Changes In Resource Availability Research Articles

Contrasting responses of different mixotrophic protists to light and nutrient availability

AbstractMixotrophic protists are important members of aquatic microbial food webs where they can dominate bacterivory and strongly impact energy and nutrient flow. While light and nutrient availability are known to impact grazing rates by mixotrophs in laboratory studies, little is known about how changes in resource availability affect mixotrophic organisms in natural communities. Here, we performed a short‐term grazing assay using fluorescently labeled bacteria in a phosphorus‐limited subalpine mountain lake to test how the availability of light and nutrients affect mixotroph grazing rates. High grazing rates by a Pseudopedinella‐like dictyochophyte were unaffected by nutrient or light manipulation. In contrast, grazing rates by pigmented cryptophytes significantly decreased upon phosphorus addition, light deprivation, and a combination of both. We compare these findings with the seasonal analysis of a 4‐yr time‐series dataset of 18S rRNA gene amplicon abundances. While cryptophytes dominated in autumn and winter and were negatively related with water column stability, Pseudopedinella amplicon abundances showed a consistent spring–summer peak and were positively related with chlorophyll a concentrations. These results demonstrate the diversity in nutritional strategies among co‐occurring mixotrophic protists, which cannot be resolved by quantification of bulk grazing rates. Moreover, these different strategies result in distinct seasonal dynamics and coexistence of different mixotrophs, suggesting their respective trajectories into future aquatic ecosystems will also differ.

Carnivore guild utilization of hunter‐provided food sources in boreal forest

Scavenging is an alternative foraging strategy to predation for many carnivore species, as they shift between predation and scavenging in response to changes in resource availability. The use of carrion may lead to interspecific competition and is thus influenced by a risk–reward trade‐off to balance coexistence with guild‐members, where smaller species are expected to be more vigilant due to their vulnerability to larger competitors. We used cameras to investigate the utilization of viscera from the annual moose Alces alces hunt by four sympatric carnivore species: wolf Canis lupus, wolverine Gulo gulo, red fox Vulpes vulpes and pine marten Martes martes in south–central Scandinavia, in relation to body size and habitat. Red foxes had highest probability of visiting viscera sites in both open and forested habitats. Visits by both red foxes and pine martens were longer in open habitats, while number of visits or activity did not differ between habitats. For pine martens, the probability of visiting viscera sites was twice as high in forest compared to open habitat; consequently, red foxes showed the highest overall use of viscera. Red foxes were most vigilant, especially in open habitat, whereas wolverines and pine martens spent a higher proportion of time feeding. Increased vigilance of red foxes facilitates extended resources use in open habitat, while for pine martens, the risk–reward decision occurs before leaving forest cover and entering open habitats. Viscera were not used to a large extent by wolves or wolverines. Wolves are generally less prone to scavenging and wolverines probably use other food resources, more suitable for caching. Overall, competition did not prevent use of viscera, probably due to small‐scale temporal segregation and limited use by the larger carnivores. Consequently, this pulse of human‐subsidized food resources before winter may have important implications for the smaller facultative scavengers.Keywords: carrion use, interspecific competition, pine marten, red fox, wolf, wolverine

A resource-based mechanistic framework for castration-resistant prostate cancer (CRPC)

