Rank Abundance Distribution Research Articles

Contributions of Urban Woodlands to Bird Diversity and Abundance in The Anatolian Side of Istanbul

Aim of study: The study aimed to assess the impact of urban woodlands on bird species diversity and abundance in the Anatolian side of Istanbul, focusing on species typically absent from urban centers but found within urban environments. The findings are intended to contribute to the development of future conservation and habitat management strategies. Area of study: The study was conducted in five areas in Üsküdar and Beykoz, including an urban center, three urban woodlands (Fethipaşa, Hidiv, and Beykoz Abrahampaşa) and a natural area in Istanbul's northern region. Material and methods: Data on bird species and their abundances were collected and tabulated through 900 point counts from April 2022 to March 2023. The data was analyzed using abundance values, species richness and diversity, identifying distribution and evenness through rank abundance distribution and curves. Similarity analysis was performed using the clustering method and species composition was compared using a Venn diagram. Main results: Seventy-two bird species were identified across the study areas. A decrease in urbanization density enhances bird species richness, diversity and evenness, with the natural area recording the highest values. Urban woodlands harbor species absent from more urbanized locations. Distinctions in species distribution and bird diversity between the areas were revealed. Research highlights: Urban woodlands are crucial areas for wildlife in metropolises, providing significance from both ecological and sociocultural perspectives. Although they may not match natural areas in species diversity, these woodlands significantly contribute to bird diversity within the urban environments. Further research is needed to explore the unique characteristics of each woodland and their contributions to urban ecosystems.

High‐throughput metabarcoding of SAR11 assemblages from the southwest Atlantic shelf and arid Patagonia: richness and associated rank abundance distributions

The SAR11 clade is likely the most abundant microbial lineage on earth. Here, we provide detailed analyses of the group’s richness and AD in poorly studied Southern microbiomes. This requires whole community composition analyses to be performed, which are also provided in conjunction with the SAR11‐specific studies. In this way, the work describes unknown aspects of the diversity of an outstanding bacterial lineage and novel data on remote and relatively little‐studied microbial communities.BackgroundMassively parallel sequencing of environmental DNA allows microbiological studies to be performed in greater detail than was possible with first‐generation sequencing. For example, it facilitates the use of approaches hitherto largely applied to flora and fauna, such as rank abundance distribution (RAD) analyses.MethodsHere, we set out to advance the knowledge on Ca. Pelagibacterales (SAR11) communities from southern South America using environmental sequences from the open ocean in the Argentine sea, the uncharted Engaño Bay, as well as a river and an oligohaline shallow lake from the Patagonian Steppe ecoregion. The structures of the SAR11 assemblages present in these ecosystems were dissected by direct and rarefaction‐based estimates of species richness, and evaluations of the corresponding abundance distributions (ADs), which was addressed by RAD analyses.ResultsMicrobial community composition analyses revealed that the studied SAR11 assemblages coexist with 27 bacterial phyla. SAR11 richness was in general very high, but ADs turned out to be highly uneven. The results were compatible with prior knowledge, and similar to that derived from point estimates of diversity. However, our comprehensive dissection allowed for more detailed quantitative comparisons to be made between the environments surveyed, and revealed differences regarding both richness and the underlying ADs.ConclusionsDespite SAR11 assemblages being extremely rich, their ADs are very uneven. Richness and ADs can vary, not only between fresh and salt water, but also between oceanic and coastal marine environments. The obtained results provide insights on general topics such as adaptation and the contrast between marine and freshwater radiations.

Power Laws Govern the Abundance Distribution of Birds by Rank

Only a few bird species are abundant. Understanding the abundance distribution of bird species is critical for conservation efforts because rare species may be more vulnerable to habitat loss, climate change, and other threats. According to new data, a log left-skewed distribution, rather than a lognormal distribution, better adjusts to the abundance distribution of bird species. We look at the rank abundance distribution rather than the species abundance distribution that use the same data and find three power laws: for the top four species; for the abundant species minus the top four; and for the rare species.

