Reduction In Competition Research Articles

Microhabitat accessibility determines peptide substrate degradation by soil microbial community.

Soil pore space, considered the most complex biomaterial that exists, generates a complex environment, that gives rise to a wide variety of properties, such as microbial diversity and carbon storage. Soils contain, at the same time, the largest carbon reservoir on earth and an immense amount of nutrient-limited microbial biomass. The reason why this carbon is not consumed by soil microbes is attributed to the complex nature of soil, which forms a labyrinth where carbon and microbes cannot be in direct contact. In the present study, by using microfluidics, we tested the effect of labyrinth-like structures of decreasing accessibility on the decomposing activity of soil microbial communities from a soil inoculum. The two parameters used to study the effect of microhabitat accessibility were either the turning angle in an array of channel-like pore structures or the fractal order in an array of maze-like pore structures. We found that in both cases, channels and mazes, decreasing accessibility produced a higher peptide substrate degradation. When we analyzed the degradation within the structures, we found that most of the activity is concentrated in the regions of intermediate accessibility. We think that the increased degradation activity in low accessibility mazes might be due to the reduced interactions within the microbial communities which leads to a reduction in competition. Lowered competition allows different communities with a wide range of metabolic strategies to cohabit in the structures, which resulted in a bulk increase of the peptide substrate degradation.IMPORTANCEThe role microbes have in the environment is highly influenced by the characteristics of their habitat. Here, we show that a complex habitat enhances the enzymatic activity of a soil microbial inoculum. This might occur due to a reduced competition in complex habitats, which allows a more diverse community to coexist and explore a wider variety of metabolic strategies. The different rates of enzymatic activity in different levels of complexity suggest emergent properties of microbial communities in complex microhabitats which could have important implication for microbial processes, such as soil carbon storage and nutrient cycling.

Market Structure and Extortion: Evidence from 50,000 Extortion Payments

Abstract How does gang competition affect extortion? Using detailed data on individual extortion payments to gangs and sales from a leading wholesale distributor of consumer goods and pharmaceuticals in El Salvador, we document evidence on the determinants of extortion payments and the effects of extortion on firms and consumers. We exploit a 2016 nonaggression pact between gangs to examine how collusion affects extortion in areas where gangs previously competed. While the pact led to a large reduction in competition and violence, we find that it increased the amount paid in extortion by approximately 20%. Much of this increase was passed through to retailers and consumers: retailers experienced an increase in delivery fees, leading to an increase in consumer prices. In particular, we find an increase in prices for pharmaceutical drugs and a corresponding increase in hospital visits for chronic illnesses. The results point to an unintended consequence of policies that reduce competition between criminal organizations.

Systematic reduction of natural enemies and competition across variable precipitation approximates buffelgrass invasiveness (Cenchrus ciliaris) in its native range.

Invasive grasses cause devastating losses to biodiversity and ecosystem function directly and indirectly by altering ecosystem processes. Escape from natural enemies, plant-plant competition, and variable resource availability provide frameworks for understanding invasion. However, we lack a clear understanding of how natural stressors interact in their native range to regulate invasiveness. In this study, we reduced diverse guilds of natural enemies and plant competitors of the highly invasive buffelgrass across a precipitation gradient throughout major climatic shifts in Laikipia, Kenya. To do this, we used a long-term ungulate exclosure experiment design across a precipitation gradient with nested treatments that (1) reduced plant competition through clipping, (2) reduced insects through systemic insecticide, and (3) reduced fungal associates through fungicide application. Additionally, we measured the interaction of ungulates on two stem-boring insect species feeding on buffelgrass. Finally, we measured a multiyear smut fungus outbreak. Our findings suggest that buffelgrass exhibits invasive qualities when released from a diverse group of natural stressors in its native range. We show natural enemies interact with precipitation to alter buffelgrass productivity patterns. In addition, interspecific plant competition decreased the basal area of buffelgrass, suggesting that biotic resistance mediates buffelgrass dominance in the home range. Surprisingly, systemic insecticides and fungicides did not impact buffelgrass production or reproduction, perhaps because other guilds filled the niche space in these highly diverse systems. For example, in the absence of ungulates, we showed an increase in host-specific stem-galling insects, where these insects compensated for reduced ungulate use. Finally, we documented a smut outbreak in 2020 and 2021, corresponding to highly variable precipitation patterns caused by a shifting Indian Ocean Dipole. In conclusion, we observed how reducing natural enemies and competitors and certain interactions increased properties related to buffelgrass invasiveness.