Cancer therapy often leads to the selective elimination of drug-sensitive cells from the tumour. This can favour the growth of cells resistant to the therapeutic agent, ultimately causing a tumour relapse. Castration-resistant prostate cancer (CRPC) is a well-characterised instance of this phenomenon. In CRPC, after systemic androgen deprivation therapy (ADT), a subset of drug-resistant cancer cells autonomously produce testosterone, thus enabling tumour regrowth. A previous theoretical study has shown that such a tumour relapse can be delayed by inhibiting the growth of drug-resistant cells using biotic competition from drug-sensitive cells. In this context, the centrality of resource dynamics to intra-tumour competition in the CRPC system indicates clear scope for the construction of theoretical models that can explicitly incorporate the underlying mechanisms of tumour ecology. In the current study, we use a modified logistic framework to model cell–cell interactions in terms of the production and consumption of resources. Our results show that steady state composition of CRPC can be understood as a composite function of the availability and utilisation efficiency of two resources-oxygen and testosterone. In particular, we show that the effect of changing resource availability or use efficiency is conditioned by their general abundance regimes. Testosterone typically functions in trace amounts and thus affects steady state behaviour of the CRPC system differently from oxygen, which is usually available at higher levels. Our data thus indicate that explicit consideration of resource dynamics can produce novel and useful mechanistic understanding of CRPC. Furthermore, such a modelling approach also incorporates variables into the system’s description that can be directly measured in a clinical context. This is therefore a promising avenue of research in cancer ecology that could lead to therapeutic approaches that are more clearly rooted in the biology of CRPC.

Optimizing energy solutions: A techno-economic analysis of solar-wind hybrid power generation in the coastal regions of Bangladesh

Hybrid renewable energy systems have acquired attention worldwide for their ability to harness multiple renewable sources parallelly like solar, wind, and hydropower, presenting numerous advantages. Bangladesh is forced to rely on the traditional fossil fuel-powered power generation infrastructure in order to meet the nation’s increasing need for electricity. The goal of this paper is to improve the percentage of renewable energy in Bangladesh’s energy landscape by addressing the technical, economic, and environmental elements of building a specialized hybrid system at Patenga Sea Beach through a methodical approach. This study is the first to pinpoint and address Patenga Sea Beach’s limits in light of Shah Amanat International Airport’s nearby location in Chittagong. In order to build the suggested system, a daily load demand of 1000 kWh and an annual peak demand of 53.57 kW were taken into account. The analysis shows that this system has a levelized cost of energy (LCOE) of 0.03$, generating 4,604.591 MWh of power annually. Findings from HOMER reveal an initial capital outlay of $350,688 for initial capital investment, with an annual O&M cost of $3,821, contributing to its cost-effectiveness. During the span of its lifetime, the hybrid system can also avoid 5,767 tons of CO2. The simulation program PVsyst has been utilized to assess the PV system-specific performance, viability, and outcomes. According to the PVsyst evaluation, the PV system has an 89 % system performance ratio, a 0.017$ levelized cost of energy, and a break-even period of only 6.6 years. The sensitivity analysis examines renewable resources, factoring in climate change’s effects on solar irradiation, wind speed, replacement cost, and operational expenses. It validates the hybrid system’s viability across various environmental scenarios, demonstrating resilience to changes in renewable resource costs and availability. The suggested hybrid system can be placedto minimize costs associated with energy generation, circumvent structural and geographic limitations, improve the Patenga Sea beach’s visual appeal, and lower greenhouse gas emissions. In addition to supporting future decisions about the deployment of hybrid systems, this research could assist in the integration of sustainable and renewable energy sources into the national grid.

Reassessment of the emergency medical service deployment indication catalogue after traffic accidents

The emergency physician indication catalogue is based on outdated studies and provides limited guidance for alarm criteria following traffic accidents. Advances in vehicle safety technology and changes in available resources necessitate are-evaluation of the indications. The aim of this retrospective registry study is to identify preclinically assessable variables for severe injuries sustained in traffic accidents. Atotal of 47,145 individuals involved in accidents between 1 January 2000 and 31 December 2021 from the GIDAS database were included. Separate datasets for severe (AIS3+) and minor injuries were evaluated. Ejection (PPV 80.6%), entrapment (PPV 75.6%), burning vehicles (PPV 57.1%), challenging rescue situations (PPV 56.3%), vehicle disintegration (PPV 51.6%), and amnesia (PPV 50.3%) indicated severe injuries among vehicle occupants. For vulnerable road users (motorcyclists, cyclists, pedestrians), helmet loss (PPV 61.1%), being run over/dragging (PPV 41.9%), opponent vehicle window breakage (PPV 35.8%), and subsequent collision with objects (PPV 31.1%) were also identified. The χ2-test revealed significant associations between the variables and severe injuries. Combined variables achieved PPV values above 82%. The current emergency physician indication catalogue provides limited preclinically detectable criteria and should be revised based on the objective registry data. Query models for emergency dispatchers should be tested.

