Ecological Constraints Research Articles

Do food distribution and competitor density affect agonistic behaviour within and between clans in a high fission-fusion species?

According to the ecological model of female social relationships (EMFSR), within-group competition and between-group competition in female-bonded species are shaped by food distribution. Strong between-group contests are expected over large, monopolizable resources and high population density, but not when low-quality food is distributed across large, undefended home ranges. Within-group contests are expected to be more frequent with increasing heterogeneity among feeding sites and with group size. We tested these predictions in female Asian elephants, which show traits associated with infrequent contests-graminivory, high fission-fusion and overlapping home ranges. We examined how food distribution and competitor density affected agonistic interactions within and between female elephant clans (social groupings) in the Kabini grassland, southern India. We found stronger between-clan contest in the grassland than that known from neighbouring forests, and more frequent agonism between females between clans than within clans. Such strong between-clan contest was attributable to the grassland being a food-rich habitat patch, thus supporting the EMFSR. Within-clan agonism was also frequent, but did not increase with food heterogeneity, contradicting the EMFSR. Contrary to recent claims, increasing within-clan agonism with group size suggested ecological constraints on large groups despite high fission-fusion. High population density may explain such frequent contests despite graminivory and fission-fusion.

Global ocean spatial suitability for macroalgae offshore cultivation and sinking

Macroalgae offshore cultivation and sinking is considered a potentially practical approach for ocean-based carbon dioxide removal. However, several considerations need to be resolved to assess the effectiveness and sustainability of this approach. Currently, several studies focus on the area required for climate-relevant carbon sequestration through macroalgae cultivation and sinking without considering realistic, global spatial limitations. This study uses a spatially-explicit suitability assessment model for optimised open-ocean afforestation and sinking site designation. By applying specific maritime, ecological and industrial constraints, two maps are produced: a) suitable areas for macroalgae offshore cultivation and sinking, and b) suitable areas for macroalgae sinking only (for sequestration purposes). These data provide a more realistic approach to quantifying the ocean surface (including the corresponding depths) required for macroalgae offshore cultivation and sinking within a spatially sustainable framework. The resulting maps estimate the respective suitability areas within the EEZs of the world countries. A total area suitable for macroalgae offshore cultivation and sinking is calculated at 10.8M km2, whereas sinking-only areas account for 32.8M km2 of the offshore ocean. The implications of spatial suitability patterns at global and national levels are discussed. We suggest that the concept of ‘grow nearshore, sink offshore’ should be explored as an alternative to offshore cultivation.

Coupling RESI with Multi-Scenario LULC Simulation and Spatiotemporal Variability Analysis: An Ecological Spatial Constraint Approach

Southwest China’s arid river valleys represent ecologically vulnerable areas with intense human activity. Understanding the historical changes in LULC and land cover and projecting the impacts of various development scenarios on future LULC have become crucial for regional spatial information management and territorial spatial planning. This research analyzes the land-use changes in the Yuanmou dry-hot valley over a 30-year span from 1990 to 2020. Building upon the PLUS model, we established a coupled habitat quality spatial and multi-scenario land-use simulation model. Four development scenarios were proposed: natural progression, economic development, ecological conservation, and balanced development. We conducted simulations and evaluations of land-use in the Yuanmou dry-hot valley for 2030 using the PLUS mode, assessing the sustainability of future development scenarios under varying ecological constraints. During the simulation, three distinct RESI regions were employed as restricted development zones, integrating the three ecological constraints with the four simulation scenarios. We introduced a novel approach based on ecological environmental quality as the ecological constraint, providing a scientific reference for sustainable development in ecologically vulnerable areas. The results indicate that under ecological conservation scenarios with high-to-low RESI constraints, the ecological environment is superior to the other three scenarios. The results show the following: (1) From 1990 to 2020, aside from a continuous decrease in grassland area, there was an increasing trend in the areas of water bodies, forests, croplands, construction lands, and unused lands in the Yuanmou dry-hot valley. (2) By 2030, under all four development scenarios, the cropland area is expected to expand rapidly, while forested areas will decrease; grassland areas will decline under natural and economic development scenarios but show opposite trends under the other scenarios; and construction land and unused land areas will decrease under the ecological conservation and balanced development scenarios. (3) Land-use intensity analysis for the four scenarios indicated that, by 2030, unused lands in the Yuanmou dry-hot valley are more likely to be converted into water bodies, forests are more likely to be converted into croplands and grasslands, grasslands are more likely to be converted into croplands, croplands are more likely to be converted into grasslands, and construction lands are more likely to become unused lands. (4) Sustainable LULC management evaluations based on landscape indices reveal that ecological conservation and balanced development scenarios exhibit superior landscape connectivity and clustering. Thus, the balanced development scenario is the most appropriate LULC strategy for the Yuanmou dry-hot valley in the future. These findings provide scientific references for balancing ecological conservation and economic development in the arid river valleys of Southwest China.

