Population Abundance Research Articles

Effects of sampling effort and data sources on precision of common carp and bigmouth buffalo population estimates

Biologists often manage abundant invasive Common Carp (Cyprinus carpio) populations for suppression below population density or biomass thresholds via commercial harvest that also removes large numbers of native Bigmouth Buffalo (Ictiobus cyprinellus). Thus, biologists need population estimates to monitor abundance but often avoid them due to the time and effort required to produce population estimates and pervading estimate imprecision. While population abundance of these fishes can be challenging to estimate, commercial fishers harvest large numbers of fish that could improve population estimates with less effort from biologists. Yet, how population estimates from fishery-dependent and fishery-independent data sources compare is unknown. We compared the precision of Schnabel fishery-independent (electrofishing) and Lincoln-Petersen fishery-dependent (commercial harvest) population estimates for Common Carp and Bigmouth Buffalo in seven northwest Iowa lakes. We then assessed how sampling effort and environmental factors affected the number of fish recaptured by electrofishing and how the number of fish marked and recaptured affected estimate variability. Lincoln-Petersen estimates were more precise and provided similar abundance estimates compared with Schnabel estimates for Bigmouth Buffalo, while both models provided comparable population estimates and precision for Common Carp. Common Carp electrofishing recaptures were positively related to electrofishing effort, number of fish tagged, lake size, and water temperature. Bigmouth Buffalo recaptures were positively related to number of fish tagged and negatively related to lake area and water temperature. Coefficient of variation for fishery-dependent estimates declined with number of fish tagged and recaptured; 750 Common Carp and 150 Bigmouth Buffalo needed to be marked at large to obtain precision of CV ≤ 0.25. Our results suggest Lincoln-Petersen estimates with fishery-dependent data represent an improvement over fishery-independent estimates for Bigmouth Buffalo while both techniques provided comparable estimates for Common Carp. Incorporating harvest data into population estimates can reduce sampling effort while improving or maintaining precision.

A new dawn? Population baselines of snow leopards and other mammals of the Kishtwar High Altitude National Park, India

AbstractAccurately assessing the status of threatened species requires reliable population estimates. Despite this necessity, only a small proportion of the global distribution range of the vulnerable snow leopard (Panthera uncia) has been systematically sampled. The Indian section of the Greater Himalayas, which includes Kishtwar High Altitude National Park (KHANP), harbours potential snow leopard habitat. Nevertheless, there has been limited ecological and conservation research focusing on species that are specific to KHANP, as well as limited research on the broader biodiversity of the Greater Himalayas. We used Spatially Explicit Capture‐Recapture (SECR) models to provide—to our knowledge—the first robust snow leopard population density and abundance estimates from KHANP. We also provide a Relative Abundance Index (RAI) for non‐volant mammals (excluding small rodents). Our study sampled three catchments within the Dachhan region of KHANP—Kibber, Nanth and Kiyar—using 44 cameras over a 45‐day period between May and June 2023. We identified four unique snow leopard individuals across 15 detections in nine camera locations. SECR analysis estimated a density of 0.50 snow leopards per 100 km2 (95% confidence interval: 0.13–1.86), corresponding to an abundance of four individual (4–9) adults. Camera trapping revealed a total of 16 mammal species, including the endangered Kashmir musk deer (Moschus cupreus). Marmots (Marmota caudata) had the highest RAI of 21.3 (±0.2). Although the estimated density and abundance of snow leopards in our study area had relatively wide 95% confidence intervals, our combined results of snow leopard densities and RAIs of prey species such as ibex and marmots indicate that KHANP is a potentially important area for snow leopards. Given the geopolitical history of Jammu and Kashmir in India, the region where KHANP is located, wildlife research remains a low priority. We hope our study encourages authorities to support further research. This study is an initial step towards evaluating the potential of KHANP as a conservation landscape under the Government of India's Project Snow Leopard.