Movement ecology of an endangered mesopredator in a mining landscape

BackgroundEfficient movement and energy expenditure are vital for animal survival. Human disturbance can alter animal movement due to changes in resource availability and threats. Some animals can exploit anthropogenic disturbances for more efficient movement, while others face restricted or inefficient movement due to fragmentation of high-resource habitats, and risks associated with disturbed habitats. Mining, a major anthropogenic disturbance, removes natural habitats, introduces new landscape features, and alters resource distribution in the landscape. This study investigates the effect of mining on the movement of an endangered mesopredator, the northern quoll (Dasyurus hallucatus). Using GPS collars and accelerometers, we investigate their habitat selection and energy expenditure in an active mining landscape, to determine the effects of this disturbance on northern quolls.MethodsWe fit northern quolls with GPS collars and accelerometers during breeding and non-breeding season at an active mine site in the Pilbara region of Western Australia. We investigated broad-scale movement by calculating the movement ranges of quolls using utilisation distributions at the 95% isopleth, and compared habitat types and environmental characteristics within observed movement ranges to the available landscape. We investigated fine-scale movement by quolls with integrated step selection functions, assessing the relative selection strength for each habitat covariate. Finally, we used piecewise structural equation modelling to analyse the influence of each habitat covariate on northern quoll energy expenditure.ResultsAt the broad scale, northern quolls predominantly used rugged, rocky habitats, and used mining habitats in proportion to their availability. However, at the fine scale, habitat use varied between breeding and non-breeding seasons. During the breeding season, quolls notably avoided mining habitats, whereas in the non-breeding season, they frequented mining habitats equally to rocky and riparian habitats, albeit at a higher energetic cost.ConclusionMining impacts northern quolls by fragmenting favoured rocky habitats, increasing energy expenditure, and potentially impacting breeding dispersal. While mining habitats might offer limited resource opportunities in the non-breeding season, conservation efforts during active mining, including the creation of movement corridors and progressive habitat restoration would likely be useful. However, prioritising the preservation of natural rocky and riparian habitats in mining landscapes is vital for northern quoll conservation.

Strategies for social mobility through sports and/or school in working-class Moroccan families

ABSTRACT This article examines the social mobility strategies employed by working-class Moroccan families in the context of the complex relationship of elite sport and school. To better understand these strategies, a qualitative study, including semi-structured interviews and participant observations, was conducted in the city of Temara (on the outskirts of Rabat) with young people aged 14–20 years and parents. From the analysis of this data, I identified five themes that reflect the different investments families held in sport and/or schooling, as strategies for their children’s futures. One group of parents invested in an educational strategy that focused on academic success. In contrast, others adapted their strategies to encourage their children to pursue an athletic career if they failed academically or showed signs of potential athletic success, while another group of parents tried to protect their children from the possible adverse effects of sports commitment. Another group supported their children in their chosen paths of social mobility. Lastly, there were parents who due to precarious living conditions and family conflicts were indifferent to sports as a pathway to social mobility and instead urged their children to become more productive immediately through seeking work. These differing family strategies in relation to young people's investment in sports point to the diversity of working-class families’ responses to the tensions that emerge when school and sport come into conflict as pathways to social mobility. I acknowledge that these family strategies are not fixed but may change with changes in available resources and opportunities. However, I argue that both schools and sporting organizations need to be aware and understand the complex environments, including family investments and strategies in which students may be making choices about their futures in relation to education and sport.