Measurements-based constrained control optimization in presence of uncertainties with application to the driver commands for high-speed trains

The railway world is undergoing major changes. The advent of new technologies allows us to rethink the train system and face new challenges, but one must not forget all the ecological constraints that are now accentuated by the increase in energy costs. This paper focuses on the optimization of the driver commands to limit the energy consumption of the trains under punctuality and security constraints. This problem falls within the framework of control optimization problems for nonlinear dynamic mechanical systems in the presence of constraints and uncertainties. A four-step approach is then proposed in this paper to solve this problem: (1) the introduction of simplified and fast-to-evaluate models to model the nonlinear dynamic behavior of the train and its energy consumption; (2) the identification in a Bayesian formalism of the parameters on which these models depend from on-track measurements on commercial trains; (3) the reformulation of the optimization problem so that it integrates the uncertainties related to an imperfect knowledge of these estimated parameters; (4) the resolution of the optimization problem using evolutionary algorithms. The main specificity of this work lies in the fact that not only the objective function to be minimized, here the energy consumed by the train, is impacted by the uncertainties, but also the admissibility constraints of the solution, here punctuality and operating safety. The integration of the uncertainties in the search for the control function is thus not trivial and requires several original adaptations in order to make the final optimization problem well posed.

Ecological Constraints and Drivers for Human Dispersals and Adaptations in the Late Pleistocene and Early Holocene Environments of the East Siberian Arctic

Starting roughly 50,000 years ago, the Arctic region of East Siberia remained continuously populated by groups of anatomically modern humans including the most uncomfortable episodes in the development of the late Quaternary environment; for some of them, human presence in the area became ephemeral. At present, archaeological fossil records allow for distinguishing three main stages in human occupation of the area: Early (~50 to ~29 ka, MIS 3), middle (~29 to ~11.7 ka, MIS 2), and late (from 11.7 to ~8 ka). For most of the time, they the populated open landscapes of the Mammoth Steppe, which declined at the onset of the Holocene. Human settlement of the Arctic was driven by various abiotic and biotic factors and thus archaeologically visible cardinal cultural and technological changes correspond to the most important paleoclimatic and habitat changes in the late Pleistocene and early Holocene. Successful peopling of the Arctic was largely facilitated by the adoption of critically important innovations such as sewing technology based on the use of the eyed bone needle and the manufacture of long shafts and pointed implements made of mammoth tusks. Mammoth exploitation is seen in mass accumulations of mammoths formed by hunting. An obvious connection between archaeological materials and such accumulations is observed in the archaeological record. In the lithic technology, the early stage is presented by archaic-looking flake industries. Starting the LGM, the wedge-core based-microblade technology known as the Beringian microblade tradition spread widely following the shrinkage of the mammoth range. At the late stage, starting at the Holocene boundary, microprismatic blade technology occurs. In all stages, the complex social behavior of the ancient Arctic settlers is revealed. The long-distance transport of products, knowledge, and genes occurs due to the introduction of the land transportation system. Initial human settlement of this region is associated with carriers of the West Eurasian genome who became replaced by the population with East Asian ancestry constantly moving North under the pressure of climate change.