Impact of superabsorbent hydrogels on microbial community and atrazine fate in soils by 14C-labeling techniques

The accumulation of atrazine in soils can create environmental challenges, potentially posing risks to human health. Superabsorbent hydrogel (SH)-based formulations offer an eco-friendly approach to accelerate herbicide degradation. However, the impact of SHs on soil microbial community structure, and thus on the fate of atrazine, remains uncertain. In this study, a radioactive tracer was employed to investigate the influence of SHs on microbial communities and atrazine transformation in soils. The results revealed that the mineralization of atrazine in active soils was considerably greater than that in sterilized soils. Atrazine degradation proceeded rapidly under SH treatment, indicating the potential of SH to accelerate atrazine degradation. Furthermore, SH addition did not alter the atrazine degradation pathway in soils, which included dealkylation, dechlorination and hydroxylation. The relative abundance of dominant microbial population was influenced by the presence of SHs in the soil. Additionally, SH application led to an increased relative abundance of Lysobacter, suggesting its potential involvement in atrazine degradation. These findings reveal the significance of soil microorganisms and SH in atrazine degradation, offering crucial insights for the development of effective strategies for atrazine remediation and environmental sustainability.

Modulating butyric acid-producing bacterial community abundance and structure in the intestine of immunocompromised mice with neutral polysaccharides extracted from Codonopsis pilosula

Codonopsis pilosula, an important medicinal and edible plant in traditional Chinese medicine, is used widely as a tonifying herb for various immunodeficiency diseases. A neutral polysaccharide (CPPs-D1N1) was purified from C. pilosula, composed of fructose and glucose in a molar ratio of 97.28:2.72, with an average molecular weight of 5.985 kDa. Structural analysis revealed a backbone composed of →1)-β-D-Fruf-(2 → units with some β-D-Fruf-(2 → linkages. In a murine immunosuppression model induced by cyclophosphamide injection, oral treatment with C. pilosula polysaccharide was administered, investigating changes in gut microbiota during therapy. The polysaccharide modulated serum immunoglobulins (Ig-G, Ig-M), cytokines (IL-2, IL-6, TNFα), and spleen and thymus indices in immunodeficient mice. Additionally, functional gene primer sequencing enrichment methods revealed alterations in abundance, diversity, and structure of butyrate-producing bacterial populations in the gut, with primary differential genera identified as Butyribacter, Rumanococcus, Dysosmobacter, and Ruseburia. This study provides in vivo evidence supporting the beneficial effects of C. pilosula polysaccharide oral therapy in improving gut microbiota, particularly butyrate-producing bacteria, during treatment of immunosuppressive diseases.

Life history strategies predict responses of lacustrine fish communities to eutrophication

The demographic traits of an organism are key components of its fitness and life history theory aims at identifying the environmental drivers underlying the evolution of life history strategies. For fishes, the equilibrium species, those investing into larval survival (large eggs, parental care) rather than into absolute fecundity, are hypothesized to have evolved in stable and predictable environments with high biotic pressure. Human induced nutrient enrichment in many lakes around the world makes them increasingly subjected to perturbations such as anoxia and toxic algal blooms. We hypothesized that eutrophication results in lakes becoming more unstable, unpredictable and less resource-limited, in turn less favorable to equilibrium species. Another hypothesis states that lacustrine environment stability increases with ecosystem size. This study presents the first attempt to compare the two hypotheses in a group of 26 lakes. We found that the population abundance of equilibrium species was negatively related to increasing eutrophication. Long-lived and highly fecund periodic species responded more positively to eutrophication than short lived opportunistic species, with no parental care. This result could be demonstrated by seasonality in primary productivity which favors periodic species, disconnection from the river which prevents good colonist (i.e., opportunistic) species to (re)-establish after perturbation events, and predation by periodic species on opportunistic species. In contrast, we found no support for the ecosystem size hypothesis. Overall, we showed that human driven eutrophication affected species according to their life history strategies, reinforcing the usefulness of life history theory as a framework for assessing fish community response to a large array of human perturbations. More generally, our study emphasizes the importance of species traits to assess, explain, and predict community responses to human and natural perturbations.