Impact of Large-Scale Fire and Habitat Type on Ant Nest Density and Species Abundance in Biebrza National Park, Poland

Fire can have negative effects on the ant community by reducing species abundance through direct mortality, changes in resource availability, or foraging activity. Fire can also have positive effects, especially for opportunistic species preferring open or disturbed habitats. We assessed the direct effects of a large-scale fire on ant communities in open habitats (grassland and Carex) and moist forested peatland (birch and alder) sites in Biebrza National Park, testing three hypotheses: (i) the large-scale fire had more significant effects on ant nest density in forests than in open habitats, (ii) the post-fire ant diversity changes within sites are stronger in forests than open habitats, and (iii) ant species preferring disturbed habitats are favoured by the fire event. The fire had negative effects on ant nest density only in the Carex and grassland sites but not in the birch and alder sites, suggesting that fire had a stronger impact in open habitats than in forests. Temporal post-fire ant diversity changes within sites were stronger in forests than in open habitats. We observed higher beta diversity changes between the first and second year of the study in the burned forest sites due to colonisation, indicating a greater fire impact on species community composition followed by a higher recolonisation rate. Ant species preferring disturbed habitats were favoured by the fire. The seed-eating ant species Tetramorium caespitum, a thermophilous and opportunistic species, dominated the burned grassland site. This contrasts with other species, e.g., Lasius alienus, for which nest density decreased after fire, underlining the importance of food resource availability as a major driver of community changes after fire. Our study also underlines the importance of periodic biodiversity monitoring in conservation areas for assessing the recovery of the original status after disturbances and revealing possible habitat changes endangering the survival of local biotic communities.

Fire-modulated fluctuations in nutrient availability stimulate biome-scale floristic turnover in time, and elevated species richness, in low-nutrient fynbos heathland.

In many systems, postfire vegetation recovery is characterized by temporal changes in plant species composition and richness. We attribute this to changes in resource availability with time since fire, with the magnitude of species turnover determined by the degree of resource limitation. Here, we test the hypothesis that postfire species turnover in South African fynbos heathland is powered by fire-modulated changes in nutrient availability, with the magnitude of turnover in nutrient-constrained fynbos being greater than in fertile renosterveld shrubland. We also test the hypothesis that floristic overlaps between fynbos and renosterveld are attributable to nutritional augmentation of fynbos soils immediately after fire. We use vegetation survey data from two sites on the Cape Peninsula to compare changes in species richness and composition with time since fire. Fynbos communities display a clear decline in species richness with time since fire, whereas no such decline is apparent in renosterveld. In fynbos, declining species richness is associated with declines in the richness of plant families having high foliar concentrations of nitrogen, phosphorus and potassium and possessing attributes that are nutritionally costly. In contrast, families that dominate late-succession fynbos possess adaptations for the acquisition and retention of sparse nutrients. At the family level, recently burnt fynbos is compositionally more similar to renosterveld than is mature fynbos. Our data suggest that nutritionally driven species turnover contributes significantly to fynbos community richness. We propose that the extremely low baseline fertility of fynbos soils serves to lengthen the nutritional resource axis along which species can differentiate and coexist, thereby providing the opportunity for low-nutrient extremophiles to coexist spatially with species adapted to more fertile soil. This mechanism has the potential to operate in any resource-constrained system in which episodic disturbance affects resource availability.

Limiting resources for soil microbial growth in climate change simulation treatments in the subarctic.

