Species Abundance Distribution Research Articles

The Contributions of Sub-Communities to the Assembly Process and Ecological Mechanisms of Bacterial Communities along the Cotton Soil–Root Continuum Niche Gradient

Soil microbes are crucial in shaping the root-associated microbial communities. In this study, we analyzed the effect of the soil–root niche gradient on the diversity, composition, and assembly of the bacterial community and co-occurrence network of two cotton varieties. The results revealed that the bacterial communities in cotton soil–root compartment niches exhibited a skewed species abundance distribution, dominated by abundant taxa showing a strong spatial specificity. The assembly processes of the rhizosphere bacterial communities were mainly driven by stochastic processes, dominated by the enrichment pattern and supplemented by the depletion pattern to recruit bacteria from the bulk soil, resulting in a more stable bacterial community. The assembly processes of the endosphere bacterial communities were determined by processes dominated by the depletion pattern and supplemented by the enrichment pattern to recruit species from the rhizosphere, resulting in a decrease in the stability and complexity of the community co-occurrence network. The compartment niche shaped the diversity of the bacterial communities, and the cotton variety genotype was an important source of diversity in bacterial communities within the compartment niche. We suggest that the moderate taxa contribute to significantly more changes in the diversity of the bacterial community than the rare and abundant taxa during the succession of bacterial communities in the cotton root–soil continuum.

Evaluation of the exposure of the Mediterranean biodiversity to marine litter: the ASI – plastic busters MPAs projects connection

A number of marine species in the Mediterranean are threatened by the presence of several pressure factors, which include climate change, collisions with vessels, entanglement and ingestion of marine litter, especially plastic. Risk reduction policies can only be conceived starting from an accurate analysis of the exposure to such pressure factors. To estimate spatial abundance of both marine species and plastic litter and to assess the exposure risk, a two-stage analysis approach was applied, using aerial survey data from the ACCOBAMS Survey Initiative (ASI), in synergy with the Plastic Busters MPAs (PB MPAs) project. First, a detection function was fitted to observation data to obtain detection probabilities for individuals, then a Generalized Additive Model (GAM) was employed to estimate the spatial distribution of relative abundance, based on survey observations. A bivariate Local Indicator of Spatial Association (LISA) was then applied to the maps of relative abundance to derive risk maps of exposure of marine species to marine litter. The maps, obtained with a spatial resolution of about 10 km, allow us to identify areas with the highest neighboring abundance of taxa and marine litter, in particular for the MPAs studied by the PB MPAs project, which include the North-Western Mediterranean (Pelagos Sanctuary and Tuscan Archipelago), the Ionian and Aegean Sea (Zakynthos), and the Strait of Sicily (Cabrera Archipelago).

Larval fish community in the Bay of Whales (eastern Ross sea): Species composition, relative abundance and spatial distribution

Early life stages of fish represent a key component in the food chain of the pelagic ecosystem of the Southern Ocean, connecting producer trophic levels to those of higher predators. Pelagic larvae and early juveniles of notothenioid fishes overwhelmingly dominate the ichthyoplankton community living on the continental shelf. Scientific research surveys targeting early life stages of fish in the pelagic realm have been mainly carried out in the western Ross Sea, whereas the eastern side can be considered unexplored. As source of high primary production, the presence and timing of formation of wide ice-free areas throughout the year in the Ross Sea play a fundamental role in structuring larval fish community. The Ross Ice Shelf Polynya (RISP) is a large coastal polynya, which is driven and maintained by local prevailing winds and oceanic currents. In the present study, we report the first data on species composition, relative abundance and spatial distribution of larval fish community found off the Bay of Whales in the eastern Ross Sea. As reported for other areas of the Ross Sea, the Antarctic silverfish Pleuragramma antarcticum was by far the most abundant species, followed by other nototheniids and channichthyids in smaller amounts. The huge abundance of P. antarcticum early larvae supports the hypothesis of a potential nursery area near the Bay of Whales. Present results strongly advocate for future investigations in these poorly known and remote areas.

