The nested subset pattern (nestedness) has been widely used to explain species distributions in island and fragmented systems. Mountain sky islands serve as critical natural laboratories for understanding the evolutionary consequences of geographic isolation and climate change, but their species distribution patterns remain poorly understood. Compared to lowland fragmented habitat islands, biodiversity patterns in mountainous regions are more complex, and traditional drivers may not adequately explain the nestedness of sky islands. To uncover the underlying mechanisms of mountain biodiversity, this study sampled amphibians across 30 sky islands in the Dabie Mountains, China, aiming to explore the nestedness of amphibian assemblages and its formative mechanisms from taxonomic, functional and phylogenetic perspectives. Taxonomic nestedness was quantified by constructing species incidence matrices and calculating nestedness metrics, while functional and phylogenetic nestedness were assessed by integrating species similarities in ecological traits and phylogenetic relationships. Seven sky island characteristics and eight amphibian species traits were then selected as predictors of nestedness. Results showed that amphibian assemblages in the Dabie Mountains exhibited significant nestedness across taxonomic, functional and phylogenetic dimensions. The habitat-by-site matrix was also significantly nested. Spearman rank correlations between the selected predictors and nestedness ranks revealed that sky island area, climate stability and species traits associated with extinction vulnerability (minimum area requirement, larval stage duration, elevation range, and habitat specificity) were strongly correlated with taxonomic nestedness. Additionally, sky island area and climate stability significantly influenced functional and phylogenetic nestedness. These findings support the 'selective extinction' and 'habitat nestedness' hypotheses. To explain these results, we propose a climate stability hypothesis specific to sky islands: stable climatic conditions sustain greater species diversity, whereas climatic instability exacerbates the extinction of lineages lacking adaptive traits. This study presents the first empirical evidence of nestedness in sky island systems, extending classical hypotheses beyond lowland ecosystems and offering new insights into climate-driven assembly mechanisms affecting vulnerable taxa (e.g. amphibians). Our results indicate that conservation efforts should prioritize sky island regions with high-climate stability, large areas and diverse habitats as core areas for biodiversity protection. Moreover, species with narrow elevation ranges, large area requirements, high-habitat specificity and long larval stage durations should also be preserved to prevent local extinction.Read the free for this article on the Journal blog. 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Island endemic terrestrial vertebrates, shaped by long-term isolation and ecological specialization, are particularly vulnerable to extinction pressure in the Anthropocene. However, cross-taxon extinction patterns and their drivers remain poorly understood. Here, we compiled a global dataset of 31,865 terrestrial vertebrates, including more than 7500 island endemic species, to evaluate the patterns and drivers of extinction risk in island endemics, in comparison with continent endemics and dual-range species. We found that island endemics face significantly higher extinction risk than non-island endemics, with 3.1% extinct and 34% currently threatened since 1500 CE. Extinction risk among island endemics is unevenly distributed and taxonomically structured, tightly linked to invasive species, overexploitation, and climate change. Compared with continent endemics and dual-range species, their elevated risk is closely associated with small range size and habitat specialization, while biological traits, climate, and anthropogenic pressures also exert taxon-specific effects. These findings explain the unique vulnerability of island endemic vertebrates and inform conservation priorities across island ecosystems.

Caudata (salamanders) is a highly threatened taxonomic group with over 60% of species estimated to be threatened. However, the species traits and extrinsic factors underlying their population decline and high extinction risk remain unclear. We conducted the first global comparative analysis to investigate which factors are associated with an increased risk of decline and extinction in salamanders. We addressed the following questions: Is extinction risk randomly distributed among salamander families, and if not, which families contain more threatened species than would be expected by chance; which species traits and extrinsic factors are important in determining the extinction risk in salamanders; and are the key factors for population decline consistent with those for extinction risk in salamanders? To determine which ecological characteristics and extrinsic factors best predict extinction risk and population decline in salamanders, we employed phylogenetic generalized least squares (PGLS) models and phylogenetic logistic regression (PGLM) models, respectively. Threatened salamanders were nonrandomly distributed across nine families, among which Cryptobranchidae and Hynobiidae contained significantly more threatened species than expected. Key predictors of salamander extinction risk were breeding strategy, geographic range size, minimum elevation, human threat index, and protected area coverage. Although geographic range size, climate change, and human threats were the most important predictors of salamander extinction risk and population decline, the effect of geographic range size was the opposite between the PGLS and PGLM models. Our results suggest that priority management should focus on extinction-prone families, particularly Cryptobranchidae and Hynobiidae, and salamanders with small range sizes and sensitivity to human disturbance or climate instability.