Effects of protection and temperature variation on temporal stability in a marine reserve network.

Understanding the drivers of ecosystem stability has been a key focus of modern ecology as the impacts of the Anthropocene become more prevalent and extreme. Marine protected areas (MPAs) are tools used globally to promote biodiversity and mediate anthropogenic impacts. However, assessing the stability of natural ecosystems and responses to management actions is inherently challenging due to the complex dynamics of communities with many interdependent taxa. Using a 12-year time series of subtidal community structure in an MPA network in the Channel Islands (United States), we estimated species interaction strength (competition and predation), prey species synchrony, and temporal stability in trophic networks, as well as temporal variation in sea surface temperature to explore the causal drivers of temporal stability at community and metacommunity scales. At the community scale, only trophic networks in MPAs at Santa Rosa Island showed greater temporal stability than reference sites, likely driven by reduced prey synchrony. Across islands, competition was sometimes greater and predation always greater in MPAs compared with reference sites. Increases in interaction strength resulted in lower temporal stability of trophic networks. Although MPAs reduced prey synchrony at the metacommunity scale, reductions were insufficient to stabilize trophic networks. In contrast, temporal variation in sea surface temperature had strong positive direct effects on stability at the regional scale and indirect effects at the local scale through reductions in species interaction strength. Although MPAs can be effective management strategies for protecting certain species or locations, our findings for this MPA network suggest that temperature variation has a stronger influence on metacommunity temporal stability by mediating species interactions and promoting a mosaic of spatiotemporal variation in community structure of trophic networks. By capturing the full spectrum of environmental variation in network planning, MPAs will have the greatest capacity to promote ecosystem stability in response to climate change.

Taking firms' margin targets seriously in a model of competition in supply functions

AbstractThis article deals with the integration of industry‐level markup targets into oligopoly theory. It proposes a behavioral competition model in which firms use the average cost‐plus price to determine their supplies. Specifically, firms are assumed to increase (resp., decrease) their supplies as the market price rises over (resp., falls below) this reference price. The equilibrium market outcome lies between those corresponding to Bertrand and Cournot competition. It depends on the industry's margin target, which determines the slope of firms' supply functions. The more significant the markup target is, the lower are the firms' equilibrium supplies at any price level and the higher is the equilibrium market price. An industry‐wide commitment to targeting a markup thus reduces competition in equilibrium. The reduction in competition is more pronounced than when firms commit to linear supply functions.

Short-term interference in learning ballistic motor tasks: Refining the notion of specificity

Introduction Learning of an isometric ballistic force task (BT) can be impaired if it is followed by the learning of a visuomotor accuracy task (VMT) involving isometric contractions of the same muscles (Lundbye-Jensen et al., 2011). This phenomenon, known as retrograde interference, is thought to occur because the memory trace created after learning the BT is affected by the activation of similar neural circuits involved in the VMT (Lundbye-Jensen et al., 2011). However, it remains unclear how the contraction type involved in the two motor tasks influences potential interference effects. The aim of this study was therefore to compare the influence of a VMT involving dynamic position control or isometric force control on short-term retrograde interference in a previously learned isometric BT involving the same muscles. Methods 45 participants were randomly assigned to one of 3 groups. Participants started by learning an isometric BT involving the wrist flexors of the non-dominant hand. Participants in the first two groups then learned a VMT involving dynamic (VMTDynamic group) or isometric (VMTIsometric group) contractions of the same muscles, while participants in the third group took a break (control group). Finally, participants completed the BT retention test. Each BT training consisted of 35 trials in which participants were asked to achieve the highest rate of force development (RFDmax). The VMT training consisted of 50 trials in which participants were asked to follow a curve with a cursor. Position of the cursor was linked to the wrist flexion/extension angle (VMTDynamic) or the isometric force produced (VMTIsometric). Interference was quantified by comparing RFDmax between the end of the initial training (POST) and the start of the retention test (RET). Results A mixed design ANOVA revealed a significant interaction effect (F(2, 40) = 3.87, p = 0.029). Post hoc corrected paired t-tests showed a significant decrease in RFDmax for the VMTIsometric group between POST (2,524 ± 1,144 N/s) and RET (1,960 ± 921 N/s). In contrast, performance of the other two groups did not change (VMTDynamic group: 2,679 ± 1,321 vs. 2,499 ± 1,278 N/s; control group: 2,489 ± 1,005 vs. 2,334 ± 1,013 N/s). Discussion/Conclusion Interference was only observed in the VMTIsometric group, suggesting that the same type of contraction must be involved in the VMT and BT for short-term retrograde interference to occur. It is known that the neural control of isometric contractions is different from dynamic contractions (Duchateau & Enoka, 2016). It can therefore be speculated that the resulting reduction in neural competition between the motor tasks was sufficient to prevent interference in the VMTDynamic group. In conclusion, for retrograde interference to occur, not only must the same muscles be involved in both motor tasks, but they must also perform the same type of contraction.