Reconsidering the Price equation: Benchmarking the analytical power of additive partitioning in ecology

The Price approach allows the partitioning of composite variables into a set of additive components and has become an important tool in evolutionary and ecological research. However, because such components are not mutually independent and might be constrained by the inherent data structure, comparing and interpreting Price partitions among different datasets is not straightforward and has contributed to controversy in ecology.Here we discuss and develop null model approaches that might be used as statistical standards to normalise partition values and reduce collinearity between partitions. We use a simulation approach to estimate Price partitions of artificial data and their randomisations. Using structural equation modelling we then reveal the degree of collinearity between raw and standardised partitions.We first demonstrate that the degree of collinearity between partitions strongly depends on the data structure and then provide a general framework for null model selection. Null models that require limited additional information on the possible distribution of species richness and abundance perform best. These null models consistently reduce, but do not fully eliminate, collinearity between partitions. They assign separate type I and II error levels to each partition that differed among partitions.We argue in favour of null models that strike a balance between information need (simplicity) and complexity of additional information, but we discourage the use of simple permutation approaches that have been successful for analysing other biodiversity measures such as species richness. We highlight that the interpretation of additive partitions of complex ecological data will benefit from analyses of the dependence among partitions.

Thermal performance of ecosystems: Modeling how physiological responses to temperature scale up in communities

Understanding how ecosystems respond to their environmental temperature is a major challenge. Thermodynamic constraints on species’ metabolic rates are expected to affect ecosystem characteristics, but species interactions and interspecific variation in physiological thermal response curves (TRC) may obscure ecosystem-level responses to temperature. As a result, macroecological patterns related to temperature are still poorly understood.We investigate how physiological TRC scale up to ecosystem-level thermal responses by modifying the Tangled Nature (TaNa) model, a stochastic network model of ecology and evolution. We include new parameterizations that make reproduction, death, and mutation temperature-dependent. We find that ecosystem survival probability depends on how the minimum fitness required for species survival varies with temperature. The thermal response of ecosystem survival probability is the only ecosystem property that is sensitive to interspecific variation in TRC. Species richness scales up directly from the TRC of mutation rate, and average species population sizes are inversely related to mutation rate, with Species Abundance Distributions (SADs) exhibiting more rare species in warmer temperatures. Interactions between species are also inversely related to mutation, with positive interactions occurring more frequently in colder temperatures. The abundance of surviving ecosystems is not sensitive to temperature. This work helps clarify the specific relationships between physiological responses to temperature and ecosystem-level repercussions when species are interacting and adapting to their thermal environments.

Deviation from neutral species abundance distributions unveils geographical differences in the structure of diatom communities.

In recent years, the application of metagenomics techniques has advanced our understanding of plankton communities and their global distribution. Despite this progress, the relationship between the abundance distribution of diatom species and varying marine environmental conditions remains poorly understood. This study, leveraging data from the Tara Oceans expedition, tests the hypothesis that diatoms in sampled stations display a consistent species abundance distribution structure, as though they were sampled from a single ocean-wide metacommunity. Using a neutral sampling theory, we thus develop a framework to estimate the structure and diversity of diatom communities at each sampling station given the shape of the species abundance distribution of the metacommunity and the information of a reference station. Our analysis reveals a substantial temperature gradient in the discrepancies between predicted and observed biodiversity across the sampled stations. These findings challenge the hypothesis of a single neutral metacommunity, indicating that environmental differences substantially influence both the composition and structure of diatom communities.

The Spatiotemporal Dynamics of Insect Predator-Prey System Incorporating Refuge Effect.

The insect predator-prey system mediates several feedback mechanisms which regulate species abundance and spatial distribution. However, the spatiotemporal dynamics of such discrete systems with the refuge effect remain elusive. In this study, we analyzed a discrete Holling type II model incorporating the refuge effect using theoretical calculations and numerical simulations, and selected moths with high and low growth rates as two exemplifications. The result indicates that only the flip bifurcation opens the routes to chaos, and the system undergoes four spatiotemporally behavioral patterns (from the frozen random pattern to the defect chaotic diffusion pattern, then the competition intermittency pattern, and finally to the fully developed turbulence pattern). Furthermore, as the refuge effect increases, moths with relatively slower growth rates tend to maintain stability at relatively low densities, whereas moths with relatively faster growth rates can induce chaos and unpredictability on the population. According to the theoretical guidance of this study, the refuge effect can be adjusted to control pest populations effectively, which provides a new theoretical perspective and is a feasible tool for protecting crops.

