Constraint Hypothesis Research Articles

Environmental constraints can explain clutch size differences between urban and forest blue tits: Insights from an egg removal experiment.

Urban environments present novel ecological challenges to wild species. In birds, urban populations generally exhibit reduced clutch sizes compared to forest populations. However, whether smaller urban clutches are adaptive or a result of environmental constraints is unclear. To investigate these two hypotheses, we quantified the ability of urban and non-urban blue tits (Cyanistes caeruleus) to lay new eggs after an experimental manipulation aimed to increase egg production. We removed the first four eggs laid by urban and forest birds to test their ability to produce new eggs. If the urban environment imposes constraints on egg production, we predicted that urban birds would not lay new eggs. If the small clutches of urban birds are an adaptive response, we predicted they would lay new eggs to reach the optimal clutch size for the environment. Consistent with the environmental constraint hypothesis, our results suggest that urban females do not lay new eggs to the same extent as forest birds following egg removal. Forest birds laid approximately two new eggs after our experimental manipulation, while urban birds laid approximately 0.36 new eggs following egg removal. Our manipulation resulted in a brood reduction in the urban experimental nests, yet there was no difference in the number of fledged offspring between urban control and experimental nests. This suggests that females might be misjudging urban habitat quality and produce a clutch with more eggs than nestlings they can rear. Overall, our results suggest that environmental constraints could limit the number of eggs that urban females lay, generating urban versus non-urban differences in this trait.

Prepositional Verbs and the Individual-/Stage-Level distinction

Drawing on Catalan, we show how the aspectual classification of intransitive prepositional verbs is, partially, a predictor of their argument structure properties. Prepositional verbs qualifying as Stage-Level form a heterogeneous class, comprising both unergative and unaccusative verbs. By contrast, those prepositional verbs that qualify as Individual-Level predicates are homogenous as regards argument structure: their prepositional complement is robustly obligatory and their subject is not an external argument, suggesting that they involve a predicative configuration whose predicate is the prepositional complement. This result supports the more general Property Verbalization Constraint hypothesis (Acedo-Matellán 2019), which states that Individual-Level property predicates cannot be encoded as unergative verbs.

Activity of predators in seabird colonies decreases during the darkest compared to the brightest phase of the diel cycle below, but not above, the Arctic Circle

ABSTRACT Predator activity can structure communities temporally and influence the spatial distribution of prey. Yet, despite the influence this may have on prey species’ activity or geographic persistence, our understanding of whether diel predator activity changes geographically remains limited. Here, we conduct a case study to test whether predator activity during the darkest phase of the diel cycle increases with the duration of daylight (i.e. photoperiod) at high latitudes during summer, aligning with the photoperiod constraint hypothesis. Using both observations and experiments at one seabird colony above and one below the northern polar (Arctic) circle, we compared predator activity between the brightest and darkest phases of the diel cycle. Avian predator counts were greater and nest predation events were more common during the brightest phase of the diel cycle below the Arctic Circle (i.e. where the sun goes below the horizon) but similar across phases during polar summer (i.e. above the Arctic Circle when the sun does not set). Our results highlight the potential influence of light on activity of predator communities and suggest a possible latitudinal limit to the advantage gained by dark-active strategies for avoidance of visually hunting predators.

The zero-debt puzzle in BRICS countries: Disentangling the financial flexibility and financial constraints hypotheses

This study analyzes the zero-debt decisions of BRICS firms using a bivariate probit model. The leading hypotheses are financial flexibility and financial constraints. On the demand-side, our findings reveal that managerial debt aversion, early lifecycle stage, growth opportunities, solvency, and concentrated ownership contribute to the lack of debt. Similarly, a country's institutional quality correlates with firms' debt-free status. On the supply-side, creditors fund companies with poor financial records in countries with robust markets and economic freedom. Financial flexibility and restrictions leading to zero debt are linked to firm and institutional characteristics in emerging countries.

Evolutionary trade-offs in dormancy phenology.

