Considering Variations in Waste Composition during Waste Input‐Output Modeling

Concentrations of pollutants vary in wastes from different sources. However, existing waste input‐output (WIO) models do not take these differing concentrations into account. This article proposes a new category of model, which we are calling a waste input‐output model at the substance level (WIOS model). The WIOS model considers variations in waste composition. These variations potentially affect the life cycle inventory of the waste treatment stage. The proposed model is expected to produce more accurate results than existing WIO models that do not consider variations in the composition of wastes. In addition, the proposed model provides a method to trace substances undergoing waste treatment. In this article, use of the WIOS model is illustrated by simulating the overall environmental loads of total organic carbon from wastewater treatment at a facility in Germany. The results show that variations in the composition of wastes entering treatment significantly affect the modeled estimates of total environmental loads caused by wastewater treatment. In addition, the results of the proposed model are different from results given by existing hybrid input‐output WIO models that do not consider variations in the composition of wastewater as it undergoes treatment.     

An Input‐Output Model of Extended Producer Responsibility

Under an extended producer responsibility (EPR) system, when a producer delivers a product to the market it must also pay a takeback fee, which is used to cover the costs of end‐of‐life disposal. EPR systems are currently used in Europe and beyond to manage a variety of products, including packaging and used tires. In this article we develop an input‐output (IO) model that is able to assess the impacts of an EPR system, and is based on the waste IO (WIO) model. The WIO model is itself a hybrid‐unit model extension of the Leontief model that is able to capture the substitution effect between recycled/recovered material/energy from waste treatment and their non‐waste cognates. The resulting EPRIO model, besides the conventional direct and indirect effects of the Leontief model and the substitution effects of the WIO model, is able to capture the opportunity costs of financing the EPR system, and additionally requires the specification of an alternative waste management policy, with its own opportunity costs. The impact of an EPR policy is thus the difference between the impacts of the reference EPR and the alternative waste treament policies. The resulting model is illustrated with a simple example of a used tire management EPR system.     

An Australian Multi‐Regional Waste Supply‐Use Framework

The production of waste creates both direct and indirect environmental impacts. A range of strategies are available to reduce the generation of waste by industry and households, and to select waste treatment approaches that minimize environmental harm. However, evaluating these strategies requires reliable and detailed data on waste production and treatment. Unfortunately, published Australian waste data are typically highly aggregated, published by a variety of entities in different formats, and do not form a complete time‐series. We demonstrate a technique for constructing a multi‐regional waste supply‐use (MRWSU) framework for Australia using information from numerous waste data sources. This is the first MRWSU framework to be constructed (to the authors' knowledge) and the first sub‐national waste input‐output framework to be constructed for Australia. We construct the framework using the Industrial Ecology Virtual Laboratory (IELab), a cloud‐hosted computational platform for building Australian multi‐regional input‐output tables. The structure of the framework complies with the System of Environmental‐Economic Accounting (SEEA). We demonstrate the use of the MRWSU framework by calculating waste footprints that enumerate the full supply chain waste production for Australian consumers.     

India's E‐Waste Rules and Their Impact on E‐Waste Management Practices: A Case Study

India, like many other developed and developing countries, has adopted an extended producer responsibility (EPR) approach for electronic waste (e‐waste) management under its E‐waste (Management and Handling) Rules, 2011. Under these rules, producers have been made responsible for setting up collection centers of e‐waste and financing and organizing a system for environmentally sound management of e‐waste. In this article, we use the implementation of these rules in Ahmedabad in western India as a case study to conduct a critical analysis of the implementation of India's Rules. Interviews of main stakeholder groups, including a sample of regulated commercial establishments, regulatory agencies enforcing the Rules, informal actors involved in waste collection and handling, as well as publicly available information on the implementation constitute data for our case study. Our results indicate that while there has been an increase in the formal waste processing capacity after the implementation of the Rules, only 5% to 15% of the total waste generated is likely channeled through formal processing facilities. While the EPR regulation forced the producers to take action on a few relatively inexpensive aspects of the Rules, the collection and recycling system has not been made convenient for the consumers to deposit e‐waste in formal collection and recycling centers. Based on our findings, we argue that Indian EPR regulation should go beyond simple take‐back mandates and consider implementing other policy instruments such as a deposit‐refund system. An important implication for developing countries is the need for careful attention to instrument choice and design within EPR regulations.     

