Unpacking interplays between competitiveness, cooperativeness, and social comparison orientation: A network psychometric approach and replication.

Emerging evidence highlights the role of social comparison in competition and cooperation, yet the dynamics among competitiveness, cooperativeness, and social comparison orientation (SCO) remain underexplored. In the present study, we sought to unravel these complex interplays employing graphical Gaussian models (GGMs) and characterize the network structures utilizing cross-sectional data derived from 1073 Chinese participants. A pre-registered independent sample (n = 1348) served to examine the replicability and robustness of our initial findings. Moreover, we explored the Bayesian networks (i.e., directed acyclic graphs) to delve into their probabilistic directed dependencies. Our analysis identified an interpersonal co-opetition network where SCO bridges competitiveness and cooperativeness, emphasizing the key influence of the desire to surpass others. We also found a significant gender effect on the levels of these orientations but not on the network patterns. Additionally, the replication sample offered validation for the resultant network structure and its key nodes. In sum, these findings provide a new insight into the symbiotic relationship between competitiveness and cooperativeness within the framework of social comparison, offering significant theoretical and practical implications.

Fluorescence assay for aflatoxin B1 based on aptamer-binding triggered DNAzyme activity.

As a kind of mycotoxin, aflatoxin B1 (AFB1), which is often found in agricultural products, poses a threat to human health. Developing a simple sensitive method for AFB1 detection is in great demand. Here, we reported an aptamer-based fluorescence assay for AFB1 detection by using DNAzyme to generate and amplify a signal. We redesigned a pair of DNA sequences, which originated from the anti-AFB1 aptamer and RNA-cleaving DNAzyme 10-23. In the absence of AFB1, the aptamer hybridized with the region of the substrate-binding arm of the DNAzyme, inhibiting the activity of the DNAzyme. In the presence of AFB1, the binding of AFB1 to the aptamer led to the displacement of the DNAzyme from the aptamer. The substrate-binding arm was unblocked, and the activity of the DNAzyme was restored for the hydrolysis of the fluorophore and quencher-labeled substrate, causing a significant fluorescence increase. This assay could detect AFB1 in the dynamic range from 0.98 to 2000 nmol/L with high selectivity, and the detection limit was 0.98 nmol/L. Moreover, the assay was able to detect AFB1 in a complex sample matrix. This work provides a useful tool for the analysis of AFB1.

Local neighborhood affects stem rehydration under drought: evidence from mixtures of European beech with two different conifers.

Mixed-species forests are, for multiple reasons, promising options for forest management in Central Europe. However, the extent to which interspecific competition affects tree hydrological processes is not clear. High-resolution dendrometers capture sub-daily variations in stem diameter; they can simultaneously monitor stem growth (irreversible changes in diameter) and water status (reversible changes) of individual trees. Using the information on water status, we aimed to assess potential effects of tree species mixture, expressed as local neighborhood identity, on night-time rehydration and water stress. We deployed 112 sensors in pure and mixed forest stands of European beech, Norway spruce, and Douglas fir on four sites in north-western Germany, measuring stem diameter in 10-minute intervals for a period of four years (2019-2022). In a mixture distribution model, we used environmental variables, namely soil matric potential, atmospheric vapor pressure deficit, temperature, precipitation, and neighborhood identity to explain night-time rehydration, measured as the daily minimum tree water deficit (TWDmin). TWDmin was used as a daily indicator of water stress and the daily occurrence of sufficient water supply, allowing for stem growth (potential growth). We found that species and neighborhood identity affected night-time rehydration, but the impacts varied depending on soil water availability. While there was no effect at high water availability, increasing drought revealed species-specific patterns. Beech improved night-time rehydration in mixture with Douglas fir, but not in mixture with spruce. Douglas fir however, only improved rehydration at a smaller share of beech in the neighborhood, while beech dominance tended to reverse this effect. Spruce was adversely affected when mixed with beech. At species level and under dry conditions, we found that night-time rehydration was reduced in all species, but beech had a greater capacity to rehydrate under high to moderate soil water availability than the conifers, even under high atmospheric water demand. Our study gives new insights into neighborhood effects on tree water status and highlights the importance of species-specific characteristics for tree-water relations in mixed-species forests. It shows that drought stress of European beech can be reduced by admixing Douglas fir, which may point towards a strategy to adapt beech stands to climate change.