The dominance-diversity dilemma in animal conservation biology.

The alteration of environmental conditions has two major outcomes on the demographics of living organisms: population decline of the common species and extinction of the rarest ones. Halting the decline of abundant species as well as the erosion of biodiversity require solutions that may be mismatched, despite being rooted in similar causes. In this study, we demonstrate how rank abundance distribution (RAD) models are mathematical representations of a dominance-diversity dilemma. Across 4,375 animal communities from a range of taxonomic groups, we found that a reversed RAD model correctly predicts species richness, based solely on the relative dominance of the most abundant species in a community and the total number of individuals. Overall, predictions from this RAD model explained 69% of the variance in species richness, compared to 20% explained by simply regressing species richness on the relative dominance of the most abundant species. Using the reversed RAD model, we illustrate how species richness is co-limited by the total abundance of a community and the relative dominance of the most common species. Our results highlight an intrinsic trade-off between species richness and dominance that is present in the structure of RAD models and real-world animal community data. This dominance-diversity dilemma suggests that withdrawing individuals from abundant populations might contribute to the conservation of species richness. However, we posit that the positive effect of harvesting on biodiversity is often offset by exploitation practices with negative collateral consequences, such as habitat destruction or species bycatches.

Changes in community assembly processes and co-occurrence networks of soil diazotrophs along an elevational gradient in Tibetan alpine meadows

Shifts in soil microbial community composition along elevational gradients have been extensively studied; yet, the assembly process and co-occurrence network of soil microbes underlying these shifts remain to be explored, especially for diazotrophs that contribute to the most nitrogen input in natural ecosystems. In this study, we examined how assembly processes and co-occurrence networks of soil diazotrophs changed along an elevational gradient with four elevation levels ranging from 3200 m to 3800 m using high-throughput sequencing of the nifH gene in Tibetan alpine meadows. Our analyses showed that α-diversity of soil diazotrophs was lower at low elevations (i.e., 3200 m and 3400 m) relative to high elevations (i.e., 3600 m and 3800 m). Moreover, dominant diazotrophic phyla shifted from Actinobacteria at low elevations to Proteobacteria at high elevations. The change in diazotrophic community composition along the elevation gradient was related to the differences in soil temperature, moisture, NH4+-N concentration and pH. Species rank-abundance distribution models showed that soil diazotrophic communities were mainly assembled by deterministic processes at 3200 m, 3600 m and 3800 m elevations, and by stochastic processes at the 3400 elevation. Additionally, the complexity of diazotrophic co-occurrence networks increased with increasing elevations. Collectively, our findings highlight the change in soil diazotrophic communities along the elevation gradient and the high environmental sensitivity of soil diazotrophs, and suggest that global change could have consequences for soil diazotrophic community composition and structure in montane ecosystems.

The rank abundance distribution of large-bodied vertebrates from Natural Trap Cave, Wyoming