Enabling regional management in a changing climate through Bayesian meta‐analysis of a large‐scale disturbance

Aim Quantifying and predicting change in large ecosystems is an important research objective for applied ecologists as human disturbance effects become increasingly evident at regional and global scales. However, studies used to make inferences about large‐scale change are frequently of uneven quality and few in number, having been undertaken to study local, rather than global, change. Our aim is to improve the quality of inferences that can be made in meta‐analyses of large‐scale disturbance by integrating studies of varying quality in a unified modelling framework that is informative for both local and regional management. Innovation Here we improve conventionally structured meta‐analysis methods by including imputation of unknown study variances and the use of Bayesian factor potentials. The approach is a coherent framework for integrating data of varying quality across multiple studies while facilitating belief statements about the uncertainty in parameter estimates and the probable outcome of future events. The approach is applied to a regional meta‐analysis of the effects of loss of coral cover on species richness and the abundance of coral‐dependent fishes in the western Indian Ocean (WIO) before and after a mass bleaching event in 1998. Main conclusions Our Bayesian approach to meta‐analysis provided greater precision of parameter estimates than conventional weighted linear regression meta‐analytical techniques, allowing us to integrate all available data from 66 available study locations in the WIO across multiple scales. The approach thereby: (1) estimated uncertainty in site‐level estimates of change, (2) provided a regional estimate for future change at any given site in the WIO, and (3) provided a probabilistic belief framework for future management of reef resources at both local and regional scales.     

Consumption‐based Material Flow Accounting

In 2007, imports accounted for approximately 34% of the material input (domestic extraction and imports) into the Austrian economy and almost 60% of the GDP stemmed from exports. Upstream material inputs into the production of traded goods, however, are not yet included in the standard framework of material flow accounting (MFA). We have reviewed different approaches accounting for these upstream material inputs, or raw material equivalents (RME), positioning them in a wider debate about consumption‐based perspectives in environmental accounting. For the period 1995–2007, we calculated annual RME of Austria's trade and consumption applying a hybrid approach. For exports and competitive imports, we used an environmentally extended input‐output model of the Austrian economy, based on annual supply and use tables and MFA data. For noncompetitive imports, coefficients for upstream material inputs were extracted from life cycle inventories. The RME of Austria's imports and exports were approximately three times larger than the trade flows themselves. In 2007, Austria's raw material consumption was 30 million tonnes or 15% higher than its domestic material consumption. We discuss the material composition of these flows and their temporal dynamics. Our results demonstrate the need for a consumption‐based perspective in MFA to provide robust indicators for dematerialization and resource efficiency analysis of open economies.     

Nonparametric All‐Pairs Multiple Comparisons

Nonparametric all‐pairs multiple comparisons based on pairwise rankings can be performed in the one‐way design with the Steel‐Dwass procedure. To apply this test, Wilcoxon's rank sum statistic is calculated for all pairs of groups; the maximum of the rank sums is the test statistic. We provide exact calculations of the asymptotic critical values (and P‐values, respectively) even for unbalanced designs. We recommend this asymptotic method whenever large sample sizes are present. For small sample sizes we recommend the use of the new statistic according to Baumgartner , Weiss , and Schindler (1998, Biometrics 54 , 1129–1135) instead of Wilcoxon's rank sum for the multiple comparisons. We show that the resultant procedure can be less conservative and, according to simulation results, more powerful than the original Steel‐Dwass procedure. We illustrate the methods with a practical data set.     

Identifying Lowest‐Emission Choices and Environmental Pareto Frontiers for Wastewater Treatment Wastewater Treatment Input‐Output Model based Linear Programming

This article proposes a linear programming model that is based on the wastewater treatment input‐output model (W²IO) to identify the lowest‐emission choice among alternative feasible options for wastewater treatment; this model can be considered as an application of the waste input‐output linear programming model (WIO‐LP) to wastewater issues. Using the data of the Tokyo metropolitan W²IO table, I apply this model to obtain the optimal wastewater treatment options under alternative scenarios. The Pareto frontiers of environmental loads are derived to show the trade‐off relationships among various types of environmental load and the effect of the introduction of high‐temperature incineration of dewatered sludge on the generation of environmental loads. The main conclusion of the study is that when all three types of environmental load (landfill level, global warming potential, and chemical oxygen demand) are considered, the introduction of high‐temperature incineration causes the widening of the Pareto frontier of environmental loads and also causes it to move closer to the origin.     

