Priority Effects Research Articles

Canopy cover size and establishment rate determine biotic resistance to Aster pilosus invasion: a priority effect

Canopy cover size and establishment rate determine biotic resistance to Aster pilosus invasion: a priority effect

FASILITAS KANTOR, PRIORITAS KERJA DAN DUKUNGAN PIMPINAN TERHADAP KETERAMPILAN KERJA PEGAWAI PADA PERPUSTAKAAN DAERAH PROVINSI BENGKULU

This study aims 1) The effect of office facilities on employee job skills at the Bengkulu Province Regional Library. 2) The effect of work priority on employee job skills at the Bengkulu Province Regional Library. 3) The influence of leadership support on employee job skills at the Bengkulu Province Regional Library.) The influence of office facilities, work priorities and leadership support on employee job skills at the Regional Library of Bengkulu Province. The population in this study were all employees in the Regional Library of Bengkulu Province totaling 35 people. The research sample to be taken in this study is to use total sampling where the entire population is sampled amounting to 35 people. The results of the research, the following conclusions can be made: 1. There is a positive and significant effect of office facilities (X1) on employee job skills (Y) Bengkulu Province Regional Library. 2. There is an effect of work priority (X2) on employee job skills (Y) Bengkulu Province Regional Library. 3. There is an influence of leadership support (X3) on employee job skills (Y) Bengkulu Province Regional Library. 3. Office facilities, work priorities and leadership support together have an effect on employee job skills. There is an effect of work priority (X2) on employee job skills (Y) Bengkulu Province Regional Library. Keywords: Effect of Office Facilities, Work Priorities, Leadership Support, Employee Work Skills

Contrasting effects of nectar yeasts on the reproduction of Mediterranean plant species.

Yeasts are often present in floral nectar and can influence plant fitness directly (independently of pollinators) or indirectly by influencing pollinator visitation and behavior. However, few studies have assessed the effect of nectar yeasts on plant reproductive success or compared effects across different plant species, limiting our understanding of the relative impact of direct vs. indirect effects. We inoculated the nectar of six plant species in the field with the cosmopolitan yeast Metschnikowia reukaufii to analyze the direct and indirect effects on female reproductive success over 2 years. The pollinator assemblage for each species was recorded during both flowering years. Direct yeast effects on female fecundity were statistically nonsignificant for all plant species. There were significant indirect, pollinator-mediated effects on fruit production and seed mass for the two species pollinated almost exclusively by bumblebees or hawkmoths, with the direction of the effects differing for the quantity- and quality-related fitness components. There were no consistent effects of the yeast on maternal fecundity for any of the species with diverse pollinator assemblages. Effects of M. reukaufii on plant reproduction ranged from negative to neutral or positive depending on the plant species. The among-species variation in the indirect effects of nectar yeasts on plant pollination could reflect variation in the pollinator community, the specific microbes colonizing the nectar, and the order of microbial infection (priority effects), determining potential species interactions. Elucidating the nature of these multitrophic plant-pollinator-microbe interactions is important to understand complex processes underlying plant pollination.

Biocrusts Influence Vascular Plant Community Development, Promoting Native Plant Dominance

