Invasive plant species support each other's growth in low-nutrient conditions but compete when nutrients are abundant.

Globally, numerous ecosystems have been co-invaded by multiple exotic plant species that can have competitive or facilitative interactions with each other and with native plants. Invaded ecosystems often exhibit spatial heterogeneity in soil moisture and nutrient levels, with some habitats having more nutrient-rich and moist soils than others. The stress-gradient hypothesis predicts that plants are likely to engage in facilitative interactions when growing in stressful environments, such as nutrient-deficient or water-deficient soils. In contrast, when resources are abundant, competitive interactions between plants should prevail. The invasional meltdown hypothesis proposes that facilitative interactions between invasive species can enhance their establishment and amplify their ecological impact. Considering both hypotheses can offer insights into the complex interactions among invasive and native plants across environmental gradients. However, experimental tests of the effects of soil moisture and nutrient co-limitation on interactions between invasive and native plants at both interspecific and intraspecific levels in light of these hypotheses are lacking. We performed a greenhouse pot experiment in which we cultivated individual focal plants from five congeneric pairs of invasive and native species. Each focal plant was subjected to one of three levels of plant-plant interactions: (1) intraspecific, in which the focal plant was grown with another individual of the same species; (2) interspecific, involving a native and an invasive plant; and (3) interspecific, involving two native or invasive individuals. These plant-plant interaction treatments were fully crossed with two levels of water availability (drought vs. well-watered) and two levels of nutrient supply (low vs. high). Consistent with the stress-gradient and invasional meltdown hypotheses, our findings show that under low-nutrient conditions, the biomass production of invasive focal plants was facilitated by invasive interspecific neighbors. However, under high-nutrient conditions, the biomass production of invasive focal plants was suppressed by invasive interspecific neighbors. When competing with native interspecific neighbors, high-nutrient conditions similarly enhanced the biomass production of both invasive and native focal plants. Invasive and native focal plants were neither competitively suppressed nor facilitated by conspecific neighbors. Taken together, these results suggest that co-occurring invasive exotic plant species may facilitate each other in low-nutrient habitats but compete in high-nutrient habitats.

Neglecting non-bee pollinators may lead to substantial underestimation of competition risk among pollinators.

Due to the increasing pressures on bees, many beekeepers currently wish to move their managed livestock of Apis mellifera into little disturbed ecosystems such as protected natural areas. This may, however, exert detrimental competitive effects upon local wild pollinators. While it appears critical for land managers to get an adequate knowledge of this issue for effective wildlife conservation schemes, the frequency of this competition is not clear to date. Based on a systematic literature review of 96 studies, we assessed the frequency of exploitative competition between honey bees and wild pollinators. We found that 78% of the studies highlighted exploitative competition from honey bees to wild pollinators. Importantly, these studies have mostly explored competition with wild bees, while only 18% of them considered other pollinator taxa such as ants, beetles, bugs, butterflies, flies, moths, and wasps. The integration of non-bee pollinators into scientific studies and conservation plans is urgently required as they are critical for the pollination of many wild plants and crops. Interestingly, we found that a majority (88%) of these studies considering also non-bee pollinators report evidence of competition. Thus, neglecting non-bee pollinators could imply an underestimation of competition risks from honey bees. More inclusive work is needed to estimate the risks of competition in its entirety, but also to apprehend the context-dependency of competition so as to properly inform wildlife conservation schemes.

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.

Land-based foraging by polar bears reveals sexual conflict outside mating season.

According to sexual selection theory, the sexes are faced with opposing evolutionary goals. Male fitness benefits from access to females, whereas female fitness is constrained by food resources and safety for themselves and their offspring. Particularly in large solitary carnivores, such as polar bears (Ursus maritimus), these divergent goals can potentially lead to conflict between the sexes. Outside the mating season, when polar bears are on the move across vast distances, the consequences of such conflict can become apparent when individuals arrive at the same food source. To investigate interrelationships between the sexes, we observed successive polar bears visiting a bird breeding colony to feed on clutches of eggs. We found that males succeeded females more frequently and more closely than expected by chance. Moreover, when males were closer to conspecifics, they walked faster, spent less time in the colony and ingested less food. In contrast, female foraging performance was not associated with proximity to other bears. Irrespective of proximity, females generally spent short periods in the colony and ingested fewer clutches than males. Our results suggest that in polar bears, there is a trade-off between the benefits of food intake and the opportunities (in males) and risks (in females) posed by encountering conspecifics.