Sociality modulates nutritional carrying capacity of an endangered species

Group living has well-known costs and benefits. Large groups may experience greater competition for resources, while simultaneously benefit from reduced risk through predator dilution. When there is a tradeoff between forage acquisition and predation risk, the ability to congregate into large groups may unlock access to previously unavailable habitat with high risk of predation, thereby increasing forage available to the population. We evaluated whether forage availability increased with population size and how it was mediated through changes in group size. There was a tradeoff between forage availability and predation risk. Larger groups used areas with more forage biomass and greater predation risk than smaller groups. Group size also increased with population abundance, meaning bighorn sheep used gentler terrain and areas with more forage biomass at greater population abundance. Group size functionally increased carrying capacity by yielding access to more resources for growing populations of gregarious ungulates.

The Ediacara Biota of the Wood Canyon formation: Latest Precambrian macrofossils and sedimentary structures from the southern Great Basin

Fossils of the Ediacara Biota preserve the oldest indisputable evidence of macroscopic animal life. Although new finds continue to expand the near global distribution of such organisms, relatively abundant and diverse populations of these primarily soft-bodied taxa are known from just a handful of localities. More commonly, reports of late Precambrian fossils consist of comparably lower diversity assemblages (less than ∼10 genera), with a limited number of total specimens (less than ∼1000 reported macrofossils over a broad geographic area). Determining the factors responsible for such differences can help to fully appreciate preserved patterns of Ediacaran biodiversity.The lower member of the Wood Canyon Formation in the Death Valley region of the southern Great Basin, USA contains fossils of the Ediacara Biota. Here we redescribe previously recovered specimens based on new data from 3D surface scans and report several new finds from this unit. Although this allows the addition of two Ediacara taxa (Pteridinium and Charnia?) to the known diversity in the region, most potential macrofauna consist of amorphous, irregular forms with minimal preserved structures wherein an abiotic origin cannot be ruled out. A combination of factors – including variable taphonomic conditions, difficulty of identification and an original depauperate community – contribute to the observed diversity of this assemblage. Many biases that impact this record are either common (e.g., age, preservation requirements, difficulty of recognition) or comparable (e.g., paleoenvironmental and taphonomic controls) to known occurrences of Ediacara macrofauana. Thus, we argue this fossil record at least partially reflects the original community composition, suggesting that fossils of the lower Wood Canyon record a signal of relatively low diversity of the Ediacara Biota in the lead up to the Ediacaran-Cambrian boundary.

Growth and reproductive toxicity of bisphenol A in Oikopleura dioica at environmentally relevant concentrations

Bisphenol A (BPA), a known endocrine disruptor, is ubiquitous in various aquatic environments. Appendicularians are among the most abundant mesozooplankton populations and occupy a crucial niche in marine ecosystems. However, no toxicological data are available concerning the effects of BPA on this functional group. In this study, an evaluation of the toxicity of environmentally relevant levels of BPA (2.5–150 μg/L) on the appendicularian Oikopleura dioica, including its morphology and transcriptome, was conducted. Our results demonstrated the high sensitivity of O. dioica to BPA, with a LC50 of 142 μg/L. Exposure to 125 μg/L BPA significantly inhibited the somatic growth, gonadal development and reproduction of individuals, whereas exposure to an environmentally safe concentration (2.5 μg/L) affected female fecundity and fitness as well as male gene expression. The results of the transcriptomic analysis suggest that males were more sensitive to BPA stress at the molecular level. BPA exposure not only led to abnormal secretion of digestive enzymes and phospholipase A2, affecting the function of the digestive system and arachidonic acid but also significantly down-regulated the expression of mRNAs related to enzymes involved in carbohydrate and energy metabolism in males. These findings suggest that the current safe environmental concentrations may not be safe.

Mammary gland, skin and soft tissue tumors in pet cats: findings of the feline tumors collected from 2002 to 2022.