The microbial use of resources to sustain life and reproduce influences for example, decomposition and plant nutrient provisioning. The study of "limiting factors" has shed light on the interaction between plants and their environment. Here, we investigated whether carbon (C), nitrogen (N), or phosphorus (P) was limiting for soil microorganisms in a subarctic tundra heath, and how changes in resource availability associated with climate change affected this. We studied samples in which changes in resource availability due to climate warming were simulated by the addition of birch litter and/or inorganic N. To these soils, we supplied factorial C (as glucose), N (as NH4 NO3 ), and P (as KH2 PO4 /K2 HPO4 ) additions ("limiting factor assays," LFA), to determine the limiting factors. The combination of C and P induced large growth responses in all soils and, combined with a systematic tendency for growth increases by C, this suggested that total microbial growth was primarily limited by C and secondarily by P. The C limitation was alleviated by the field litter treatment and strengthened by N fertilization. The microbial growth response to the LFA-C and LFA-P addition was strongest in the field-treatment that combined litter and N addition. We also found that bacteria were closer to P limitation than fungi. Our results suggest that, under a climate change scenario, increased C availability resulting from Arctic greening, treeline advance, and shrubification will reduce the microbial C limitation, while increased N availability resulting from warming will intensify the microbial C limitation. Our results also suggest that the synchronous increase of both C and N availability might lead to a progressive P limitation of microbial growth, primarily driven by bacteria being closer to P limitation. These shifts in microbial resource limitation might lead to a microbial targeting of the limiting element from organic matter, and also trigger competition for nutrients between plants and microorganisms, thus modulating the productivity of the ecosystem.

Trait‐based analyses reveal global patterns in diverse diets of albacore tuna (Thunnus alalunga)

AbstractSimplifying complex species interactions can facilitate tracking and predicting functional responses to ecological stressors. This is important for highly migratory pelagic predators, exploiting diverse prey fields as they respond to dynamic environments. We reconstructed the historical resource use of albacore tuna (Thunnus alalunga) globally from the 1900s to 2015 and confirmed highly biodiverse diets with 308 prey species, and an additional 238 taxa at coarser taxonomic resolution. We synthesised prey diversity into seven functional trait guilds using hierarchical divisive clustering algorithms as a function of four traits that describe habitat use and influence predator–prey encounter rates – prey habitat association vertically in the water column, horizontally along the coastal to pelagic gradient, seasonal and diel vertical migratory behaviour. We explored variability in historical composition of albacore diets across geographies based on species identity, individual trait information and functional trait guilds using a multi‐matrix modelling framework. Taxonomic information remains important for trophic ecology, however, species‐based diet composition in albacore tuna was highly variable across geographies and years sampled, making interpretation of these patterns difficult. By simplifying species identity into habitat‐based traits, we highlight changes in prey resources consumed, such as the historical importance of near‐surface epipelagic prey resources from coastal to oceanic habitats, and seasonally migrating continental shelf prey, with less frequent pulses of deeper water and demersal taxa. Trait information and trait guilds serve as useful classification frameworks for identifying functionally redundant food web linkages across biodiverse prey, and will prove useful in tracking predators' foraging responses to changing resource availability.

Rising from the shadows: Selective foraging in model shoot parasitic plants.

Despite being sessile, plants nonetheless forage for resources by modulating their growth. Adaptative foraging in response to changes in resource availability and presence of neighbours has strong implications for performance and fitness. It is an even more pressing issue for parasitic plants, which draw resources directly from other plants. Indeed, parasitic plants were demonstrated over the years to direct their growth towards preferred hosts and invest resources in parasitism relative to host quality. In contrast to root parasites that rely mostly on chemical cues, some shoot parasites seem to profit from the ability to integrate different types of abiotic and biotic cues. While significant progress in this field has been made recently, there are still many open questions regarding the molecular perception and the integration of diverse signalling pathways under different ecological contexts. Addressing how different cues are integrated in parasitic plants will be important when unravelling variations in plant interaction pathways, and essential to predict the spread of parasites in natural and agricultural environments. In this review, we discuss this with a focus on Cuscuta species as an emerging parasitic model,and provide research perspectives based on the recent advances in the topic and plant-plant interactions in general.