A group B streptococcal type VII-secreted LXG toxin mediates interbacterial competition and colonization of the murine female genital tract.

Group B Streptococcus (GBS) asymptomatically colonizes the vagina but can opportunistically ascend to the uterus and be transmitted vertically during pregnancy, resulting in neonatal pneumonia, bacteremia, and meningitis. GBS is a leading etiologic agent of neonatal infection and understanding the mechanisms by which GBS persists within the polymicrobial female genital mucosa has the potential to mitigate subsequent transmission and disease. Type VIIb secretion systems (T7SSb) are encoded by Bacillota and often mediate interbacterial competition using LXG toxins that contain conserved N-termini important for secretion and variable C-terminal toxin domains that confer diverse biochemical activities. Our recent work characterized a role for the GBS T7SSb in vaginal colonization and ascending infection but the mechanisms by which the T7SSb promotes GBS persistence in this polymicrobial niche remain unknown. Herein, we investigate the GBS T7SS in interbacterial competition and GBS niche establishment in the female genital tract. We demonstrate GBS T7SS-dependent inhibition of mucosal pathobiont Enterococcus faecalis both in vitro using predator-prey assays and in vivo in the murine genital tract and found that a GBS LXG protein encoded within the T7SS locus (herein named group B streptococcal LXG Toxin A) contributes to these phenotypes. We identify BltA as a T7SS substrate that is toxic to E. coli and S. aureus upon induction of intracellular expression along with associated chaperones. Finally, we show that BltA and its chaperones contribute to GBS vaginal colonization. Altogether, these data reveal a role for a novel T7b-secreted toxin in GBS mucosal persistence and competition.IMPORTANCECompetition between neighboring, non-kin bacteria is essential for microbial niche establishment in mucosal environments. Gram-positive bacteria encoding T7SSb have been shown to engage in competition through the export of LXG-motif-containing toxins, but these have not been characterized in group B Streptococcus (GBS), an opportunistic colonizer of the polymicrobial female genital tract. Here, we show a role for GBS T7SS in competition with mucosal pathobiont Enterococcus faecalis, both in vitro and in vivo. We further find that a GBS LXG protein contributing to this antagonism is exported by the T7SS and is intracellularly toxic to other bacteria; therefore, we have named this protein group B streptococcal LXG Toxin A (BltA). Finally, we show that BltA and its associated chaperones promote persistence within female genital tract tissues, in vivo. These data reveal previously unrecognized mechanisms by which GBS may compete with other mucosal opportunistic pathogens to persist within the female genital tract.

How can we measure resource quality when resources differ in many ways? Deconstructing shelter quality in a social fish.

Resource quality is an important concept in ecology and evolution that attempts to capture the fitness benefits a resource affords to an organism. Yet "quality" is a multivariate concept, potentially affected by many variables pertaining to the resource, its surroundings, and the resource chooser. Researchers often use a small number of proxy variables to simplify their estimation of resource quality, but without vetting their proxies against a wider set of potential quality estimators this approach risks overlooking potentially important characteristics that can explain patterns of resource use in their study systems. Here we used Neolamprologus multifasciatus, a group-living cichlid fish that utilizes empty snail shells as shelter resources, to examine how shells were used by, and partitioned among, group members in relation to a range of attributes, including shell size, intactness, texture, spatial position, and usage by heterospecifics. This approach generated a comprehensive picture of what characteristics contribute to the attractiveness and quality of each shell resource, confirming the importance of two previously proposed shell characteristics, size and intactness, but highlighting the influences of other unexplored variables, including shell spatial position and usage by heterospecifics. We also present a generally applicable "resource attractiveness index" as a means to estimate resource quality based on resource choice data. This index incorporates information from any number of resource characteristics and is of particular use when researchers wish to quantify resource value, but many characteristics jointly contribute to the value and attractiveness of the resource.

Kinematics of Two Special Endurance Trials: A Methodological Contribution to 400-m Performance.