How can high-quality development improve the ecotourism efficiency in the region of ecological constraints of China? Empirical evidence from the Yellow River Basin

Despite the massive impacts of ecotourism on regional development, only limited papers empirically examined the responses of the regional development factors to ecotourism in the context of an ecological constraints region. To fill this gap, the primary aim of this paper is to reveal how ecotourism efficiency is affected by quality regional development in the region of ecological constraints. The second aim is to investigate the moderating role of ecological constraints in building relationships of ecotourism efficiency and quality regional development factors. The research was conducted in the Yellow River Basin, a prime area for ecological protection and high-quality regional development in China. Data gathered from 2010 to 2019 were used to analyze ecotourism efficiency by using the super–slacks-based measurement method. Findings indicated that four quality regional development factors—innovative, green, open, and shared factors—have positive impacts on ecotourism efficiency in the Yellow River Basin. Ecological constraints moderate the relationship between ecotourism efficiency and quality regional development. The study makes a significant contribution to the literature in terms of both managing the ecological constraints and improving the sustainability of ecotourism in the region of quality development.

Reconstructing 15 000 years of southern France temperatures from coupled pollen and molecular (branched glycerol dialkyl glycerol tetraether) markers (Canroute, Massif Central)

Abstract. Climatic changes in southern Europe during the Holocene are characterized by a strong spatial and temporal heterogeneity whose patterns are still poorly understood, notably the presence or not of a Holocene thermal maximum (HTM; 10 000–6000 cal BP). The climatic patterns also differ according to the proxies used (e.g. pollen, chironomid) and the latitude of the record. Here, a multi-proxy approach combining pollen and lipid biomarkers (branched glycerol dialkyl glycerol tetraethers, brGDGTs) is applied to the Canroute sedimentological sequence (Massif Central, France) to reconstruct the climatic variation over the last 15 000 years in southern Europe. This area is poorly documented in terms of vegetation and climate change. To provide reliable climate reconstructions, we have (1) performed a multi-method approach applied to pollen (modern analogue technique, MAT; weighted averaging partial least squares regression, WA-PLS; boosted regression trees, BRT; and random forest, RF) and molecular biomarkers brGDGTs (five calibrations) and (2) investigated the role of modern databases and calibrations in climate reconstructions. Three different databases were tested for pollen data: one global database based on a Eurasian pollen database and two regional databases corresponding to Mediterranean–Temperate Europe and Temperate Europe–Scandinavian databases respectively. Five global calibrations were tested for lipid biomarkers including four for soil and one for peat. Results show that the use of different modern databases highlights the importance of considering environmental and ecological constraints when using transfer functions on pollen sequences. Pollen- and brGDGT-inferred climate trends are consistent, notably for the Late Glacial and the Early and Late Holocene. However, the reconstructions notably differ concerning the presence of a Holocene thermal maximum with the MAT pollen-based method, but no difference is apparent with the BRT pollen method nor brGDGT. The temperature reconstructions estimated from the two independent pollen and lipid proxies are then compared to regional climate signals (chironomids, pollen, molecular biomarkers) to better understand global regional climatic patterns in southern Europe. Altogether, our results from the Canroute sequence and those already available in southern Europe reveal that for the Late Glacial and Early Holocene, the regional climate trends are consistent between sites and proxies, supporting the reliability of their reconstructions despite some discrepancies. During the Holocene, the temperature signal of Canroute does not indicate the clear presence of a pronounced HTM, but rather stable temperatures.

Reduced GSH Acts as a Metabolic Cue of OPDA Signaling in Coregulating Photosynthesis and Defense Activation under Stress.

12-oxo-phytodienoic acid (OPDA) is a primary precursor of jasmonates, able to trigger autonomous signaling cascades that activate and fine-tune plant defense responses, as well as growth and development. However, its mechanism of actions remains largely elusive. Here we describe a dual-function messenger of OPDA signaling, reduced glutathione (GSH), that cross-regulates photosynthesis machinery and stress protection/adaptation in concert, optimizing plant plasticity and survival potential. Under stress conditions, the rapid induction of OPDA production stimulates GSH accumulation in the chloroplasts, and in turn leads to protein S-glutathionylation in modulating the structure and function of redox-sensitive enzymes such as 2-cysteine (Cys) peroxiredoxin A (2CPA), a recycler in the water-water cycle. GSH exchanges thiol-disulfides with the resolving CysR175, while donating an electron (e-, H+) to the peroxidatic CysP53, of 2CPA, which revives its reductase activity and fosters peroxide detoxification in photosynthesis. The electron flow protects photosynthetic processes (decreased total non-photochemical quenching, NPQ(T)) and maintains its efficiency (increased photosystem II quantum yield, ΦII). On the other hand, GSH also prompts retrograde signaling from the chloroplasts to the nucleus in adjusting OPDA-responsive gene expressions such as Glutathione S-Transferase 6 (GST6) and GST8, and actuating defense responses against various ecological constraints such as salinity, excess oxidants and light, as well as mechanical wounding. We thus propose that OPDA regulates a unique metabolic switch that interfaces light and defense signaling, where it links cellular and environmental cues to a multitude of plant physiological, e.g., growth, development, recovery, and acclimation, processes.