Natural Trap Cave (NTC) is a well-known fossil locality located in Wyoming that contains a discontinuous record of sediments from the early Sangamonian (∼150 ka) to the present and produces a diverse vertebrate assemblage from 2-9 and 23–47 cal ka BP. This study examines changes in the rank abundance distribution (RAD) of NTC's large-bodied (>8 kg) vertebrates, to assess the stability of the local ecosystem surrounding the cave across the Late Pleistocene-Holocene transition. RADs were generated based on 2208 skeletal elements from four stratigraphic units, collected by Gilbert and Martin from 1974 to 1979. All bones included in this study had: a north-west grid coordinate, a known depth below the sediment surface, were over 20% complete and taxonomically diagnostic. Isotaphonomy was assessed using multinomial regressions of %MAU against multiple taphonomic variables: size, shape, degree of abrasion and weathering, fracture type, percent complete, original bulk density, and surface area to volume ratio. Changes in RADs were analyzed using rank abundance curves (RACs), Wilcoxon Rank Sums test, and kurtosis. RADs were also fit to a suite of standard ecological models (i.e., geometric, log-series, zero-sum multinomial, & log-normal) using maximum likelihood and the Akaike Information Criterion corrected for small sample size (AICc). The four faunal assemblages show little variation in taphonomic biasing, so any changes in the RADs reflects changes in the ecosystem. The four RACs showed little change in their shape or faunal composition and are dominated by a few abundant taxa, representing an ecosystem that experienced perturbations (i.e., a concave RAC and a kurtosis value > 3). The Wilcoxon Rank Sums test found no statistical difference among the RADs from the lower three stratigraphic units. This means that the abundance structure of the large-bodied vertebrates did not change prior to (35.8–25.3 cal ka BP) or during the Last Glacial Maximum (25.3–17.2 cal ka BP) and the local ecosystem surrounding NTC never approached equilibrium. The uppermost stratigraphic unit represented a mixed Late Pleistocene and Early Holocene assemblage, so changes in ecosystem structure from the Last Glacial Maximum to the Holocene (10.5 cal ka BP – present) cannot be evaluated. Unfortunately, the ecological models used in this study provide little insight into the maturity or processes influencing the formation of the local ecosystem surrounding NTC because only three models produced a ΔAICc value between 4.4 and 6.7.

Different deterministic versus stochastic drivers for the composition and structure of a temperate grassland community

It is a central goal of current community ecology to explore the pattern and mechanism of community response to anthropogenic disturbances. Most researches focus on the response of community composition, which is based on the presence/absence or relative abundances of different species. However, the response of species-identity-independent community structure, such as the rank-abundance distribution, remains relatively understudied. We conducted a ten-year nitrogen addition experiment in a temperate steppe, with nine nitrogen rates under fencing (un-mowed) or mowing conditions. Mowing and nitrogen addition significantly altered both the composition and structure of plant communities. While the relative importance of stochastic change in community composition under mowing was not significantly different from that under fencing, the relative importance of stochastic change in community structure under mowing was significantly larger than that under fencing. Overall, our results demonstrated that mowing led to different drivers for the community composition and structure, meaning that mowing promoted the stochastic allocation of material and energy in primary producers in the grassland ecosystem.

High functional redundancy drives vegetation recovery in Campo rupestre affected by wildfires

• Campo rupestre vegetation tends return to an unburned state after a wildifre • Species composition did not affect functional diversity in Campo rupestre vegetation • Plant cover reestablished in a period of two years after wildfire • Cover reestablishment was driven mainly by cespitose hemicryptophyte High heterogeneity of the floristic component and rapid post-burn vegetation recovery have been reported for Campo rupestre , an azonal peinobiome characterized by a fire-prone vegetation establishing on nutrient-impoverished soils. Although these two key conditions are already known for Campo rupestre , the relationship between them still poorly understood. To test whether floristic composition influences the pattern of post-fire regeneration, we monitored the vegetation recovery of three floristically dissimilar Campo rupestre sites for two consecutive years following wildfires. For each site, we conducted species similarity ordination, rank-abundance distribution, divergence from species to life-form diversity analyses (with an index of diversity divergence) and plant cover in twenty 1 m × 1m plots (10 in burned and 10 in unburned patches). The plots were resampled every four months from December 2015 (one month after wildfire) to November 2017 (24 months after wildfire), totaling seven temporal measurements. We found that the burned grasslands tended to return to a pre-fire state that is similar to control plots that did not burn in 2015. However, each community presented different trajectories in floristic transitions and different degrees of species similarity in relation to an adjacent unburned area. Despite these floristic differences, the three sites reached similar plant cover measures in relation to the non-burned areas. No differences were found for life-form diversity and abundance distribution between communities, suggesting that the differences in floristic composition did not alter the abundance and diversity of functional groups. We conclude that, despite differences in the floristic component, there is high functional redundancy among Campo rupestre communities periodically exposed to wildfires, leading to a similar dynamic of plant recovery during post-fire regeneration.