Competing for research funding: Key elements impacting the evaluation of grant proposal.

As funding is one of the key pillars of research activity, identifying the factors that impact the evaluation results in research funding competitions remains challenging, due to the heterogeneity of funding instruments. In this context, our study aims to identify the elements that ensure the application's success, comparing two perspectives: one of the applicant and the other based on the evaluation grid. The empirical investigation focuses on a survey of 243 Romanian researchers. As analysis methods, we use a binary logistic regression model to correlate the success in funding competitions for research projects with a set of factors considered determinants. The results show that the researcher's past performance influences the proposal's future performance/success, with the quality of the project director's previous publications, and its international visibility being the key drivers of successful research project applications.

ActA-mediated PykF acetylation negatively regulates oxidative stress adaptability of Streptococcus mutans.

Dental caries is associated with microbial dysbiosis caused by the excessive proliferation of Streptococcus mutans in dental biofilms, where oxidative stress serves as the major stressor to microbial communities. The adaptability of S. mutans to oxidative stress is a prerequisite for its proliferation and even for exerting its virulence. Protein acetylation is a reversible and conserved regulatory mechanism enabling bacteria to rapidly respond to external environmental stressors. However, the functions of protein acetylation in regulating oxidative stress adaptability of S. mutans are still unknown. Here, we unveil the impact of acetyltransferase ActA-mediated acetylation on regulating the oxidative stress response of S. mutans. actA overexpression increased the sensitivity of S. mutans to hydrogen peroxide and diminished its competitive ability against Streptococcus sanguinis. In contrast, actA deletion enhanced oxidative stress tolerance and competitiveness of S. mutans. The mass spectrometric analysis identified pyruvate kinase (PykF) as a substrate of ActA, with its acetylation impairing its enzymatic activity and reducing pyruvate production. Supplementation with exogenous pyruvate mitigated oxidative stress sensitivity and restored competitiveness in multi-species biofilms. In vitro acetylation analysis further confirmed that ActA directly acetylates PykF, negatively affecting its enzymatic activity. Moreover, 18 potential lysine-acetylated sites on PykF were identified in vitro, which account for 75% of lysine-acetylated sites detected in vivo. Taken together, our study elucidates a novel regulatory mechanism of ActA-mediated acetylation of PykF in modulating oxidative stress adaptability of S. mutans by influencing pyruvate production, providing insights into the importance of protein acetylation in microbial environmental adaptability and interspecies interactions within dental biofilms. IMPORTANCE: Dental caries poses a significant challenge to global oral health, driven by microbial dysbiosis within dental biofilms. The pathogenicity of Streptococcus mutans, a major cariogenic bacterium, is closely linked to its ability to adapt to changing environments and cellular stresses. Our investigation into the protein acetylation mechanisms, particularly through the acetyltransferase ActA, reveals a critical pathway by which S. mutans modulates its adaptability to oxidative stress, the dominant stressor within dental biofilms. By elucidating how ActA affects the oxidative stress adaptability and competitiveness of S. mutans through the regulatory axis of ActA-PykF-pyruvate, our findings provide insights into the dynamic interplay between cariogenic and commensal bacteria within dental biofilms. This work emphasizes the significance of protein acetylation in bacterial stress response and competitiveness, opening avenues for the development of novel strategies to maintain oral microbial balance within dental biofilms.

Plant competition cues activate a singlet oxygen signaling pathway in Arabidopsis thaliana.

