system (the advection-diffusion-reaction system within a phenomenological model of photosynthesis and photoinhibition), (ii) the fluid dynamics (Navier-Stokes equations), and (iii) the irradiance field description (Beer-Lambert law). To validate the method, a simple case study leading to hydrodynamically induced fluctuating light conditions was chosen. The integration of computational fluid dynamics (ANSYS Fluent) revealed the inner property of the system, the flashing light enhancement phenomenon, known from experiments.ConclusionOur physically accurate model of microalgae culture naturally exhibits features of real system, can be applied to any geometry of microalgae mass cultivation and thus is suitable for biotechnological applications.

Global patterns of Rhododendron diversity: The role of evolutionary time and diversification rates

AbstractAimUnderstanding the evolution of the latitudinal diversity gradient (i.e. increase in species diversity towards the tropics) is a prominent issue in ecology and biogeography. Disentangling the relative contributions of environment and evolutionary history in shaping this gradient remains a major challenge because their relative importance has been found to vary across regions and taxa. Here, using the global distributions and a molecular phylogeny of Rhododendron, one of the largest genera of flowering plants, we aim to compare the relative contributions of contemporary environment, evolutionary time and diversification rates in generating extant species diversity patterns.LocationGlobal.Time periodUndefined.Major taxa studiedRhododendron.MethodsWe compiled the global distributions of all Rhododendron species, and constructed a dated molecular phylogeny using nine chloroplast genes and seven nuclear regions. By integrating these two datasets, we estimated the temporal trends of Rhododendron diversification, and explored the global patterns of its species diversity, net diversification rates, and species ages. Next, we reconstructed the geographical ancestral area of the clade. Finally, we compared the relative contribution of contemporary environment, time‐for‐speciation, and diversification rates on the species diversity pattern of Rhododendron.ResultsIn contrast to the predictions of the time‐for‐speciation hypothesis, we found that although Rhododendron originated at a temperate latitude, its contemporary species diversity is highest in the tropics/subtropics, suggesting an into‐the‐tropics colonization for this genus. We found that the elevated diversification induced by heterogeneous environmental conditions in the tropics/subtropics shapes the global pattern of Rhododendron diversity.Main conclusionsOur findings support tropical and subtropical mountains as not only biodiversity and endemism hotspots, but also as cradles for the diversification of Rhododendron. Our study emphasizes the need of unifying ecological and evolutionary approaches in order to gain comprehensive understanding of the mechanisms underlying the global patterns of plant diversity.

Changes in alpine plant communities under climate change: Dynamics of snow‐meadow vegetation in northern Japan over the last 40 years

AbstractQuestionAlpine plant communities are often distributed as a mosaic reflecting micro‐scale heterogeneity of environmental conditions, indicating the importance of diverse habitats in maintaining species diversity in alpine ecosystems. Because snow‐meadow vegetation is particularly sensitive to climate change, species composition and community structure may have changed over the last few decades in response to global warming. The aim of the present study is to quantify changes in species diversity and snow‐meadow community composition over the last 40 years.LocationTaisetsu Mountains, Hokkaido, Japan.MethodsThe presence and ground cover of plant species were surveyed in two snow‐meadow sites in 1971–1972 (44 and 113 plots) and 2012 (85 and 115 plots). In addition, soil moisture and snowmelt time were measured in every plot in 2012. Changes in species richness, functional types and species composition between the survey periods were analysed.ResultsCommunity structure of snow‐meadow vegetation has changed significantly. Although the total number of species at each site was the same between the survey periods, Shannon's diversity index and species richness per plot have increased. Moreover, similarity in species composition among community types has been enhanced, indicating the mosaic structure of alpine vegetation has become obscure. The relative dominance of forbs (particularly tall herbaceous species) decreased, while that of shrubs increased. The distribution of community types reflected the snowmelt and soil moisture conditions.ConclusionsSignificant changes have occurred in vegetation structure in the alpine snow‐meadows, possibly due to accelerated snow melt and drier soil conditions linked to global warming. To predict the dynamics of alpine vegetation, we need to clarify how micro‐scale heterogeneity of environmental conditions is modified by global change.