The soil and its biota can shape the development of colonizing vascular plant communities. Because they occupy soil surfaces where most seeds disperse to, biological soil crusts (biocrusts) are uniquely positioned to influence vascular plant communities established by direct seeding, e.g., for restoration. We created mesocosms of soil overtopped by intact biocrust transplants from the field, varying in key community attributes: total cover, species richness, and proportional cover of mosses relative to lichens. We seeded the same diverse mixture of vascular plants into all mesocosms, including desired native species and problematic exotic invasive species. We tracked plant community development for two full growing seasons, both under ambient outdoor conditions and with supplemental irrigation to remove the influence of water limitation. Under ambient conditions, we found that total biocrust cover suppressed exotic plant emergence and biocrust richness slightly promoted native emergence (r = −0.23 to −0.39) but had weaker and less consistent effects on cover of either native or exotic plants (r ≤ |0.25|). Early emergence events were generally strong drivers of vascular plant recruitment (r = 0.17–0.78) and continued to influence community composition after 2 years, suggesting a priority effect. Biocrust cover also promoted final plant biomass under ambient conditions (r = 0.17–0.33) but did not influence the total cumulative number of native species (r ≤ |0.07|) nor the fecundity of exotics (r ≤ |0.08|). Biocrusts’ influence on total vascular plant biomass was minor. When water was added, biocrust effects sometimes switched from positive or negative to neutral, or vice-versa, indicating that our detection probability of biocrust effects on plants changes with moisture availability. Our results demonstrate that the condition of pre-existing biocrust communities can influence—but not strongly dictate—the outcome of multi-species restoration seedings, mostly positively or neutrally under normal conditions, but switching to potentially negatively under irrigated conditions. Our study also suggests that locations with more intact and richer biocrust communities might be slightly more conducive to successful seeding outcomes, while also providing additional contributions to ecosystem functions. As such, biocrusts, alongside vascular plants, have a role in restoring damaged or degraded ecosystems.

Initial wood trait variation overwhelms endophyte community effects for explaining decay trajectories

AbstractMicrobial organisms, environmental conditions and their interactions govern many ecosystem processes. Recent studies have highlighted the importance of priority effects, that is, the identity of potential decomposers present early in community assembly, in determining resulting decay rates especially for wood. In diverse forests, available woody substrates differ chemically and structurally with implications for their role as both habitats and resources for microbes. Both wood traits and microbial communities at the start of the decay process affect subsequent decay rates, but the relative magnitude of effects is not known. In this work, we sought to ask a simple question: what are the relative effects of microbial communities and wood traits?We characterized fungal and oomycete endophytes with amplicon sequencing from stems of 22 woody species growing in woodlands near Richmond, NSW, Australia, and measured 11 traits to capture variation in the physical and chemical wood substrates. To evaluate the consequence of endophyte diversity and wood traits on the trajectory of decay, stem samples were sequentially harvested over 5 years to quantify the decay rate, its consistency and how it varies through time.We did not find evidence to support particular initial endophyte compositions leading to faster decay. Instead, initial wood attributes were much more powerful in explaining decay trajectories with smaller, less dense stems with high water, low N and low lignin concentrations decomposing consistently faster.These data show that initial wood traits have long‐lasting consequences on decay unlike natural variation in endophyte communities, supporting the idea that community member functions are highly redundant. Wood substrate‐driven environmental filtering, rather than endophyte‐driven priority effects, had a stronger effect on decay when real‐world levels of diversity in wood traits were considered.Read the freePlain Language Summaryfor this article on the Journal blog.

Experimental evaluation of ecological principles to understand and modulate the outcome of bacterial strain competition in gut microbiomes

It is unclear if coexistence theory can be applied to gut microbiomes to understand their characteristics and modulate their composition. Through experiments in gnotobiotic mice with complex microbiomes, we demonstrated that strains of Akkermansia muciniphila and Bacteroides vulgatus could only be established if microbiomes were devoid of these species. Strains of A. muciniphila showed strict competitive exclusion, while B. vulgatus strains coexisted but populations were still influenced by competitive interactions. These differences in competitive behavior were reflective of genomic variation within the two species, indicating considerable niche overlap for A. muciniphila strains and a broader niche space for B. vulgatus strains. Priority effects were detected for both species as strains’ competitive fitness increased when colonizing first, which resulted in stable persistence of the A. muciniphila strain colonizing first and competitive exclusion of the strain arriving second. Based on these observations, we devised a subtractive strategy for A. muciniphila using antibiotics and showed that a strain from an assembled community can be stably replaced by another strain. By demonstrating that competitive outcomes in gut ecosystems depend on niche differences and are historically contingent, our study provides novel information to explain the ecological characteristics of gut microbiomes and a basis for their modulation.