Fewer bowl traps and more hand netting can increase effective number of bee species and reduce excessive captures.

Reports increasingly point to substantial declines in wild bee abundance and diversity, yet there is uncertainty about how best to measure these attributes in wild bee populations. Two commonly used methods are passive trapping with bee bowls or active netting of bees on flowers, but each of these has drawbacks. Comparing the outcomes of the two methods is complicated by their uncomparable units of effort. The abundance distribution of bee species is also typically highly skewed, making it difficult to accurately assess diversity when rarer species are unlikely to be caught. The effective number of species, or Hill numbers, provides a way forward by basing the response metric on the number of equally abundant species. Our goal is to compare the effective number of bee species captured between hand netting and bowl trapping in wheatgrass prairie in South Dakota and tallgrass prairie in Minnesota, USA. Species overlap between the two methods ranged from ~40% to ~60%. Emphasis placed on rare species was important, so that 95% confidence limits overlapped between the two methods for species richness but netting exceeded trapping for Shannon's and Simpson's diversities. Netting always captured more bee species with fewer bee individuals than trapping. In most cases, the number of bees captured in bowl traps indicated substantial over-sampling, with little increase in bee species detected. Correlations between bee and floral abundance, richness, and diversity differed between netted and trapped samples. We conclude that netting and trapping together produce a more complete account of species richness, but shifting sampling emphasis from trapping to netting will result in fewer bees, but more bee species captured. Due to the different relationships between bee and floral diversities that depended on sampling method, it is unwise to compare habitat associations determined by netting with those determined by trapping.

Diversity and dynamics of tintinnids communities from Romanian Black Sea, in 2021

Tintinnids are tiny ciliates from microzooplankton that are very important due to their implication in the microbial food web and for the fact that in the last two decades a considerable number of non-indigenous species have entered and acclimatized in the Black Sea basin. The paper presents the species diversity and dynamic of microzooplanktonic tintinnids’ abundance as a result of two cruises carried out in May-June and August-September 2021, along the Romanian Black Sea coast. We identified 23 tintinnid species in total, with a higher diversity in the surface layer compared to those of depth. The species Eutintinnus sp. and Salpingella decurtata were found eclusively in the 10 m layer. Tintinnopsis cylindrica represented 74% of the mean biomass of tintinnid’s community from May-June, the best quantitative representation recorded in the Romanian coast's northern sector. Amphorellopsis acuta represented 91% of the mean biomass of tintinnid’s community in August-September. The biotic component was also correlated with temperature and salinity to give more information regarding spatial and temporal variations from one area to the other. The findings contribute to the knowledge of microzooplankton communities in the Romanian Black Sea region. The data on species composition, abundance distribution, and environmental correlations enhance our understanding of the ecological dynamics and potential ecological implications of tintinnid communities. This study brings valuable information to the understanding of the microzooplankton component in the Black Sea ecosystem.

A model for the hydrogenation and charge states of fullerene C60. Implications for diffuse interstellar band research

The diffuse interstellar bands (DIBs) are a set of sim 600 absorption features at optical and near-infrared wavelengths that are found in the interstellar medium in the Milky Way and other galaxies. They remain mostly unidentified and represent the greatest unsolved mystery in astronomical spectroscopy of the past 100 years. Many studies indicate that the carrier molecules are likely carbonaceous molecules, such as polycyclic aromatic hydrocarbons (PAHs) or fullerenes, a theory that is supported by the identifications of five DIBs in the near-infrared attributed to C$_ This work aims to narrow down which compounds related to C$_ $ could be promising DIB carrier candidates.\ We did so by conducting a theoretical study of its hydrogenation and charge balance. We defined a system of relevant reactions, and for each reaction we computed or derived from the literature a reaction rate coefficient. Assuming a steady state, we then computed a distribution of relative abundances in each hydrogenation and charge state. From the model outcomes, we expect the most abundant hydrogenated buckminsterfullerene compound in the diffuse interstellar medium to be C$_ $H$^+$.