Functional traits and environmental conditions predict community isotopic niches and energy pathways across spatial scales

Abstract Despite ongoing research in food web ecology and functional biogeography, the links between food web structure, functional traits and environmental conditions across spatial scales remain poorly understood. Trophic niches, defined as the amount of energy and elemental space occupied by species and food webs, may help bridge this divide. Here, we ask how the functional traits of species, the environmental conditions of habitats and the spatial scale of analysis jointly determine the characteristics of trophic niches. We used isotopic niches as a proxy of trophic niches, and conducted analyses at spatial scales ranging from local food webs and metacommunities to geographically distant sites. We sampled aquatic macroinvertebrates from 104 tank bromeliads distributed across five sites from Central to South America and compiled the macroinvertebrates’ functional traits and stable isotope values (δ15N and δ13C). We assessed how isotopic niches within each bromeliad were influenced by the functional trait composition of their associated invertebrates and environmental conditions (i.e., habitat size, canopy cover [CC] and detrital concentration [DC]). We then evaluated whether the diet of dominant predators and, consequently, energy pathways within food webs reflected functional and environmental changes among bromeliads across sites. At last, we determined the extent to which the isotopic niches of macroinvertebrates within each bromeliad contributed to the metacommunity isotopic niches within each site and compared these metacommunity‐level niches over biogeographic scales. At the bromeliad level, isotopic niches increased with the functional richness of species in the food web and the DC in the bromeliad. The diet of top predators tracked shifts in prey biomass along gradients of CC and DC. Bromeliads that grew under heterogeneous CC displayed less trophic redundancy and therefore combined to form larger metacommunity isotopic niches. At last, the size of metacommunity niches depended on within‐site heterogeneity in CC. Our results suggest that the trophic niches occupied by food webs can predictably scale from local food webs to metacommunities to biogeographic regions. This scaling process is determined by both the functional traits of species and heterogeneity in environmental conditions. A plain language summary is available for this article.

Metacommunity analysis of meiobenthos of deep-sea sediments from the Gulf of Mexico

Metacommunity theory is a conceptual framework addressing the interdependence of local interactions and regional processes, especially when it is difficult to relate community structure and the environment at different spatial scales. To test the applicability of this theory to meiobenthos, 27 deep-sea sediment samples from the Gulf of Mexico were analyzed for meiobenthic and nematode community distribution and structure along with a set of environmental variables. Spatial and temporal heterogeneity in environmental conditions were found among sampling stations, and some variables, such as depth, inorganic carbon, carbon/nitrogen ratio, bottom-water oxygen, and percentage of sand, proved influential on total community abundance. Nematodes were the dominant meiofaunal group and its abundance highly variable among sites and sampling periods. Nematofauna was dominated by bacterivores, which also possessed the highest maturity index. Environmental characteristics showed a significant relation with community structure, not so the dispersal of nematode genera. In light of our findings, we posit that the deep-sea meiobenthos of the Gulf of Mexico may represent a metacommunity following the “species-sorting model.” This inference is based on the different taxonomic structures among sampling stations correlating with environmental differences, in the presence of local niche diversification and limited dispersal.

A systematic methodology for the robust quantification of energy efficiency at wastewater treatment plants featuring Data Envelopment Analysis

This article examines the potential benefits of using Data Envelopment Analysis (DEA) for conducting energy-efficiency assessment of wastewater treatment plants (WWTPs). WWTPs are characteristically heterogeneous (in size, technology, climate, function …) which limits the correct application of DEA. This paper proposes and describes the Robust Energy Efficiency DEA (REED) in its various stages, a systematic state-of-the-art methodology aimed at including exogenous variables in nonparametric frontier models and especially designed for WWTP operation. In particular, the methodology systematizes the modelling process by presenting an integrated framework for selecting the correct variables and appropriate models, possibly tackling the effect of exogenous factors. As a result, the application of REED improves the quality of the efficiency estimates and hence the significance of benchmarking. For the reader's convenience, this article is presented as a step-by-step guideline to guide the user in the determination of WWTPs energy efficiency from beginning to end. The application and benefits of the developed methodology are demonstrated by a case study related to the comparison of the energy efficiency of a set of 399 WWTPs operating in different countries and under heterogeneous environmental conditions.