This study aimed to determine changes in the kinematics of sprint steps based on progressive muscular fatigue during high-intensity 350-m and 500-m trials. Twelve elite healthy male 400-m sprinters with a minimum of six years of regular sprint training experience were recruited. They were divided into two groups for the experiment: a 350-m and a 500-m trial group. Time and kinematics of sprinting step motion for specific segments, i.e., starting to final stages of each trial, were obtained using the Opto Jump-Microgate optical measurement system. The starting phase of each sprint was defined as the section without muscular fatigue (noF), and the final phase was the sprint under muscular fatigue (onF). Each last 25 m of the 50-m evaluated section containing ten complete running steps was selected for detailed statistical analysis. Various patterns of temporal and spatial variables of sprinting efforts were observed between 350-m and 500-m trials. Each trial result was influenced by significant individual changes (p < 0.05). All variables indicated that the two distances differed significantly in terms of running kinematics. This was confirmed by significant differences in the mean step frequency (p < 0.001), which presented a difference of 11.75%, and the mean step speed (p < 0.001). As a result of these changes, a hierarchical intermittent endurance training pattern was defined. The research concluded that special endurance (intermittent sprints) based on 350 m differed significantly in kinematics from sprints over 500 m. Therefore, it should be assumed that the distance of 350 m is more similar in its kinematics to the 400-m competition. This should encourage coaches and athletes to apply a 350-m distance in training developing special endurance, especially in the pre-competitive and competitive periods.

Which factor reduces pharmaceutical expenditure, number of entrants or price variance? Updated generic drug markets in South Korea.

BACKGROUND: Introducing more generics has been a successful strategy for lowering pharmaceutical prices and expenditure. However, the effect of the strategy depends on the pricing schemes for generics. We aimed to update the South Korean generic markets in terms of effective competition, and to examine the effects of number of manufacturers and price variance on pharmaceutical expenditure. METHODS: We constructed balanced panel data provided by the Health Insurance Review and Assessment Service covering 726 reimbursed substances from 2019 to 2023. We developed original indicators to analyze the generic markets: the maximum-minimum price variance (MMPV) and the maximum-weighted price variance (MWPV). Panel regression with fixed and time-fixed effects was used. RESULTS: Over the study period, the number of manufacturers increased from 17.81 in 2019 to 20.98 in 2020 and then decreased to 18.70 in 2023. The MMPV increased from 204.70 in 2019 to 230.07 in 2022 and then decreased slightly to 225.34 in 2023. The MWPV increased from 59.70 in 2019 to 72.58 in 2023. Two types of segmented markets were noteworthy: low use of low-cost generics with sufficient manufacturers and high use of low-cost generics with insufficient manufacturers. In the fixed and time-fixed effects panel analyses, the MWPV presented a negative association with the number of manufacturers and a positive association with the MMPV. CONCLUSIONS: A newly introduced tiered pricing scheme, designed to differentiate generic prices, was associated with a decrease in the number of manufacturers and an increase in price dispersion. The pricing schemes for generics should be designed with price variance in mind and limit the number of too many generics in South Korea.

Neural mechanisms underlying competition-induced optimal decisions in individuals with high entrepreneurial intention.

In a rapidly changing and uncertain business environment, individuals with high entrepreneurial intention (HEI) inevitably need to compete or cooperate with others to maximize their gains. However, the effects of competition and cooperation on the risky decision-making and neural mechanisms of individuals with HEI are not clear. By combining the modified Devil Task and electroencephalogram (EEG) technology, the current study showed that a competition context is more likely to motivate optimal decisions and enhance the total decision gains for individuals with HEI than a cooperation context. A positive relationship between the frequency of optimal decisions and the total gains of decision-making for individuals with HEI was also found, and this relationship was mediated by the degree of entrepreneurial intention. The EEG results showed that individuals with HEI made decisions in the competition context with greater P2 amplitude of frontal regions than in the cooperation context, and source localization analyses revealed that this difference in brain activity was manifested in the medial prefrontal cortex. Finally, the results revealed a positive relationship between the P2 amplitude and the degree of entrepreneurial intention of individuals with HEI. Overall, the study suggests that competition is an effective way to motivate individuals with HEI to make optimal decisions and, thus, maximize their profits, providing new perspectives on ways to promote successful entrepreneurship.