Continental‐scale tree‐ring‐based projection of Douglas‐fir growth: Testing the limits of space‐for‐time substitution

A central challenge in global change research is the projection of the future behavior of a system based upon past observations. Tree‐ring data have been used increasingly over the last decade to project tree growth and forest ecosystem vulnerability under future climate conditions. But how can the response of tree growth to past climate variation predict the future, when the future does not look like the past? Space‐for‐time substitution (SFTS) is one way to overcome the problem of extrapolation: the response at a given location in a warmer future is assumed to follow the response at a warmer location today. Here we evaluated an SFTS approach to projecting future growth of Douglas‐fir (Pseudotsuga menziesii), a species that occupies an exceptionally large environmental space in North America. We fit a hierarchical mixed‐effects model to capture ring‐width variability in response to spatial and temporal variation in climate. We found opposing gradients for productivity and climate sensitivity with highest growth rates and weakest response to interannual climate variation in the mesic coastal part of Douglas‐fir's range; narrower rings and stronger climate sensitivity occurred across the semi‐arid interior. Ring‐width response to spatial versus temporal temperature variation was opposite in sign, suggesting that spatial variation in productivity, caused by local adaptation and other slow processes, cannot be used to anticipate changes in productivity caused by rapid climate change. We thus substituted only climate sensitivities when projecting future tree growth. Growth declines were projected across much of Douglas‐fir's distribution, with largest relative decreases in the semiarid U.S. Interior West and smallest in the mesic Pacific Northwest. We further highlight the strengths of mixed‐effects modeling for reviving a conceptual cornerstone of dendroecology, Cook's 1987 aggregate growth model, and the great potential to use tree‐ring networks and results as a calibration target for next‐generation vegetation models.     

Architecture and self‐assembly of the SARS‐CoV‐2 nucleocapsid protein

The COVID‐2019 pandemic is the most severe acute public health threat of the twenty‐first century. To properly address this crisis with both robust testing and novel treatments, we require a deep understanding of the life cycle of the causative agent, the SARS‐CoV‐2 coronavirus. Here, we examine the architecture and self‐assembly properties of the SARS‐CoV‐2 nucleocapsid protein, which packages viral RNA into new virions. We determined a 1.4 Å resolution crystal structure of this protein's N2b domain, revealing a compact, intertwined dimer similar to that of related coronaviruses including SARS‐CoV. While the N2b domain forms a dimer in solution, addition of the C‐terminal spacer B/N3 domain mediates formation of a homotetramer. Using hydrogen‐deuterium exchange mass spectrometry, we find evidence that at least part of this putatively disordered domain is structured, potentially forming an α‐helix that self‐associates and cooperates with the N2b domain to mediate tetramer formation. Finally, we map the locations of amino acid substitutions in the N protein from over 38,000 SARS‐CoV‐2 genome sequences. We find that these substitutions are strongly clustered in the protein's N2a linker domain, and that substitutions within the N1b and N2b domains cluster away from their functional RNA binding and dimerization interfaces. Overall, this work reveals the architecture and self‐assembly properties of a key protein in the SARS‐CoV‐2 life cycle, with implications for both drug design and antibody‐based testing.     

Constraints imposed by non‐functional protein–protein interactions on gene expression and proteome size

Crowded intracellular environments present a challenge for proteins to form functional specific complexes while reducing non‐functional interactions with promiscuous non‐functional partners. Here we show how the need to minimize the waste of resources to non‐functional interactions limits the proteome diversity and the average concentration of co‐expressed and co‐localized proteins. Using the results of high‐throughput Yeast 2‐Hybrid experiments, we estimate the characteristic strength of non‐functional protein–protein interactions. By combining these data with the strengths of specific interactions, we assess the fraction of time proteins spend tied up in non‐functional interactions as a function of their overall concentration. This allows us to sketch the phase diagram for baker's yeast cells using the experimentally measured concentrations and subcellular localization of their proteins. The positions of yeast compartments on the phase diagram are consistent with our hypothesis that the yeast proteome has evolved to operate closely to the upper limit of its size, whereas keeping individual protein concentrations sufficiently low to reduce non‐functional interactions. These findings have implication for conceptual understanding of intracellular compartmentalization, multicellularity and differentiation.     