Influence of surface flattening on biodiversity of terrestrial arthropods during early stages of brown coal spoil heap restoration

Heterogeneity of environmental conditions is the crucial factor supporting biodiversity in various habitats, including post-mining sites. The effects of micro-topographic heterogeneity on biodiversity and conservation potential of arthropod communities in post-industrial habitats had not been studied before now. At one of the largest European brown coal spoil heaps, we sampled eight groups of terrestrial arthropods with different life strategies (moths, spiders, ground beetles, ants, orthopteroids, centipedes, millipedes, and woodlice), in successionally young plots (5–18 y), with a heterogeneous wavy surface after heaping, and compared the communities with plots flattened by dozing. A combination of the standardized quantitative sampling, using two different methods, and a paired design of the plot selection enabled a robust analysis. Altogether, we recorded 380 species of the focal arthropods, 15 of them nationally threatened. We revealed the importance of the micro-topographic heterogeneity for the formation of the biodiversity of arthropods in their secondary refuges. The communities with higher biodiversity and conservation value were detected in the plots with heterogeneous surfaces; exceptions were ground beetles and millipedes. The surface flattening, often the first step of technical reclamation projects, thus suppress biodiversity of most terrestrial arthropods during the restoration of post-mining sites. Since the communities of both surface types differed, the proportional presence on both surfaces could be more efficient in supporting the local biodiversity. We suggest reducing the surface dozing for the cases with other concerns only, to achieve a proportional representation of both surface types. Such a combination of different restoration approaches would, thus, efficiently support high biodiversity of groups with various needs.

Between-population differences in the genetic and maternal components of body mass in roe deer

BackgroundUnderstanding the genetic and environmental mechanisms governing variation in morphology or phenology in wild populations is currently an important challenge. While there is a general consensus that selection is stronger under stressful conditions, it remains unclear whether the evolutionary potential of traits should increase or decrease with increasingly stressful conditions. Here, we investigate how contrasting environmental conditions during growth may affect the maternal and genetic components of body mass in roe deer, the most abundant and widespread wild ungulate in Western Europe. Body mass is a key life history trait that strongly influences both survival and reproductive performance in large herbivores. We used pedigrees and animal models to determine the variance components of juvenile and adult winter body mass in two populations experiencing contrasting early-life conditions.ResultsOur analyses showed that roe deer at Chizé, where habitat was poor and unpredictable, exhibited very low genetic variance in juvenile body mass. Instead, variance in mass was mainly driven by among-cohort differences in early-life conditions and maternal environment. In contrast, roe deer at Bogesund, where resource availability during the critical period of fawn rearing was higher, displayed a substantial level of genetic variance in body mass. We discuss the potential role of past demography and viability selection on fawn body mass on the erosion of genetic variance in the poor habitat.ConclusionsOur study highlights the importance of accounting for both spatial (i.e. between-population variation) and temporal (i.e. cohort variation) heterogeneity in environmental conditions, especially in early life, to understand the potential for adaptive responses of wild populations to selection.

Some European green roof norms and guidelines through the lens of biodiversity: Do ecoregions and plant traits also matter?

Green infrastructure and in particular green roofs are crucial to meet the challenge of sustainable urbanisation fostered by the current European Research and Innovation agenda. Several documents were issued in the last decades in Europe for regulating the design, construction and up-keep of roof greening. In particular, the actual German guidelines have been widely adopted as a reference basis for green roof design and regulation worldwide, because of its exhaustiveness and proven building- and landscaping tradition. With the aim to assess the effectiveness of green roof guidelines and norms in supporting plant and soil biodiversity in different ecoregions, and particularly of the Mediterranean one, the German guidelines, the Swiss and Italian norms are screened and discussed in this paper. The German guidelines were chosen for their traditional referential role, the Swiss norm for its peculiar biodiversity approach, the Italian one for its application on a territory with remarkably heterogeneous environmental conditions, stretching from Alpine to Mediterranean ecosystems. Even if the three documents at comparison addressed to some extent biodiversity-related matters, none of them deepened the relationship between plant species selection (local ecotypes), growing medium composition (materials, granular size and thickness) and system build-ups (multi-layers and/or single-layer systems). This is a crucial point for countries, like Italy, encompassing very different climatic conditions. It was concluded that at the current knowledge a guideline/norm taking into account the peculiarities of green roof design in the Mediterranean ecoregion has to be widely refined.