Tree diversity and community composition in sacred forests are superior than the other community forests in a human-dominated landscape of Meghalaya

Tree diversity and community composition in six sacred forests (SF) of Meghalaya were compared with those of six adjacent community forests (CF) to understand how protection provided to sacred forests by the communities impacts their diversity and community characteristics. The SFs harboured a greater number of tree species (187) compared to the CFs (56). Tree density in the SFs ranged from 750 trees ha−1 (MKSF) to 1470 trees ha−1 (MTSF) while in CFs, it was 875 trees ha−1 (ILCF) to 1236 trees ha1 (NBCF). Among the SFs, the highest basal area was recorded in MNSF (56.89 m2 ha−1) and least in NBSF (40.75 m2 ha−1), while among the CFs tree basal area ranged from 23.7 m2 ha−1 in MKCF to 36.0 m2 ha−1 in MNCF. The canopy cover in SFs ranged from 73.3 to 86.2% while in CFs it ranged from 54.3 to 70.8%. Species rank abundance distribution (RAD) curve or dominance-diversity curve showed high equitability and low dominance in all the six SFs while the RAD curve showed high dominance and low equitability in all the six CFs. The dominance-diversity curve in the SFs followed a log-normal distribution whereas the CFs exhibited a broken stick distribution pattern. Among the CFs, Pinus kesiya was the dominant tree species in five out of six study sites. The dominant species were different for different SFs, which were Microtropis discolour (ILSF), Citrus latipes (MNSF), Castanopsis tribuloides (MTSF), Castanopsis armata (NBSF), Myrica esculenta (NKSF) and Taxus wallichiana (MKSF). SFs were characterized by high diversity and low dominance as seen in old-growth forests. Shannon’s diversity index (H′) in the SFs ranged from 2.06 to 4.28 indicating high tree diversity, while in CFs it was 0.76–2.61 reflecting relatively lower diversity. Simpson’s dominance index for trees was higher in CFs (0.09–0.73) than the SFs (0.02–0.26).

How exogenous influent communities and environmental conditions affect activated sludge communities in the membrane bioreactor of a wastewater treatment plant.

In this study, the residual population of influent and activated sludge (AS) communities was defined based on their occurrence frequency and relative abundance through long-term and fine-scale sampling from the membrane bioreactor (MBR) of a wastewater treatment plant (WWTP). There were 481 OTUs defined as the residual OTUs, which taken up 67.90 ± 9.36% of relative abundance in the influent community. Besides, 6.76 ± 5.71% of the residual population migrated to and remained in the AS community. Additionally, the residual populations were more likely to be anaerobes and microaerobes. As the most predominant genus from residual community, the relative abundance of Arcobacter was reduced from 15.78 ± 3.58% in the influent to 1.15 ± 1.35% in the AS. The residues that migrated from the influent have increased the richness and evenness of AS community, as well as the dissimilarities among samples over long-term. The rank-abundance distribution showed identical pattern for the residual species between influent and AS. By adopting the analysis of neutral model, 2766 out of 7491 shared OTUs between influent and AS communities were identified as neutral OTUs, which respectively made up 53.9% and 41.8% of the total relative abundance of influent and AS communities. These indicated that the AS community was to some extent, but not entirely assembled by neutral process. For the residual community in the AS, dissolved oxygen (DO) was positively associated with several aerobic genera, meanwhile influent chemical oxygen demand (COD) had positive relationship with genus Pseudomonas. Last but most importantly, the influent community could not inoculate the nitrifiers in the AS, but instead, was able to inoculate the denitrifiers; as well as enhance the biodiversity and the ability of resisting external disturbance for the AS community in MBR.