Seasonal animal dormancy is widely interpreted as a physiological response for surviving energetic challenges during the harshest times of the year (the physiological constraint hypothesis). However, there are other mutually non-exclusive hypotheses to explain the timing of animal dormancy, that is, entry into and emergence from hibernation (i.e. dormancy phenology). Survival advantages of dormancy that have been proposed are reduced risks of predation and competition (the 'life-history' hypothesis), but comparative tests across animal species are few. Using the phylogenetic comparative method applied to more than 20 hibernating mammalian species, we found support for both hypotheses as explanations for the phenology of dormancy. In accordance with the life-history hypotheses, sex differences in hibernation emergence and immergence were favored by the sex difference in reproductive effort. In addition, physiological constraint may influence the trade-off between survival and reproduction such that low temperatures and precipitation, as well as smaller body mass, influence sex differences in phenology. We also compiled initial evidence that ectotherm dormancy may be (1) less temperature dependent than previously thought and (2) associated with trade-offs consistent with the life-history hypothesis. Thus, dormancy during non-life-threatening periods that are unfavorable for reproduction may be more widespread than previously thought.

Evolutionary trade-offs in dormancy phenology

Seasonal animal dormancy is widely interpreted as a physiological response for surviving energetic challenges during the harshest times of the year (the physiological constraint hypothesis). However, there are other mutually non-exclusive hypotheses to explain the timing of animal dormancy, that is, entry into and emergence from hibernation (i.e. dormancy phenology). Survival advantages of dormancy that have been proposed are reduced risks of predation and competition (the ‘life-history’ hypothesis), but comparative tests across animal species are few. Using the phylogenetic comparative method applied to more than 20 hibernating mammalian species, we found support for both hypotheses as explanations for the phenology of dormancy. In accordance with the life-history hypotheses, sex differences in hibernation emergence and immergence were favored by the sex difference in reproductive effort. In addition, physiological constraint may influence the trade-off between survival and reproduction such that low temperatures and precipitation, as well as smaller body mass, influence sex differences in phenology. We also compiled initial evidence that ectotherm dormancy may be (1) less temperature dependent than previously thought and (2) associated with trade-offs consistent with the life-history hypothesis. Thus, dormancy during non-life-threatening periods that are unfavorable for reproduction may be more widespread than previously thought.

Body size shapes song in honeyeaters.

Birdsongs are among the most distinctive animal signals. Their evolution is thought to be shaped simultaneously by habitat structure and by the constraints of morphology. Habitat structure affects song transmission and detectability, thus influencing song (the acoustic adaptation hypothesis), while body size and beak size and shape necessarily constrain song characteristics (the morphological constraint hypothesis). Yet, support for the acoustic adaptation and morphological constraint hypotheses remains equivocal, and their simultaneous examination is infrequent. Using a phenotypically diverse Australasian bird clade, the honeyeaters (Aves: Meliphagidae), we compile a dataset consisting of song, environmental, and morphological variables for 163 species and jointly examine predictions of these two hypotheses. Overall, we find that body size constrains song frequency and pace in honeyeaters. Although habitat type and environmental temperature influence aspects of song, that influence is indirect, likely via effects of environmental variation on body size, with some evidence that elevation constrains the evolution of song peak frequency. Our results demonstrate that morphology has an overwhelming influence on birdsong, in support of the morphological constraint hypothesis, with the environment playing a secondary role generally via body size rather than habitat structure. These results suggest that changing body size (a consequence of both global effects such as climate change and local effects such as habitat transformation) will substantially influence the nature of birdsong.

Acoustic difference in advertisement calls among two sympatric Boulenophrys species: A confirmatory case to acoustic niche hypothesis and morphological constraint hypothesis.

In anurans, acoustic communication is the most important form of communication at the interspecific and intraspecific levels. Acoustic diagnostic features may be a potential alternative to morphometric and molecular diagnostics. Here, we assessed the variations in advertisement calls between two sympatric species, Boulenophrys leishanensis and Boulenophrys spinata, that share their breeding season and breeding sites. In addition, we investigated any potential relationships between call parameters and body size. We found that the advertisement calls of both species are simple calls. The two species exhibited significant differences in all call parameters. Both B. leishanensis and B. spinata showed a significant negative correlation with their body size on dominant frequency. These differences in call parameters may play an important role in interspecific recognition. Additionally, because intraspecific acoustic variation reflects body size, calls may be relevant for sexual selection. Our study supports the acoustic niche hypothesis and the morphological constraint hypothesis and calls are a valid tool for distinguishing between the two species of Boulenophrys in the field.

Can stakeholders’ attention to innovation promote corporate innovation?