Citric acid is the major organic acid affecting citrus fruit taste, which varies widely in the citrus family. An acidless kumquat, a small-fruited citrus species (Citrus crassifolia), has been developed and has become popular on the market. To investigate the molecular basis of the acidless phenotype in Huapi (HP) kumquat, it was crossed with early-flowering, high-acid Hong Kong (HK) kumquat to generate an F1 population, providing a system to dissect the genetic and molecular basis of citric acid accumulation. Organic acid content exhibited a wide and continuous distribution across three consecutive years, which is consistent with quantitative inheritance. Bulked segregant analysis sequencing mapped a major locus, and integration with transcriptomic data identified the GRAS transcription factor SCARECROW-like protein 9 (ChSCL9) as a candidate major-effect gene, showing high expression in HP fruit and low expression in HK fruit. Subcellular localization confirmed that ChSCL9 is a transcription factor. Functional analyses-including CRISPR-Cas9 gene editing, overexpression in kumquat, and RNA interference (RNAi) in citrus juice sacs-demonstrated that ChSCL9 negatively regulates citric acid accumulation. Biochemical experiments showed that ChSCL9 directly represses the expression of the R2R3-MYB gene ChPH4 and the vacuolar P-ATPase gene ChPH5, both of which are key genes for vacuolar acidification, thereby inhibiting citric acid accumulation. These results identify ChSCL9 as a key regulator of citric acid in kumquat, reveal an upstream regulator of PH4, and provide targets for citrus flavor improvement and rational design for citrus breeding.

To establish standardized DNA fingerprinting and molecular identification systems for mandarin citrus, we analyzed 69 mandarin accessions via fluorescent SSR capillary electrophoresis to construct DNA molecular fingerprints and unique molecular identity cards. Eighteen highly polymorphic SSR primer pairs were screened, yielding 239 genotype calls and 147 alleles. The number of amplified alleles per primer pair ranged from 4 to 18, with polymorphic information content (PIC) values varying from 0.411 to 0.650. Ten core primer pairs were further selected, achieving a discrimination rate of 65.2% (45 out of 69 accessions distinguished). Utilizing these fluorescent SSR markers, we established DNA molecular fingerprints and unique molecular identity cards for all 69 accessions. Among them, 45 accessions possessed unique fingerprints, whereas the remaining 24 indistinguishable accessions were clustered into six groups. Each cluster contained both wild (4 accessions total) and cultivated (20 accessions total) resources with high genetic similarity, which merits further investigation. This study provides a practical foundation for the authentication, conservation, and genetic relationship analysis of mandarin germplasm resources and establishes a technical framework for standardizing mandarin variety identification.

Background: Leaves are the main organs involved in photosynthesis. They capture light energy and promote gas exchange, and their size and shape affect yield. Identifying the regulatory networks and key genes that control citrus leaf size is essential for increasing citrus crop yield. Methods: In this study, transcriptome sequencing was performed on three leaf materials: the ‘Cuimi’ kumquat (Nor) variety and its leaf variants, larger-leaf (VarB) and smaller-leaf (VarS) varieties. Results: Correlation and principal component analyses revealed a relatively close correlation between Nor and VarS. A total of 7264 differentially expressed genes (DEGs), including 2374 transcription factors (TFs), were identified, and 254 DEGs were common among the three materials. GO and KEGG enrichment analyses revealed significant enrichment in glucose metabolism, cell wall composition, starch biosynthesis, and photosynthesis pathways. WGCNA identified three specific modules related to the different leaf sizes of these three citrus materials. Fifteen candidate genes related to leaf size, including three transcription factors, Fh5g30470 (MYB), Fh7g07360 (AP2/ERF), and Fh5g02470 (SAP), were identified on the basis of connectivity and functional annotations. Conclusions: These findings provide a theoretical foundation for a deeper understanding of the molecular mechanisms underlying citrus leaf size and offer new genetic resources for the study of citrus leaf size.