Potential roles of the interactions between gut microbiota and metabolites in LPS-induced intrauterine inflammation (IUI) and associated preterm birth (PTB)

BackgroundPrenatal exposure to intrauterine inflammation (IUI) is a crucial event in preterm birth (PTB) pathophysiology, increasing the incidence of neurodevelopmental disorders. Gut microbiota and metabolite profile alterations have been reported to be involved in PTB pathophysiology.Method and resultsIn this study, IUI-exposed PTB mouse model was established and verified by PTB rate and other perinatal adverse reactions; LPS-indued IUI significantly increased the rates of PTB, apoptosis and inflammation in placenta tissue samples. LPS-induced IUI caused no significant differences in species richness and evenness but significantly altered the species abundance distribution. Non-targeted metabolomics analysis indicated that the metabolite profile of the preterm mice was altered, and differential metabolites were associated with signaling pathways including pyruvate metabolism. Furthermore, a significant positive correlation between Parasutterella excrementihominis and S4572761 (Nb-p-coumaroyltryptamine) and Mreference-1264 (pyruvic acid), respectively, was observed. Lastly, pyruvic acid treatment partially improved LPS-induced IUI phenotypes and decreased PTB rates and decreased the apoptosis and inflammation in placenta tissue samples.ConclusionThis study revealed an association among gut microbiota dysbiosis, metabolite profile alterations, and LPS-induced IUI and PTB in mice models. Our investigation revealed the possible involvement of gut microbiota in the pathophysiology of LPS-induced IUI and PTB, which might be mediated by metabolites such as pyruvic acid. Future studies should be conducted to verify the findings through larger sample-sized animal studies and clinical investigations.

Latitudinal richness patterns in a temperate forest region: disentangling the effects of evenness, density and aggregation

It is well known that species diversity declines with increasing latitude. However, the underlying causes and mechanisms remain ambiguous due to effects of scale, the shape of the species abundance distributions (SAD), the total number of individuals (N) and the spatial aggregation of individuals (AGG). In this study, we examine how SAD, N and AGG contribute to the latitudinal richness gradient. Our study is based on a dataset that includes tree, shrub, and herbaceous plants collected from 445 permanent forest plots scattered across an expansive temperate forest region, covering latitudes from 39.71°N to 53.37°N. We compared multiple diversity patterns along the latitude between three life forms (trees, shrubs and herbs) and analyzed the effects of SAD, N and AGG on the latitudinal richness gradient. Our results reveal a general decline in most diversity measures along the latitudinal gradient, with the exception of herbaceous plants. Furthermore, we observed consistent effects of AGG and SAD on the latitudinal richness gradient across all three life forms. Specifically, a decreasing species evenness with increasing latitude led to a reduction in richness, while the simultaneous decrease in spatial aggregation, along with the effects of total number of individuals, collectively contributed to the decline in species richness with increasing latitude. However, the effect of total abundance varies among life forms, with a negligible effect on tree richness, a negative effect on shrub richness, and a significantly positive effect on herbaceous richness. These findings highlight the dependency of the “more-individuals hypothesis” on specific life forms. Our study shows that decomposing species richness into community structure components provides an opportunity for linking specific processes to latitudinal diversity gradients.