The Role of Biomass in Decarbonisation Efforts: Spatially Enriched Energy System Optimisation Modelling

Forests are a potentially carbon-negative energy source and function as carbon sinks. However, both of these functions have become threatened significantly by spruce bark beetle infestation in Czechia. This paper assesses how this ecological issue may affect the future energy mix, and in the process, affect carbon emission reduction targets and the available share of renewable energy sources (RESs). We assess several forest development scenarios with three policy incentives: subsidising wood pellet production, striving for climate neutrality, and adhering to ecological constraints. We build a spatially enriched energy system model, TIMES-CZ, based on Eurostat’s NUTS3 regions. We find that the spruce bark beetle infestation may not exert a lasting influence on overall decarbonisation pathways, the energy mix, or system-wide costs in any forest scenario. The RESs share is affected only until 2030, and the effect is minimal, at <1.5 percentage points. Nevertheless, Czechia’s RES contribution is far below the 45% 2030 EU target. Subsidising wood pellet production is a costly transition that does not contribute to meeting the target. Limiting forest biomass availability and adhering to ecological constraints increase the overall system costs and worsen the chances of meeting decarbonisation targets.

Coupling coordination analysis of resources, economy, and ecology in the Yellow River Basin

The development of the Yellow River Basin (YRB) has been constrained by resource utilization, ecological conservation, and economic growth. The aim of this study was to establish a theoretical framework for characterizing the relationships among resources, economy, and ecology in the YRB using panel data and remote sensing data from nine provinces in the basin from 2002 to 2022. Furthermore, a coupling coordination degree model and geographical detector model were used to evaluate the spatiotemporal coupling and relevant factors. Our findings were manifold. (1) The coupling coordination degree in the YRB and its provinces has improved to varying degrees, with upstream provinces showing stronger coordination than midstream and downstream provinces. (2) The most significant growth rates were observed during 2002–2006 and 2014–2018. However, a noticeable decline in the coupling coordination degree occurred during 2006–2010, indicating that ecological constraints and negative effects were pronounced when resource constraints were not apparent. (3) The average coupling coordination degree of resources, economy, and ecology in the YRB in 2022 was 0.684. Excellent coordination was observed in Shandong Province and Henan Province, and good coordination was observed in Shaanxi Province and Shanxi Province. (4) In the initial part of the study period, the water resource supply, demand, and allocation had strong effects on the coordination degree. Over time, the focus shifted from a single system to multiple systems, which increased the similarity in the explanatory power of different factors. Additionally, an in-depth analysis using the coupling coordination degree and relevant factors was conducted to characterize the policy orientations of different periods in the YRB. Policy recommendations were provided on the basis of the natural conditions and socio-economic conditions of the YRB. The findings of this study have implications for coupling coordination relationships and high-quality development in the YRB. Generally, our results provide key insights that will aid coordinated and sustainable regional development.

Modeling Ecological Constraints on a CO2 Pipeline Network.

Carbon capture, utilization, and storage (CCUS) are a critical set of strategies to decarbonize the industrial and power sectors and to mitigate global climate change. Pipeline infrastructure connecting CO2 sources and sinks, if not planned strategically, can cause environmental and social impacts by disturbing local landscapes. We investigated the impacts of these considerations on optimal CO2 pipeline routing and sink locations by modifying and leveraging an open-source CCUS infrastructure model, SimCCS. We expanded SimCCS from a cost-minimizing to a multiobjective framework, explicitly incorporating environmental protection objectives. We estimated trade-offs between private costs and environmental and social impacts. Using a version of the model focused on the southeastern United States, we modeled seven scenarios with varying weights given to environmental impacts to evaluate how the pipeline network responds to the multiobjective optimization. We found that the optimal path is sensitive to environmental and social impact considerations in that a small increase in pipeline length (and cost) significantly avoids large environmental and social impacts. We hope such a tool can be used to improve the pipeline permitting and siting processes and contribute to the achievement of decarbonization goals with minimal environmental impacts.