Direct and plant trait‐mediated effects of the local environmental context on butterfly oviposition patterns

Variation in the intensity of plant–animal interactions over different spatial scales is widespread and might strongly influence fitness and trait selection in plants. Differences in traits among plant individuals have been shown to influence variation in interaction intensities within populations, while differences in environmental factors and community composition are shown to be important for variation over larger scales. However, little is still known about the relative importance of the local environmental context vs. plant traits for the outcome of interactions within plant populations. We investigated how oviposition by the seed‐predator butterfly Phengaris alcon on its host plant Gentiana pneumonanthe was related to host plant traits and to local environmental variation, as well as how oviposition patterns translated into effects on host plant fruit set. We considered the local environmental context in terms of height of the surrounding vegetation and abundance of the butterfly's second host, Myrmica ants. The probability of oviposition was higher in plants that were surrounded by lower vegetation, and both the probability of oviposition and the number of eggs increased in early‐flowering and tall plants with many flowers in the three study populations. Flowering phenology, shoot height and flower production were, in turn, related to higher surrounding vegetation. Myrmica abundance was correlated with vegetation height, but had no effect on oviposition patterns. Oviposition and subsequent seed predation by the caterpillars strongly reduced host plant fruit set. Our results show that plant–animal interactions are context‐dependent not only because the context influences the abundance or the behavior of the animal interactor, but also because it influences the expression of plant traits that affect the outcome of the interaction. The results also demonstrate that heterogeneity in environmental conditions at a very local scale can be important for the outcomes of interactions.

Evaluation of the possibility of equalizing the fluid temperature in a hydrolevelling system by mixing

Measurement systems that are based on the hydrostatic leveling method in ideal conditions allow one to control vertical displacements with accuracy of the order of one micrometer. Heterogeneous and time-varying environmental conditions have a significant effect on the measurement error. One way to reduce it is to equalize the temperature of the fluid in a hydrostatic level by mixing liquid inside it before taking measurements. In this paper, it is estimated that this operation can be performed by modeling the fluid circulation process in a simplified analog of the hydrostatic level taking into account a heat transfer through the hose wall. The fluid dynamics is described by the Reynolds averaged Navier-Stokes equations, which are closed by the SST turbulence model. The given analytical estimates of heat transfer coefficients on the side surface of the hose are refined on the basis of experiments at two values of the flow rate of water flowing through the pipe. The evolution of the temperature field is found from the numerical solution of the conjugate heat transfer problem by the finite volume method. In the test example, in which two parts of the hydrostatic level are located in the areas with markedly different temperature, the heterogeneity of the temperature field at different times has been estimated. The mixing time sufficient to achieve a temperature close to the homogeneous distribution of the flowing fluid in the hydrostatic level is determined at different volumes of the mixer. The proposed approach can be used under real external conditions for the selection of optimal parameters of the pump: flow rate, mixing time and mixing tank volume. The temperature field obtained in the calculation can serve as a basis for estimating the achievable accuracy of the measurement system.

Simulation of Escherichia coli Dynamics in Biofilms and Submerged Colonies with an Individual-Based Model Including Metabolic Network Information.

Clustered microbial communities are omnipresent in the food industry, e.g., as colonies of microbial pathogens in/on food media or as biofilms on food processing surfaces. These clustered communities are often characterized by metabolic differentiation among their constituting cells as a result of heterogeneous environmental conditions in the cellular surroundings. This paper focuses on the role of metabolic differentiation due to oxygen gradients in the development of Escherichia coli cell communities, whereby low local oxygen concentrations lead to cellular secretion of weak acid products. For this reason, a metabolic model has been developed for the facultative anaerobe E. coli covering the range of aerobic, microaerobic, and anaerobic environmental conditions. This metabolic model is expressed as a multiparametric programming problem, in which the influence of low extracellular pH values and the presence of undissociated acid cell products in the environment has been taken into account. Furthermore, the developed metabolic model is incorporated in MICRODIMS, an in-house developed individual-based modeling framework to simulate microbial colony and biofilm dynamics. Two case studies have been elaborated using the MICRODIMS simulator: (i) biofilm growth on a substratum surface and (ii) submerged colony growth in a semi-solid mixed food product. In the first case study, the acidification of the biofilm environment and the emergence of typical biofilm morphologies have been observed, such as the mushroom-shaped structure of mature biofilms and the formation of cellular chains at the exterior surface of the biofilm. The simulations show that these morphological phenomena are respectively dependent on the initial affinity of pioneer cells for the substratum surface and the cell detachment process at the outer surface of the biofilm. In the second case study, a no-growth zone emerges in the colony center due to a local decline of the environmental pH. As a result, cellular growth in the submerged colony is limited to the colony periphery, implying a linear increase of the colony radius over time. MICRODIMS has been successfully used to reproduce complex dynamics of clustered microbial communities.

