Ecology and Evolution最新文献

Global change is enriching terrestrial ecosystems with multiple nutrients and amplifying interannual variation in precipitation. Grassland productivity may be co-limited by combinations of nitrogen (N), phosphorus (P), and potassium (K). How these nutrients may interact with each other or with varying precipitation to influence the contributions of dominant species and functional groups to aboveground net primary productivity (ANPP) and species diversity is rarely considered. We fertilized a mesic grassland for 5 years with all combinations of N, P, and K+ micronutrients in the first year (Kμ) to test which nutrients (1) limited ANPP and functional group biomass, (2) reordered dominant species and impacted plant species diversity, and (3) interacted with annual precipitation to influence these responses. Adding N and P together disproportionately increased ANPP, but adding both N and P or N and Kμ disproportionately increased forb biomass to account for nearly all (90%) of ANPP. Grass biomass was correlated with light availability, not nutrients, and legume biomass decreased with added N, with or without other nutrients. Nutrient combinations (mainly NP and NPKμ) causing the greatest increases in forb biomass and ANPP also resulted in replacement of dominant species by an annual forb and decreased species diversity (Shannon index), evenness, and species richness. Nutrient combinations (P, Kμ, PKμ) not increasing biomass favored dominance by C4 grasses and increased species richness. N effects on ANPP, species diversity, and richness were greater in years with higher annual precipitation. Annual precipitation interacted with all three nutrients to exert sometimes positive and sometimes negative feedback on the abundance of the most dominant species. Dominant species drive nutrient effects on community productivity and species diversity. An expanded definition of nutrient limitation incorporating constituent responses will improve understanding of anthropogenic nutrient inputs on ecosystem productivity and related ecosystem services.

Understanding the relationship between environmental DNA (eDNA) concentration and taxa abundance is essential for the advancement of quantitative biodiversity monitoring. We experimentally manipulated biomass of three freshwater fish species of monitoring interest—the Italian-endemic Squalius lucumonis and the exotic-invasive Pseudorasbora parva and Lepomis gibbosus—under controlled conditions (flow-through 310 and 1330 L tanks). Following eDNA collection (2 L water filtration) and Real-Time PCR quantification, Generalized Additive Mixed Models (GAMMs) revealed: (i) monotonic non-linear relationships of moderate-to-high magnitude (0.42 < partial-R² < 0.62), with eDNA concentrations plateauing at intermediate biomasses in smaller-sized taxa; and (ii) a significant effect of experimental replicates (tanks) in two out of three species. These findings suggest that eDNA-based biomass quantification should not assume linearity, and emphasize the critical role of replication to account for inherent uncertainty, likely driven by inter- and intra-individual variations in eDNA shedding rates.

Understanding how limited energy constrains fish populations in fragile high-altitude lakes is essential for sustainable fisheries management. This study developed a satellite-based framework that integrated MODIS-derived chlorophyll a data with a vertically generalised production model. This framework was used to map Fish Potential Production (FPP) and establish a novel Fish Carrying Capacity Index (FCCI) for the endemic naked carp (Gymnocypris przewalskii) in Qinghai Lake, China, from 2002 to 2024. Over the 23-year period, lake-wide fish production increased 50-fold (from 2592 to 127,500 t) alongside an upward trend in FPP driven by primary production. Seasonally, FPP per unit area peaked in summer (July–August: 30–50 g/m²) and declined in spring (May–June: 0–30 g/m²). Spatially, the highest values occurred near riverbank and tributary estuaries, whereas central waters remained low. The FCCI revealed significant heterogeneity; the northwestern regions experienced high food demand pressure (FCCI > 0.5), while the southeastern areas were underutilised (FCCI < 0.3). As the lake-wide FCCI never exceeded 0.6, the current level of primary productivity can support further strategic restocking, provided that releases are redirected to the southeast to relieve pressure on the northwest. This study demonstrates how remote sensing can be used to balance fish conservation and production goals in sensitive plateau ecosystems.