Oxidative stress responses of Arabidopsis to reflected low red to far-red signals (R:FR ≈ 0.3) generated by neighboring weeds or an artificial source of FR light were compared with a weed-free control (R:FR ≈1.6). In the low R:FR treatments, induction of the shade avoidance responses (SAR) coincided with increased leaf production of singlet oxygen (1O2). This 1O2 increase was not due to protochlorophyllide accumulation and did not cause cell death. Chemical treatments, however, with 5-aminolevulinic acid (the precursor of tetrapyrrole biosynthesis) and glutathione (a quinone A reductant) enhanced cell death and growth inhibition. RNA sequencing revealed that transcriptome responses to the reflected low R:FR light treatments minimally resembled previously known Arabidopsis 1O2 generating systems that rapidly generate 1O2 following a dark to light transfer. The upregulation of only a few early 1O2 responsive genes (6 out of 1931) in the reflected low R:FR treatments suggested specificity of the 1O2 signaling. Moreover, increased expression of two enzyme genes, the SULFOTRANSFERASE ST2A (ST2a) and the early 1O2-responsive IAA-LEUCINE RESISTANCE (ILR)-LIKE6 (ILL6), which negatively regulate jasmonate level, suggested that repression of bioactive JAs may promote the shade avoidance (versus defense) and 1O2 acclimation (versus cell death) responses to neighboring weeds.

Does financialization inhibit enterprise innovation? Analysis of innovation behavior of Chinese enterprises based on evolutionary game.

Enterprise innovation remains a cornerstone of economic development, with the direct influence of financialization on enterprise innovation standing as a critical factor. In contrast with the existing research, this study constructs an evolutionary game model by utilizing the Cournot model to analyze the innovation behavior of enterprises, and analyzes the influence of financialization on enterprise innovation by incorporating investment returns, market competition, and demand scale into the research framework. In addition, this study selects the sample of the Chinese non-financial listed enterprises and using panel data for the period 2009 to 2021. Based on the findings from the empirical analysis, this study reveals that excessive financialization hinders innovation in Chinese enterprises. Additionally, an intermediary pathway involving 'financialization - investment returns - enterprise innovation' is identified as a transmission mechanism. The demand scale generated by innovation inversely correlates with the inhibitory effects of financialization on enterprise innovation behavior. Meanwhile, heightened market competition amplifies the inhibitory influence of financialization on innovation. This study provided valuable empirical evidence, facilitating the enhancement of enterprise innovation efficiency.

Hydrophilic interaction liquid chromatography: An efficient tool for assessing thorium interaction with phosphorylated biomimetic peptides.

In the field of nuclear toxicology, the knowledge of the interaction of actinides (An) with biomolecules is of prime concern in order to elucidate their toxicity mechanism and to further develop selective decorporating agents. In this work, we demonstrated the great potential of hydrophilic interaction liquid chromatography (HILIC) to separate polar thorium (Th) biomimetic peptide complexes, as a key starting point to tackle these challenges. Th4+ was used as plutonium (Pu4+) analogue and pS16 and pS1368 as synthetic di- and tetra-phosphorylated peptides capable of mimicking the interaction sites of these An in osteopontin (OPN), a hyperphosphorylated protein. The objective was to determine the relative affinity of pS16 and pS1368 towards Th4+, and to evaluate the pS1368 selectivity when Th4+ was in competition complexation reaction with UO22+ at physiological pH. To meet these aims, HILIC was simultaneously coupled to electrospray ionization mass spectrometry (ESI-MS) and inductively coupled plasma mass spectrometry (ICP-MS), which allowed to identify online the molecular structure of the separated complexes and quantify them, in a single step. Dedicated HILIC conditions were firstly set up to separate the new dimeric Th2(peptide)2 complexes with good separation resolution (peptide = pS16 or pS1368). By adding pS16 and pS1368 in different proportions relatively to Th4+, we found that lower or equal proportions of pS16 with respect to pS1368 were not sufficient to displace pS1368 from Th2pS13682 and pS16 proportion higher than pS1368 led to the formation of a predominant ternary complex Th2(pS16)(pS1368), demonstrating preferential Th4+ binding to the tetra-phosphorylated peptide. Finally, online identification and quantification of the formed complexes when Th4+ and UO22+ were mixed in equimolar ratio relatively to pS1368 showed that in spite of pS1368 has been specifically designed to coordinate UO22+, pS1368 is also Th4+-selective and exhibits stronger affinity for this latter than for UO22+. Hence, the results gathered through this approach highlight the impact of Th4+ coordination chemistry on its interaction with pS1368 and more widely to its affinity for biomolecules.