Temperature and microclimate refugia use influence migratory timings of a threatened grassland bird

BackgroundSeasonal changes in resource availability are known to influence the migratory behaviour of animals, including both timing and distance. While the influence of environmental cues on migratory behaviour has been widely studied at the population level, it has rarely been examined at the spatial scale at which individuals experience their environment. Here, we test the hypothesis that individuals exposed to similar large-scale environmental cues may vary in migratory behaviour in response to the different microclimate conditions they experience at fine scales.MethodsWe combine high-spatial and temporal resolution microclimate and habitat information with GPS tracking data for a partially migratory threatened grassland bird. Data from 47 little bustards (Tetrax tetrax; 67 breeding events) tracked between 2009 and 2019 was used to (i) evaluate individual consistency in migratory behaviour (timing and distance) and (ii) assess whether the local environmental characteristics experienced by individuals – and in particular their use of microclimate refugia - influence distance and timing of migration, from and to the breeding sites.ResultsMigratory distance was consistent for birds tracked over multiple years, while the timing of migration showed high variability among individuals. Departures from breeding areas spanned from May to August, with a few birds remaining in their breeding areas. Vegetation greenness (a proxy for food availability) was positively associated with the time birds spent in the breeding area. The best model also included a positive effect of microclimate refugia availability on breeding season length, although an interaction with temperature suggested that this effect did not occur at the highest relative temperatures. The return date to breeding grounds, although spanning from September to April, was not influenced by the environmental conditions or food availability.ConclusionsFood availability, measured by a vegetation greenness proxy, was associated with later migration at the end of the breeding season. Availability of cooler microclimate refugia may also allow for later departures from the breeding sites in all but the hottest conditions. Management measures that increase microclimate refugia availability and provide foraging resources can thus potentially increase the length of the breeding season for this species.

Assessment of climate change impacts for two tributary basins of the Irtysh River in Kazakhstan

Information about the climate change impacts on river discharge of 2 tributary basins of the Irtysh River, the Oba and Ulbi, is important for effective management of the water resources of the Shulba reservoir in Kazakhstan. The main aim of the study was to investigate potential changes in water resource availability in the study basins. To assess the projected changes, the process-based eco-hydrological model SWIM was used under 2 Representative Concentration Pathway (RCP) climate scenarios obtained from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP). Our results show an increase in mean annual temperature of 6.1°C, an increase in average annual precipitation of 7.5 to 14%, an increase in annual average discharge for the Oba (6 to 8%) and smaller discharge changes (below 5%) for the Ulbi at the end of the century under RCP8.5—a scenario of comparatively high greenhouse gas emissions—compared to the reference period (1981-2010). Seasonal variations are marked by the peak discharge occurring up to a month earlier, a decrease in the duration of snow accumulation and a reduction in discharge during the summer months. The peak discharge period is prolonged in time, and a slight increase in river discharge could be expected from October to December. Possible future changes in climate may have serious impacts on water resources, agriculture and economic development in the case study basins. The results of this study can be extrapolated to other neighboring basins in Kazakhstan with similar climatic and geophysical characteristics.

Research on dynamic decision-making for product assembly sequence based on Connector-Linked Model and deep reinforcement learning

Assembly sequence planning (ASP) is a critical challenge in the manufacturing industry, involving the arrangement of components to maximize production efficiency and reduce costs. Solving the ASP problem is not only hindered by its NP-hard nature, making it difficult to obtain optimal solutions, but also requires making rapid decisions in the face of dynamic changes in resource availability during the actual assembly process. This paper proposes a Deep reinforcement learning (DRL) approach to tackle the ASP problem. DRL learns optimal assembly strategies through interactions between an intelligent agent and its environment, using a reward function as a long-term objective to guide decision-making, ultimately enabling the acquisition of near-optimal solutions. DRL exhibits high scalability and reusability, leveraging previously acquired knowledge to adapt to dynamic changes in the assembly environment. First, a connector-based graph structure is introduced to decompose assembly products into a series of connector-based assembly elements. These elements are then transformed into a matrix format for use as input to the DRL method. Second, an encoder-decoder architecture tailored to the ASP problem is developed. This architecture utilizes mask mechanism to ensure that the generated assembly sequences adhere to assembly priority constraints while adapting to dynamic changes in resource availability during assembly. Finally, policy gradient methods are employed to train the DRL model, enabling it to generate assembly sequences with lower costs and higher efficiency. Experimental results demonstrate the effectiveness of the proposed approach. Furthermore, compared to heuristic algorithms, DRL exhibits faster decision-making capabilities and better adaptability to dynamic resource changes during the assembly process.