Wildlife trade poses a major threat to biodiversity, yet the drivers determining which species are traded are not fully understood. Through a comprehensive collection of official and online trade data, we applied a binomial test to identify families that contain an unexpectedly large or small number of traded species. We also analyzed which factors predispose reptile species to be traded and explored whether traded species were more likely to be threatened with extinction. Of the 10,919 reptile species in our dataset, 3889 species (35.6%) were traded. There was strong evidence for taxonomic biases in trade risk. In particular, all turtle and crocodilian families had higher trade risk than other reptiles. Species with large body sizes, habitat generalists, insular endemics, and those found in regions with high gross domestic product were traded in greater quantities and more frequently. Species with small and large ranges were more frequently involved in trade, suggesting a demand for rare and common species in wildlife trade. When connecting trade risk to extinction risk, data-deficient and not-evaluated species had fewer traded species and were less likely to be traded than threatened or nonthreatened ones. Nonetheless, these species warrant special conservation attention considering their rarity, limited range size, and insufficient legal protection. Given the increased attention given to wildlife trade, we suggest implementing stronger regulatory measures to monitor and control the trade of reptile species, particularly those belonging to families with a high risk of being traded. Efforts should also prioritize the protection of species exhibiting traits that make them highly susceptible to exploitation. Finally, promoting international collaboration for stricter enforcement of wildlife trade regulations and support of sustainable trade practices can help mitigate the negative impacts on biodiversity.

Turtles and tortoises (chelonians) are among the most threatened vertebrates worldwide, yet the factors determining their high extinction risk and their resilience to further challenges are not fully understood. Here, we compile a dataset comprising intrinsic and extrinsic variables for chelonians to reveal their current risk patterns and extinction vulnerability to future climatic and anthropogenic threats. The results show that at-risk species are predominantly characterized by large body size, small ranges, high functional distinctness, and intense human threat levels, with high representation in the Indomalayan region. Notably, 18.6% of currently unevaluated species are projected to be threatened with extinction. Furthermore, the projected rates of climatic and environmental changes across species' distributions are significantly higher than the rates of evolution for traits linked to resilience to climate change and altered environments. Overall, this study provides insights for prioritizing conservation actions and underscores the urgent need to prevent future extinctions of chelonians.

Citrus anthracnose is a significant preharvest and postharvest disease that severely impacts the quality and shelf-life of citrus, leading to substantial economic losses. In this study, Sodium diacetate (SDA) (1.8 g/L) completely inhibited mycelial growth and reduced spore germination by 67.69% in vitro. Furthermore, SDA (36 g/L) demonstrated an inhibition rate of 72.73% on the diameter of the spots in vivo. Microscopic analysis using optical and scanning electron microscopy revealed that SDA treatment caused significant deformation and shrinkage of the mycelium of C. gloeosporioides. Further staining experiments indicated that SDA compromised the integrity of the cell membrane and cell wall of the pathogen. The formation of lipid droplets (LDs) was confirmed by transmission electron microscopy and Nile Red staining. By integrating transcriptome analysis, we identified changes in the expression of five differentially expressed genes associated with lipid metabolism pathways. The results showed that the expression of four genes involved in membrane lipid metabolism, CgPlpp4, CgPprp1, CgPATb2, and CgPATb1 was significantly downregulated, resulting in disrupted lipid metabolism pathways and an increase in the accumulation of intracellular lipid droplets. In conclusion, SDA treatment disrupts the internal cellular structure and homeostasis of C. gloeosporioides, inducing the accumulation of intracellular lipid droplets, an increase in hydrogen peroxide levels, and a corresponding rise in antioxidant enzyme activity. These findings suggest that SDA could be a promising, safe, and efficient fungicide for controlling citrus anthracnose. Provides a theoretical basis for the postharvest storage and preservation of citrus and the lipid droplet metabolism of C. gloeosporioides.