How competition play a role in dental pricing? A study on French medico-administrative and tax reports dataset.

OBJECTIVES: French dentists charge additional fees for dental prostheses. This paper aims to provide new information on the determinants of dental price setting and inform public decision-making in the context of the widespread rejection of prosthetic dental care for financial reasons. We focus on the competitive mechanism in the dental prosthetics market and measure the impact of the density of professionals and competitors' prices on the fees charged by dentists. METHODS: We use data merging from an administrative health insurance database and information from tax declarations of French dentists. We test the effect of competitor prices and competition on individual price-setting using instrumental variables. The database obtained included 29,220 dentists. RESULTS: Practitioners' prices grow with competitors' prices (+1€ in competitor prices entails an increase of + 0.37€ in the practitioner's price). Women set lower prices, and having a young child in the household predicts an increase in price of 6.8€ (p-value=0.014). Rural areas present lower fees than urban areas (+11.4€ (p value=0.000)). CONCLUSION: Prosthetic prices are strategic complements that are compatible with the application of monopolistic competition in the dental care market. We encourage the regulator to develop competitive mechanisms, for example, through a public offer at moderate prices.

Unravelling drivers of local adaptation through evolutionary functional-structural plant modelling.

Local adaptation to contrasting environmental conditions along environmental gradients is a widespread phenomenon in plant populations, yet we lack a mechanistic understanding of how individual agents of selection contribute to this evolutionary process. Here, we developed a novel evolutionary functional-structural plant (E-FSP) model that recreates local adaptation of virtual plants along an environmental gradient. First, we validate the model by testing if it can reproduce two elevational ecotypes of Dianthus carthusianorum occurring in the Swiss Alps. Second, we use the E-FSP model to disentangle the relative contribution of abiotic (temperature) and biotic (competition and pollination) selection pressures to elevational adaptation in D. carthusianorum. Our results suggest that elevational adaptation in D. carthusianorum is predominantly driven by the abiotic environment. The model reproduced the qualitative differences between the elevational ecotypes in two phenological (germination and flowering time) and one morphological trait (stalk height), as well as qualitative differences in four performance variables that emerge from G × E interactions (flowering time, number of stalks, rosette area and seed production). Our approach shows how E-FSP models incorporating physiological, ecological and evolutionary mechanisms can be used in combination with experiments to examine hypotheses about patterns of adaptation observed in the field.

IGF-I concentration determines cell fate by converting signaling dynamics as a bifurcation parameter in L6 myoblasts.

Insulin-like growth factor (IGF)-I mediates long-term activities that determine cell fate, including cell proliferation and differentiation. This study aimed to characterize the mechanisms by which IGF-I determines cell fate from the aspect of IGF-I signaling dynamics. In L6 myoblasts, myogenic differentiation proceeded under low IGF-I levels, whereas proliferation was enhanced under high levels. Mathematical and experimental analyses revealed that IGF-I signaling oscillated at low IGF-I levels but remained constant at high levels, suggesting that differences in IGF-I signaling dynamics determine cell fate. We previously reported that differential insulin receptor substrate (IRS)-1 levels generate a driving force for cell competition. Computational simulations and immunofluorescence analyses revealed that asynchronous IRS-1 protein oscillations were synchronized during myogenic processes through cell competition. Disturbances of cell competition impaired signaling synchronization and cell fusion, indicating that synchronization of IGF-I signaling oscillation is critical for myoblast cell fusion to form multinucleate myotubes.

Climate and land use/land cover changes increasing habitat overlap among endangered crested ibis and sympatric egret/heron species.