Automatic differentiation of Eucalyptus species through Sentinel-2 images, Worldview-3 images and LiDAR data

Eucalyptus constitutes one of the most common tree genera used in forest plantations worldwide. In Europe, Eucalyptus trees are especially common in the Northwest of the Iberian Peninsula, E. nitens and E. globulus being the most commonly cultivated species. Each species presents particularities that lend to different exploitation strategies and industrial usages. Therefore, updated knowledge about the abundance and spatial distribution of the different species is important for forest planning. This is a special challenge for areas where forest land is highly fragmented. Remote sensing has been used to efficiently monitor the distribution of the Eucalyptus genera, however little research has been able to map specific Eucalyptus species. This study evaluates the efficiency of Sentinel-2 data, Worldview-3 images, and Airborne LiDAR data in the differentiation of E. nitens and E. globulus. Supervised classifications were performed using neural networks for these data sets both individually and in combination. The highest accuracies were obtained when using Sentinel-2 data in combination with LiDAR point clouds and when using Sentinel-2 data in a multitemporal approach. The best time of year to differentiate between the two species is during the emergence of spring shoots. Worldview-3 images have a moderate capacity to differentiate between the two species, although this is increased when textural metrics are included. This study can serve as the basis for generating Eucalyptus species distribution maps, which will allow for improved forest management and planning.

Controls on long-term changes in bathyal bivalve biomass: The Pleistocene glacial–interglacial record in the eastern Mediterranean

The biomass of aquatic organisms largely determines the mass and energy flow within an ecosystem, but the long-term impact of environmental change on biomass is not well constrained for a number of clades. Here, we test the hypothesis that bivalve biomass is negatively impacted by warming climate over time. This study is based on a fossil marine bivalve fauna recovered from hemipelagic sediments deposited in the eastern Mediterranean during climate cycles (marine isotope stages (MIS) 22–18; 900–712 kyr B.P.) of the Early–Middle Pleistocene Transition. We reconstruct individual shell biomasses from fossils and discuss the various biotic and abiotic factors that controlled long-term shell biomass patterns across this important interval in the Earth climate system. The results are contrary to the original hypothesis, suggesting that the response to temperature is not universal. Nevertheless, a decrease in median biomass is observed during the MIS 19 warm period and can be possibly attributed to the combined effect of multiple drivers that cooperated at that critical time in the past, including higher temperature and primary productivity, reduced ventilation of the sea floor, biodiversity changes due to geographic range shifts, and considering species- and age-specific thermal tolerances. Generally, bivalve biomass at the community level is determined by relative abundance and shell biomass-frequency distribution. In our study, the relative abundance and median biomass of small species do not increase or decrease, respectively, in warmer periods. However, larger species are negatively affected by warming both in terms of relative abundance and biomass.

Understory vegetation diversity patterns of Platycladus orientalis and Pinus elliottii communities in Central and Southern China.

As a vital component of arbor forests, understory vegetation serves as an essential buffer zone for storing carbon due to its strong capacity for community regeneration. This study aimed to identify the diversity pattern and construction mechanism of Platycladus orientalis and Pinus elliottii understory vegetation based on large-scale sample surveys. The Bayesian Information Criterion value of species abundance distribution (SAD) indicated that the Zipf and Zipf-Mandelbrot models were the best-fitting models. The SAD and gambin fitting results suggested that the Pi. elliottii community had a more balanced structure, with most species being relatively abundant. The multiple regression tree model detected four and six indicator species in P. orientalis and Pi. elliottii communities, respectively. The α-diversity index increased with a rise in altitude and showed a wavy curve with latitude. Linear regression between the β diversity and environmental and geographic distance indicated that the P. orientalis and Pi. elliottii understory communities tended to be dominated by different ecological processes. The partition of β diversity indicated that both communities were dominated by turnover processes, which were caused by environmental classification or spatial constraints. This study helped to understand the diversity maintenance in the P. orientalis and Pi. elliottii understory vegetation communities, and will benefit for diversity restoration and conservation of pure conifer forests.