Successful applications of DNA barcoding rely on the accurate taxonomic identification of sequence fragments. When biological surveys with DNA barcoding target underexplored biological communities, sequence-based identification is often conducted using incomplete databases that do not fully cover the regional species pool. Consequently, specimens to be identified may include species not present in reference databases. Such unknown or “out-of-distribution” samples can cause misidentification if left undetected. A similarity cutoff is commonly used to detect out-of-distribution samples before taxonomic assignment, but its effectiveness has not been carefully studied. In this study, we evaluated the performance of out-of-distribution detection for DNA barcoding with genetic distance and deep learning metrics. Using extensively sampled datasets of multiple insect taxa, we measured the performance of identification and out-of-distribution detection under conditions in which genetic variations in species were sufficiently sampled. Although identification with DNA barcoding is a highly accurate process, even with short noisy fragments, out-of-distribution detection was more susceptible to a reduction in performance due to sequence noise and a lack of diagnosable characters. When fragments shorter than 300 bp were used for out-of-distribution detection, large performance reductions were observed irrespective of detection methods. Our results provide guidelines for designing unknown-proof identification procedures by determining factors affecting out-of-distribution detection performance.

The presence of sexual characteristics typical of one sex in the opposite sex is more common than has been previously recognized. When changes in the environment or the genome alter sex-specific regulatory processes, individuals may develop novel reproductive phenotypes. We recently discovered a population of the live-bearing fish Pseudopoecilia fria (Cyprinodontiformes: Poeciliidae) in which females were found to possess gonopodia, reproductive organs normally exclusive to male fish that are used in the transfer of sperm in mating. While we are not yet able to identify the specific mechanisms underlying this phenotype, we tentatively attribute it to female masculinization. We document that this process has occurred in a significant proportion of the females sampled in the population. Geometric morphometric analyses showed that females were potentially divided into two discrete phenotypes, though with considerable intra-group variance. Additionally, all females with gonopodia were gravid, and one individual gave birth to live offspring. Therefore, these alternate female morphs appear reproductively functional. We discuss several potential explanations for this phenomenon, including exposure to masculinizing water-borne pollutants and the remote possibility of a fixed polymorphism. Additionally, we suggest a number of lines of research which could be motivated by this discovery.

Despite the extensive diversity of African flora, significant gaps remain in taxonomic research and biodiversity conservation, including under-sampling in highly diverse regions, a shortage of taxonomic expertise, limited financial resources and delays in species descriptions. Type specimens act as effective proxies for tracking the discovery and description of species, providing a historical baseline for assessing taxonomic effort and our understanding of biodiversity. This study presents the first comprehensive analysis of Fabaceae species collected in Mozambique, one of the most diverse and ecologically important plant families in the region. It offers new insights into the taxonomic, spatial and temporal patterns shaping current botanical knowledge through an analysis of Fabaceae type specimens collected in Mozambique. We identified 273 type specimens, including 126 recognised taxa, with a notable proportion of endemism (44 strict-endemic and 18 near-endemic taxa) and a predominance of woody growth forms. Nearly 40% of these taxa lack IUCN conservation assessments, highlighting significant information gaps. The findings reveal that collection activity peaked during colonial botanical initiatives, driven by a small group of prolific collectors and influenced by spatial biases towards southern and central provinces. Using generalised linear modelling, we demonstrate that collection locations were significantly affected by elevation, slope, land cover and proximity to roads and harbours, reflecting the interaction between biogeographic patterns and accessibility. By identifying these historical and geographic biases, our study deepens understanding of Mozambique's botanical heritage and provides a crucial baseline for future floristic and conservation efforts in underexplored regions. Furthermore, this research underscores the vital role of herbarium type specimens as scientific resources supporting taxonomic research and conservation planning, emphasising the importance of preserving and digitising these collections to enhance their accessibility and utility.