Macroinvertebrate diversity and rarity in non-glacial Alpine streams

Alpine landscapes are being transformed through the rapid recession of glaciers, resulting in the development of numerous non-glacial headwater streams inhabited by a diverse assemblage of macroinvertebrates. We examined spatial patterns in biodiversity and rarity of macroinvertebrates in 41 non-glacial streams from five glacierized catchments in the Swiss Alps undergoing rapid glacial recession over the last decades. Water physico-chemistry and food resources (periphyton, benthic organic matter) varied widely among streams within each catchment, while no significant differences occurred among catchments. Variability in community composition was similar among streams within each catchment but differed among catchments, reflecting differences in catchment-scale species pools due to biogeographical context and season. Overall, 101 taxa from ca 33,000 individuals collected were identified in the streams with 7–33 taxa found in individual streams. Some 64% of the taxa comprised less than 5% of the total abundances at the streams (rare in abundance) with 78% of the taxa being represented by less than 5% of the most common taxon (Baetis sp.), whereas 47% of the taxa were found in less than 10% of the streams (rare in distribution). No taxon was found at all sites (maximum presence at 85% of the sites), while 15% of the taxa were found at 50% of the sites or more. However, analyzing the rank-abundance distribution showed that rarity was less prevalent than previously shown in other ecosystems. The results indicated that community assembly of alpine headwater streams is a complex interaction between environmental properties (habitat filtering), habitat stability coupled with dispersal (source sink dynamics), and time since deglaciation (island biogeography). Integrating these processes is essential towards understanding ongoing colonization events in headwater streams of alpine catchments as glaciers continue to recede.

Effects of mixed lactic acid bacteria on intestinal microbiota of mice infected with Staphylococcus aureus

BackgroundThe stability of intestinal microorganisms plays an important role in human health, as the intestines perform important functions in the human body. Staphylococcus aureus is a Gram-positive, facultative anaerobic bacteria, it causes human infection worldwide, and is a major pathogen that causes intestinal infection. Mixed lactic acid bacteria (LAB) may have potential in the prevention and treatment of S. aureus infection. In the present study, we examined the effects of mixed LAB treatment on intestinal microbiota modulation in mice infected with S. aureus.ResultsHigh-throughput sequencing of the V3-V4 region of the bacterial 16S rRNA gene showed that the mixed LAB maintained the richness and diversity of the microbiota in the mouse intestine. By establishing operational taxonomic units and using rarefaction analysis, rank-abundance distribution curves, heat maps, Venn diagrams, bacterial community structures, and hierarchical clustering analysis, Bacteroidales, Lachnospiraceae, Bacteroides and Prevotellaceae were the most abundant taxa in the samples, we found that the composition of the intestinal microbiota was similar between the protection group administered mixed LAB and the negative control group.ConclusionsStaphylococcus aureus destroys the stable intestinal microbiota structure of mice, treatment with mixed LAB could prevent S. aureus infection in mice and improve the structure of the intestinal microbiota.

How adaptive immunity constrains the composition and fate of large bacterial populations

Features of the CRISPR-Cas system, in which bacteria integrate small segments of phage genome (spacers) into their DNA to neutralize future attacks, suggest that its effect is not limited to individual bacteria but may control the fate and structure of whole populations. Emphasizing the population-level impact of the CRISPR-Cas system, recent experiments show that some bacteria regulate CRISPR-associated genes via the quorum sensing (QS) pathway. Here we present a model that shows that from the highly stochastic dynamics of individual spacers under QS control emerges a rank-abundance distribution of spacers that is time invariant, a surprising prediction that we test with dynamic spacer-tracking data from literature. This distribution depends on the state of the competing phage-bacteria population, which due to QS-based regulation may coexist in multiple stable states that vary significantly in their phage-to-bacterium ratio, a widely used ecological measure to characterize microbial systems.