Bacterial communities in the upper soil layers in the permafrost regions on the Qinghai-Tibetan plateau

The Qinghai-Tibetan plateau (QTP) is the largest middle-low latitude permafrost region on earth, while little is known about the microbial community in this area. Here, we investigated the bacterial community in the upper 30cm soils in the permafrost regions on the central QTP using Illumina sequencing technology. In these soils, the most abundant phyla were Acidobacteria, Proteobacteria, and Bacteroidetes. The depth was significantly correlated with Acidobacteria, Proteobacteria, Nitrospirae, and Gemmatimonadetes. The soil pH and the gravel content were significantly positively correlated with Bacteroidetes. The active layer thickness was significantly correlated with Bacteroidetes and Arabinonates. Although these factors were closely correlated with the relative abundances of specific bacterial phyla, the overall bacterial community structure was mainly affected by pH, soil organic carbon content, and the mean annual precipitation, while the community structure had no significant relationship with the active layer thickness. Our results suggested that the permafrost region on the QTP had greatly heterogeneous environmental conditions, and the responses of microbial communities to permafrost degradation would also be affected by other factors such as precipitation, soil texture and vegetation.

Intraspecific variation in reproductive characters is associated with the strength of sexual selection in the hermaphroditic land snail Cornu aspersum

Intraspecific variation in sexual traits may arise from a variety of processes such as genetic drift, sexual selection, or spatial heterogeneity of environmental conditions. Recent empirical studies suggest that sexual selection may vary with environmental conditions accelerating differentiation of sexual traits among populations. Land snails are simultaneously hermaphroditic animals characterized by low mobility and limited dispersal, so that life cycle characteristics of their populations are strongly influenced by local environmental conditions. In this study, we report results on intraspecific variation in sexual selection intensity as well as in behavioral and anatomical reproductive traits in the land snail Cornu aspersum. We performed a common garden experiment of adult snails originating from four populations from either of two regions in Greece differing in habitat temperature and predictability of rainfall during their reproductive season. Our results indicate substantial intraspecific variation in the opportunity for sexual selection, which was associated with differences in both behavioral and anatomical reproductive characters. Snails from populations that experienced unpredictable habitat conditions expanded their reproductive activity period, exhibited higher mating frequency, and showed longer copulation duration, relative to snails living in more predictable habitats. Additionally, snails originating from populations with unpredictable habitat conditions showed a distinct reproductive morphology with a shorter bursa tract length, which we interpret as indicative of an enhanced ability to hydrolyze the received spermatophores. We conclude that local environmental conditions experienced by the different populations could have triggered differences in the opportunity for sexual selection, which may ultimately lead to allopatric speciation through sexual selection. Environment-dependent sexual selection is considered to promote allopatric speciation of distant populations. However, empirical studies testing for geographic differences in the strength of sexual selection and associated reproductive characters are scarce. In C. aspersum, variation in both behavioral and anatomical reproductive traits among populations is well-documented, but the extent to which this is driven by diverse pressures of sexual selection under heterogeneous environmental conditions among populations remains unexplored. We demonstrate that snails from two geographically distant regions of Greece, with contrasting natural habitats, differ mainly in their behavioral traits and in several morphological traits, which are associated with differences in the opportunity for pre- and post-copulatory sexual selection.