Drivers of functional and phylogenetic structures of mountain bird assemblages along an altitudinal gradient from the montane to alpine zones

Understanding the process underlying the spatial gradients in biodiversity is a fundamental issue in ecology. Altitudinal gradients are ideal systems for examining the community assembly process because they represent rapid changes in environmental conditions over relatively short distances. The functional and phylogenetic approaches allow a deeper mechanistic understanding of the underlying assembly process. However, whether community assembly from montane to alpine zones is driven more by ecological constraints or human settlement patterns is not fully resolved and may vary by system. Here, we examined the phylogenetic and trait-based functional structures from the montane to alpine zones and clarified the effects of natural environmental factors and human-induced landscape transformation on the breeding bird assemblage on Mount Norikura, central Japan. Breeding birds from 700 to 3026 m a.s.l. were surveyed in 2016–2017. Bird community structures were examined based on species richness, functional and phylogenetic structures. A null modelling approach was performed to examine functional and phylogenetic cluster/overdispersion structures; clustering and overdispersion imply species elimination by environmental filters and limiting similarity as a corollary of competitive exclusion of species, respectively. Furthermore, we examined the relative effect of natural environments and human disturbance. Bird species richness was high in the mountain base to mid-elevation, then decreased with elevation. We found a contrasting pattern in the phylogenetic and functional structures in the alpine zone: phylogenetic overdispersion and functional clustering. In contrast, the functional and phylogenetic structures were clustered in the upper parts of the subalpine zone. The functional and phylogenetic clusterings in the lower parts of the subalpine and montane zones were negligible with the weak effects of the environmental filtering. Single-trait analysis showed that the high abiotic tolerance and foraging or nesting capabilities in treeless environments were clustered in the alpine zone, and mobility was clustered in the subalpine zones. Natural environments strongly affected bird community structures, but human disturbance added species to assemblages in the mountain base to mid-elevation and changed the functional and phylogenetic structures. Our findings highlight that filtering by severe natural environments is a fundamental community assembly process in high mountain regions, whereas filtering effects can be weaker at lower elevations. Furthermore, the filtering effect should differ between the alpine and the upper parts of the subalpine zones because of different combinations of clustered traits. Climate change and landscape transformation pressures may strongly impact biodiversity in the alpine and subalpine zones, respectively.

Human occupations of upland and cold environments in inland Spain during the Last Glacial Maximum and Heinrich Stadial 1: The new Magdalenian sequence of Charco Verde II.

The settlement of cold and arid environments by Pleistocene hunter-gatherers has been a heated topic in Paleolithic Archaeology and the Quaternary Sciences for years. In the Iberian Peninsula, a key area for studying human adaptations to such environments is composed by the large interior and upland regions of the northern and southern plateaus (Mesetas) and bordering areas. As, traditionally, these regions have been relatively under-investigated compared to the ecologically more favored coastal areas of the peninsula, our knowledge of the human settlement of the whole Iberian hinterland remains scarce for the Last Glacial. In this paper we present the discovery and first geoarcheological, paleoenvironmental and chronometric evidence obtained at Charco Verde II, a new site close to the southwestern foothills of the Iberian system range (Guadalajara province, Spain), bearing a sequence of Magdalenian human occupations starting at least at 20.8-21.4 ka cal BP during the Last Glacial Maximum, and covering Greenland Stadial 2 until ∼15.1-16.6 ka cal BP, including Heinrich stadial 1. As this site is located in an upland region which today faces one of the harshest climates in Iberia, such occupation sequence, occurred during some of the coldest and most arid phases of the Last Glacial, has relevant implications for our understanding of human-environment-climate interactions and population dynamics in Iberia and Western Europe. These findings support the hypothesis that the Iberian hinterland was not avoided by Upper Paleolithic hunter-gatherers due to ecological constraints, but it hosted a complex and relatively dense settlement at least in some areas, even during cold periods. This suggest, one more time, that the historical scarcity of Upper Paleolithic sites in inland Iberia is, to a significant extent, an artifact of research bias.