Sprinting to the top: comparing quality of distance variety and specialization between swimmers and runners.

Objectives: To compare performance progression and variety in race distances of comparable lengths (timewise) between pool swimming and track running. Quality of within-sport variety was determined as the performance differences between individual athletes' main and secondary race distances across (top-) elite and (highly-) trained swimmers and runners. Methods: A total of 3,827,947 race times were used to calculate performance points (race times relative to the world record) for freestyle swimmers (n = 12,588 males and n = 7,561 females) and track runners (n = 9,230 males and n = 5,841 females). Athletes were ranked based on their personal best at peak performance age, then annual best times were retrospectively traced throughout adolescence. Results: Performance of world-class swimmers differentiates at an earlier age from their lower ranked peers (15-16 vs. 17-20 year age categories, P < 0.05), but also plateaus earlier towards senior age compared to runners (19-20 vs. 23 + year age category, P < 0.05), respectively. Performance development of swimmers shows a logarithmic pattern, while runners develop linearly. While swimmers compete in more secondary race distances (larger within-sport variety), runners specialize in either sprint, middle- or long-distance early in their career and compete in only 2, 4 or 3 other race distances, respectively. In both sports, sprinters specialize the most (P < 0.05). Distance-variety of middle-distance swimmers covers more longer rather than sprint race distances. Therefore, at peak performance age, (top-) elite female 200 m swimmers show significantly slower sprint performances, i.e., 50 m (P < 0.001) and 100 m (P < 0.001), but not long-distance performances, i.e., 800 m (P = 0.99) and 1,500 m (P = 0.99). In contrast, (top-) elite female 800 m middle-distance runners show significantly slower performances in all their secondary race distances (P < 0.001). (Top-) elite female athletes specialize more than (highly-) trained athletes in both sports (P < 0.05). Conclusions: The comparison to track running and lower ranked swimmers, the early performance plateau towards senior age, and the maintenance of a large within-sport distance variety indicates that (top-) elite sprint swimmers benefit from greater within-sport specialization.

Dispersal of a dominant competitor can drive multispecies coexistence in biofilms.

Despite competition for both space and nutrients, bacterial species often coexist within structured, surface-attached communities termed biofilms. While these communities play important, widespread roles in ecosystems and are agents of human infection, understanding how multiple bacterial species assemble to form these communities and what physical processes underpin the composition of multispecies biofilms remains an active area of research. Using a model three-species community composed of Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis, we show with cellular-scale resolution that biased dispersal of the dominant community member, P. aeruginosa, prevents competitive exclusion from occurring, leading to the coexistence of the three species. A P. aeruginosa bqsS deletion mutant no longer undergoes periodic mass dispersal, leading to the local competitive exclusion of E. coli. Introducing periodic, asymmetric dispersal behavior into minimal models, parameterized by only maximal growth rate and local density, supports the intuition that biased dispersal of an otherwise dominant competitor can permit coexistence generally. Colonization experiments show that WT P. aeruginosa is superior at colonizing new areas, in comparison to ΔbqsS P. aeruginosa, but at the cost of decreased local competitive ability against E. coli and E. faecalis. Overall, our experiments document how one species' modulation of a competition-dispersal-colonization trade-off can go on to influence the stability of multispecies coexistence in spatially structured ecosystems.

Plant antagonistic facilitation across environmental gradients: a soil-resource ecosystem engineering model.

Theory questions the persistence of nonreciprocal interactions in which one plant has a positive net effect on a neighbor that, in return, has a negative net impact on its benefactor - a phenomenon known as antagonistic facilitation. We develop a spatially explicit consumer-resource model for belowground plant competition between ecosystem engineers, plants able to mine resources and make them available for any other plant in the community, and exploiters. We use the model to determine in what environmental conditions antagonistic facilitation via soil-resource engineering emerges as an optimal strategy. Antagonistic facilitation emerges in stressful environments where ecosystem engineers' self-benefits from mining resources outweigh the competition with opportunistic neighbors. Among all potential causes of stress considered in the model, the key environmental parameter driving changes in the interaction between plants is the proportion of the resource that becomes readily available for plant consumption in the absence of any mining activity. Our results align with theories of primary succession and the stress gradient hypothesis. However, we find that the total root biomass and its spatial allocation through the root system, often used to measure the sign of the interaction between plants, do not predict facilitation reliably.