First records of two planktonic Indo-Pacific diatoms: Chaetoceros bacteriastroides and C. pseudosymmetricus in the Adriatic Sea

Summary Unusual occurrence of planktonic diatom species, Chaetoceros bacteriastroides and Chaetoceros pseudosymmetricus , was noticed in three different marine ecosystems of Adriatic Sea: the Krka Estuary and Telascica Bay in the Central Adriatic, and in southern Adriatic offshore. From 2010 to 2015, these two Chaetoceros species were recorded in heterogeneous environmental conditions and in a very low abundances. Both species are regarded as very rare in world oceans, and consequently knowledge of their distribution and ecology is rather poor. Primarily described from tropical waters and showing Indo-Pacific distribution, C . bacteriastroides and C . pseudosymmetricus findings in Adriatic represent the northernmost records in world's oceans and seas. For C. pseudosymmetricus this is also the first occurrence in European seas. Areal expansion and introduction of new phytoplankton species in the Adriatic Sea might be related to different circulation regimes in the Ionian Sea and the concurrent rise in sea temperature in the Mediterranean in the last decade. Recent investigations have shown that entering currents, of either Atlantic/Western Mediterranean or Eastern Mediterranean origin, modify the composition of the plankton community in the Adriatic by bringing different newcomers.

A conceptual model of the controlling factors of soil organic carbon and nitrogen densities in a permafrost-affected region on the eastern Qinghai-Tibetan Plateau

Many investigations of the preservation of soil organic carbon (SOC) in permafrost regions have examined roles of geomorphology, pedogenesis, vegetation cover, and permafrost within particular regions. However, it is difficult to disentangle the effects of multiple factors on the SOC in permafrost regions due to the heterogeneity in environmental conditions. Based on data from 73 soil study sites in permafrost regions of the eastern Qinghai-Tibetan Plateau, we developed a simple conceptual model, which relates SOC to topography, vegetation, and pedogenesis. We summarized the dominant factors and their controls on SOC using 31 measured soil physiochemical variables. Soil texture explains approximately 60% of the variations in the SOC stocks for the upper 0–2 m soil. Soil particle size closely correlates to soil moisture, which is an important determinant of SOC. Soil salinity and cations are important factors as well and can explain about 10% of the variations in SOC. The SOC and total nitrogen (TN) stocks for the 1–2 m depths have larger uncertainties than those of upper 1 m soil layer. The vegetation, pH, and bulk density mainly affects SOC and TN stocks for the upper 1 m soil layers, while the active layer thickness and soil particle size have greater influence on SOC and TN stocks for the 1–2 m soils. Our results suggest that the soil particle size is the most important controller of SOC pools, and the stocks of SOC and TN are strongly effected by soil development processes in the permafrost regions of the eastern Qinghai-Tibetan Plateau.

DIGONESTIC ENVIRONMENTAL MONITERING SYSTEM IN A POULTRY HOUSE

This experiment was conducted at a closed poultry house , Poultry Research Station , office of Agricultural Research, Ministry of Agriculture, Baghdad, Iraq, for the period from 2/9 to 14/03/2016 for total rearing of 35 days. To diagnose and monitoring the Environmental factors such as temperature, humidity , density, and the carbon dioxide levels inside the house during winter season, and its impact on the productive performance of broiler chickens Rose 308 breed .The dimensions of the house was ,length 35 m x width 7.5 m x Height 2.5 m, by total space volume 3656.25 m3. The ventilation system in the house was (negative pressure type). The house is totally closed, small fans for (minimum ventilation) in the winter are functioned, and large fans for ventilation in the evaporative cooling operation were used in the summer. 1000 sexed birds were used in this experiment imported through commercial hatchery in Abu Ghraib. The house was divided into three thermal Zones in order to find out whether heterogeneity in environmental conditions is existed in the house and at bird level .as a result the impact on the homogeneity in the weights of marketed birds . The treatments have been distributed into 32 rearing cages by the following order: 8 cages with the density of 50 birds / cage, the remaining 24 cages were divided into the density of 25 birds / cage. The results showed that there were significant differences between the treatments in the rate of body weight ,body weight gain, feed intake and feed conversion efficiency among densities and the three thermal zones due to the presence of cool air leaks into the house at the front ,End of the house, and its sides especially when fans are on , along with dead Air pockets that were identified in many places in the middle of the housed, yet this Zone was the one that had the best productive traits in comparison with the other two zones. The purpose of this experiment is to study environmental parameters homogeneity inside the shed in addition to impact of CO2 levels and impact of birds density on productive traits.

Seasonal variations in cardiovascular disease.