Dual labeling with 5‐bromo‐2'‐deoxyuridine and 5‐ethynyl‐2'‐deoxyuridine for estimation of cell migration rate in the small intestinal epithelium

Small intestinal epithelium is a self‐renewing system in which the entire sequence of cell proliferation, differentiation, and removal is coupled to cell migration along the crypt‐villus axis. We examined whether dual labeling with different thymidine analogues, 5‐bromo‐2'‐deoxyuridine (BrdU) and 5‐ethynyl‐2'‐deoxyuridine (EdU), can be used to estimate cell migration rates on the villi of small intestines in rats. Rats received a single intraperitoneal injection of BrdU and EdU within a time interval, and signals in tissue sections were examined by immunohistochemistry and the “click” reaction, respectively. We successfully observed BrdU‐ and EdU‐positive cells on the epithelium with no cross‐reaction. In addition, we observed an almost complete overlapping of BrdU‐ and EdU‐positive cells in rats administered simultaneously with BrdU and EdU. By calculating the cell migration rate by dividing the distance between the median cell positions of the distribution of BrdU‐ and EdU‐positive cells by the time between the injection of BrdU and EdU, we estimated approximately 9 and 5 μm/h for the cell migration rates on the villi in the jejunum and ileum, respectively. We propose that dual labeling with BrdU and EdU within a time interval, followed by detecting with immunohistochemistry and the click reaction, respectively, is useful to estimate accurately the cell migration rate in the intestinal epithelium in a single animal.     

Using expert knowledge to incorporate uncertainty in cause‐of‐death assignments for modeling of cause‐specific mortality

Implicit and explicit use of expert knowledge to inform ecological analyses is becoming increasingly common because it often represents the sole source of information in many circumstances. Thus, there is a need to develop statistical methods that explicitly incorporate expert knowledge, and can successfully leverage this information while properly accounting for associated uncertainty during analysis. Studies of cause‐specific mortality provide an example of implicit use of expert knowledge when causes‐of‐death are uncertain and assigned based on the observer's knowledge of the most likely cause. To explicitly incorporate this use of expert knowledge and the associated uncertainty, we developed a statistical model for estimating cause‐specific mortality using a data augmentation approach within a Bayesian hierarchical framework. Specifically, for each mortality event, we elicited the observer's belief of cause‐of‐death by having them specify the probability that the death was due to each potential cause. These probabilities were then used as prior predictive values within our framework. This hierarchical framework permitted a simple and rigorous estimation method that was easily modified to include covariate effects and regularizing terms. Although applied to survival analysis, this method can be extended to any event‐time analysis with multiple event types, for which there is uncertainty regarding the true outcome. We conducted simulations to determine how our framework compared to traditional approaches that use expert knowledge implicitly and assume that cause‐of‐death is specified accurately. Simulation results supported the inclusion of observer uncertainty in cause‐of‐death assignment in modeling of cause‐specific mortality to improve model performance and inference. Finally, we applied the statistical model we developed and a traditional method to cause‐specific survival data for white‐tailed deer, and compared results. We demonstrate that model selection results changed between the two approaches, and incorporating observer knowledge in cause‐of‐death increased the variability associated with parameter estimates when compared to the traditional approach. These differences between the two approaches can impact reported results, and therefore, it is critical to explicitly incorporate expert knowledge in statistical methods to ensure rigorous inference.     

An alternative structural isoform in amyloid‐like aggregates formed from thermally denatured human γD‐crystallin

The eye lens protein γD‐crystallin contributes to cataract formation in the lens. In vitro experiments show that γD‐crystallin has a high propensity to form amyloid fibers when denatured, and that denaturation by acid or UV‐B photodamage results in its C‐terminal domain forming the β‐sheet core of amyloid fibers. Here, we show that thermal denaturation results in sheet‐like aggregates that contain cross‐linked oligomers of the protein, according to transmission electron microscopy and SDS‐PAGE. We use two‐dimensional infrared spectroscopy to show that these aggregates have an amyloid‐like secondary structure with extended β‐sheets, and use isotope dilution experiments to show that each protein contributes approximately one β‐strand to each β‐sheet in the aggregates. Using segmental ¹³C labeling, we show that the organization of the protein's two domains in thermally induced aggregates results in a previously unobserved structure in which both the N‐terminal and C‐terminal domains contribute to β‐sheets. We propose a model for the structural organization of the aggregates and attribute the recruitment of the N‐terminal domain into the fiber structure to intermolecular cross linking.     