Caragana, a keystone leguminous species dominating arid semi-fixed deserts in northern China, forms specialized symbiotic nitrogen-fixing partnerships with Mesorhizobium, which are indispensable for sustaining ecosystem function globally. However, the roles of membrane transporters and nucleotide repair genes in conferring survival advantages to desert-dwelling Mesorhizobium across desert environments remained poorly elucidated. Therefore, a total of 68 representative Mesorhizobium strains associated with Caragana, isolated from five geographically distant areas (A to E) in the desert belt of northern China, were investigated to elucidate the pivotal roles of three membrane transporters (cysW, exoY, idhA) and two nucleotide repair genes (mutS, uvrC) in microbial adaptation to environmental stress. Phylogenetic analysis results revealed that strains assigned to the same genospecies primarily clustered by genetic lineage rather than geographic origin, with stronger intralineage sequence cohesion observed relative to interregional divergence. Notably, phylogenetic trees of membrane transporter genes, nucleotide repair genes, and core genes showed high topological congruence, underscoring their concerted evolutionary dynamics and shared selective pressures. Furthermore, consistent nucleotide diversity (π), low πN/πS ratios (<< 1.0) and genetic distance (Dxy) across populations indicated that purifying selection predominated in membrane transporters and nucleotide repair genes. Elevated recombination impact (r/m) and frequency (ρ/θ) revealed that homogenizing gene flow, rather than mutation, was the primary driver of population differentiation enabling rapid adaptation to desert environments.

Invasive species are a significant threat to a variety of ecosystems in Florida, with freshwater habitats being of particular concern. Two nonnative species of fish with established populations that are priority organisms for monitoring and management programs are the bullseye snakehead (BS; Channa species complex) and Asian swamp eel (ASE; Monopterus species complex). Recent technological advances have seen the emergence of environmental DNA (eDNA) analysis as a useful tool for the detection and monitoring of target organisms and to assess removal efforts. In this study, a duplex digital polymerase chain reaction (dPCR) was developed, optimized, and validated on control samples and field samples from locations with documented occurrences of target organisms. The assay developed, which allows simultaneous detection of both fish species when present in a sample, demonstrated highly efficient amplification for the corresponding target species with individual assays failing to cross-amplify. Under controlled conditions, high levels of eDNA were detected as early as five minutes post-introduction of BS to water. Additionally, field eDNA samples yielded varying levels of positive amplification for both species based on comparison of fluorescence levels to positive controls (both tissue extract and plasmids with appropriate inserts). These data indicate that through careful assay design and stringent parameter optimization, eDNA results obtained for monitoring of these two fish species can be a viable and cost-effective strategy to detect the presence of these species simultaneously as well as to evaluate the success of removal efforts.

Gaire, S., S. Gharti, R. Bhusal, B. Bhattarai, S. Timilsina, D. Dhungana. 2026. “Effects of the Irregular Shelterwood System on Regeneration Dynamics of Shorea robusta Gaertn. f. in Baijalpur Community Forest.” Nepal Ecology and Evolution 16, no. 1: e72885. https://doi.org/10.1002/ece3.72885.

Figure 3 in the published article is incorrect. The corrected Figure 3 is shown below.

We apologize for this error.

Biodiversity monitoring at large spatial and temporal scales is essential for informing conservation policies. The International Waterbird Census (IWC) is one of the longest-running global citizen science monitoring schemes, providing critical information to several international agreements. However, analyzing IWC count data poses statistical challenges, including zero inflation, overdispersion, spatial autocorrelation, and missing data. While various modeling approaches have been used to estimate waterbird population size and trends, their ability to handle these issues and the implications for trend estimates remain unassessed. Using IWC count data from five species in the East Atlantic Flyway, we compared four modeling approaches: TRIM (TRends and Indices for Monitoring data), LORI (Low-Rank Interactions), and two generalized linear mixed models (GLMMs) with simple or optimized parametrizations. We benchmarked their performance in addressing zero inflation, overdispersion, and spatial autocorrelation across different realistic sampling designs (i.e., alternative dataset configurations). Our results highlight significant limitations in commonly used methods. Simple GLMMs, TRIM, and LORI generally failed to mitigate both zero inflation and overdispersion. In contrast, optimized GLMMs improved model convergence and better addressed these issues by selecting appropriate probability distributions. However, no single distribution performed consistently well across species and sampling designs. Spatial structures were effective in reducing spatial autocorrelation in most cases. We recommend a careful species-specific selection of statistical methods when analyzing count data, as inadequate models may misrepresent population trends and thus misguide conservation efforts. Future research should explore the integration of advanced hierarchical and spatio-temporal models to improve inference from large-scale citizen science datasets.