Cardiovascular disease (CVD) follows a seasonal pattern in many populations. Broadly defined winter peaks and clusters of all subtypes of CVD after 'cold snaps' are consistently described, with corollary peaks linked to heat waves. Individuals living in milder climates might be more vulnerable to seasonality. Although seasonal variation in CVD is largely driven by predictable changes in weather conditions, a complex interaction between ambient environmental conditions and the individual is evident. Behavioural and physiological responses to seasonal change modulate susceptibility to cardiovascular seasonality. The heterogeneity in environmental conditions and population dynamics across the globe means that a definitive study of this complex phenomenon is unlikely. However, given the size of the problem and a range of possible targets to reduce seasonal provocation of CVD in vulnerable individuals, scope exists for both greater recognition of the problem and application of multifaceted interventions to attenuate its effects. In this Review, we identify the physiological and environmental factors that contribute to seasonality in nearly all forms of CVD, highlight findings from large-scale population studies of this phenomenon across the globe, and describe the potential strategies that might attenuate peaks in cardiovascular events during cold and hot periods of the year.

Determinants, selection and heritability of docility in wild eastern chipmunks (Tamias striatus)

Many behavioural traits show important inter-individual phenotypic and genetic variation despite strong potential selection that should reduce this variability. Spatial and temporal heterogeneity in environmental conditions has been proposed to maintain such variation but empirical evidences supporting this hypothesis are still scarce for behavioural traits. Here, we analysed the repeatability and the ecological and individual factors that influence the expression of docility across different environmental contexts in wild eastern chipmunks (Tamias striatus) studied over a period of 10 years. We also estimated the heritability of docility and the patterns of viability selection acting on this trait for adults and juveniles. Docility was moderately repeatable among various contexts and was positively affected by age, was higher in males than that in females, was higher during the fall and decreased with population density. Heritability of docility was low at 0.17. We found disruptive selection for the survival of adults only, individuals more or less docile than average having a higher survival. Our study confirms that docility is both phenotypically and genetically variables and that disruptive selection might maintain the variability in this trait. Documenting the factors allowing the maintenance of phenotypic and genetic variation of behavioural traits within natural populations is a central objective in ecology and evolution. Here, we studied a wild eastern chipmunk population over 10 years and recorded docility, a personality trait, on both juveniles and adults. We showed that docility was repeatable and that it was also heritable and influenced by different individual and environmental factors. Importantly, we also found that disruptive viability selection was acting on adult docility independently of environmental variations. Our results show that docility is both phenotypically and genetically variable and that patterns of selection acting on this trait can maintain personality heterogeneity across temporally varying environmental conditions in the wild.

Population-Level Differentiation in Growth Rates and Leaf Traits in Seedlings of the Neotropical Live Oak Quercus oleoides Grown under Natural and Manipulated Precipitation Regimes.

Widely distributed species are normally subjected to spatial heterogeneity in environmental conditions. In sessile organisms like plants, adaptive evolution and phenotypic plasticity of key functional traits are the main mechanisms through which species can respond to environmental heterogeneity and climate change. While extended research has been carried out in temperate species in this regard, there is still limited knowledge as to how species from seasonally-dry tropical climates respond to spatial and temporal variation in environmental conditions. In fact, studies of intraspecific genetically-based differences in functional traits are still largely unknown and studies in these ecosystems have largely focused on in situ comparisons where environmental and genetic effects cannot be differentiated. In this study, we tested for ecotypic differentiation and phenotypic plasticity in leaf economics spectrum (LES) traits, water use efficiency and growth rates under natural and manipulated precipitation regimes in a common garden experiment where seedlings of eight populations of the neotropical live oak Quercus oleoides were established. We also examined the extent to which intraspecific trait variation was associated with plant performance under different water availability. Similar to interspecific patterns among seasonally-dry tropical tree species, live oak populations with long and severe dry seasons had higher leaf nitrogen content and growth rates than mesic populations, which is consistent with a “fast” resource-acquisition strategy aimed to maximize carbon uptake during the wet season. Specific leaf area (SLA) was the best predictor of plant performance, but contrary to expectations, it was negatively associated with relative and absolute growth rates. This observation was partially explained by the negative association between SLA and area-based photosynthetic rates, which is contrary to LES expectations but similar to other recent intraspecific studies on evergreen oaks. Overall, our study shows strong intraspecific differences in functional traits in a tropical oak, Quercus oleoides, and suggests that precipitation regime has played an important role in driving adaptive divergence in this widespread species.