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• Sea-level rise (SLR) thresholds for salt marsh stability vary by spatial patterns. • PC1 of landscape metrics yields smaller SLR threshold than from total area alone. • How spatial resolution impacts SLR thresholds differs by landscape metrics used. • Spatial configuration's effect on SLR thresholds is smaller with smaller salt marsh areas. • Spatial patterns should be comprehensibly accounted for to derive SLR thresholds. Ecological threshold is an important concept to indicate the boundary of alternate states of ecosystems driven by environmental conditions and to facilitate evaluation of ecosystem resilience. Sea-level rise (SLR) thresholds for the stability of salt marshes, if studied in two dimensions, are generally derived based on total areas without systematic accounting for spatial patterns related to edges, shapes, and contagions of patches. As these spatial patterns are potentially important for functions and ecosystem services of salt marshes and they are likely to be impacted by SLR in a different way from the total areas, it is necessary to study SLR thresholds based on these spatial patterns to obtain a more comprehensive understanding of salt marsh resilience to SLR. This research compares the SLR thresholds based on these spatial patterns of salt marshes to those based on total areas alone across different spatial resolutions. The spatial patterns of salt marshes were quantified by 26 commonly used landscape metrics, predicted from a mechanistic wetland change model. At spatial resolutions of 2–100 m, SLR thresholds were first derived using individual landscape metrics and then the first principal component that explained >80% of total variance of these metrics showing threshold responses to SLR. In order to separate the effect of spatial configuration from composition, a neutral model which simulated the same amount of salt marsh change as the mechanistic model but at the random locations was applied. The SLR thresholds were derived based on the simulations from the neutral model and compared to those from the mechanistic model. The results show that total area-based SLR thresholds do not comprehensively represent salt marshes' resilience to SLR. Particularly, I find 1) the derived SLR thresholds vary from 7.29 to 11.12 mm/yr for 2100 based on landscape metrics used, 2) the SLR threshold based on the first principal components (7.99 mm/yr) is smaller than that based on the total area only (8.40 mm/yr), 3) the SLR thresholds are scale dependent, and 4) the spatial configuration' effect on SLR thresholds is smaller for smaller salt marsh areas compared to larger salt marsh areas. This study highlights the need to account for different spatial patterns of salt marshes and apply wetland maps with a spatial resolutions of 30 m or finer in deriving SLR thresholds, as using total areas alone or coarser-resolution maps may provide a biased interpretation that salt marshes are more resilient to SLR than they actually are. [ABSTRACT FROM AUTHOR]

A cultural practice can spread because it is transmitted with high fidelity, but also because biased transformation leads to its reinvention. The respective effect of these two mechanisms, however, may only be quantified if we can measure and detect high-fidelity transmission. This paper proposes wholesale copying, the reproduction of a set of elements as a set, as an operational definition. Using two corpus of heraldic designs (total n = 13,453), we apply information-theoretic tools to detect cases of wholesale copying and gauge their incidence. Heraldic designs are composed according to rigorous combinatorial rules. Wholesale copying causes the frequency of a design to increase out of proportion with the frequency of the motif and tinctures that make it up. Comparing the frequency of designs with that of their component motifs and tinctures, we show that the amount of information carried by a design tracks its inheritance along family lines. A model predicting the frequency of heraldic designs based solely on the frequency of their component parts systematically outperforms one that assumes a mix of wholesale copying and random mutation (with realistic mutation rates). These findings are consistent with low but non-null incidences of wholesale copying in the diffusion of heraldic designs. [ABSTRACT FROM AUTHOR]

Little is known about the forces that determine the assembly of diverse bacterial communities inhabiting drinking water treatment filters and how this affects drinking water quality. Two contrasting ecological theories can help to understand how natural microbial communities assemble; niche theory and neutral theory, where environmental deterministic factors or stochastic factors predominate respectively. This study investigates the development of the microbial community on two common contrasting filter materials (quartz sand and granular activated carbon-GAC), to elucidate the main factors governing their assembly, through the evaluation of environmental (i.e. filter medium type) and stochastic forces (random deaths, births and immigration). Laboratory-scale filter columns were used to mimic a rapid gravity filter; the microbiome of the filter materials, and of the filter influent and effluent, was characterised using next generation 16S rRNA gene amplicon sequencing and flow-cytometry. Chemical parameters (i.e. dissolved organic carbon, trihalomethanes formation) were also monitored to assess the final effluent quality. The filter communities seemed to be strongly assembled by selection rather than neutral processes, with only 28% of those OTUs shared with the source water detected on the filter medium following predictions using a neutral community model. GAC hosted a phylogenetically more diverse community than sand. The two filter media communities seeded the effluent water, triggering differences in both water quality and community composition of the effluents. Overall, GAC proved to be better than sand in controlling microbial growth, by promoting higher bacterial decay rates and hosting less bacterial cells, and showed better performance for putative pathogen control by leaking less Legionella cells into the effluent water. [ABSTRACT FROM AUTHOR]