Biofilm phenotypes and internal community succession determines distinct growth of anammox bacteria in functional anammox biofilms

In this study, time-series anammox functional biofilms were obtained in a lab-scale simultaneous partial nitritation/anammox process for treating high-strength ammonium. The variations in the biofilm phenotypes, community succession, and anammox bacteria abundance over time were evaluated using optical microscopy, 16S rRNA gene sequencing, and qPCR. The result revealed that biofilm has three distinct stages of the community development trajectory across a 182-day temporal scale. Anammox bacteria growth rates were 0.035 d−1, 0.0015 d−1, and 0.011 d−1, respectively. The diversity and network analysis suggested that the positive priority effect of ammonia oxidizing bacteria was the primary factor for the rapid proliferation of anammox bacteria, and the species replacement triggering priority effect forfeiture and substituted functional recruitment were reasons for the slow proliferation and stable proliferation of anammox bacteria, respectively. Taken together, the higher microbial diversity and stable community composite were key prerequisites for the proliferation of the anammox bacteria.

Initial floral visitor identity and foraging time strongly influence blueberry reproductive success

Priority effects occur when the order of species arrival affects subsequent ecological processes. The order that pollinator species visit flowers may affect pollination through a priority effect, whereby the first visitor reduces or modifies the contribution of subsequent visits. We observed floral visitation to blueberry flowers from honeybees, stingless bees or a mixture of both species and investigated how (i) initial visits differed in duration to later visits; and (ii) how visit sequences from different pollinator taxa influenced fruit weight. Stingless bees visited blueberry flowers for significantly longer than honeybees and maintained their floral visit duration, irrespective of the number of preceding visits. In contrast, honeybee visit duration declined significantly with an increasing number of preceding visits. Fruit weight was positively associated with longer floral visit duration by honeybees but not from stingless bee or mixed species visitation. Fruit from mixed species visits were heavier overall than single species visits, because of a strong priority effect. An initial visit by a stingless bee fully pollinated the flower, limiting the pollination contribution of future visitors. However, after an initial honeybee visit, flowers were not fully pollinated and additional visitation had an additive effect upon fruit weight. Blueberries from flowers visited first by stingless bees were 60% heavier than those visited first by honeybees when total floral visitation was short (∼1 min). However, when total visitation time was long (∼ 8 min), blueberry fruit were 24% heavier when initial visits were from honeybees. Our findings highlight that the initial floral visit can have a disproportionate effect on pollination outcomes. Considering priority effects alongside traditional measures of pollinator effectiveness will provide a greater mechanistic understanding of how pollinator communities influence plant reproductive success.

Prior residency improves the performance of a habitat specialist in a degrading environment

AbstractThe effect of habitat loss on the decline of habitat specialists has been well documented in coral reef fishes, since they have a restricted habitat preference. However, the different competitive advantages of specialists and generalists can impact their performance within varying habitat conditions. The order in which species arrive into a community influences competitive outcomes; these ‘priority effects’ may modify communities within degrading resource scenarios as individuals migrate in search of higher quality resources. In this study, we investigated: how sequence and timing of arrival affects interactions between a habitat generalist and a specialist in healthy and degrading environments, and how prior residency interacts with habitat quality and species identity to affect propensity to migrate. We conducted manipulative field studies using the damselfishes Pomacentrus amboinensis, a habitat generalist, and Pomacentrus moluccensis, a live coral specialist, on live or dead coral habitats, with timing of arrival differing between early and late arrivers (residents and intruders, respectively) by 1, 3 or 24 h. Our results demonstrated that the strength of priority effects (i.e., aggression intensity) increased with increasing timing of arrival when the P. moluccensis arrived after P. amboinensis, suggesting that as the perceived value of the habitat patch increased (owing to increasing ownership duration and defence investment), the tendency to defend it increased. Propensity to migrate from dead to live coral was greater for P. moluccensis compared to P. amboinensis; however, arriving after P. amboinensis significantly reduced willingness to migrate to its preferred live coral habitat, indicating an inhibitory priority effect, directly affecting future persistence. The degree that ecological versatility and priority effects combine to modify competitive outcomes in coral reef fishes has important consequences for the persistence of specialist species in the face of environmental degradation, and has implications for predicting how our changing environment will affect fish communities.