Long-term conservation tillage changes the diversity, assembly and network stability of the diazotrophic community

Diazotrophs make important contributions to nitrogen (N) inputs in agricultural ecosystems. However, strong evidence on the effects of conservation tillage (CT) on the coexistence and assembly of diazotrophic communities and related mechanisms is lacking. Here, we studied the impacts of long-term CT on the coexistence and assembly patterns of diazotrophic communities. Compared to traditional tillage (CK), CT significantly reduced both the N fixation rate (0–10 cm) and the alpha diversity of the diazotrophic community while increasing the density of the diazotrophic and overall bacterial communities. CT also reduced the competitive relationships within the diazotrophic community and enhanced network stability. Furthermore, diazotroph assembly was dominated by deterministic processes (68.63%) under CK, and stochastic processes (58.82%) under CT. Soil depth and total N (TN) were identified as crucial predictors shaping the assembly processes of diazotrophic communities under different tillage practices. The relative influence of stochastic processes on the diazotrophic community under CT varied more significantly with increasing soil depth. Overall, tillage practices and soil depth had significant influences on the coexistence and assembly processes of the soil diazotrophic community. Moreover, long-term CT may impact the selection of N fixation agents and the specific taxa associated with N fixers. Our results indicated that in CT systems, relatively sufficient nutrient availability leads to a reduction in interspecies competition, an increase in network stability, and a greater influence of stochastic processes on community assembly. These findings may help us better understand biological N fixation in sustainable agricultural systems.

Worldwide Late Pleistocene and Early Holocene population declines in extant megafauna are associated with Homo sapiens expansion rather than climate change

The worldwide extinction of megafauna during the Late Pleistocene and Early Holocene is evident from the fossil record, with dominant theories suggesting a climate, human or combined impact cause. Consequently, two disparate scenarios are possible for the surviving megafauna during this time period - they could have declined due to similar pressures, or increased in population size due to reductions in competition or other biotic pressures. We therefore infer population histories of 139 extant megafauna species using genomic data which reveal population declines in 91% of species throughout the Quaternary period, with larger species experiencing the strongest decreases. Declines become ubiquitous 32–76 kya across all landmasses, a pattern better explained by worldwide Homo sapiens expansion than by changes in climate. We estimate that, in consequence, total megafauna abundance, biomass, and energy turnover decreased by 92–95% over the past 50,000 years, implying major human-driven ecosystem restructuring at a global scale.

Livestock grazing promotes legume abundance under increased nutrient loads: Mechanistic evidence from a temperate grassland

AbstractQuestionLegumes are a key component of rangelands because they play an important role in animal nutrition and the entrance of nitrogen (N) into ecosystems through symbiotic fixation. Legume abundance is commonly low in N‐enriched environments because of competition with grasses and non‐legume forbs. Both haying and livestock grazing remove plant biomass and reduce light limitation to plant growth, with the difference that livestock may selectively consume legumes. This study examines how legumes respond to grazing, haying and fertilization, and what mechanisms explain legume abundance in rangelands.LocationFlooding Pampa, Argentina.MethodsWe performed two manipulation field experiments over 3 years. First, a factorial of rangeland management (intact, haying, or grazing) under two nutrient levels (ambient and increased N, phosphorus [P] and potassium [K]); and second, a factorial of rangeland management (intact or haying) and N × P addition. We evaluated legume, grass and non‐legume forb abundance and ground‐level light in three to five replicates of our experiments over 3 years.ResultsNPK fertilization increased legume abundance consistently under grazing, and temporarily under haying, but had no effect in the intact grassland. Also, P addition increased legume abundance only under haying when N was not added. Temporal changes in legume abundance were positively associated with changes in ground‐level light, which increased with haying and grazing, but decreased with fertilization in the intact grassland, and negatively with grass abundance.ConclusionsThe negative effects of nutrients on legume abundance were offset by the positive effects of livestock. The reduction in grass competition and increase in ground‐level light due to grazing and haying explained the positive responses of legume abundance to nutrients in this temperate grassland. Our results highlight the importance of considering the interactive response of legume abundance to grazing and fertilization, which are becoming common practices in rangelands.