The influence of environmental context on community composition in artificial rockpools associated with seawalls

Artificial structures have become widespread features of coastal marine environments, and will likely proliferate further over the coming decades. These constitute new hard substrata in the marine environment which provide a fundamentally different habitat than natural shores. Eco-engineering solutions aim to ameliorate these differences by combining ecological knowledge and engineering criteria in the construction and modification of artificial substrata. Vertipools™ are artificial bolt-on rockpools intended for deployment on seawalls, where they have been shown to provide biodiversity benefits. In this study, a total of 32 Vertipools were retrofitted on eight seawalls in different environmental contexts (estuarine vs marine and urban vs rural) along the Irish Sea coastline, and were exposed to the environment for a period of two years. After two years, there were no differences in species richness, species-abundance distributions, diversity, or community composition between the specific environmental contexts examined here. Site-level variation was significant, and communities on Vertipools deployed in marine contexts were more variable in general than those in estuarine contexts. Community composition differed significantly between structural sections of the Vertipools, indicating that different sections provide specific microhabitats for colonisation. This study indicates that Vertipools provide biodiversity benefits in a variety of environmental contexts, and therefore are broadly viable as an eco-engineering solution.

The Impact of Goat Milk Pretreatment with Pulsed Electric Fields on Cheese Quality.

To reduce the microbial load in goat's milk, which is less thermally stable than cow's milk, an alternative processing method was used in this study. This involved treating the milk with pulsed electric fields (PEFs) (at 10 kV·cm-1, with 50 µs pulses for 3 Hz) and then heat-treating it at 63 °C for 6.0 s, as well as using heat treatment alone at 75 °C for 3.4 s. Cheeses were made using both types of milk treatment, and samples were collected after 5, 15, and 25 days of ripening for DNA extraction and purification, followed by high-throughput sequencing on the MiSeq Illumina sequencing platform. Analysis of the bacterial populations in the two types of cheese using various diversity indices revealed no significant differences in species richness and abundance, although there was a trend for the PEF-treated cheese to have a less diverse set of species with an uneven distribution of relative abundance. However, when examining the composition of the microbial communities in the two types of cheese using Weighted UniFrac analysis and Analysis of Similarities, there were significant differences in the presence and abundance of various species, which could have implications for the development of starter cultures. Concerning physicochemical properties (pH, aw, moisture content, total acidity and L, and a and b color parameters), the results also reveal that, generally, no significant differences were found, except for the color parameter, where cheeses treated with PEF demonstrated more whiteness (L) and yellowness (b) during ripening. Sensory scores for typicity (caprylic, goaty, and acetic) increased over time, but between treatments, only small differences were perceived by panellists in cheese with 5 days of ripening. Concerning texture firmness and cohesiveness, the PEF+HT samples presented lower values than the HT samples, even over storage time. In general, concerning quality parameters, similar behavior was observed between the treatments during the ripening period.

Cisco population characteristics in Wisconsin lakes in relation to lake‐ and landscape‐level factors

AbstractObjectiveDeclines in Cisco Coregonus artedi populations in some inland lakes have prompted assessments of Cisco occurrence and extirpation risk in relation to various stressors to identify refuge lakes and factors that promote Cisco persistence. However, most previous assessments have focused on presence–absence of Cisco rather than examining how population characteristics, such as relative abundance or growth, might change in relation to lake‐ and landscape‐level environmental factors. Consequently, our specific objectives were to identify important environmental factors explaining variation in Cisco relative abundance and growth and to determine whether population metrics describing size and age distributions were related to relative abundance in Wisconsin inland lakes.MethodsCisco were collected from 48 inland Wisconsin lakes during 2011–2015 using vertical monofilament gill nets and population‐specific relative abundance estimates (catch per unit effort [CPUE]) were quantified as the number of individuals per gill‐net night. Sagittal otoliths were removed from a subsample of Cisco for age estimation and growth was indexed as mean total length (TL; mm) at age 2. Length and age data were used to develop a suite of metrics describing size and age distributions of each population. Random forest models were used to evaluate relationships between 10 biologically relevant predictor variables representing variation in physical, climatic, catchment, and limnological characteristics and Cisco CPUE and growth. Pearson correlations were used to determine whether population characteristics were related to CPUE.ResultCisco populations exhibited large variation in relative abundance, growth, and size and age distributions. Best‐fit random forest models explained approximately 25% of the variation in Cisco CPUE and 46% of the variation in growth. Growing degree‐days and variables associated with availability, quality, and quantity of suitable oxythermal conditions were identified as important predictors of both Cisco CPUE and growth; CPUE was also identified as an important predictor of growth. Mean TL and mean TL at age 2 were negatively related to Cisco CPUE, whereas mean age, number of age‐classes present, and maximum observed age were positively related to CPUE.ConclusionOur results suggest that maintenance of suitable oxythermal habitat conditions may be critical to conserving abundant Cisco populations. Our assessment also provides insights on how Cisco populations may respond to environmental and anthropogenic stressors, which could aid ongoing and future conservation and management efforts in Wisconsin and elsewhere.