Impact of competition on reimbursement decisions for cancer drugs in China: an observational study.

Background: Annual Chinese National negotiations for including innovative drugs in the National Reimbursement Drug List (NRDL) reveal an increasing number of new drugs with overlapping action mechanisms of action and similar indications. Yet, it is unclear if competition affects reimbursement decisions. Thus, we explored the impact of competition on reimbursement decisions for cancer drugs in China. Methods: We identified the cancer drugs involved in NRDL negotiations from 2017 to 2022 and focused on the initial reimbursement decision for eligible newly negotiated drugs. Drugs were classified as within-class competitors based on their equivalent biological mechanisms of action and approved indications, including identified and potential competitors. Other variables included drug type, clinical benefit and safety, monthly drug cost, and disease incidence rate. We employed traditional univariate and multivariate Firth's penalized logistic regression to assess the association between reimbursement decisions and variables at the indication and drug levels. Findings: Between 2017 and 2022, 102 cancer drugs corresponding to 141 indications were studied, and 66 drugs (64.7%) covering 95 indications (67.4%) were added to the NRDL. The proportion of reimbursements for indications with identified competition was significantly higher than that for indications without identified competition (84.6% vs 52.6%, p < 0.0001). However, the difference in reimbursement proportions between groups with and without potential competition was not statistically significant (66.7% vs 68.3%, p = 0.84). Firth's penalized logistic regression showed that identified competition was positively correlated with successful NRDL inclusion, whereas potential competition had no significant effect on negotiation outcomes. Improved overall survival or progression-free survival were positively associated with NRDL inclusion, whereas disease incidence negatively impacted reimbursement decisions. Interpretation: Improved clinical benefit and identified competition were positively correlated with NRDL inclusion. In China's value-based negotiation model, clinical benefits served as a crucial foundation of price negotiation for cancer drugs, and market competition helped these drugs enter the NRDL at more reasonable prices. This has important implications for reimbursement decisions and accessibility and affordability improvement for innovative drugs worldwide. Funding: National Natural Science Foundation of China (No. 72104151).

Who learns more: the impact of dual-player and single-player modes in a serious game on dental students' factual knowledge.

BACKGROUND: The use of serious games in medical education provides a bridge between rapidly developing technology and traditional health-care teaching. Building on a promising web-based serious game for reviewing and acquiring factual knowledge in dental education, the present study investigated the benefits of a dual-player mode and various game options for enhancing knowledge gain and study motivation. METHODS: Before the intervention, students' dental knowledge and game experience were assessed using a pre-knowledge test and questionnaire-based self-assessment. Students in the clinical study phase (n = 57) were stratified based on prior knowledge and gender and then randomly assigned to two groups, with two player modes: single player (SP) and dual player (DP). In the SP group, each participant played alone, whereas in the DP group, the participants played against a previously determined peer. For a period of 4 weeks, the students were able to playfully acquire knowledge from the field of operative dentistry using METIS, a serious game application with three different game options (Marathon, Sprint, and Time). After the intervention phase, both groups completed a post-knowledge test. The usability of the serious game was evaluated with a self-assessment questionnaire. RESULTS: The competitive game mode (DP mode; M = 8.92, SD = 1.85) resulted in an increase in the factual knowledge test that was a mean of 2.49 points higher than the SP mode (M = 5.89, SD = 2.19; p < 0.001). The DP group also found the game significantly more helpful for learning (p = 0.04) and engaged more with the teaching content because of the app (p = 0.04). Overall, the usability of METIS was rated as excellent, and students successfully improved their knowledge of dentistry after game play with both game modes (SP, DP, p < 0.001), with the game option "Marathon," which involves playing the largest number of questions, being the most preferred. CONCLUSIONS: These results suggest that serious games such as METIS are a suitable educational medium for increasing students' knowledge and interest in the field, and that competition with peers provides even greater motivation to engage with the learning content.

Interspecific competition models and resource inequality between individuals.