Why human olfaction should not be modeled on theories and tasks of vision.

In this paper we analyze some key concepts and problems in olfaction and argue that many concepts borrowed from vision are not helpful in elucidating the functions of human olfaction. This is illustrated with several examples. Olfaction is rarely in the focus of human attention. Olfaction is, compared to vision, a 'hidden sense', but still guides many important behaviors by way of unattended unconscious olfactory perception and implicit memory. Not all olfactory processing, however, is of an unconscious nature. Flavors, and the pleasures gained from them, are most often consciously perceived. These are experiences mostly determined by olfaction, taste, touch and chemesthesis. Our analyses lead us to conclude that olfaction should not be modeled on vision, neither conceptually nor with respect to the problems solved by the two senses. A critical examination of the ecological and physical constraints of olfaction and the other senses should be given priority. Such analyses will further our understanding of which problems are solved by the different senses and how they collaborate to guide us through the world.

Growth Simulations of Urban Underground Space with Ecological Constraints Using a Patch-Based Cellular Automaton

The growth simulation of urban underground space (UUS) under the consideration of ecological constraints can effectively reveal the characteristics and trends of UUS changes, and provide a basis for planning the construction of sustainable and livable ecological cities. Therefore, this study considers urban ecological space as a constraint mechanism for UUS development and conducts a simulation study of the dynamic and complex UUS growth process, with a view toward guiding UUS planning under a long-term overall vision. In this study, a patch-based cellular automaton (CA) model is constructed to simulate the dynamic and complex growth process of UUS, subject to the ecological constraints generated by the agent-based land allocation optimization model. The spatial drivers of UUS growth simulation are determined based on the Random Forest (RF) algorithm. The results of the research case in Tianfu New District, Chengdu City, demonstrate that UUS expansion with ecological constraints exhibits sustainable characteristics. However, the growth rate of the UUS development scale is significantly lower when ecological constraints are present compared to when they are not. This study’s results contribute to urban management by finding a balance between UUS development and ecological space conservation, and providing theoretical support for rational UUS planning and decision making in the construction of low-carbon cities.

Ecological and economic assessment of sustainable spatial land management in the context of global climate change: economic and mathematical modeling

This article emphasises that the degree of anthropogenic (ecodestructive) impact on the state of agricultural production is the main criterion for assessing the development of sustainable spatial land management under certain ecological and economic constraints. The aim of the study is to model the ecological and economic assessment of the transformation of the territorial-spatial management of agricultural land at different levels of management, taking into account the impact of anthropogenic (ecodestructive) factors to ensure sustainable land use in the context of global climate change. Thus, the methodology of territorial-spatial analysis of the efficiency of transformation of modern agricultural land use and use of land and resource potential is aimed at determining its holistic assessment as a systemic and complex phenomenon. An economic-mathematical model for calculating the optimal structure of sown areas by placing crops between production structures of different levels of management, taking into account their susceptibility to the action of a particular ecodestructive (anthropogenic) factor, is proposed. The allocation of agricultural production based on the presented model implies redistribution of production of certain types of products, taking into account minimisation of economic losses from anthropogenic (ecodestructive) factors, in particular, industrial air pollution. The paper considers the possibilities of quantifying the economic consequences of climate change in the system of agricultural land use. It is proved that the assessment of economic losses from climate change in the system of sustainable agricultural land use requires the development of a system of cost standards that correspond to the input climate parameters. This article presents natural indicators and regional adjustment coefficients of agricultural production in case of an increase in the average annual air temperature by one degree, with differentiation by regions of Ukraine. An algorithm for economic assessment of the impact of changes in the thermal regime of the atmosphere on the efficiency of the crop production industry is presented. The proposed modelling of the territorialspatial improvement of agricultural land use efficiency is a methodological approach to assessing the environmental consequences of transforming the efficiency of management in agriculture in terms of reducing and preventing economic losses from anthropogenic (ecodestructive) factors in the context of global climate change. So, the practical implementation of the presented methodological approach to the economic assessment of the impact of global climate change on agriculture will allow to substantiate recommendations for the formation of a system of actions that would allow to avoid or at least reduce the negative climate impact.

Spatial aggregation patterns in four mistletoe species: ecological and environmental determinants.