How ballot access laws increase primary competition and decrease party unity

How do electoral institutions affect primary competition and legislative behavior? This paper examines the understudied electoral rule known as ballot access laws, advancing the novel theory that denying ballot access to minor candidates forces these outsiders into major parties. I find that in American states that adopt high ballot access thresholds experience higher rates of ideological heterogeneity and primary competition, and those that reduce their thresholds experience a reduction in heterogeneity and competition. Using an original dataset on state-level changes to ballot access thresholds from 1990 to 2018, I find that an increase in the number and type of primary competition leads to an increase in heterogeneity within both party caucuses. This paper adds to the literature on legislative behavior and electoral institutions, demonstrating institutions role in shaping electoral competition and the ideology of those represented in office.

Bioenergy-livestock integration in Brazil: Unraveling potentials for energy production and climate change mitigation

Future projections indicate an expansion for both food and energy demands, which can increase pressure on land use, while there is an urgent global need for climate change mitigation. Bioenergy is foreseen as key option to meet future energy demands and reduce greenhouse gas (GHG) emissions, however its sustainability depends on locations and regional characteristics. Simultaneously, agricultural production models that co-produce food, feed, and energy offer sustainability synergies and co-benefits, but site-specific sustainability assessments of their large-scale implementation are missing. This study presents a bottom-up approach to assess spatially explicit sustainability aspects of bioenergy-livestock integrated systems (BLI) in Brazil and shed light on their contribution to future energy demands, to climate change mitigation targets, and their impacts on selected ecosystem services, including bioenergy production, climate change mitigation, reduction of food competition, biodiversity conservation, and avoided deforestation. The proposed integration considers livestock intensification and use of biofuels by-products as animal feed supplement, taking advantage of synergies between these two value chains. The expansion of the BLI system in the Center-South region of Brazil produce up to 89 billion liters of ethanol, enough to meet future domestic ethanol demands from multiple shared socioeconomic pathways and generating surpluses for export. This production takes place on 16 million hectares of pastureland within the Sugarcane Agroecological Zoning, excluding the Amazon and Pantanal biomes, and biodiversity hotspots. BLI expansion mitigate up to 250 million tonnes of CO2eq and generate 15 billion dollars of profits. The best locations to maximize the selected ecosystem services are west of São Paulo, east of Mato Grosso do Sul, and the south-central region of the states of Goiás. This study may encourage the formulation of enhanced public policies for the integration of bioenergy and livestock value chains and guide a sustainable large-scale deployment of BLI systems.

Population demography of the Blackbuck Antilope cervicapra (Cetartiodactyla: Bovidae) at Point Calimere Wildlife Sanctuary, India

Demographic research utilizing vital rates and life tables is a standard aspect of planning protection and management strategies for wildlife populations. The Blackbuck Antilope cervicapra population at Point Calimere Wildlife Sanctuary, Tamil Nadu, has undergone fluctuations in recent decades. The cause remains elusive, and conservation efforts may be hampered by a lack of population data. This study aimed to estimate demographic parameters using population count and age-sex classification data collected for the years 2017─2020. The overall mean population estimate derived from line-transect distance sampling was 719, with annual estimates of 716, 727, 711, and 722 for the years 2017–2020 respectively. In total, 64% of Blackbucks counted were adults, 19% subadults, and 17% fawns. Mortality was highest for adult and subadult classes for the composite female class, and fawn mortality was 20%. The net reproductive rate (R0) was as low as 3.28 offspring per generation contrasted with a rather longer mean generation time (G) as 4.75 years. Thus, the study observes a decrease in Blackbuck numbers postulated in earlier research to be driven principally by a conglomerate of factors, including reduction of usable space and interspecific resource competition. Our findings provide a baseline demography of the species and highlights the value of long-term demographic monitoring of age sex classes to understand the evolution of life histories.