BACKGROUND: Candidatus Liberibacter asiaticus (CLas) is the most prevalent pathogen causing the globally prevalent citrus Huanglongbing (HLB). The citrus relative Citrus australasica F. Muell. shows tolerance to HLB. In this study, we grafted HLB-tolerant Ca (C. australasica) and HLB-susceptible Cs (C. sinensis) Osbeck branches onto healthy C. reticulate Blanco ‘Shatangju’ (SH) and CLas-infected (SI) rootstocks. RESULTS: To understand HLB tolerance mechanisms in C. australasica, a comprehensive analysis of transcriptomic and proteomic data of leaves from CaSH, CaSI, CsSH, and CsSI was conducted. Differentially expressed genes (DEGs) between CaSI and CaSH were enriched in acridone alkaloid biosynthesis. In contrast, some DEGs between CsSI and CsSH were enriched in plant hormone signal transduction, and MAPK signaling pathway. Several differentially expressed proteins (DEPs) between CaSI and CaSH were enriched in phenylpropanoid biosynthesis, whereas several DEPs between CsSI and CsSH were enriched in amino acids biosynthesis. In response to CLas infection, several genes involved in amino acid metabolism pathway and citrate cycle pathway showed opposite trends in C. australasica and C. sinensis. Among these genes with opposite expression trends, it is noteworthy that in response to HLB, arogenate/prephenate dehydratase and phenylalanine-4-hydroxylase in phenylalanine and tyrosine biosynthesis remained stable in C. australasica. In addition, glutamate dehydrogenase and amino acid N-acetyltransferase, which are involved in arginine metabolism, were up-regulated in CLas-infected C. australasica. The expression levels of isocitrate dehydrogenase, malate dehydrogenase, and aconitate hydratase, which are involved in the citrate cycle, were higher in CaSI than in CsSI. CONCLUSIONS: These data suggest that the stabilization of phenylalanine biosynthesis and the up-regulation of arginine biosynthesis contribute to HLB-tolerance of C. australasica, and that the changes in enzymes in the citrate cycle pathway and flow of carbon sources to arginine biosynthesis reduce the energy supply for HLB pathogens. These results provide new insights into the mechanism of HLB-tolerance in C. australasica, and provide a theoretical molecular basis for breeding HLB-tolerant citrus varieties.

Turtles and tortoises (chelonians) possess a variety of ecological characteristics, including long lifespans and protective shells, which have enabled them to survive and adapt to environmental challenges since the Triassic period. However, many characteristics of chelonians have turned into disadvantages for their populations in the Anthropocene. Currently, there remains a lack of comprehensive data on the morphological, life-history, and ecological characteristics of all chelonians on a global scale. Consequently, our study aims to collect a complete trait database of global chelonians (CheloniansTraits), which may help bridge the knowledge gap regarding the identity and ecology of global chelonians and thereby aiding future conservation endeavors. We compiled 69 trait data for all 358 recognized chelonian species, utilizing ~2,000 literature sources, covering 33 morphological, 21 life-history, 7 ecological traits, and 8 conservation information. This database serves as a uniquely valuable resource for exploring evolutionary, biogeographical, and ecological inquiries related to chelonians, as well as elucidating key aspects of ecological strategy variation among species.

Loose-skin mandarins (LSMs) are among the oldest domesticated horticultural crops, yet their domestication history and the genetic basis underlying the formation of key selected traits remain unclear. We provide a chromosome-scale and haplotype-resolved assembly for the ancient Chinese citrus variety Nanfengmiju tangerine. Through the integration of 77 resequenced and 114 published citrus germplasm genomes, we categorize LSMs into 12 distinct groups based on population genomic analyses. We infer that the ancestors of modern cultivated mandarins diverged from wild mandarins in Daoxian approximately 500,000 years ago, when they entered the Yangtze and Pearl River Basins. There, they were domesticated into four ancient cultivation groups, forming the cornerstone of modern Chinese LSM cultivation. We identify selective sweeps underlying quantitative trait loci and genes related to important fruit quality traits, including sweetness and size. We reveal that the co-selection of sugar transporter and metabolism genes are associated with increased fruit sweetness. Significant alterations in the auxin and gibberellin signaling networks may contribute to the enlargement of LSM fruits. We also provide a comprehensive, high-spatiotemporal-resolution atlas of allelic gene expression during citrus fruit development. We detect 5890 allele pairs showing specific expression patterns and a significant increase in variation levels. Our study provides valuable genomic resources and further revises the origin and domestication history of LSMs, offering insights for genetic improvement of citrus plants.

Mandarin (Citrus reticulata) is broadly recognized as one of the foremost citrus crops globally. Our study identified the Xingan mandarin (Citrus reticulata ‘Xingan’) as a primitive type found near Maoer Mountain. This report provides a high-resolution, chromosome-scale genome assembly for the Xingan mandarin. The total size of the genome assembly is an impressive 325.12 Mb, including contig N50 and scaffold N50 values of 29.32 Mb and 29.62 Mb, respectively. Notably, we successfully anchored approximately 93.08% of the assembled sequences onto nine pseudochromosomes. Our predictions identified 30,581 protein-coding genes, 166 miRNAs, 415 tRNAs, 728 rRNAs, 325 snRNAs, and 659 snoRNAs. We were able to predict the functions of 27,242 genes, constituting 89.08% of the total protein-coding genes. A notable finding of our study was the high degree of genome synteny between the Xingan mandarin and the Mangshan mandarin (Citrus reticulata ‘Mangshan’), reinforcing their genetic similarity. The acquisition of the chromosome-level genome for the Xingan Mandarin represents a significant milestone, laying an indispensable foundation for rigorous molecular investigations of this species. Moreover, it is poised to invigorate advanced research in comparative genomics within the Citrus genus.