Zoogeography of the shallow-water holothuroids of the western Indian Ocean

Aim To analyse the zoogeography of the shallow‐water holothuroids of the western Indian Ocean (WIO). Based on this analysis we ask to what extent differences in species’ ability to disperse across potential barriers provide an explanation for holothuroid zoogeography. Location Shallow‐waters (50 m isobaths) of the WIO, extending from Suez to Cape Town and from the coastline of East Africa upward to 65° E. Methods Data for the analysis were obtained from Samyn's (2003) monograph on the shallow‐water sea cucumbers of the WIO. A species presence/absence matrix with a resolution of 1° latitude/longitude was constructed. These cells were assigned to eight coarser operational geographical units, which were delimited on the basis of published faunistic and geological borders. The analytical zoogeographical methods employed were cluster analysis on several β‐diversity coefficients and parsimony analyses of endemicity. The influence of life‐history strategies on the distribution pattern was analysed through examination of latitudinal and longitudinal gradients, and by plotting cumulative curves for species number against range size. Results The shallow‐water holothuroid fauna of the WIO can be split into several biogeographical units. To the north, we found evidence that the northern Red Sea holothuroid fauna differs from that of the southern Red Sea. The latter has closest affinity with south‐east Arabia and the Persian Gulf, and thus the biogeographical barrier of Bab‐el‐Mandab nowadays seems to be of minor importance. The cold upwelling at the east coast of Somalia forms an effective barrier for holothuroids and especially those with lecitothrophic (short‐lived) larvae. Even though the circumtropical biogeographical pattern is not well resolved, important taxonomic turnovers suggest that it is composed of several distinct subprovinces. Taxonomic turnover is at least partially dictated by the dispersion capacity of the different orders. Main conclusions This study concludes that the WIO is best split into at least three biogeographical realms: (1) the Red Sea and associated Arab Basin, (2) the asymmetrical circumtropical region stretching from the horn of Africa to southern Mozambique, and (3) southern Africa. Conspicuous differences in dispersal abilities of the three dominant orders are identified. The biogeography of the WIO is best explained by: (1) species’ dispersion ability, (2) the prevalent current patterns, and (3) to a lesser, geographically limited extent, recent geological history. As a serendipitous discovery, we found that Rapoport's rule does not hold in the WIO.     

Input-Output Analysis of Waste Management

A new scheme of hybrid life-cycle assessment (LCA) termed the waste input-output (WIO) model is presented that ex-plicitly takes into account the interdependence between the flow of goods and waste. The WIO model has two distin-guishing features. First, it expands the Leontief environmental input-output (EIO) model with respect to waste flows. It turns out that the EIO model is a special case of the WIO model in which there is a strict one-to-one correspondence between waste types and treatment methods. By relaxing this condition, the WIO model provides a general framework for LCA of waste management. Second, the WIO model takes into account the "dynamics of waste treatment", which refers to the fact that the input-output relationships of waste treatment are significantly affected by the level and composition of waste feedstock, by incorporating an engineering process model of waste treatment. Because waste treatment is expected to accept whatever waste is generated by industry and households, a proper consideration of this feature is vital for LCA of waste management. We estimated a WIO table for Japan and applied it to evaluating effects of alternative waste management poli-cies with regard to regional concentration of incineration and the sorting of waste with regard to flammability. We found that concentrating treatment in a small number of large incin-erators combined with an increased degree of sorting could decrease both landfill consumption and the emission of carbon dioxide.     

Volatiles from green‐lipped mussel as a lead to vespid wasp attractants

Vespid wasps (Vespula vulgaris L. and V. germanica Fab. Hymenoptera; Vespidae) are highly abundant in 1 million ha of New Zealand's indigenous beech forests (Nothofagus spp.) and have had detrimental effects on the New Zealand native fauna. This hyperabundance is due in part to the vast supply of carbohydrate‐rich honeydew produced by scale insects Ultracoelostoma spp. native to New Zealand. Current control methods include the use of wet cat food as a protein source with insecticide as a lure‐and‐kill‐based system, but there are problems with fresh baits degrading rapidly, and a more durable formulation would enable the expansion and longevity of wasp control. Four crude protein baits were tested for vespid attraction. Green‐lipped mussels had the highest vespid catch of the crude baits tested, and aged and fresh mussels were equally attractive. From headspace analysis of the green‐lipped mussel volatiles, a series of butanoate esters, 3‐octanone and 1‐octen‐3‐ol were identified as possible attractants. These compounds were tested individually and in various blend combinations for the attraction of Vespula wasps in matagouri vegetation at the edge of beech forests. We found synergistic effects between single attractive compounds when tested in various combinations, and the multicomponent lures were more attractive to these wasps than heptyl and octyl butanoate, previously identified attractants for vespid species. The new multicomponent lures could form the basis for a new generation of attractants for social wasps that can provide sustained control methods for invasive vespid wasps.     