Climate and land use/land cover (LULC) changes have far-reaching effects on various biological processes in wildlife, particularly interspecific interactions. Unfortunately, interspecific interactions are often overlooked when assessing the impacts of environmental changes on endangered species. In this study, we examined niche similarities and habitat overlaps between wild Crested Ibis and sympatric Egret and Heron species (EHs) in Shaanxi, China, using Ecological niche models (ENMs). We aimed to forecast potential alterations in habitat overlaps due to climate and LULC changes. The results showed that although EHs possess a broader niche breadth compared to the Crested Ibis, they still share certain niche similarities, as indicated by Schoener's D and Hellinger's I values exceeding 0.5, respectively. Notably, despite varying degrees of habitat reduction, the shared habitat area of all six species expands with the changes in climate and LULC. We suggest that with the climate and LULC changes, the habitats of sympatric EHs are likely to suffer varying degrees of destruction, forcing them to seek refuge and migrate to the remaining wild Ibis habitat. This is primarily due to the effective conservation efforts in the Crested Ibis habitat in Yangxian County and neighboring areas. Consequently, due to the niche similarity, they will share and compete for limited habitat resources, including food and space. Therefore, we recommend that conservation efforts extend beyond protecting the Crested Ibis habitat. It is crucial to control human activities that contribute to LULC changes to safeguard the habitats of both Crested Ibis and other sympatric birds.

A Cancer Subpopulation Competition Model Reveals Optimal Levels of Immune Response that Minimize Tumor Size.

Breast cancer is a complex disease with significant phenotypic heterogeneity of cells, even within a single breast tumor. Emerging evidence underscores the significance of intratumoral competition, which can serve as a key contributor to cancer drug resistance, imparting substantial clinical implications. Understanding the competitive dynamics is paramount as it can significantly influence disease progression and treatment outcomes. In the present work, a mathematical model was developed using a system of differential equations to describe the dynamic interactions between two cancer subtypes (each further classified into cancer stem cells and tumor cells) and innate immune cells. The purpose of the model is to comprehensively understand the competitive interactions between the heterogeneous subpopulations. The equilibrium points and stability analysis for each equilibrium point were established. Model simulations showed that the competition between two cancer subtypes directly affects the number of both species. When competition between two cancer subtypes is strong, increasing the immune response rate specific to the more competitive species effectively reduces the tumor size. However, if the competition is relatively weak, an optimal immune response rate is required to minimize the total number of tumor cells. Rates below the optimal level fail to reduce the population of the stronger species, whereas rates above the optimal level can lead to the recurrence of the weaker species. Overall, this model provides insights into breast cancer dynamics and guides the development of effective treatment strategies.

Taxonomy of Pseudomonas spp. determines interactions with Bacillus subtilis.

Bacilli and pseudomonads are among the most well-studied microorganisms commonly found in soil and frequently co-isolated. Isolates from these two genera are frequently used as plant beneficial microorganisms; therefore, their interaction in the plant rhizosphere is relevant for agricultural applications. Despite this, no systematic approach has been employed to assess the coexistence of members from these genera. Here, we screened 720 fluorescent soil isolates for their effects on Bacillus subtilis pellicle formation in two types of media and found a predictor for interaction outcome in Pseudomonas taxonomy. Interactions were context-dependent, and both medium composition and culture conditions strongly influenced interactions. Negative interactions were associated with Pseudomonas capeferrum, Pseudomonas entomophila, and Pseudomonas protegens, and 2,4-diacetylphloroglucinol was confirmed as a strong (but not exclusive) inhibitor of B. subtilis. Non-inhibiting strains were closely related to Pseudomonas trivialis and Pseudomonas lini. Using such a non-inhibiting isolate, Pseudomonas P9_31, which increased B. subtilis pellicle formation demonstrated that the two species were spatially segregated in cocultures. Our study is the first one to propose an overall negative outcome from pairwise interactions between B. subtilis and fluorescent pseudomonads; hence, cocultures comprising members from these groups are likely to require additional microorganisms for coexistence. IMPORTANCE: There is a strong interest in the microbial ecology field to predict interaction among microorganisms, whether two microbial isolates will promote each other's growth or compete for resources. Numerous studies have been performed based on surveying the available literature or testing phylogenetically diverse sets of species in synthetic communities. Here, a high throughput screening has been performed using 720 Pseudomonas isolates, and their impact on the biofilm formation of Bacillus subtilis was tested. The aim was to determine whether a majority of Pseudomonas will promote or inhibit the biofilms of B. subtilis in the co-cultures. This study reports that Pseudomonas taxonomy is a good predictor of interaction outcome, and only a minority of Pseudomonas isolates promote Bacillus biofilm establishment.