Tropical and temperate differences in the trophic structure and aquatic prey use of riparian predators.

The influence of aquatic resource-inputs on terrestrial communities is poorly understood, particularly in the tropics. We used stable isotope analysis of carbon and nitrogen to trace aquatic prey use and quantify the impact on trophic structure in 240 riparian arthropod communities in tropical and temperate forests. Riparian predators consumed more aquatic prey and were more trophically diverse in the tropics than temperate regions, indicating tropical riparian communities are both more reliant on and impacted by aquatic resources than temperate communities. This suggests they are more vulnerable to disruption of aquatic-terrestrial linkages. Although aquatic resource use declined strongly with distance from water, we observed no correlated change in trophic structure, suggesting trophic flexibility to changing resource availability within riparian predator communities in both tropical and temperate regions. Our findings highlight the importance of aquatic resources for riparian communities, especially in the tropics, but suggest distance from water is less important than resource diversity in maintaining terrestrial trophic structure.

Shifts in risk sensitivity and resource availability alter fat stores for a large mammal following extreme winter conditions

Abstract For species that inhabit environments where resource availability may be unpredictable, balance of resource allocation to life‐history traits can have heightened consequences for survival, reproduction, and ultimately, fitness. Acquisition and allocation of energy to maintenance, capital gain and reproduction should be in tune with the landscape an animal inhabits—environmental severity, food availability and population size all influence the resources animals have and dictate the ways they should be allocated. In seasonal environments, animals that experience periods of extreme resource limitation (e.g. harsh winters) may favour allocation of resources to body reserves to secure their survival at the cost of reproduction (i.e. risk averse). In contrast, the same accumulation of body reserves may not be necessary to survive in relatively benign landscapes where instead, allocation to reproduction is favoured (i.e. risk prone). According to the theory of risk‐sensitive allocation of resources, when animals are exposed to unprecedented or life‐threatening conditions, they may shift resource allocation to favour building capital over allocation in reproduction to preempt against encountering another life‐threatening event in the future. Using data from a long‐term project on a highly site‐faithful and long‐lived species, mule deer (Odocoileus hemionus), we evaluated how a life‐threatening winter and the associated changes in resource availability resulting from a population reduction influenced how animals acquired and allocated energy to survival (i.e. fat accumulation). Per capita precipitation, and the associated reduction in population abundance after the severe winter, had a positive influence of accrual of fat over summer. After the extreme physiological stress of a hard winter, deer starting spring with low body reserves accumulated 2.8 percentage points more fat over summer compared with before the experience of a bad winter and had an increased probability of recruiting fewer offspring. Fat stores can interact with environment, life history and behaviour to influence survival during periods of resource scarcity. For a long‐lived herbivore, we documented shifts in risk tolerance associated with fat accrual in preparation for winter, supporting the notion that risk‐sensitive allocation of resources may be plastic—an essential adaptation for animals to cope with rapidly changing landscapes. Read the free Plain Language Summary for this article on the Journal blog.