AimIslands are regarded as ideal ecosystems for exploring biodiversity patterns. However, numerous islands have also suffered large numbers of species extinctions due to human activities. The extent to which such species extinctions have influenced our ability to understand biodiversity patterns, particularly the factors regulating island biodiversity, is still unclear. The purpose of our study was to disentangle the effects of recent human-driven extinctions on island biodiversity patterns.LocationZhoushan Archipelago, China.TaxonLarge and medium-sized mammals.MethodsWe conducted field surveys on 30 islands with available recent data on large and medium-sized mammals. We then calculated the alpha diversity and beta diversity from taxonomic, phylogenetic, and functional facets for natural (including both extinct and extant populations) and current assemblages (excluding extinct populations) on 24 islands that supported at least one extant mammal species. Finally, we assessed the changes in these diversity metrics and their key drivers between natural and current assemblages.ResultsBoth alpha and beta diversity of taxonomic, phylogenetic, and functional facets have decreased in current assemblages compared to natural assemblages. Additionally, distance to the nearest mainland had significant effects on all alpha diversity metrics for natural assemblages, and island area significantly influenced all beta diversity metrics for natural assemblages, but these effects were not observed in current assemblages.Main ConclusionsOur findings showed that fundamental diversity patterns at both alpha and beta levels have been rapidly altered by human-driven extinctions, highlighting humans as a major force in island ecosystems. We thus emphasise that assessing biodiversity patterns based on natural assemblages is important to improve our understanding of the evolutionary and ecological determinants of island biodiversity as well as to provide a benchmark for biodiversity conservation.

Pummelo (Citrus maxima) is one of the most important citrus crops and have genetically contributed sweet orange, lemon and most citrus cultivars. It has been cultivated for c. 4000 years in China and is also distributed in many Southeast Asian countries. Nevertheless, the origin and dispersal of pummelo remain elusive. We conducted whole-genome sequencing for 290 pummelo accessions from China and Southeast Asia (SEA). Our findings indicated that pummelo was originated in Yunnan province. The divergence of the China-SEA accessions occurred c. 2000 years ago and the divergence was likely facilitated through the Maritime Silk Road. We detected the divergence of genomic regions associated with fruit flavor and color, indicating different selection by human activities in different regions. A gene encoding lycopene cyclase 2 (LCYB2) exhibited a high degree of divergence in expression and sequence between red-flesh and white-flesh pummelos. A SNP in the coding region of LCYB2 resulted in a reduction in lycopene β-cyclizing enzyme activity, leading to the accumulation of lycopene and the development of the red-flesh trait. This study reveals the origin and evolutionary history of pummelo and provides insights into the genomic basis for the divergence of fruit flavor and color.

Utilizing 32 previously identified S ribonuclease (S-RNase) gene sequences and abundant citrus resources, this study designed specific primers for 10 S-RNase genes. A total of 32 pairs of primers were used to analyze the self-incompatibility genotypes (S-genotypes) of 241 citrus resources, encompassing 105 mandarins, 47 pummelos, 69 oranges, and 20 lemons and citrons. These results provide theoretical guidance for parent selection in production and breeding programs. Among the 215 samples analyzed, two normal S-genotypes were identified, while no S-genotypes were detected in three samples. Notably, 21 samples, primarily citrons, exhibited amplification of only one S-genotype. Additionally, two pummelo samples showed amplification of three S-genotypes each. The integration of S-genotype and selfing phenotype identification revealed five newly discovered self-compatible mutated materials: Changsha ‘Shatian’ pummelo, large-fruited red pummelo, slender leaf ‘Mangshanyegan’, ‘Shatangju’, and W. Murcott. These findings provide valuable resources for investigating the self-compatibility mechanism in citrus.