Cancer is a leading cause of death in cats, and the rate of such disease has been increasing recently. Nonetheless, feline oncology represents an important area of study not only for the health and wellbeing of cats but also for human health since various types of cancer in cats share similarities to those found in humans. Therefore, epidemiological studies on feline oncology may suggest environmental and genetic factors contributing to cancer in cats, which can eventually be translated to improve human cancer care. To provide an initial understanding of the epidemiology of feline neoplasms, a descriptive study was undertaken using a dataset documenting cases of feline cancer gathered from the Liguria region (northwest Italy) spanning from 2002 to 2022. The database includes tumor location, morphological codes of the International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3), feline's breed, sex, neuter status, date of birth, date of diagnosis, national territorial unit code of the town of the owner's residence, and an alphanumeric string uniquely identifying the owner's surname. The dataset involves a population of 4,399 cats, including 3,195 females (1,425 neutered) and 1,204 males (750 neutered). Our results indicate that mammary gland tumors are the most represented tumors in the female population, while soft tissue and skin cancers appear to have a higher abundance in the male population during the periods investigated (2002-2022). Moreover, Poisson regression analysis showed that not neutered female cats have a significantly increased risk of developing mammary gland tumors compared to the neutered female population [proportional morbidity ratio (PMR) neutered vs. not neutered = 0.58, 95% CI: 0.47-0.72]; meanwhile, for both sexes, for soft tissue and skin tumors, being neutered appears to be a risk factor (PMR neutered vs. not neutered = 2.26, 95% CI: 1.86-2.73; PMR neutered vs. not neutered = 1.16, 95% CI: 0.89-1.51). Finally, the evaluation of the Ligurian municipalities pollution, based on wild boars data (i.e., biomonitors), which coexisted with cats, was correlated to cancer development for all the tumors investigated (in polluted areas, estimated PMRs ranged from 42.61 to 80.13, 95% CI: 29.94-105.11). Overall, the data presented here suggest the use of the feline population as a possible animal model for human health, i.e., sentinel.

Genome-wide association studies reveal the genetic basis of growth and carcass traits in Sichuan Shelduck

China has abundant local duck resource populations, and evaluating the characteristics of these breeds will help improve development and utilization. In this study, we conducted the first investigations of growth and slaughter performance on Sichuan Shelduck (n = 240), an endangered duck local breed. The average body weight is 1497.91g at 90 days of age. According to the growth curve through data recorded every 2 weeks, we observed a low relative growth rate (RGR) for the early growth stage. The RGR shows a decreasing trend with age increasing in the stage from 0 to 56 days of age. The SNP-based heritability estimation showed the growth rate has a relatively high heritability, indicating high genetic stability for this trait. In the correlation analysis, the percentage of leg muscle is positively correlated with the absolute growth rate (AGR) at 28-42 days of age, whereas it is negatively correlated with the earlier stages, exhibiting a time-specific correlation result. Additionally, genome-wide association studies (GWAS) identified PCSK6, TOX2, and TOMM7 as potential candidate genes influencing AGR (42-56) and AGR (56-90), while the candidate genes of slaughter traits were PTP4A2, FAM110B, TOX, UBXN2B, and FCHSD2. These results provide an important reference for further understanding the genetic basis of growth and meat production performance of Sichuan Shelduck.

Phylogenetic proximity drives temporal succession of marine giant viruses in a five-year metagenomic time-series.

Nucleocytoplasmic Large DNA Viruses (NCLDVs, also called giant viruses) are widespread in marine systems and infect a broad range of microbial eukaryotes (protists). Recent biogeographic work has provided global snapshots of NCLDV diversity and community composition across the world's oceans, yet little information exists about the guiding 'rules' underpinning their community dynamics over time. We leveraged a five-year monthly metagenomic time-series to quantify the community composition of NCLDVs off the coast of Southern California and characterize these populations' temporal dynamics. NCLDVs were dominated by Algavirales (Phycodnaviruses, 59%) and Imitervirales (Mimiviruses, 36%). We identified clusters of NCLDVs with distinct classes of seasonal and non-seasonal temporal dynamics. Overall, NCLDV population abundances were often highly dynamic with a strong seasonal signal. The Imitervirales group had highest relative abundance in the more oligotrophic late summer and fall, while Algavirales did so in winter. Generally, closely related strains had similar temporal dynamics, suggesting that evolutionary history is a key driver of the temporal niche of marine NCLDVs. However, a few closely-related strains had drastically different seasonal dynamics, suggesting that while phylogenetic proximity often indicates ecological similarity, occasionally phenology can shift rapidly, possibly due to host-switching. Finally, we identified distinct functional content and possible host interactions of two major NCLDV orders-including connections of Imitervirales with primary producers like the diatom Chaetoceros and widespread marine grazers like Paraphysomonas and Spirotrichea ciliates. Together, our results reveal key insights on season-specific effect of phylogenetically distinct giant virus communities on marine protist metabolism, biogeochemical fluxes and carbon cycling.