Most classical discrete-time population models of interspecific competition have emerged as population-level phenomenological models with no evident basis at the individual level. This study shows that the Hassell-Comins model, a widely used discrete-time model of interspecific competition, can be derived in a bottom-up manner from a simple model of random resource competition between individuals of two species as an expression of expected population sizes in the next generation. The random competition leads to inequalities in resource allocation between individuals, which are related to the key parameters of the Hassell-Comins model that determine the density dependence of each species. The relationship between population-level parameters, such as intra- and interspecific competition coefficients, and individual-level parameters is discussed in detail, as is how the derived competition equations depend on the degree of inequality within each species. By considering limits of maximum or minimum resource inequality within each species, the derived model can describe interspecific competition for various combinations of two species exhibiting ideal scramble or ideal contest intraspecific competition.

Navigating the innovation policy dilemma: How subnational governments balance expenditure competition pressures and long-term innovation goals.

In the pursuit of economic growth, the role of innovation has become increasingly important, posing dilemmas for subnational governments as they navigate the balance between expenditure competition and long-term investments in innovation. This study aimed to investigate the intricate relationship between fiscal pressures and the pursuit of innovation goals faced by regional authorities. To achieve this, a systematic literature review was conducted, synthesizing more than 150 studies published within the past 15 years. Keyword searches were conducted across multiple databases, and additional scholarly articles were incorporated through citation tracking. Rigorous qualitative analysis techniques, including inductive coding and thematic analysis, were employed to distill conceptual insights from the literature. The analysis performed in this review reveals extensive discussions regarding the influence of competition on innovation outcomes, encompassing a wide range of perspectives. The potential advantages of localization are emphasized by some viewpoints, while others caution against the risks of inadequate investment. The effective coordination of policies across multiple levels of governance to maximize synergies between national and subnational innovation systems emerges as a complex yet crucial challenge. It is observed that collaborative networks, which facilitate knowledge exchange through industrial clustering and public-private linkages, play a significant role in leveraging regional innovation assets. Strategic approaches that successfully balance competition with long-term capacity development have been demonstrated by leading jurisdictions. These findings highlight the significance of tailored policy frameworks that account for the unique contexts of each region, providing opportunities to harness competitive motivations while sustaining investments in innovation. Ongoing coordination is essential to strike a balance between responsiveness and coherence across diverse territories. This study offers practical guidance and academic insights on strategies to align decentralized imperatives, aiming to optimize prosperity through knowledge creation within evolving multi-level innovation systems. By shedding light on these strategies, the research contributes to both practical and academic understandings of how to effectively navigate and capitalize on the dynamics of such systems.

Asymmetric Adaption in Social Learning: Understanding the Dilemma of Competition and Cooperation.

The constant challenge in social interactions involves making informed decisions in the face of competitive and cooperative dilemmas. The decision-making process can be influenced by various factors present in the social context. According to the behavior-pattern-categorization framework of information acquisition, potential biases may develop at all stages of decision-making as information about social context is progressively entered and integrated. In this study, employing the Chicken Game, we investigated the influence of varying information levels within the behavior-pattern-categorization framework (i.e., competitiveness of behavior choice, uncertainty of behavior pattern, and sociality of category) on decision-making in the dilemma of competition and cooperation. Combined with reinforcement learning models, our findings from three experiments showed that participants exhibited basic complementary behavior, becoming less competitive against highly competitive opponents and vice versa. Notably, individuals exhibited varying adaptation rates to different levels of opponent competitiveness and fluctuations. Specifically, participants adapted slower to highly competitive opponents and faster to cooperative opponents. This asymmetric adaptation in social learning is related to the rate at which various levels of information are updated. The current study disentangles the different levels of information acquisition and highlights the asymmetric processing that can occur during the updating of information within each level.

Game theory elucidates how competitive dynamics mediate animal social networks.