An uncertain multi-objective model for simultaneous design of supply chain and assemblers considering sustainable development: a case study

Supply chain network design (SCND) problems are used to formulate and make strategic decisions on the number of facilities, network facility location and plant capacity, to ensure the optimal delivery of products from manufacturers to end consumers. On the other hand, assembly line balancing (ALB) problems provide details on operational decisions which encompass production levels and inventories and therefore should be flexible enough to react when changes in resource availability and product demands occur. Integration of the SCND and ALB problems has thus been explored to develop a more holistic model and to further improve the efficiency of the supply chain. This study develops a novel SCND-ALB optimization model which considers economic, environmental, and social objectives in determining the optimal design and operational conditions of the supply chain under flexible cycle time of the assembly lines. Furthermore, for the first time a zigzag type belief degree model is integrated to address system uncertainties of the SCND-ALB problem. Two multi-objective solution approaches are then considered to simultaneously account for the three sustainability objectives. A case study on the production of a nozzle is explored to demonstrate the capabilities of the model.

Soil seed banks provide a storage effect in post-logging regrowth forests of southeastern Australia

Despite the importance of soil seed banks in diversity maintenance, our understanding of plant response to changes in resource availability is largely limited to above-ground vegetation. We investigated how forest structure and edaphic properties influenced the above-ground vegetation and soil seed banks following logging in montane regrowth forests dominated by Eucalyptus regnans in the Central Highlands of southeastern Australia. We surveyed above-ground vegetation, soil seed banks, forest structure and soil properties across 20 harvest units, aged 16 to 20 years. A total of 80 species were identified in above-ground vegetation with 72 species in the soil seed bank, with only 34% of species co-occurring in both species’ pools. Climate, soil, topography, and light availability shaped plant composition but the relative importance of these properties varied among individual species and pools of diversity (combined, above-ground, soil seed bank, life form). Annual heat moisture index (AHMI) was the most important factor that influenced plant community composition across all species pools with individual species positively associated with AHMI. Acacia, but not Eucalyptus stem density further moderated plant response via effects on both light availability and soil nitrogen at the stem exclusion phase of stand development. Structurally mediated controls on above-ground community composition flow through to the soil seed bank via above-ground diversity effects on below-ground composition. For the combined species pool, individual species were most frequently related to Acacia stem density that on average explained 20% of model variation. Soil nutrients accounted for most of the model variation for individual species in above-ground (26%), soil seed bank (20%) and non-woody (32%) pools of diversity, with AHMI accounting for most of the model variation for woody species (18%). The differential response of individual species and community composition to gradients in resource availability across different pools of species diversity and life forms clearly demonstrates a storage effect in wet temperate forests of southeastern Australia that promotes post-disturbance recruitment and persistence. Our work suggests logging interacts with broad environmental controls to shape species diversity. The key role of Acacia stem density as a biotic filter of plant diversity provides opportunity to shape future plant diversity through management interventions such as thinning in the early stages of stand development. With native forest harvesting of these forests set to end from 2024, our findings provide important information on future patterns of plant diversity as logged forests recover over time, opportunities for management interventions in shaping plant composition, and potential impacts of future wildfire.

Seasonal variation in trophic structure and community niche dynamics of an Arctic coastal community of marine vertebrates

Temporal variation in food web structure is widespread among highly seasonal environments, such as the Arctic, and is driven by changes in resource availability. Variation in resource availability can lead to species differences in diet composition, isotopic niche width, and trophic position (TP) across seasons. Here, we used tissue samples that represent two distinct turnover rates for diet (liver = shorter term, muscle = longer term) from 18 fish and three marine mammal species to investigate seasonal (i) variation in TPs within the Southampton Island marine ecosystem of Hudson Bay, (ii) variation in consumer isotopic niche width within this part of the food web, and (iii) variation in community niche dynamics among a fish and marine mammal community using stable carbon (δ13C) and nitrogen (δ15N) isotope analyses. Many zooplanktivores and piscivores increased in TP in summer (i.e., shorter-term turnover period), whereas benthic feeders dependent on ice-obligate prey decreased in TP. Most isotopic niche widths and community metrics (δ15N range, total ellipse area, mean centroid distance) were higher in liver than muscle. Our findings demonstrate seasonal changes in TPs, which suggests that Arctic communities may be differentially affected by longer ice-free periods and earlier onset of primary production due to accelerated climate change.