The wastewater treatment plant (WWTP) effluent discharge affects the microorganisms in the receiving water bodies. Despite the ecological significance of microbial communities in pollutant degradation and element cycling, how the community diversity is affected by effluent remains obscure. Here, we compared the sediment bacterial communities exposed to different intensities of WWTP effluent discharge in Hangzhou Bay, China: i) a severely polluted area that receives effluent from an industrial WWTP, ii) a moderately polluted area that receives effluent from a municipal WWTP, and iii) less affected area that inner the bay. We found that the sediment bacterial diversity decreased dramatically with pollution levels of inorganic nutrients, heavy metals, and organic halogens. Microbial community assembly model analysis revealed increased environmental selection and decreased species migration rate in the severely polluted area, resulting in high phylogenetic clustering of the bacterial communities. The ecological networks were less complex in the two WWTP effluent receiving areas than in the inner bay area, as suggested by the smaller network size and lower modularity. Fewer negative network associations were detected in the severely (6.7%) and moderately (8.3%) polluted areas than in the less affected area (16.7%), indicating more collaborative inter-species behaviors are required under stressful environmental conditions. Overall, our results reveal the fundamental impacts of WWTP effluents on the ecological processes shaping coastal microbial communities and point to the potential adverse effects of diversity loss on ecosystem functions. [Display omitted] • Bacterial community diversity decreases with coastal pollution levels. • Coastal WWTP effluent discharge inhibits species migration. • The impact of pollutants on bacterial diversity is greater than spatial distance. • WWTP effluent discharge decreases bacterial community network complexity. [ABSTRACT FROM AUTHOR]

What causes interindividual variation in fitness? Evidence of heritability of latent individual fitness traits has resparked a debate about the causes of variation in life histories in populations: neutralism versus empirical adaptationism. This debate about the processes underlying observed variation pits neutral stochastic demographic processes against evolutionarily relevant differences among individual fitness traits. Advancing this debate requires careful consideration of differences among inference approaches used by proponents of each hypothesis. Here we draw parallels between several disciplines focusing on processes generating variation in individuals’ life-course, and we contrast methodologies to disentangle these processes. We draw on other disciplines to clarify terminology, risks of flawed inference, and expand the panel of hypotheses and formalizations of processes generating variation in life histories. [ABSTRACT FROM AUTHOR]

The effect of land-use changes on plant diversity is an important issue, as plant diversity is vital to maintaining of threatened insect diversity in agro-ecosystems. Although many studies have examined patterns of a few threatened species, few studies have examined a large number of threatened species while comparing organisms of different trophic levels. Observed and expected community assembly patterns of common and threatened species should be evaluated along land-use gradients in agro-ecosystems, using species richness and red list indicator (RLI). This study examined local and regional diversity of plants and herbivorous insects among abandoned, traditional, and intensified land-use types in semi-natural grasslands and compared observed and expected values via null model analysis. This study showed that the richness and RLI of plants and herbivorous insects were maintained in the traditional land-use. However threatened plants and herbivorous insects at sites of land abandonment and intensified use were significant lower than null model expectations. Although, plant richness, rather than RLI, was responsible for maintaining richness and the RLIs of herbivorous insects, plant richness did not linearly correlate with plant RLIs. Threatened plants did not depend on plant richness, it will be vital to identify and conserve unique environments for diversity of plants and herbivores. In conclusion, we should reintroduce traditional land-use practices in intensified use and abandoned grasslands. National and local governmental support for the appropriate management of semi-natural grasslands is beneficial for biodiversity conservation at both the local (e.g., present study area) and national (Japanese) levels. [ABSTRACT FROM AUTHOR]