BACKGROUND: While most game theoretical models assume that individuals randomly interact with all other group members, strong evidence indicates that individuals tend to preferentially interact with some of them. The position of an individual in a network affects, among other factors related to survival, its predation risk and competitive success. Here I then modified the Hawk-Dove game to explore the effect of social network structure on competitive strategy of individuals that differ in their fighting ability and may adjust their use of the Hawk, Dove and Assessor tactics to maximize their foraging success when they meet opponents they are connected with. RESULTS: From randomly generated networks, I demonstrate that phenotypic assortment by fighting ability reduces individuals' aggressiveness and, as such, favours cooperative interactions. Furthermore, the success of individuals with the weakest fighting ability is usually highest within networks where they most frequently meet opponents with the same fighting ability as their own, suggesting they might benefit from breaking connections with strong contestants. This might be the case when strong contestants systematically rely on the aggressive Hawk tactic or the risk of being predated is low and independent of the number of neighbours. Thus, I extended the model and built a dynamic model to allow individuals not only to adjust their behaviour to local conditions but also to modify the structure of the social network. The number of connections and degree of phenotypic assortment are then affected by ecological factors (e.g. resources value and predation risk), but above all by whether individuals can reliably assess the competitive ability of their opponents and adjust their behaviour accordingly. CONCLUSIONS: These findings provide strong evidence that behaviour can play a key role in shaping network structure and highlight the importance of considering the coevolution of network and behaviour to apprehend its consequences on population dynamics.

Career Length After Surgically Treated ACL Plus Collateral Ligament Injury in Elite Athletes.

BACKGROUND: Limited data are available regarding career length and competition level after combined anterior cruciate ligament (ACL) and medial- or lateral-sided surgeries in elite athletes. PURPOSE: To evaluate career length after surgical treatment of combined ACL plus medial collateral ligament (MCL) and ACL plus posterolateral corner (PLC) injuries in elite athletes and, in a subgroup analysis of male professional soccer players, to compare career length and competition level after combined ACL+MCL or ACL+PLC surgeries with a cohort who underwent isolated ACL reconstruction (ACLR). STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A consecutive cohort of elite athletes undergoing combined ACL+MCL and ACL+PLC surgery was analyzed between February 2001 and October 2019. A subgroup of male elite soccer players from this population was compared with a previously identified cohort having had isolated primary ACLR without other ligament surgery. A minimum 2-year follow-up was required. Outcome measures were career length and competition level. RESULTS: A total of 98 elite athletes met the inclusion criteria, comprising 50 ACL+PLC and 48 ACL+MCL surgeries. The mean career length after surgical treatment of combined ACL+MCL and ACL+PLC injuries was 4.5 years. Return-to-play (RTP) time was significantly longer for ACL+PLC injuries (12.8 months; P = .019) than for ACL+MCL injuries (10.9 months). In the subgroup analysis of soccer players, a significantly lower number of players with combined ACL+PLC surgery were able to RTP (88%; P = .003) compared with 100% for ACL+MCL surgery and 97% for isolated ACLR, as well as requiring an almost 3 months longer RTP timeline (12.9 months; P = .002) when compared with the isolated ACL (10.2 months) and combined ACL+MCL (10.0 months) groups. However, career length and competition level were not significantly different between groups. CONCLUSION: Among elite athletes, the mean career length after surgical treatment of combined ACL+MCL and ACL+PLC injuries was 4.5 years. Professional soccer players with combined ACL+PLC surgery returned at a lower rate and required a longer RTP time when compared with the players with isolated ACL or combined ACL+MCL injuries. However, those who did RTP had the same career longevity and competition level.

Trait-Fitness Associations via Fecundity and Competition in a Two-Million-Year-Long Fossil Record.

AbstractThe evolution of phenotypic traits is usually studied on generational timescales or across species on million-year timescales. We bridge this conceptual gap by using high-density sampling of a species lineage, Microporella agonistes (Bryozoa, Cheilostomatida), over 2 million years of its evolutionary history, to ask whether trait-fitness associations are consistent with evolutionary trait models often applied to phenotypic time series. We use average fecundity and competitive outcome as two different fitness components, where competitive outcome is a proxy for partial survival. Examining three quantitative traits in multivariate analyses, we present evidence that some traits experienced substantial selective pressures, in part controlled by past environments. A complex interplay of resource competition with an altering set of competitors and past temperatures has contributed to the changing patterns of phenotypes within the focal species. A comparison with congeneric species living in the same regional community suggests that size traits are more temporally variable and less constrained than shape traits. Our analyses also show that while controls on phenotypes are complex and varied in time, ecological and evolutionary processes that unfold on shorter timescales are not inconsistent with macroevolutionary patterns observed on longer timescales.