Present Status of Fish Diversity and Population Abundance of Selected Fish Species in Khudiya Dam, Mungeli Chhattisgarh, India

Present Status of Fish Diversity and Population Abundance of Selected Fish Species in Khudiya Dam, Mungeli Chhattisgarh, India

Habitat characteristics shaping zoantharians’ distribution at intertidal habitats of the Canary Islands

Ocean warming is facilitating the proliferation of zoantharians worldwide due to their thermophilic affinities. However, other anthropogenic factors, such as declining water quality, have been appointed to favour the occurrence of zoantharians dominated areas and barrens. Subtropical and tropical intertidal habitats are especially vulnerable to zoantharians outbreaks due to the progressive increase in ocean temperature and because it is where most human pressure is concentrated. The aim of this study was to evaluate the abundance of intertidal zoantharians populations, related to habitat characteristics (rugosity and submerged substrate) and the presence of other benthic organisms, such as sessile invertebrates and macroalgae. Number and coverage of zoantharian colonies were recorded in transects (20 × 4 m) along 25 intertidal rocky platforms of the Canarian Archipelago, and photographic techniques in quadrats were used to examine the relationships between the percentage of substrate cover of zoantharians, macroalgae and sessile invertebrates by means of correlations analyses. Results indicated that high levels of rugosity favour the abundance and coverage of Palythoa aff. clavata and Zoanthus pulchellus, and the proportion of submerged substrate was also important in determining Zoanthus coverages. The presence of extensive macroalgae communities was seen to reduce zoantharian coverages, being the only sessile organisms that were able to outcompete them for space in the Canary Islands. Thus, this study provided valuable information about patterns of abundances and coverages of intertidal zoantharians useful for future monitoring of intertidal populations of zoantharians in Canary Islands and their interaction with surrounding marine organisms.

Spatiotemporal plasticity of prey selection in the wolf

AbstractUnder an optimal foraging scenario, prey selection would be expected to occur when food resources are abundant. A positive frequency‐dependent prey selection would elicit prey switching when the abundance of main food resources decreases, potentially favouring community resilience to the effects of intensive, selective predation on a single prey. We assessed whether a positive frequency‐dependent prey selection by the wolf Canis lupus occurred in two areas hosting abundant populations of wild ungulates, one in northern (Słowiński National Park, Poland) and the other one in southern (Maremma Regional Park, Italy) Europe, throughout a cold semester. In Słowiński, ungulate community was dominated by red deer Cervus elaphus (57% availability) over wild boar Sus scrofa (35%) and roe deer Capreolus capreolus (8%); wild boar and fallow deer Dama dama (43–37%) were more abundant than roe deer (20%) in Maremma. In both areas, wolf diet was dominated by wild ungulates, with a major use of red deer in Słowiński and wild boar in Maremma. Prey selection occurred in both areas, and it was addressed towards the most abundant prey in Słowiński, that is, the red deer, but only towards the wild boar in Maremma, where the fallow deer was used according to availability. In Slowinski, high red deer density may have driven wolf prey selection, while the shifting of activity rhythms of the fallow deer in the Maremma as antipredator response to wolf presence may have reduced predation. Despite its comparable densities between the two areas, the wild boar was selected in Maremma and under‐used in Słowiński. Results provide partial support to positive frequency‐dependent selection, emphasising the spatiotemporal plasticity of wolf–prey relationships. The relative role of prey density and other factors (e.g., antipredator behavioural responses) should be assessed at longer temporal scales.