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: We explore how cultural heterogeneity evolves without strong selection pressure or environmental differences between groups. Using a neutral transmission model with an isolation-by-distance spatiality, we test the effect of a simple representation of cultural ‘memory’ on the dynamics of heterogeneity. We find that memory magnifies the effect of affinity while decreasing the effect of individual learning on cultural heterogeneity. This indicates that, while the cost of individual learning governs the frequency of individual learning, memory is important in governing its effect. [Copyright &y& Elsevier]

Abstract: The neutral model of cultural evolution, which assumes that copying is unbiased, provides precise predictions regarding frequency distributions of traits and the turnover within a popularity-ranked list. Here we study turnover in ranked lists and identify where the turnover departs from neutral model predictions to detect transmission biases in three different domains: color terms usage in English language 20th century books, popularity of early (1880–1930) and recent (1960–2010) USA baby names, and musical preferences of users of the Web site Last.fm. To help characterize the type of transmission bias, we modify the neutral model to include a content-based bias and two context-based biases (conformity and anti-conformity). How these modified models match real data helps us to infer, from population scale observations, when cultural transmission is biased, and, to some extent, what kind of biases are operating at individual level. [Copyright &y& Elsevier]

[Display omitted] • Acetogens and short fatty acid oxidisers were inhibited by ammonia. • Syntrophic acetate oxidisers emerged after ammonia addition. • Syntrophic interactions enabled recovery after complete process failure. • Similar recovery behaviour was observed between the six replicate bioreactors. • Presence of zeolite did not allowed to alleviate the ammonia shock. Anaerobic digestion allows to produce sustainable energy but the microbial community involved in this process is highly sensitive to perturbations. In this study, a longitudinal experiment was performed in two sets of triplicate bioreactors to evaluate the influence of ammonia addition on AD microbiome and its recovery. Zeolite was added in three reactors to mitigate the inhibition. Microbial dynamics were monitored with 16S rRNA sequencing at 15 time points. Dominant methanogenic pathways were determined with gas isotopic signature analysis. Zeolite addition did not enable to reduce ammonia inhibition or improve the process under the conditions tested. In all the bioreactors, ammonia inhibition sharply decreased the methane production but the process could restart thanks to the increase of hydrogenotrophic archaea and syntrophic bacteria. Interestingly, similar behaviour was observed in the six reactors. Neutral modelling and null model were used and showed that a deterministic process governed the recovery of AD microbiome after failure. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper is to implement a simple model for exploring the influence of different multi-scale incentive networks affecting farmer decision on landscape changes. Three scales of networks are considered: a global ‘policy’ network promoting specific land uses, an intermediate ‘social’ network where land use practices are shared and promoted collectively and a local ‘neighborhood’ network where land use practices are influenced by those of their neighbors. We assess the respective and combined influence of these networks on landscape pattern (fragmentation and heterogeneity) and dynamics, taking into account agronomic constraints (assimilated to crop successions). Simulations show that combination of incentive networks does not have linear and/or cumulative influence on landscape changes. Comparison of simulated scenarios highlights that a combination of two networks tends to improve landscape heterogeneity and fragmentation; scenarios combining all networks could lead to two opposite landscape configuration illustrating emergence of landscape dynamics. Finally, this study emphasizes that landscape complexity has also to be understood through the multiplicity of pathways of landscape changes rather than the assessment of the resulting landscape patterns. [Copyright &y& Elsevier]

While neutral theory and models have stimulated considerable literature, less well investigated is the effect of topology on neutral metacommunity model simulations. We implemented a neutral metacommunity model using two different stream network topologies, a widely branched network (wide tree) and a narrowly branched network (high tree), both represented as binary trees. The wide tree had fewer exceedances of carrying capacity, higher final number of individuals per community, and greater community (α) diversity than the high tree. The difference in diversity increased with increasing dispersal rate. We infer that the greater connectivity of the wide tree facilitated more even spatial dispersal, which limited carrying capacity exceedances and associated random deletions, which, in turn, resulted in higher diversity. Effects specifically due to topology should be considered in analyses of community patterns for mobile aquatic species. [Copyright &y& Elsevier]