The Usefulness of 4‐Amino‐3‐hydroxyphenylalanine as a Specific Marker of Pheomelanin

Reductive hydrolysis of pheomelanin with hydriodic acid (HI) gives two aminohydroxyphenylalanine isomers, 4‐amino‐3‐hydroxyphenylalanine (`specific AHP') and 3‐amino‐4‐hydroxyphenylalanine (3‐aminotyrosine, AT), which derive from the oxidative polymerization of 5‐S‐cysteinyldopa, and 2‐S‐cysteinyldopa, respectively. Since we first introduced this analytical method, the combined amount of AHP and AT (`total AHP') has been extensively used as a marker of pheomelanin. However, one problem with using total AHP as a marker is that background levels originate from precursors other than pheomelanin. Considerable and variable amounts of background AT are produced from other sources, most likely nitrotyrosine residues in proteins. In order to overcome this problem, we developed HPLC conditions which enable the direct injection of the HI reduction products into the HPLC system allowing good separation of AHP and AT. In this way we could study the importance of both degradation products separately and their specificity as markers for pheomelanin. The usefulness of the present method is validated using human hair samples of various colours which were divided into dark, fair or red colours. The combined amount of specific AHP and AT shows an excellent correlation with total AHP, and the amount of specific AHP also correlates with the amount of total AHP. We also examined total AHP and specific AHP values against pyrrole‐2,3,5‐tricarboxylic acid (PTCA) values in the human hair samples. These results show that specific AHP measurement gives a more prominent segregation for the ratio of specific AHP to PTCA among hairs of various colours than the ratio of total AHP to PTCA. Thus, we conclude that `specific AHP' is a more specific marker of pheomelanin than is `total AHP'.     

Isoform‐specific cleavage of 14‐3‐3 proteins in apoptotic JURL‐MK1 cells

The proteins of 14‐3‐3 family are substantially involved in the regulation of many biological processes including the apoptosis. We studied the changes in the expression of five 14‐3‐3 isoforms (β, γ, ε, τ, and ζ) during the apoptosis of JURL‐MK1 and K562 cells. The expression level of all these proteins markedly decreased in relation with the apoptosis progression and all isoforms underwent truncation, which probably corresponds to the removal of several C‐terminal amino acids. The observed 14‐3‐3 modifications were partially blocked by caspase‐3 inhibition. In addition to caspases, a non‐caspase protease is likely to contribute to 14‐3‐3's cleavage in an isoform‐specific manner. While 14‐3‐3 γ seems to be cleaved mainly by caspase‐3, the alternative mechanism is essentially involved in the case of 14‐3‐3 τ, and a combined effect was observed for the isoforms ε, β, and ζ. We suggest that the processing of 14‐3‐3 proteins could form an integral part of the programmed cell death or at least of some apoptotic pathways. J. Cell. Biochem. 106: 673–681, 2009. © 2009 Wiley‐Liss, Inc.     

Taming fitness: Organism‐environment interdependencies preclude long‐term fitness forecasting

Fitness is a central but notoriously vexing concept in evolutionary biology. The propensity interpretation of fitness is often regarded as the least problematic account for fitness. It ties an individual's fitness to a probabilistic capacity to produce offspring. Fitness has a clear causal role in evolutionary dynamics under this account. Nevertheless, the propensity interpretation faces its share of problems. We discuss three of these. We first show that a single scalar value is an incomplete summary of a propensity. Second, we argue that the widespread method of “abstracting away” environmental idiosyncrasies by averaging over reproductive output in different environments is not a valid approach when environmental changes are irreversible. Third, we point out that expanding the range of applicability for fitness measures by averaging over more environments or longer time scales (so as to ensure environmental reversibility) reduces one's ability to distinguish selectively relevant differences among individuals because of mutation and eco‐evolutionary feedbacks. This series of problems leads us to conclude that a general value of fitness that is both explanatory and predictive cannot be attained. We advocate for the use of propensity‐compatible methods, such as adaptive dynamics, which can accommodate these difficulties.