Dispersal limits poleward expansion of mangroves on the west coast of North America

While much attention has been paid to the climatic controls of species' range limits, other factors such as dispersal limitation are also important. Temperature is an important control of the distribution of coastal mangrove forests, and mangrove expansion at multiple poleward range limits has been linked to increasing temperatures. However, mangrove abundances at other poleward range limits have been surprisingly insensitive to climate change, indicating other drivers of range limitation. For example, along the west coast of North America, the poleward mangrove range limits are found on the Baja California and mainland coasts of Mexico, between 26°48ʹ and 30°18ʹN. Non‐climatic factors may play an important role in setting these range limits as 1) the abundance of range limit populations has been relatively insensitive to climate variability and 2) an introduced population of mangroves has persisted hundreds of kilometers north of the natural range limits. We combined a species distribution model with a high‐resolution oceanographic transport model to identify the roles of climate and dispersal limitation in controlling mangrove distributions. We identified estuarine habitat that is likely climatically suitable for mangroves north of the current range limits. However, propagules from current mangrove populations are unlikely to reach these suitable locations due to prevailing ocean currents and geomorphic factors that create a patchy distribution of estuarine habitat with large between‐patch distances. Thus, although climate change is driving range shifts of mangroves in multiple regions around the world, dispersal is currently limiting poleward mangrove expansion at several range limits, including the west coast of North America.

Predicting trawl catches using environmental DNA

Abstract Quantifying the biomass, or number of individuals, diversity, and distribution of marine species is a critical aspect of understanding and managing marine ecosystems. In recent years, there has been growing interest in using environmental DNA (eDNA) for marine ecosystem management and biodiversity assessment. However, the main challenge hindering eDNA applicability has been the inability to infer absolute species abundances from multispecies analysis (eDNA metabarcoding). In this study, we demonstrate a way forward by estimating the abundance of commercially important fish species in a Norwegian fjord using a joint Bayesian statistical model of traditional trawl-catch data and molecular data derived from eDNA. Using this model, we accurately predict out-of-sample trawl catches using eDNA alone. Moreover, our model provides empirical estimates for key processes linking marine eDNA concentration to the fish population abundance estimated from trawl observations, including trawl catchability, DNA shedding, degradation, dilution, transport, recovery rate, and isolation efficiency. These processes, including amplification efficiencies correcting for Polymerase Chain Reaction (PCR) bias, are species-specific and enable the translation of eDNA metabarcoding data into abundances. These findings have broad implications for the use of eDNA in marine ecosystem management and conservation efforts.

Understanding Balanophyllia regia Distribution in the Canary Islands: Effects of Environmental Factors and Methodologies for Future Monitoring

The future of marine ecosystems is at risk due to climate change and other human impacts. Specifically, due to ocean warming, some tropical species are expanding their populations while populations of temperate species are in regression, making the establishment of conservation measures imperative to maintain local biodiversity. In this study we establish a baseline on the distribution and abundance of the temperate coral Balanophyllia regia from the Canary Islands. We found that the main environmental factors determining B. regia’s distribution and abundance were sea surface temperature and hydrodynamic conditions. Areas under large wave action and colder environments enhanced this warm-temperate species’ development. Since its metabolic performance depends exclusively on the surrounding environment, we also propose a methodology to potentially monitor climate change on coastal habitats through this azooxanthellate calcified coral. Results of a tagging experiment showed that a concentration of 20 mg/mL of calcein during 6 h might be enough to in situ label polyps of B. regia without compromising corallite survival. Long-term monitoring of population abundances and growth rates of B. regia through calcein tagging will allow us to identify alterations in local ecosystems early and focus future conservation investments on the most vulnerable areas with higher ecological and economic value.