Strong conditionality in plant-fungal community assembly after soil inoculation in post-agricultural grasslands

Soil inoculation from plant species-rich into species-poor grasslands may enable the establishment of self-facilitating networks between microbes and vegetation, thereby steering ecosystem development.We conducted a three-year experiment that covered a wide range of post-agricultural grasslands to determine how succession is affected by the interactive effects of edaphic properties, grass layer removal and hay or soil fragment transfer from a late-successional donor grassland.Soil inoculation generally impacted community assembly of vegetation and fungi, but not of prokaryotes. Effects were strongest when preceded by removal of the grass layer, indicating the importance of priority effects and dispersal limitation. Inoculation enabled the establishment of putative rhizosphere-associated fungal taxa, particularly from the families Helotiaceae, Glomeraceae and Archaeorhizomycetaceae. Nonetheless, effect sizes were mostly small, as was overall resemblance of the receptor grasslands to the donor. Fungal communities were primarily shaped by environmental filters and only reached a high resemblance to the donor in nutrient-poor sites. Shifts in the vegetation were strongest in those grasslands where the mycobiome more closely resembled that of the donor.Soil inoculation generally facilitates colonization by target plant and fungal communities, where establishment success of the former can be predicted by the latter, but the final outcome of succession is environmentally determined.

Characteristics of spatiotemporal variations in coupling coordination between integrated carbon emission and sequestration index: A case study of the Yangtze River Delta, China

• Analyzes the degree of coupling coordination between integrated carbon emissions and sequestration. • Analyzes the coercive effect of economic development on the degree of coupling and coordination. • Analyzes the restraint effect of ecological environment on the degree of coupling and coordination. • Analyzes the effects of regional government decision-making priority with different development characteristics. To explore the degree of coupling coordination between carbon emissions and sequestration, a theoretical analysis framework of integrated carbon emission and sequestration index was constructed, and an evaluation index system was constructed based on the economic development, population growth, energy emissions, land use and other indicators. Then, a comprehensive index method and a coupling coordination degree model were used to analyze the characteristics of spatiotemporal variation in the degree of coupling coordination between economic development carbon emissions and ecological environment quality in the Yangtze River Delta (YRD) from 2005 to 2017. A grey relational degree model was used to identify driving factors, and the influence of governmental decision-making priorities on the degree of coupling coordination was simulated. The results showed that: (1) the total carbon emissions of the YRD are still increasing, and vegetation carbon sequestration is stable. Before 2003, carbon emissions and absorption were basically in balance, but they gradually became unbalanced after 2003. (2) The degree of coupling coordination between economic development carbon emissions and ecological environment quality in the YRD is in a period of turning and rising, and the number of high-quality development cities is also increasing, but the entire region remains in the slightly unbalanced stage of coupling coordination. (3) The coordination degree is closely related to the quality of the ecological environment, and areas with higher ecological environmental evaluation scores have higher coordination degrees. The degree of population spatial agglomeration, quality of economic development and efficiency of land use are the main factors that affect the ecological environment. The maintenance of ecological service functions and proportion of expenditures for environmental protection have an increasing impact on the quality of economic development. (4) Governmental decision-making priorities currently significantly affect the coupling coordination trends; the environmental restraint of economic development is increasingly strengthened, and it is necessary to pay more attention to the improvement of environmental quality while improving the quality of economic development. To a certain extent, this research may provide a reference for policy makers in creating sustainable development policies.

The Effect of Priority Given to Donor Card Holders on the Allocation of Livers for Transplant-Evidence From 7 Years of the Israeli Priority Program.

The Effect of Priority Given to Donor Card Holders on the Allocation of Livers for Transplant-Evidence From 7 Years of the Israeli Priority Program.