Damming of streams due to the construction of a highway in the Amazon rainforest favors individual trophic specialization in the fish (Bryconops giacopinii).

In Amazonian streams, damming caused by road construction changes the system's hydrological dynamics and biological communities. We tested whether the degree of specialization in fish (Bryconops giacopinii) individuals is higher in pristine stream environments with intact ecological conditions than in streams dammed due to the construction of a highway in the Amazon rainforest. To achieve this, stomach content data and stable isotopes (δ13C and δ15N) in tissues with varying isotopic incorporation rates (liver, muscle, and caudal fin) were used to assess the variation in consumption of different prey over time. The indices within-individual component (WIC)/total niche width (TNW) and individual specialization were employed to compare the degree of individual specialization between pristine and dammed streams. The condition factor and stomach repletion of sampled individuals were used to infer the intensity of intraspecific competition in the investigated streams. The species B. giacopinii, typically considered a trophic generalist, has been shown to be, in fact, a heterogeneous collection of specialist and generalist individuals. Contrary to our expectations, a higher degree of individual specialization was detected in streams dammed by the highway. In dammed streams, where intraspecific competition was more intense, individuals with narrower niches exhibited poorer body conditions than those with broader niches. This suggests that individuals adopting more restricted diets may have lower fitness, indicating that individual specialization may not necessarily be beneficial for individuals. Our results support the notion that intraspecific competition is an important mechanism underlying individual specialization in natural populations. Our results suggest that environmental characteristics (e.g., resource breadth and predictability) and competition for food resources interact in complex ways to determine the degree of individual specialization in natural populations.

Ethics of Residency Candidates Using Application Consulting Services.

While the prevalence is still being determined, more medical students are utilizing application consulting companies when applying to competitive residencies such as dermatology. We outline the structure of these companies, the scope of services provided, and the costs associated. We also discuss the ethical implications for the use in the residency application process of such firms and the impact of these practices on the candidate selection process. Finally, we offer possible solutions and measures that mitigate the impact of the use of consulting firms in residency applications. Application consulting services are meant to assist clients in maximizing their chances for a successful application cycle. Many companies cater to both prospective residency and pre-medical candidates, including "Med School Insiders," "BeMo Academic Consulting," and "Elite Medical Prep." The scope of application consulting services is vast. Clients can request services such as personalized school selection, application advising, document preparation review [e.g., curriculum vitae (CV), personal statements, and essays), electronic residency application service (ERAS)], and interview coaching. Another service offered is residency match advising, which details specific requirements programs desire. Prospective clients would gain a significant advantage, mainly when used at the outset of medical school training when planning a trajectory for competitive specialties. We review the ethical issues associated with using these consulting services.

The child the apple eats: processing of argument structure in Mandarin verb-final sentences.