Accounting for spatio-temporal distribution changes in size-structured abundance estimates for a data-limited stock of Raja clavata

Abstract Vulnerability of elasmobranchs to fishing and declines in populations over the last decades have prompted calls for improved fisheries management and conservation efforts. The Raja clavata (Thornback ray) population in the Greater North Sea ecoregion is a population that has historically shown marked declines with increasing industrialized fishing, while a lack of robust catch data of commercial fisheries hampers assessment of population abundance. Using fisheries-independent survey catch data haul-by-haul surface area estimates, we employ integrated-nested Laplace approximation to estimate total and size-class abundances of R. clavata. By accounting for spatio-temporal changes in the population, size selectivity between survey gears, and minimizing bias from partially overlapping survey areas, we demonstrate major changes in the abundance and distribution over the past three decades. Notably, increases of abundance in the Eastern English Channel and south-eastern North Sea result in an overall increase in the abundance and biomass of the population. Our findings expand understanding of the spatio-temporal dynamics and exploitation of this data-limited stock, emphasizing the potential for improved population abundance estimates to inform future stock assessments.

Asynchronous abundance fluctuations can drive giant genotype frequency fluctuations.

Large stochastic population abundance fluctuations are ubiquitous across the tree of life1-7, impacting the predictability of population dynamics and influencing eco-evolutionary outcomes. It has generally been thought that these large abundance fluctuations do not strongly impact evolution, as the relative frequencies of alleles in the population will be unaffected if the abundance of all alleles fluctuate in unison. However, we argue that large abundance fluctuations can lead to significant genotype frequency fluctuations if different genotypes within a population experience these fluctuations asynchronously. By serially diluting mixtures of two closely related E. coli strains, we show that such asynchrony can occur, leading to giant frequency fluctuations that far exceed expectations from models of genetic drift. We develop a flexible, effective model that explains the abundance fluctuations as arising from correlated offspring numbers between individuals, and the large frequency fluctuations result from even slight decoupling in offspring numbers between genotypes. This model accurately describes the observed abundance and frequency fluctuation scaling behaviors. Our findings suggest chaotic dynamics underpin these giant fluctuations, causing initially similar trajectories to diverge exponentially; subtle environmental changes can be magnified, leading to batch correlations in identical growth conditions. Furthermore, we present evidence that such decoupling noise is also present in mixed-genotype S. cerevisiae populations. We demonstrate that such decoupling noise can strongly influence evolutionary outcomes, in a manner distinct from genetic drift. Given the generic nature of asynchronous fluctuations, we anticipate that they are widespread in biological populations, significantly affecting evolutionary and ecological dynamics.

Characterization of the forehead skin microbiome in the early phase of acne.

The skin microbiota is known to be imbalanced in acne vulgaris, but the changes occurring during the early stages of acne onset remain poorly described. To characterize the skin microbiome of subclinical stages of acne in adults and adolescents. The composition and diversity of the microbiota from non-lesional skin on the forehead of subjects with mild-to-moderate acne were compared to the ones from non-acne subjects. Analyses of skin swab samples were performed using high-throughput sequencing of the V1-V3 regions of the bacterial 16S ribosomal RNA gene, the tuf gene fragment of Staphylococcus species and the internal transcribed spacer (ITS1) region of the fungal rRNA gene to determine the relative abundance, alpha-diversity and beta-diversity of bacteria and fungi. Compared with non-acne subjects, acne subjects had a higher abundance of Cutibacterium (72.4% vs. 57.8%) and lower abundances of Corynebacterium (2.8% vs. 4.8%) and Streptococcus (1.4% vs. 3.2%). Bacterial alpha- and beta-diversity indices also differed significantly between the two groups, reflecting differences in richness, evenness, abundance and phylogenetic distance between bacterial populations. Differences were also observed at the level of Staphylococcus species: S. capitis was predominant in skin samples from non-acne subjects (46.7%), whereas S. epidermidis was the most abundant Staphylococcus species in non-lesional forehead skin areas of acne subjects (44.2%). Conversely, no significant between-group differences were found for fungi, with Malasseziales being the predominant order in both subject groups. Dysbiosis was observed very early in subclinical acne stages of the forehead skin, with the overall abundance, richness and evenness of the bacterial population being lower in acne than in non-acne skin samples. Dysbiosis was also found at the level of Staphylococcus species. The development of acne lesions could therefore be prevented by using a skin care product that rebalances facial skin microbiota at very early stages.