MEDICO-SOCIAL ASPECTS OF THE GENERAL AND PRIMARY DISABILITY IN CHILDREN POPULATION LIVING IN THE URBANIZED AREA

The aim of the investigation was to make an analysis of the primary and general disability in children population living in the industrial Levoberezhniy district of the city of Voronezh under the exposure to the constant anthropogenic load. The analysis was made according to the statistical form №19 «Information about children with disabilities». The duration of the period of the investigation amounted of 9 years (2009-2017). The general disability level in the industrial Levoberezhniy district was determined to be 11.24±0.33 / 1000 of the children population, and primary disability level accounted for - 1.36±0.18 / 1000 of children population. The most number of children with disabilities is in the group of 5-9 years. The majority of disabled children were shown to be boys (60.48±0.86%). Diseases of the nervous system held the 1st position in rank-abundance distribution in the general invalidity structure of children - 24.7%, (cerebral palsy and other paralytic disorders were the most frequently occurred), 2nd was occupied by congenital anomalies - 23.59% (out of them, anomalies of the nervous system), 3rd - diseases of the ear and mammillary tubercle - 17.68%, 4th - endocrine - 11.32% (of them diabetes), 5th - diseases of the bone-muscular system and connective tissue - 5.26% (of them juvenile arthritis). Structure of reasons for the primary disability in different age groups and general age structure have the important practical value for planning of the medico-social inspection and rehabilitation of children with disabilities.

Urban land transformations and its implication on tree abundance distribution and richness in Kumasi, Ghana

Despite the rapid urban transformation in green space in most cities in Ghana, knowledge on urban tree diversity and the evidence of the consequences of built-up expansion on trees is scanty. This article provides a novel contribution to the current urban trees abundance and richness in Kumasi Metropolitan Area, Ghana. Post classification change detection technique was applied to quantify urban land use land cover (LULC) transformations (urban forest, agricultural, riparian vegetation and built-up) from 2007 to 2017. Species rank abundance distribution and richness were quantified using geometric series and individual-based rarefaction models. A total of 858 individual trees belonging to 76 taxa were recorded across the four LULC classes. Species abundance distributions in three LULC types varied substantially, with the exception of riparian LULC (slope [k] 0.08660.12, v2P 19.42, P0.15). Land use pressure led to a 13.56km2 reduction in forest cover, while built-up and agricultural LULC increased by 31.13 and 1.85km2, respectively. These disturbances did not only affect indigenous tree dominance (41.3%) in favour of exotic species (58.7%) in the agricultural and built-up LULC types but also impacted on tree abundance (n126) and richness (n28) in agricultural land compared to abundance (n280) and richness (n67.86) in forest cover. Despite the contribution of LULC transformation to increase in tree diversity, there is the likelihood of future dominance of exotic species in the Metropolis if urban planners do not institute measures to conserve indigenous species.

Niche partitioning in tenebrionid species (Coleoptera: Tenebrionidae) inhabiting Mediterranean coastal dunes

We analyzed the abundance, distribution and niche overlap of species (Pianka's Ojk index) in tenebrionid beetle communities inhabiting different biotopes in Tyrrhenian and Adriatic sand dunes. The rank abundance distribution of the different species has the form of a geometric series in both communities as predicted by the niche preemption hypothesis for communities in harsh environments. Mean niche overlap values did not deviate significantly from null expectations, which indicates random interspecific interactions. These results, coupled with evidence of species habitat preferences, led us to conclude that the community organization of tenebrionid species inhabiting coastal dunes is determined more by habitat preferences than interspecific competition.

Microbial community distribution and dominant bacterial species analysis in the bio-electrochemical system treating low concentration cefuroxime

In a previous study, the authors found that a bio-electrochemical system could increase the antibiotic removal efficiency by approximately 60%. Researchers desired to examine how the microbial community changed. Thus, Illumina high-throughput sequencing was used to explore the community structures in the bio-electrochemical system and a conventional sequencing batch biofilm reactor. Through establishing operational taxonomic units, rank-abundance distribution curves, Venn diagrams, bacterial community structures, and heatmaps, the result showed that the microbial richness and diversity were reduced in the bio-electrochemical system and that Xanthomonadaceae was dominant species. In addition, copies of three types of β-lactam antibiotic resistance genes were detected, and the bio-electrochemical system showed the smallest number. Overall, this research implied that Xanthomonadaceae plays a role in removing cefuroxime and that the bio-electrochemical system has the potential to remove organisms’ antibiotic resistance genes.

Abundance Inequality in Freshwater Communities Has an Ecological Origin.