Biochar promoted microbial iron reduction in competition with methanogenesis in anaerobic digestion

Microbial Fe (III) reduction generally could outcompete methanogenesis due to its thermodynamic advantage, while the low bioavailability of Fe (III) compounds limits this process in the anaerobic digestion system, which could result in the low recovery of vivianite. Therefore, this study investigated the competition between Fe (III) reduction and methanogenesis in the presence of different biochar (pyrochar and hydrochar). The results showed that pyrochar obtained at 500 °C (P5) resulted in the highest Fe (III) reduction (80.3%) compared to the control experiment (29.1%). P5 also decreased methane production by 9.4%. Both conductivity and surface oxygen-containing functional groups contributed to the promotion of direct electron transfer for Fe (III) reduction. Genomic-centric metatranscriptomics analysis showed that P5 led to the highest enrichment of Geobacter soli A19 and induced the significant expression of out membrane cytochrome c and pilA in Geobacter soli A19, which was related to higher Fe (III) reduction.

Practice Competition and Treatment of Newly Diagnosed Prostate Cancer

To examine the effect of urology practice market competition on use of treatment in men with newly diagnosed prostate cancer. We performed a retrospective national cohort study of 48,067 Medicare beneficiaries with newly diagnosed prostate cancer between 2014 and 2018. The primary exposure was urology practice-level market competition. Markets were established by the flow of patients to a practice using a variable radius approach. Practice level competition was measured annually using the Herfindahl-Hirschman Index. The primary outcome was use of treatment for prostate cancer (ie, surgery, radiation, or cryotherapy) stratified by 10-year risk of noncancer mortality. Between 2014 and 2018, there was a decrease in the total percent of urologists practicing in small single-specialty groups (49%-41%) with an increase in multispecialty practices (38%-47%). After adjusting for demographic and clinical characteristics, a lower percentage of men underwent treatment in practices with low competition relative to those managed in practices with high competition (70% vs 67.0%, P <.001). Among men with the highest risk of noncancer mortality, those managed in practices in the least competitive markets were less likely to receive treatment relative to men managed by practices in the most competitive markets (48% vs 60%, P-value<.001). Reduction in competition between urology practices is not associated with greater use of treatment in men with newly diagnosed prostate cancer, particularly in those with a high risk of noncancer mortality.

Temporal avoidance as a means of reducing competition between sympatric species.

Human activity has modified the availability of natural resources and the abundance of species that rely on them, potentially changing interspecific competition dynamics. Here, we use large-scale automated data collection to quantify spatio-temporal competition among species with contrasting population trends. We focus on the spatial and temporal foraging behaviour of subordinate marsh tits Poecile palustris among groups of socially and numerically dominant blue tits Cyanistes caeruleus and great tits Parus major. The three species exploit similar food resources in mixed groups during autumn-winter. Using 421 077 winter recordings of individually marked birds at 65 automated feeding stations in Wytham Woods (Oxfordshire, UK), we found that marsh tits were less likely to join larger groups of heterospecifics, and they accessed food less frequently in larger groups than in smaller ones. Marsh tit numbers within groups declined throughout the diurnal and winter periods, while the number of blue and great tits increased. However, sites that attracted larger groups of these heterospecifics also attracted more marsh tits. The results suggest that subordinate species exhibit temporal avoidance of socially and numerically dominant heterospecifics, but have limited ability for spatial avoidance, indicating that behavioural plasticity enables only a partial reduction of interspecific competition.