Abstract: This paper presents alternative implementations of boundary analysis to: (1) quantify rate changes across boundaries both in an absolute (rate difference) and relative (rate ratio) ways, (2) detect changes of a minimum magnitude by using a null hypothesis of non-uniform risk, (3) account for spatial patterns and population sizes in the randomization procedure, and (4) compute multi-edge p-values for use in multiple testing correction. Simulation studies demonstrate that accounting for spatial autocorrelation and population size in the randomization procedure improves the discriminant power of the statistic, leading to a higher agreement between target and detected edges according to van Rijsbergen’s F-measure. The increase in power and F-measure was strongest for the tests based on the null hypothesis of non-uniform risk across the edge. Multiple testing correction slightly decreases the classification accuracy, yet it reduces substantially the proportion of false positives that becomes very close to the significance level when using the new procedure based on multi-edge p-values. [ABSTRACT FROM AUTHOR]

Abstract: This paper introduces a methodological framework for performance assessment of spatial dynamic models by means of map comparison. The objective is to discern to what extent model performance, expressed by a variety of metrics, can be attributed to endogenously modeled processes or to exogenous model inputs. For this purpose, neutral models of landscape change are introduced that are subject to the same boundary conditions and constraints as the probed model, but otherwise are random except for a reluctance to change. The neutral models serve as benchmark and the difference in performance with the model under investigation can be attributed to the endogenous qualities of the model. Furthermore, the framework makes performance measures over multiple criteria and scales mutually comparable, thus providing insight in strengths and weaknesses of the model. The framework is applied for the performance assessment of a Constrained Cellular Automata land use model for La Réunion (Fr.). Map comparison metrics of land use presence and structure are evaluated at multiple scales. For criteria of land use presence the land use model outperforms the neutral models only at coarse scales, but for criteria of land use structure it performs better on all scales. [Copyright &y& Elsevier]

Abstract: Topology affects outcomes of processes in planar networks. Hexagon tessellations have different performance than, and are often superior to, square tessellations in applications such as fluid dynamics, percolation theory, self-avoiding walks, survey sample design, and quantization. Hexagon tessellations and square tessellations using both von Neumann and Moore neighborhoods were examined as a network topology for neutral ecology community models, following the simulation approach of Graham Bell. These models, which assume identical life history and movement properties for each individual of each species, produce collective properties of communities, such as abundance distributions, range distributions, spatial variation in abundance, species–area curves, and spatial variation in species composition, that match many empirical patterns. The simulations in this study varied the dispersal rate but kept birth, death, and immigration rates constant. For these experiments, ending community populations, species richness, Shannon diversity, and Simpson diversity were clearly different for the different topologies, but the relationship between the topologies varied as the dispersal rate changed. Empirical distributions of the performance measures also showed clear differences among topologies. The interaction of topology with dispersal, spatial boundary effects, and other parameters of these models appears to be quite complex and warrants further research. [Copyright &y& Elsevier]

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The behavior of several landscape pattern metrics were tested against various pattern scenarios generated by neutral landscape models, including number of classes, scale-map extent, scale-resolution, class proportion, aggregation level—RULE, and aggregation level—SimMap. The results demonstrate that most of the metrics are sensitive to certain pattern scenarios, yet are not sensitive to others; therefore, none of them is appropriate for all aspects of a landscape pattern. Despite these limitations, some of these metrics are recommended for future use, which include total number of patches, average patch size, total edge density, double-logged fractal, contagion, and aggregation index. Special attention should be paid to the relationships between metric values and ecological processes rather than the numbers themselves. [Copyright &y& Elsevier]

Abstract: Understorey gaps are common in subtropical forests where pole-size trees are harvested for building materials. The creation of artificial understorey gaps has the potential to affect tree regeneration and the maintenance of forest tree diversity by locally increasing resource availability (light, nutrients, moisture). Understorey tree gaps had significantly lower foliage density in the 3–10-m stratum and higher soil moisture. However, fine root biomass and nutrient availability (N, P, K, Corg) were not different to controls in the intact understorey. Light intensity at the forest floor was a function of the age of the understorey gap, being greater in recent gaps but was not different between older gaps and the controls in intact understorey. The early regeneration community in gaps was different in composition from under intact understorey. Understorey gaps appeared to promote the regeneration of understorey species (density and species richness) by increasing community-wide seedling establishment of understorey species. However, understorey gaps had no effect on the early regeneration of canopy species. We argue that under low harvesting intensity (11.6% of the available pole-size stems), understorey gaps have a neutral role in the long-term maintenance of understorey species diversity and no apparent role in the long-term maintenance of canopy tree species diversity. These results suggest that low levels of subsistence harvesting of understorey species will not detrimentally affect the overall species composition of scarp forest. [Copyright &y& Elsevier]