Disentangling how multiple traits drive 2 strain frequencies in SIS dynamics with coinfection

A general theory for competitive dynamics among many strains at the epidemiological level is required to understand polymorphisms in virulence, transmissibility, antibiotic resistance and other biological traits of infectious agents. Mathematical coinfection models have addressed specific systems, focusing on the criteria leading to stable coexistence or competitive exclusion, however, due to their complexity and nonlinearity, analytical solutions in coinfection models remain rare. Here we study a 2-strain Susceptible-Infected-Susceptible (SIS) compartmental model with co-infection/co-colonization, incorporating five strain fitness dimensions under the same framework: variation in transmissibility, duration of carriage, pairwise susceptibilities to coinfection, coinfection duration, and transmission priority effects from mixed coinfection. Taking advantage of a singular perturbation approach, under the assumption of strain similarity, we expose how strain dynamics on a slow timescale are explicitly governed by a replicator equation which encapsulates all traits and their interplay. This allows to predict explicitly not only the final epidemiological outcome of a given 2-player competition, but moreover, their entire frequency dynamics as a direct function of their relative variation and of strain-transcending global parameters. Based on mutual invasion fitnesses, we analyze and report rigorous results on transition phenomena in the 2-strain system, strongly mediated via endemic coinfection prevalence. We show that coinfection is not always a promoter of coexistence; instead, its effect to favour or prevent polymorphism is non-monotonic and depends on the type and level of phenotypic differentiation between strains. This framework offers a deeper analytical understanding of 2-strain competitive games in coinfection, with theoretical and practical applications in epidemiology, ecology and evolution.

Capital Structure Priority Effects in Durations, Stock-Bond Comovements, and Factor Pricing Models

Abstract We show theoretically and empirically that the durations of corporate securities are monotonically related to their capital structure priority, with equity often having a negative duration. The magnitude of this effect increases with firm leverage. We use these insights to challenge existing results on stock-bond comovements and factor pricing. For example, though overlooked, higher leverage and lower priority reduce the correlation between corporate security and government bond returns, and these variables explain time-series and cross-sectional variation in correlations; traditional market model regressions significantly understate corporate bond betas; and regressions on standard term and default factors dramatically overstate interest rate and default risk. (JEL G12, G13)

Differential priority effects impact taxonomy and functionality of host-associated microbiomes.

Most multicellular eukaryotes host complex communities of microorganisms, but the factors that govern their assembly are poorly understood. The settlement of specific microorganisms may have a lasting impact on community composition, a phenomenon known as the priority effect. Priority effects of individual bacterial strains on a host's microbiome are, however, rarely studied and their impact on microbiome functionality remains unknown. We experimentally tested the effect of two bacterial strains (Pseudoalteromonas tunicata D2 and Pseudovibrio sp. D323) on the assembly and succession of the microbial communities associated with the green macroalga Ulva australis. Using 16S rRNA gene sequencing and qPCR, we found that both strains exert a priority effect, with strain D2 causing initially strong but temporary taxonomic changes and strain D323 causing weaker but consistent changes. Consistent changes were predominately facilitatory and included taxa that may benefit the algal host. Metagenome analyses revealed that the strains elicited both shared (e.g., depletion of type III secretion system genes) and unique (e.g., enrichment of antibiotic resistance genes) effects on the predicted microbiome functionality. These findings indicate strong idiosyncratic effects of colonizing bacteria on the structure and function of host-associated microbial communities. Understanding the idiosyncrasies in priority effects is key for the development of novel probiotics to improve host condition.

Altering native community assembly history influences the performance of an annual invader

Understanding the determinants of early invasion resistance is a major challenge for designing plant communities that efficiently repel invaders. Recent evidence highlighted the significant role of priority effects in early community assembly as they affect species composition, structure and functional properties, but the consequences of native community assembly history on the success of subsequent invasions has not been elucidated yet. In a greenhouse experiment, we investigated how (1) the identity of the first native colonizing species (one of two grasses: Dactylis glomerata and Lolium perenne, or two legumes: Onobrychis viciifolia and Trifolium repens), each introduced four weeks before the rest of the native community, and (2) timing of species establishment (synchronous vs. sequential sowing), influenced early establishment success of Ambrosia artemisiifolia, an annual noxious weed in Europe. First colonizer identity and establishment timing both affected early biomass production and composition of the community, and had implications for A. artemisiifolia early invasion success. Invasion success decreased when all native individuals were sown simultaneously, quickly generating a high biomass production, while it increased when the productive N-fixing legume T. repens was sown first. These findings support that native species assembly history matters to invasion resistance in the early growth stages, thus opening the way to more effective invasive species management strategies in restoration.