Mandarin Chinese is typologically unusual among the world's languages in having flexible word order despite a near absence of inflectional morphology. These features of Mandarin challenge conventional linguistic notions such as subject and object and the divide between syntax and semantics. In the present study, we tested monolingual processing of argument structure in Mandarin verb-final sentences, where word order alone is not a reliable cue. We collected participants' responses to a forced agent-assignment task while measuring their electroencephalography data to capture real-time processing throughout each sentence. We found that sentence interpretation was not informed by word order in the absence of other cues, and while the coverbs BA and BEI were strong signals for agent selection, comprehension was a result of multiple cues. These results challenge previous reports of a linear ranking of cue strength. Event-related potentials showed that BA and BEI impacted participants' processing even before the verb was read and that role reversal anomalies elicited an N400 effect without a subsequent semantic P600. This study demonstrates that Mandarin sentence comprehension requires online interaction among cues in a language-specific manner, consistent with models that predict crosslinguistic differences in core sentence processing mechanisms.

Coevolution of spermatozoa and spermathecae in Lonchopteridae (Diptera).

Across the species of spear-winged flies (Diptera: Lonchopteridae) there is a remarkable variation in size of the female reproductive tract, especially of the spermathecae. In this family there are two tubular spermathecae, which are divided into four morphologically and histologically distinct sections of different lengths and functions. The dimensions of the spermathecae and their individual sections were examined across 11 Lonchoptera species and related to the dimensions of the respective spermatozoa. 3D reconstructions from serial sectioning made it possible to include the volume in these considerations, which is a new approach in this context. Results show that the spermathecae are always longer than the respective spermatozoa. There is a highly significant positive linear correlation between the length of the spermatozoa and the length of the spermathecae in total as well as some of the individual spermathecal sections, suggesting a coevolution of these characters. Moreover, the volume of the spermathecae is much larger in those species with longer and more voluminous spermatozoa, but the volume increase is not sufficient to keep constant the number of spermatozoa that fit within. The observed patterns are discussed with respect to their functional and evolutionary implications, including a new hypothesis on the possible selective advantage of increased spermatozoon length.

Long-term effects of pre-weaning social housing on response to a social and housing transition in pregnant heifers.

Dairy cattle are routinely managed in social groups and subject to various management and social transitions, yet conventional approaches to rearing dairy calves limit social experience during early weeks of life. The objective of this study was to evaluate long-term effects of dairy calf social housing, with calves housed individually or in pairs, on long-term behavioral responses observed in pregnant heifers following social regrouping and introduction to a novel housing environment. Holstein heifers were raised during the milk-feeding period (provided 8 L/d milk replacer) in either individual pens (n = 20 heifers) or paired pens (n = 20 pens; 1 focal heifer/pen) and subsequently identically managed in groups on pasture from 9 weeks of age. At 30 d before expected calving, pregnant heifers were moved from pasture to a free stall barn, which represented introduction to a novel social group and an unfamiliar housing environment. Behavior was continuously recorded from video for 24 h, beginning at 0000 h on the day after introduction, to characterize feeding behavior, locomotor activity, and stall usage, as well as social proximity and competitive behavior surrounding the feed bunk and stall. Stocking density of the free stall barn fluctuated and was categorized as low (≤75%, 100 × animals in pen/available stalls), medium (>75%, 100%), or high (≥100%). Body weights obtained following calving indicated that previously PH heifers were heavier (632.3 vs. 593.4 kg; PH vs. IH), and body weight was included as a covariate in analysis of feeding behavior. Upon introduction to the free stall pen, previously PH heifers spent more time walking (1.9 vs. 1.3 min/h) with no effect of calf social housing on duration of lying time. However, stall use was subject to an interaction between previous housing treatment and stocking density and differed overall between previous housing treatments; previously PH heifers spent less time in the stall, particularly at high stocking density (29.4 vs. 48 min/h), due to shorter (29.6 vs. 95.7 min/visit) but marginally more frequent stall visits. Previously pair-housed heifers were also less likely to be displaced from a stall (44 vs. 85% of heifers replaced; PH vs. IH). Feeding behavior was similarly influenced by previous housing treatment particularly at high stocking density, with previously PH heifers spending more time feeding (8.2 vs. 4.2 min/h) and visiting the feed bunk more frequently (1.5 vs. 0.8 visits/h). These results suggest that preweaning social housing had long-term effects on behavior and ability to adapt to a novel environment which became most apparent under heightened competitive pressure.