Plant spatial distribution is an important topic in ecology as it determines species coexistence and biodiversity dynamics. Usually, plants show clustered distributions in nature. Mistletoes are a good example of aggregated distributions, as they form dense aggregations due to several factors (availability of competent hosts, seed dispersal vectors, microclimate conditions). We analysed four native mistletoe species with divergent life histories and host ranges: Desmaria mutabilis and Tristerix corymbosus from the temperate rainforests of southern Chile; and Tristerix aphyllus and Tristerix verticillatus from the northern semi-desert zone. While T. corymbosus and T. verticillatus have a wide host range, T. aphyllus and D. mutabilis are specialists that can parasitize only a few plant species. We hypothesized that specialized species would be more aggregated due to ecological and environmental restrictions. We used heterogeneous Poisson models to quantify spatial aggregation. Three of the four mistletoe species were spatially clustered at both environments, with aggregation being stronger in the temperate rainforest of southern Chile and particularly in the host-specialist species. Our results suggest that environmental constraints are more important than ecological constraints (host range) in shaping mistletoe spatial structure. Mistletoe aggregated spatial distribution depends primarily on the environment that they inhabit, which conditions host spatial availability, and arrangement.

A new critical social science research agenda on pesticides

The global pesticide complex has transformed over the past two decades, but social science research has not kept pace. The rise of an enormous generics sector, shifts in geographies of pesticide production, and dynamics of agrarian change have led to more pesticide use, expanding to farm systems that hitherto used few such inputs. Declining effectiveness due to pesticide resistance and anemic institutional support for non-chemical alternatives also have driven intensification in conventional systems. As an inter-disciplinary network of pesticide scholars, we seek to renew the social science research agenda on pesticides to better understand this suite of contemporary changes. To identify research priorities, challenges, and opportunities, we develop the pesticide complex as a heuristic device to highlight the reciprocal and iterative interactions among agricultural practice, the agrochemical industry, civil society-shaped regulatory actions, and contested knowledge of toxicity. Ultimately, collaborations among social scientists and across the social and biophysical sciences can illuminate recent transformations and their uneven socioecological effects. A reinvigorated critical scholarship that embraces the multifaceted nature of pesticides can identify the social and ecological constraints that drive pesticide use and support alternatives to chemically driven industrial agriculture.

Breaking the cliché: sex reversal in size dimorphism and mobility in South American Allocosinae (Lycosidae) spiders

Abstract Typically, females and males are expected to have characteristic sexual strategies and patterns of size dimorphism, but these generalizations are subject to exceptions. The occurrence of atypical cases has been related to species or populations from environments under strong physical, ecological and/or social constraints. Allocosa marindia and Allocosa senex are two coastal spiders (Lycosidae: Allocosinae) with reversal in sex roles and sexual size dimorphism. Males are larger than females, and females are the mobile sex that initiates courtship. It is unclear whether the occurrence of non-typical sexual traits in Allocosinae spiders is correlated with coastal habitats. Our aim was to study sexual size dimorphism and surface mobility in Allocosinae spiders from different habitats throughout South America. We revised specimens from scientific collections and performed 3-day samplings to collect individuals and determine nocturnal surface mobility. We analysed a total of 1071 Allocosinae adult individuals from 18 species and/or morphotypes. Our results revealed new species inhabiting coastal habitats with reversal in sexual size dimorphism and higher nocturnal surface activity in females; however, not all coastal species shared those characteristics. Future studies will focus on studying other ecological, physiological and/or phylogenetic factors that could be shaping the origin and maintenance of sex role reversal in Allocosinae.

Ecological constraints on audience size in the digital media system: evidence from the longitudinal tracking data from 2019 to 2022

Abstract The current high-choice media environment is characterized by increasingly intense competition for audience resources among media products. Drawing on research in organizational ecology and communication, audience behavior, and media economics, this study provides an ecological explanation for audience size in the digital media system. The analysis of Comscore’s aggregate audience data on the use of 64 digital media platforms over a 38-month period from 2019 to 2022 shows that a platform’s audience size is negatively associated with its niche overlap with another platform. This competitive effect of niche overlap on a platform’s current audience size is moderated by its previous audience size (size dependence) and species membership in the environment (species dependence). The results also support the short- and long-term stability of audience size.