PurposeGiven the significance of innovation in enabling firms to maintain a long-term competitive edge and secure excess profits, this paper aims to investigate whether and how stakeholders’ attention to innovation (SATI) influences corporate innovation.Design/methodology/approachThis paper introduces a novel variable, SATI, which is achieved by segmenting stakeholders’ attention into two categories: attention to innovation and attention to other facets, using textual analysis methods. Subsequently, this paper empirically examines the influence of SATI on corporate innovation.FindingsThis paper finds that SATI positively affects corporate innovation input, and the result remains true after addressing possible endogeneity issues using instrumental variable regression. Furthermore, the positive effect of SATI on corporate innovation is stronger in firms facing greater financing constraints, thus verifying the financing constraints hypothesis. The positive effect is also stronger in firms with lower risk-taking levels, thus confirming the innovation failure tolerance hypothesis. Further analysis suggests that SATI increases both corporate innovation output and efficiency, thus ruling out the catering hypothesis.Originality/valueThis paper highlights the importance of SATI in driving corporate innovation. It enriches the literature on the repercussions of stakeholders’ attention and determinants of corporate innovation. In addition, it provides practical suggestions for further implementing China’s national innovation-driven development strategy.

The global distribution of angiosperm genome size is shaped by climate.

Angiosperms, which inhabit diverse environments across all continents, exhibit significant variation in genome sizes, making them an excellent model system for examining hypotheses about the global distribution of genome size. These include the previously proposed largegenome constraint, mutational hazard, polyploidy-mediated, and climate-mediated hypotheses. We compiled the largest genome size dataset to date, encompassing 16 017 (> 5% of known) angiosperm species, and analyzed genome size distribution using a comprehensive geographic distribution dataset for all angiosperms. We observed that angiosperms with large range sizes generally had small genomes, supporting the large genome constraint hypothesis. Climate was shown to exert a strong influence on genome size distribution along the global latitudinal gradient, while the frequency of polyploidy and the type of growth form had negligible effects. In contrast to the unimodal patterns along the global latitudinal gradient shown by plant size traits and polyploid proportions, the increase in angiosperm genome size from the equator to 40-50°N/S is probably mediated by different (mostly climatic) mechanisms than the decrease in genome sizes observed from 40 to 50°N northward. Our analysis suggests that the global distribution of genome sizes in angiosperms is mainly shaped by climatically mediated purifying selection, genetic drift, relaxed selection, and environmental filtering.

Unpacking the relations of transcription and oral language to written composition in kindergarten children

In the present study we examined the contributions of transcription and foundational oral language skills to written composition outcomes in a sample of kindergartners. Two hundred and eighty-two kindergarten students from 49 classrooms participated in this study. Children's writing-related skills were examined using various tasks. Latent structural equation modeling was used to test the hypothesis that transcription moderates the relation between foundational oral language and compositional productivity and quality for kindergarten writers. This hypothesis is one possible manifestation of the Developmental Constraints Hypothesis (DCH). In support of the DCH, transcription had a strong constraining effect on both composition quality and productivity. Additionally, transcription moderated the relation between foundational oral language skills and composition quality, although the moderation was negative. There was no signification moderation of transcription on the foundational oral language -composition productivity relation. Implications of the findings and future directions are discussed including challenges assessing composition in young, beginning writers.

A Study on the Long-Term Performance of Mergers in the Korean Stock Market

This study analyzes the merger-related hypotheses which are managerial overconfidence hypothesis, controlling shareholder interest hypothesis, synergy hypothesis, financial constraint hypothesis, and momentum hypothesis through long-term performance analysis of acquiring firms. As a result of empirical analysis, first, the three-year event-time buy-andhold excess return (BHAR) was about -10% for both the average and median values which is statistically significant. Second, through both calendar-time portfolio excess return and BHAR, we find that the stronger the management's overconfidence is, the lower the longterm performance is. On the other hand, in the case of mergers by horizontal combinations, there was a positive synergy effect. This means that the management overconfidence hypothesis, the financial constraint hypothesis, the momentum hypothesis of merger performance, and the synergy hypothesis are established. Despite the poor long-term performance of mergers between domestic companies, this study provides implications that the merger may be mainly due to unreasonable overconfidence of managers and short-term perspectives of management.

Testing Financial Constraint Hypothesis of Investment in NEPSE Listed Companies

This study aims to test financing constraints of Nepalese firms and its impact on investment behavior by controlling the accelerator effect. It divides the firms into Financially Constrained (FC) and Unconstrained (UC) group using discriminant analysis and uses Econometric Model to analyze investment cashflow sensitivities (ICFS) of firms. The data comprised the accounting observations (n=256) obtained from the annual reports of 16 non-financial companies listed in Nepal Stock Exchange Ltd. Results show that financially constrained firm exhibit higher cashflow sensitivity indicating significant influence of financing constraints on Nepalese firm's investment behavior. It documents the evidence of financial market inefficiency, urging for policy prescriptions to address these constraints and spur investment and growth.