Manipulating overstory density and mineral soil exposure for optimal natural regeneration of Scots pine

In northern boreal region the growth of forests is slow, and yield and profit are low, which is why low reforestation costs are important for profitable forestry. If natural regeneration is successful, expensive artificial forest regeneration (planting or direct seeding) can be avoided. In this study, we look at the impact of overstory density and site preparation on natural regeneration and seedling growth of Scots pine. Study stands were established in different parts of Northern Finland and in each stand following treatments: 50, 150 and 250 trees ha−1 or unthinned control, where the stand density was ≥ 250 trees ha−1, were randomly allocated to experimental plots. In addition, site preparation (disc trenching, 4000–5000 m ha−1) was carried out on two experimental plots in which tree density was either 50 or 150 trees ha−1. In the experimental stands seedling number, age and growth were monitored for 11 years. Monitoring revealed that the number of seedlings increased with decreasing tree density. Average seedling height growth was very low or even non-existent in the unthinned control and in the densest (250 trees ha−1) treatment, but increased when the density of trees decreased. The highest seedling number and the highest growth were achieved when the tree density was 50 trees ha−1 and the soil was prepared to expose mineral soil. Achieving e.g. 2000 seedlings ha−1, would need about 40% exposition of mineral soil. The required low tree density implies that not only seed supply from seed trees and site preparation is important for regeneration success in northern boreal Scots pine forests but also the reduction of competition by mature trees.

Mortality reduces overyielding in mixed Scots pine and European beech stands along a precipitation gradient in Europe

Many studies show that mixed species stands can have higher gross growth, or so-called overyielding, compared with monocultures. However, much less is known about mortality in mixed stands. Knowledge is lacking, for example, of how much of the gross growth is retained in the standing stock and how much is lost due to mortality. Here, we addressed this knowledge gap of mixed stand dynamics by evaluating 23 middle-aged, unthinned triplets of monospecific and mixed plots of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) repeatedly surveyed over 6–8 years throughout Europe. For explanation of technical terms in this abstract see Box 1.First, mixed stands produced more gross growth (+10%) but less net growth (−28%) compared with the weighted mean growth of monospecific stands. In monospecific stands, 73% of the gross growth was accumulated in the standing stock, whereas only 48% was accumulated in mixed stands. The gross overyielding of pine (2%) was lower than that of beech (18%). However, the net overyielding of beech was still 10%, whereas low growth and dropout of pine caused a substantial reduction from gross to net growth.Second, the mortality rates, the self- and alien-thinning strength, and the stem volume dropout were higher in mixed stands than monospecific stands. The main reason was the lower survival of pine, whereas beech persisted more similarly in mixed compared with monospecific stands.Third, we found a 10% higher stand density in mixed stands compared with monospecific stands at the first survey. This superiority decreased to 5% in the second survey.Fourth, the mixing proportion of Scots pine decreased from 46% to 44% between the first and second survey. The more than doubling of the segregation index (S) calculated by Pielou index (S increased from 0.2 to 0.5), indicated a strong tendency towards demixing due to pine.Fifth, we showed that with increasing water supply the dropout fraction of the gross growth in the mixture slightly decreased for pine, strongly increased for beech, and also increased for the stand as a whole.We discuss how the reduction of inter-specific competition by thinning may enable a continuous benefit of diversity and overyielding of mixed compared with monospecific stands of Scots pine and European beech.

Management of trees and palms in swidden fallows by the Kichwa people in the Ecuadorian Amazon

IntroductionThe chakra is a cropping system used by the indigenous Kichwa people of the Ecuadorian Amazon that is advocated as a sustainable form of agriculture that ensures food production without impeding ecosystem functioning. Trees and palms are central to the benefits obtained from chakras, however, little is known about the management of these trees and palms. In this research we aimed to understand how the Kichwa people manage these species in chakras and what drives them to do so. Material and methodsWe conducted participatory observation research in three Kichwa communities during which we researched 18 chakras belonging to different households. In each chakra we identified the tree and palm species, counted their number, and measured their diameter at 1.3 m aboveground. Additionally, each household was interviewed on the use and management of these species. Results and discussionA total of 740 individual trees and palms were inventoried. Nearly all species in chakras were being actively managed, with the reduction of competition and the protection of seedlings being the most applied practices. This appears to be driven mainly by utilitarian values, as most species were used, most commonly for food and construction. Previous studies indicated that agroecological and mythical values also incite the management of trees and palms, which was not the case in this study. This difference is probably because of cultural erosion or cultural gender roles that affected data acquisition. ConclusionsThree important implications arise from this research: 1) future research should acknowledge and adequately address the large variation that exists among chakras, especially regarding their differences in number and size of trees and palms; 2) trees and palms in chakras should not be assumed to be managed inherently sustainably; 3) the understanding that economic and utilitarian considerations induce active management of palms and trees in chakras can lead to effective conservation policies.