An evaluation of parapatric distributions among ecologically similar rattlesnakes (Viperidae:Crotalus) in North American warm deserts

AbstractParapatric distributions between ecologically similar species have the potential to reveal the effects of limiting similarity in large-scale patterns of species coexistence. We present a qualitative model that predicts three different types of parapatric boundaries between competing species pairs: gap parapatry, abrupt parapatry and narrow sympatry. Our model integrates both niche-based and neutral theory perspectives of coexistence in the context of climatic tolerances, species equivalence, contingencies of dispersal history, priority effects and a heterogeneous patchwork of optimal and suboptimal habitat. Using species distribution models, tests of niche overlap and phylogeographical data, we evaluated assumptions and conditions of this model for four species of mostly allopatric, rock-dwelling rattlesnakes (Viperidae: Crotalus) inhabiting arid mountain ranges of the Mohave–Sonoran desert system of western North America. Our model was adequate for predicting the different types of range boundaries observed across this guild of ecologically similar species. Where species distributions were separated by a steep climatic gradient without evidence of recent dispersal, we observed gap parapatry; where historical dispersal was asymmetric, we observed abrupt parapatry; and finally, where historical dispersal was symmetric, we observed narrow sympatry.

Understory plant community responses to widespread spruce mortality in a subalpine forest

AbstractAimsSpruce beetles (Dendroctonus rufipennis) are causing widespread spruce (Picea spp.) mortality in subalpine forests in western North America. Spruce beetles are changing forest structure and composition by killing a dominant overstory species, but we know little about how the understory community responds to the increase in resource availability brought about by spruce mortality, what mechanisms drive its response, or how its response affects other forest properties and processes.LocationGlacier Lakes Ecosystem Experiments Site, Medicine Bow Mountains, Wyoming, USA.MethodsWe measured understory community cover and richness in 75 permanent plots during and 10 years after an epidemic spruce beetle outbreak, and measured trait values for 46 common understory species. We used linear regression to determine how the understory community has changed over time and along a gradient of spruce mortality, and to evaluate the relative support for two mechanisms contributing to species responses.ResultsUnderstory cover nearly doubled between sampling periods and increased the most where spruce mortality was most severe. Understory richness doubled and showed a weak positive trend with spruce mortality. Understory species with the largest increases in cover were the most frequent across the landscape before the disturbance, were the tallest at maturity and had the lowest leaf turgor loss points. Fir seedling density decreased over time, with decreases lessening with increases in understory cover. Changes in spruce seedling density were not predicted by changes in understory cover.ConclusionsOur findings highlight some of the diverse ways in which understory communities can be altered by spruce beetle outbreaks, and how the direction and magnitude of change can depend on the amount of spruce mortality as well as on priority effects and traits of pre‐disturbance species. Our findings also highlight how understory community changes can have implications for other forest properties and processes, such as tree regeneration and forest recovery.

Climate warming may increase the frequency of cold-adapted haplotypes in alpine plants

Modelling of climate-driven range shifts commonly treats species as ecologically homogeneous units. However, many species show intraspecific variation of climatic niches and theory predicts that such variation may lead to counterintuitive eco-evolutionary dynamics. Here, we incorporate assumed intraspecific niche variation into a dynamic range model and explore possible consequences for six high-mountain plant species of the European Alps under scenarios of twenty-first century climate warming. At the species level, the results indicate massive range loss independent of intraspecific variation. At the intraspecific level, the model predicts a decrease in the frequency of warm-adapted haplotypes in five species. The latter effect is probably driven by a combination of leading-edge colonization and priority effects within the species’ elevational range and was weakest when leading-edge expansion was constrained by mountain topography The resulting maladaptation may additionally increase the risk that alpine plants face from shrinkage of their ranges in a warming climate.

The Effects of Disparate Priorities on Geospatial Multi-Criteria Decision Analysis to Facilitate the Renewable Energy Transition

The Effects of Disparate Priorities on Geospatial Multi-Criteria Decision Analysis to Facilitate the Renewable Energy Transition