Comparing diversity of the terrestrial mammal communities inhabiting native forests and exotic plantations in southern Chile

The mammal community of the Coastal Range of southern Chile has been little studied even though they inhabit an environment under severe threats due to anthropic disturbance. During the spring-summer seasons of 2020–2021 and 2021–2022, we characterized the communities of wild terrestrial mammals in a native forest (NF) and an exotic plantation of Eucalyptus (PL) of the Coastal Range of Osorno province by phototrapping. We used 1,060 camera-trap days in the NF and 960 camera-trap days in the PL to explore the effect of habitat type on wild mammal diversity in two localities (L-1 and L-2). We quantified the species richness, abundance, community similarity and daily distribution of mammal communities. Species richness was higher in the NF (7–8 spp) than in the PL (3–4 spp). Two community similarity index (CSI) was significantly higher between native forests (CSI = 0.728 ± 0.088) than between Eucalyptus plantations (CSI = 0.211 ± 0.097) (95% CI). Mean abundance was also higher in the NF than in the PL (L-1: 0.011 vs. 0.004 occurrence/camera-trap day (OCT); L-2: 0.008 vs. 0.004 OCT). In L-1, the most abundant mammals in the NF were Leopardus guigna (45.3% of relative occurrence (RO)) and Pudu puda (18.9% RO), and in the PL, they were Lycalopex culpaeus (50% RO) and L. guigna (37.5% RO). In L-2, the highest abundances in the NF were for P. puda (34.5% RO) and Puma concolor (27.6% RO), while in the PL, P. puda was predominant (66.7% RO). In NF of both localities, 22.2% of melanic L. guigna individuals were observed. The highest frequency of occurrences in both locations was between 12:00 and 23:59 hours, with 60% and 76.9% of detections, respectively. The species richness found in native forest is in accordance with studies carried out in other temperate rainforests of southern Chile. In addition, native forests support a richer and more similar community of terrestrial mammals than exotic forest plantations, which indicates that native forests are the main habitat for most mammals detected and that exotic plantations function as a complementary habitat for some species.

Exploring intrinsic distribution of phytoplankton relative abundance and biomass in combination with continental-scale field investigation and microcosm experiment

Phytoplankton are primary producers in aquatic ecosystems and their diversity directly affects the community stability and primary productivity. However, the commonly used diversity indices (such as Shannon and Pielou indices) were originally derived from other fields rather than ecology and did not have a direct biological explanatory function. There is still a need to incorporate biological explanatory functions into diversity evaluation methods and theories to bridge the gap between phytoplankton biodiversity and biological characteristics. This study aimed to explicate the intrinsic distribution patterns of phytoplankton relative abundance and biomass. Our study demonstrated an exponential distribution pattern of phytoplankton relative abundance and biomass ranking through field investigations of 367 phytoplankton samples in China and microcosm experiments, respectively. Microcosm experiments illustrated that the linear distribution of the specific growth rate ranking resulted in an exponential distribution of the relative phytoplankton biomass ranking due to exponential growth patterns. Through mathematical deduction, it was found that the three indices a, k and N in the exponential distribution could be considered as the critical relative abundance of extinction, competition coefficient and the environmental taxa capacity, respectively. We found that a was positively correlated with Shannon index and Pielou index, k was negatively correlated with Shannon index, Pielou index and Chao1 index. In addition, N and Chao1 index were almost exactly the same. Our study obtained these indices based on the distribution pattern of phytoplankton, enabling a comprehensive analysis of the phytoplankton community and providing novel insights for further evaluating the health of aquatic ecosystems.