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tree species distribution has been investigated along 45 km of line transects in the tropical rain forest of the Dja Fauna Reserve in Cameroon. The spatial patterns were expressed by the probabilities that two trees are conspecific according to the distance separating them, providing information on the degree of species clumping as well as on alpha- and beta-diversity. Our objective was to assess the relative importance of habitat heterogeneity and limited dispersal in determining these patterns by: (1) comparing the patterns observed within and across major habitats; (2) comparing the patterns with the ones expected under a neutral hypothesis where limited dispersal is the sole factor. Although, habitat heterogeneity affected the distribution of many species, our results suggest that limited dispersal was the major factor affecting the degree of species clumping. The pattern observed was similar to the one found in Amazonia by Condit et al. [Science 295 (2002) 666]. We discuss the relevance of neutral models of tree communities to study the dispersal abilities of tree species. [Copyright &y& Elsevier]

[Display omitted] • Diverse protists inhabit in the giant panda gut ecosystem. • Fungal communities are more sensitive to sampling site than other microorganisms. • The neutral model could predict the distribution of most of microbial ASVs. • Diet is the main driving factor of ARGs variation in the giant panda gut microbiome. • Two multitrophic communities are identified, which all contribute to ARGs variation. The mammal gut is a rich reservoir of antibiotic resistance genes (ARGs), and the relationship between bacterial communities and ARGs has been widely studied. Despite ecological significance of microeukaryotes (fungi and protists), our understanding of their roles in the mammal gut microbiome and antibiotic resistome is still limited. Here, we used amplicon sequencing, metagenomic sequencing and high-throughput quantitative PCR to examine microbiomes and antibiotic resistomes of 41 giant panda fecal samples from individuals with different genders, ages, sampling sites and diet. Our results show that diverse protists inhabit in the giant panda gut ecosystem, dominated by consumers. Higher abundance of protistan consumers was detected in the elder compared to sub-adult and adult giant pandas. Diet is the main driving factor of variation in ARGs in the giant panda gut microbiome. Weighted correlation network analysis identified two key microbial modules from multitrophic communities, which all contributed to the variation in ARGs in the giant panda gut. Protists occupied an important position in the two modules which were dominated by fungal taxa. Deterministic processes made a more important contribution to microbial community assembly of the two modules than to bacterial, fungal and protistan communities. This study sheds new light on how key microbial modules contribute to the variation in ARGs, which is crucial in understanding dynamics of antibiotic resistome in the mammal gut, particularly endangered species. [ABSTRACT FROM AUTHOR]

Microplastics have emerged as a new anthropogenic substrate that can readily be colonized by microorganisms. Nevertheless, microbial community succession and assembly among different microplastics in nearshore mariculture cages remains poorly understood. Using an in situ incubation experiment, 16S rRNA gene amplicon sequencing, and the neutral model, we investigated the prokaryotic communities attached to polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) in a mariculture cage in Xiangshan Harbor, China. The α-diversities and compositions of microplastic-attached prokaryotic communities were significantly distinct from free-living and small particle-attached communities in the surrounding water but relatively similar to the large particle-attached communities. Although a distinct prokaryotic community was developed on each type of microplastic, the communities on PE and PP more closely resembled each other. Furthermore, the prokaryotic community dissimilarity among all media (microplastics and water fractions) tended to decrease over time. Hydrocarbon-degrading bacteria Alcanivorax preferentially colonized PE, and the genus Vibrio with opportunistically pathogenic members has the potential to colonize PET. Additionally, neutral processes dominated the prokaryotic community assembly on PE and PP, while selection was more responsible for the prokaryotic assembly on PET. The assembly of Planctomycetaceae and Thaumarchaeota Marine Group I taxa on three microplastics were mainly governed by selection and neutral processes, respectively. Our study provides further understanding of microplastic-associated microbial ecology in mariculture environments. Image 1 • Prokaryotic communities on three microplastics are distinct in a mariculture cage. • Prokaryotes on microplastics are more similar to the large particle-attached. • Distinct processes govern prokaryotic community assembly on three microplastics. This study provides new insights into the prokaryotic community succession and assembly on different microplastics in a nearshore mariculture cage by a three-month in situ incubation experiment. [ABSTRACT FROM AUTHOR]