MP48-02 PRACTICE COMPETITION AND TREATMENT OF NEWLY DIAGNOSED PROSTATE CANCER

You have accessJournal of UrologyCME1 Apr 2023MP48-02 PRACTICE COMPETITION AND TREATMENT OF NEWLY DIAGNOSED PROSTATE CANCER Avinash Maganty, Samuel Kaufman, Mary Oerline, Lillian Lai, Megan Caram, Brent Hollenbeck, and Vahakn Shahinian Avinash MagantyAvinash Maganty More articles by this author , Samuel KaufmanSamuel Kaufman More articles by this author , Mary OerlineMary Oerline More articles by this author , Lillian LaiLillian Lai More articles by this author , Megan CaramMegan Caram More articles by this author , Brent HollenbeckBrent Hollenbeck More articles by this author , and Vahakn ShahinianVahakn Shahinian More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003294.02AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Financial incentives can affect management of prostate cancer, particularly in circumstances in which the decision to treat is discretionary. Consolidation of physician practices can lead to reduction in market competition and higher prices, which may influence behavior around prostate cancer care. The extent to which urology practice market competition impacts use of treatment in men with newly diagnosed prostate cancer is unclear. METHODS: We performed a retrospective national cohort study of 48,067 Medicare beneficiaries with newly diagnosed prostate cancer between 2014 and 2018. The primary exposure was urology practice-level market competition. Markets were established by the flow of patients to a practice using a variable radius approach. Practice level competition was measured annually using the Herfindahl-Hirschman Index (HHI). The primary outcome was use of treatment for prostate cancer (i.e., surgery, radiation, or cryotherapy) stratified by 10-year risk of non-cancer mortality. RESULTS: Between 2014 and 2018, there was a decrease in the total percent of urologists practicing in small single specialty groups (49% to 41%) with an increase in multispecialty practices (38% to 47%). After adjusting for demographic and clinical characteristics, a lower percentage of men underwent treatment in practices with low competition relative to those managed in practices with high competition (67% vs 70%, p<0.001). Among men with the highest risk of non-cancer mortality, those managed in practices in the least competitive markets were less likely to receive treatment relative to men managed by practices in the most competitive markets (48% vs. 60%, p<0.001). CONCLUSIONS: Reduction in competition between urology practices is not associated with greater use of treatment in men with newly diagnosed prostate cancer, particularly in those with a high risk of non-cancer mortality. Source of Funding: Avinash Maganty is supported by funding from the National Cancer Institute Postdoctoral Fellow Award F32 Grant F32 CA275021-01This work is also supported by a Research Scholar Grant from the American Cancer Society (RSGI-21-097-01-HOPS) © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e654 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Avinash Maganty More articles by this author Samuel Kaufman More articles by this author Mary Oerline More articles by this author Lillian Lai More articles by this author Megan Caram More articles by this author Brent Hollenbeck More articles by this author Vahakn Shahinian More articles by this author Expand All Advertisement PDF downloadLoading ...

Interspecific facilitation favors rare species establishment and reduces performance disparities among adults

AbstractQuestionsA variety of mechanisms sustain diversity in natural communities as a result of ecological interactions between organisms. Competition has been studied extensively in the context of species maintenance, but facilitation is often conceptualized as simply reducing competition between functionally different species, which tends to decline throughout the plants' life span. Here we explore how interspecific facilitation may sustain diversity throughout the species' life by avoiding the extinction of locally rare species at juvenile stages and reducing performance disparities between neighbors of differing species at mature stages.MethodsTo do so, we measured whether rarer species relied more on facilitation than abundant ones in semiarid shrubland in southeast Spain. A mechanistic explanation of this relationship was subsequently tested by correlating rarity with the species' affinity to a particularly edaphic stressful environment. Finally, we assessed whether growing associated with neighbors in vegetation patches shaped by facilitation could balance performance disparities between species when they become adults.ResultsWe show that facilitation (i) favors the rare species, which, in addition, tend to be those with low affinity to the stressful environment, and (ii) reduces the performance dissimilarities among plants growing associated within multispecific vegetation patches compared to plants growing alone.ConclusionsThese facilitative effects, beyond the reduction of competition between functionally similar species, might ensure positive and long‐lasting effects of biotic interactions, implying a more critical role for facilitation in preserving biodiversity than previously thought.