Testing the large genome constraint hypothesis in tropical rhizomatous herbs: life strategies, plant traits and habitat preferences in gingers.

Plant species with large genomes tend to be excluded from climatically more extreme environments with a shorter growing season. Species that occupy such environments are assumed to be under natural selection for more rapid growth and smaller genome size (GS). However, evidence for this is available only for temperate organisms. Here, we study the evolution of GS in two subfamilies of the tropical family Zingiberaceae to find out whether species with larger genomes are confined to environments where the vegetative season is longer. We tested our hypothesis on 337 ginger species from regions with contrasting climates by correlating their GS with an array of plant traits and environmental variables. We revealed 16-fold variation in GS which was tightly related to shoot seasonality. Negative correlations of GS with latitude, temperature and precipitation emerged in the subfamily Zingiberoidae, demonstrating that species with larger GS are excluded from areas with a shorter growing season. In the subfamily Alpinioideae, GS turned out to be correlated with the type of stem and light requirements and its members cope with seasonality mainly by adaptation to shady and moist habitats. The Ornstein-Uhlenbeck models suggested that evolution in regions with humid climates favoured larger GS than in drier regions. Our results indicate that climate seasonality exerts an upper constraint on GS not only in temperate regions but also in the tropics, unless species with large genomes find alternative ways to escape from that constraint.

Grooming reciprocation in Himalayan tahr and the cognitive constraint hypothesis

AbstractThe cognitive constraint hypothesis maintains reciprocity is rare among animals because it requires cognitive capabilities that are rare, if not absent, in animals. In particular, it suggests that temporal discounting, limited memory, and limited capability of complex calculations make long‐term reciprocation essentially impossible for animals. The cognitive constraint hypothesis therefore predicts that, if reciprocity ever occurs in animals, it should always be immediate. In this study, we tested for long‐term reciprocation in Himalayan tahr (Hemitragus jemlahicus), a species that is not notable for its advanced cognitive capabilities. We showed that tahr are able to reciprocate grooming over extended time periods, that is, that they groom preferentially those individuals from which they receive more grooming even when all cases of immediate reciprocation are excluded from analysis. These results do not support the cognitive constraint hypothesis. We note the cognitive constraint hypothesis makes two silent assumptions: that all reciprocation is necessarily calculated and that it is based on partner control processes. We suggest these assumptions are unwarranted, and that most group living animals base their ability to reciprocate on emotionally based partner choice.

Body size and trophic level increase with latitude, and decrease in the deep-sea and Antarctica, for marine fish species.

The functional traits of species depend both on species' evolutionary characteristics and their local environmental conditions and opportunities. The temperature-size rule (TSR), gill-oxygen limitation theory (GOLT), and temperature constraint hypothesis (TCH) have been proposed to explain the gradients of body size and trophic level of marine species. However, how functional traits vary both with latitude and depth have not been quantified at a global scale for any marine taxon. We compared the latitudinal gradients of trophic level and maximum body size of 5,619 marine fish from modelled species ranges, based on (1) three body size ranges, <30, 30-100, and >100 cm, and (2) four trophic levels, <2.20, 2.20-2.80, 2.81-3.70, >3.70. These were parsed into 5° latitudinal intervals in four depth zones: whole water column, 0-200, 201-1,000, and 1,001-6,000 m. We described the relationship between latitudinal gradients of functional traits and salinity, sea surface and near seabed temperatures, and dissolved oxygen. We found mean body sizes and mean trophic levels of marine fish were smaller and lower in the warmer latitudes, and larger and higher respectively in the high latitudes except for the Southern Ocean (Antarctica). Fish species with trophic levels ≤2.80 were dominant in warmer and absent in colder environments. We attribute these differences in body size and trophic level between polar regions to the greater environmental heterogeneity of the Arctic compared to Antarctica. We suggest that fish species' mean maximum body size declined with depth because of decreased dissolved oxygen. These results support the TSR, GOLT and TCH hypotheses respectively. Thus, at the global scale, temperature and oxygen are primary factors affecting marine fishes' biogeography and biological traits.