The hollow-shaped species abundance distribution (SAD) and its allied rank abundance distribution (RAD)-showing that abundance is unevenly distributed among species-are some of the most studied patterns in ecology. To explain the nature of abundance inequality, I developed a novel framework identifying environmental favorability, which controls the balance between reproduction and immigration, as the ultimate source and species stress tolerance as a proximate factor. Thus, under harsh conditions, only a few tolerant species can reproduce, while some sensitive species can be present in low numbers due to chance immigration. This would lead to high abundance inequality between the two groups of species. Under benign conditions, both groups can reproduce and give rise to higher abundance equality. To test these ideas, I examined the variability in the parameters of a Poisson lognormal fit of the SAD and a square root fit of the RAD in diatom and fish communities across US streams. Indeed, as environmental favorability increased, more sensitive forms were able to establish large populations, diminishing the abundance disparity between locally common and rare species. Finally, it was demonstrated that in diatoms, the RAD belonged to the same family of relationships as those of population density with body size and regional distribution.

Inter-annual species-level variations in an abyssal polychaete assemblage (Sta. M, NE Pacific, 4000 m)

Understanding the dynamics of abyssal community structure and function has become increasingly important as deep-sea resource exploitation and climate change pressures are expected to ramp up. This time-series study investigates macrofaunal polychaete dynamics at a station in the North East Pacific (Sta. M; 35° N 123° W, 4000m, 1991–2011). Infaunal polychaete species were identified and their proxy biomass and proxy energy use rate estimated. The assemblage comprised 167 species, having a composition consistent with other abyssal areas globally. Significant changes in univariate and multivariate parameters (rank abundance distribution, Simpson’s diversity index, and species and functional group composition) were detected across 1991–2011. However, no change in biomass or energy use rate was apparent through the time-series. The largest changes in the polychaete assemblage coincided with both an increase in sinking particulate organic carbon flux to the seafloor in 2007, and a 40km relocation of the sampling location to a site 100m shallower, preventing a conclusive assessment of which might drive the observed variation. Analyses prior to the change of sampling location showed that the polychaete assemblage composition dynamics were primary driven by food supply variation. Changes in several species were also lagged to changes in POC flux by 4–10months. The polychaete fauna exhibited a significant positive relationship between total density and total energy use rate, suggesting population-level tracking of a common resource (e.g. POC flux food supply). Neither compensatory nor energetic zero-sum dynamics were detected among the polychaete assemblage, but the results suggest that the latter occur in the macrofaunal community as a whole. The results do indicate (a) potential control of species composition, and the density of individual key species, by food supply, when the time-series prior to the sampling location was analysed separately, and (b) generally sensitive detection of environmental change by species-level analysis of the abyssal polychaete assemblage.

A new method to analyse species abundances in space using generalized dimensions

Summary Species–area relationships (SAR) and species‐abundance distributions (SAD) are among the most studied patterns in ecology, due to their application to both theoretical and conservation issues. One problem with these general patterns is that different theories can generate the same predictions, and for this reason, they cannot be used to detect different mechanisms of community assembly. A solution is to search for more sensitive patterns, for example by extending the SAR to the whole SAD. A generalized dimension (Dq) approach has been proposed to study the scaling of SAD, but to date, there has been no evaluation of the ability of this pattern to detect different mechanisms. An equivalent way to express SAD is the rank‐abundance distribution (RAD). Here I introduce a new way to study SAD scaling using a spatial version of RAD: the species‐rank surface (SRS), which can be analysed using Dq. Thus, there is an old Dq based on SAR (), and a new one based on SRS (). I perform spatial simulations to examine the relationship of Dq with SAD, spatial patterns and number of species. Finally, I compare the power of both Dq, SAD, SAR exponent and the fractal information dimension to detect different community patterns using a continuum of hierarchical and neutral spatially explicit models. The SAD, and all had good performance in detecting models with contrasting mechanisms. , however, had a better fit to data and allowed comparisons between hierarchical communities where the other methods failed. The SAR exponent and information dimension had low power and should not be used. SRS and could be interesting methods to study community or macroecological patterns.