Preference and performance of the generalist aphid Myzus persicae on closely and distantly related plant species

AbstractThe ability of herbivorous insects to discriminate suitable host plants for the development of their progeny is not homogenous. Herbivores with broader diets show weaker correlation between oviposition preference and offspring performance in comparison with specialist insects. The neural constraints hypothesis postulates that due to neural limitation, generalist insects would have greater difficulty in processing a large number of stimuli from diverse host plants. Under this framework, it is expected that generalists would be more efficient in discriminating suitable plants when faced with more similar stimuli from closely related plants (simplified environment), and less efficient when faced with more diverse stimuli from unrelated plants (complex environment). In this study, we evaluated this in the generalist aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae). Preference was evaluated as the aphid's ability to discriminate between congeneric plant species or between plants from different families. The congeneric host plants were the cultivated potato, Solanum tuberosum L., the wild potato, Solanum commersonii Dunal, tomato, Solanum lycopersicum L., and eggplant, Solanum melongena L. (Solanaceae). The plant species of different families used were spinach, Spinacia oleracea L. (Amaranthaceae), squash, Cucurbita maxima Duchesne (Cucurbitaceae), and basil, Ocimum basilicum L. (Lamiaceae). Performance was evaluated as the population growth in one generation on whole‐plant conditions and on excised leaves. The results showed positive correlations between settlement and larviposition preferences and the performance of M. persicae for all comparisons between unrelated plant species. Positive correlations between preference and performance were also observed for two of the three comparisons between congeneric plants. These results indicate that M. persicae can efficiently discriminate between suitable plants for their progeny regardless of the degree of relatedness of the plants, which is at odds with the neural constraints hypothesis. The results contribute to the knowledge of host selection mechanisms in generalist herbivores, particularly in an underrepresented insect group.

Receding Galerkin Optimal Control with High-Order Sliding Mode Disturbance Observer for a Boiler-Turbine Unit

The control of the boiler-turbine unit is important for its sustainable and robust operation in power plants, which faces great challenges due to the control unit’s serious nonlinearity, unmeasurable states, variable constraints, and unknown time-varying lumped disturbances. To address the above issues, this paper proposes a receding Galerkin optimal controller with a high-order sliding mode disturbance observer in a composite scheme, in which a high-order sliding mode disturbance observer is first employed to estimate the lumped disturbances based on a deviation form of the mathematical model of the boiler-turbine unit. Subsequently, under the hypothesis of state constraint, a receding Galerkin optimal controller is designed to compensate the lumped disturbances by embedding their estimates into the mathematically based predictive model at each sampling time instant. With the help of an interpolation polynomial, Gauss integration, and nonlinear solvers, an optimal control law is then obtained based on a Galerkin optimization algorithm. Consequently, disturbance rejection, target tracking, and constraint handling performance of a controlled closed-loop system are improved. Some simulation cases are conducted on a mathematical boiler-turbine unit model to demonstrate the effectiveness of the proposed method, which is supported by the quantitative result analysis, such as tracking and disturbance rejection performance indexes.

Dividend payouts under a societal crisis: Financial constraints or signaling?

Dividend payouts of Chinese firms are typically flexible and unstable, and firms have leeway to change dividends in response to a crisis. Using this setting, we document that Chinese listed firms tend to decrease dividend payouts under the coronavirus crisis, supporting our financial constraints hypothesis instead of the alternative dividend signaling hypothesis. The baseline result is robust to a series of sensitivity checks. Underlying mechanism tests show that the negative effect of COVID-19 on dividend policies is enhanced in high-constrained groups compared to that in low-constrained groups. Further analysis of crisis-related factors reveals that the main result is enhanced when firms engage in international diversification, when firms have greater labor intensity and when firms are nonstate-owned.

COVID-19 and corporate tax avoidance: International evidence

Governments across the globe initiated various tax reforms in the post- Global Financial Crisis period to rein in aggressive corporate tax avoidance for managing budget deficits. These developments created new realities in the international business environment by altering the costs and benefits of corporate tax management. Yet, we have a limited understanding of the effectiveness of tax reforms in controlling corporate tax avoidance at the global level. COVID-19 offers a litmus test for how corporates manage their taxes during the pandemic in light of past tax reforms. We use financial constraints and reputational costs as two contradicting theoretical perspectives to explain corporate tax avoidance during the crisis. Consistent with the financial constraints hypothesis, we find that firms avoid taxes amid COVID-19 to prevent liquidity crunches. Our study also highlights the role of country-level information and governance quality in curbing tax avoidance during extreme events like COVID-19. Our findings call for an immediate tax policy intervention to limit corporate tax avoidance during the ongoing pandemic phases.