The prolonged utilization of copper (Cu)-containing fungicides results in Cu accumulation and affects soil ecological health. Thus, a pot experiment was conducted using Citrus reticulata cv. Shatangju with five Cu levels (38, 108, 178, 318, and 388 mg kg−1) to evaluate the impacts of the soil microbial processes, chemistry properties, and citrus growth. These results revealed that, with the soil Cu levels increased, the soil total Cu (TCu), available Cu (ACu), organic matter (SOM), available potassium (AK), and pH increased while the soil available phosphorus (AP) and alkali-hydrolyzable nitrogen (AN) decreased. Moreover, the soil extracellular enzyme activities related to C and P metabolism decreased while the enzymes related to N metabolism increased, and the expression of soil genes involved in C, N, and P cycling was regulated. Moreover, it was observed that tolerant microorganisms (e.g., p_Proteobacteria, p_Actinobacteria, g_Lysobacter, g_Sphingobium, f_Aspergillaceae, and g_Penicillium) were enriched but sensitive taxa (p_Myxococcota) were suppressed in the citrus rhizosphere. The citrus biomass was mainly positively correlated with soil AN and AP; plant N and P were mainly positively correlated with soil AP, AN, and acid phosphatase (ACP); and plant K was mainly negatively related with soil β−glucosidase (βG) and positively related with the soil fungal Shannon index. The dominant bacterial taxa p_Actinobacteriota presented positively correlated with the plant biomass and plant N, P, and K and was negatively correlated with plant Cu. The dominant fungal taxa p_Ascomycota was positively related to plant Cu but negatively with the plant biomass and plant N, P, and K. Notably, arbuscular mycorrhizal fungi (p_Glomeromycota) were positively related with plant P below soil Cu 108 mg kg−1, and pathogenic fungi (p_Mortierellomycota) was negatively correlated with plant K above soil Cu 178 mg kg−1. These findings provided a new perspective on soil microbes and chemistry properties and the healthy development of the citrus industry at increasing soil Cu levels.

AimIdentifying key factors that render certain species more vulnerable to fragmentation is vital for elucidating processes underlying extinction and targeting conservation priorities. However, few studies have explored the delayed ecological responses of species following isolation. To bridge the gap, we conducted comprehensive analyses of correlates of extinction vulnerability and biogeographical variation in amphibians over long-term fragmentation.LocationZhoushan Archipelago, China.MethodsWe sampled the occupancy of amphibians on 37 land-bridge islands. We calculated three metrics of extinction vulnerability (population extinction rate, island occupancy frequency and species nestedness ranking) for each species and correlated these variables with eight species' traits. We further explored biogeographical variations in amphibians by relating five biogeographical variables to species' probability of occurrence and calculated the threshold for the persistence of each species on islands.ResultsSpecies with low natural abundance, larger egg sizes, smaller clutch sizes or restricted geographical distributions were more likely to experience higher population extinction rates and species nestedness rankings, while lower island occupancy frequencies across islands. Although most species were found on larger islands, we observed significant increases in the occurrence probabilities with island area for five species. The estimated areas with a 50% chance of occurrence ranged from 0.39 to 199.5 km2. Interestingly, the likelihood of occurrence of Hyla chinensis (treefrog) was negatively related to distance to the mainland after controlling for the effect of area.Main ConclusionsOur study highlights the variation in the fragmentation sensitivity of amphibians. Species distribution was primarily regulated by area-related extinction, particularly for those with 'slow' life history strategies or restricted ranges. Overall, management efforts should focus on species with extinction-prone traits and landscape features that threaten the persistence of populations. Future studies should consider the sequential separation of island populations and the interaction of traits to reveal the fate of species to fragmentation.

Insight into the non-random distribution patterns of species in different regions is a foundational aim of research in community ecology and biogeography. The nestedness pattern, which investigates changes in species composition and abundance, has been widely used in numerous studies. However, studies on the nestedness of benthic diatoms are extremely rare, and consequently little has been mentioned of their assemblage mechanisms. To fill this gap, based on 168 benthic diatom species from 147 sampling sites in the Thousand Island Lake (TIL) catchment, we calculated their nestedness and niche width with the aim of i) analyzing the nestedness of benthic diatoms communities with different attachment abilities in TIL; ii) calculating niche width differences between nested and idiosyncratic species with different attachment abilities; iii) investigating the differences in alpha and beta diversity between nested and idiosyncratic sites; iv) examining whether environmental variables influencing the nestedness of benthic diatom communities are dependent on attachment ability. The results demonstrated a significant nestedness pattern in the benthic diatom metacommunity, and the sampling sites of low attachment species not only exhibited a nestedness pattern, but also with a lower nestedness value compared to the sampling sites of all species. Nested and idiosyncratic species differed in niche width, whereas differences between nested and idiosyncratic species of low attachment species were smaller. Additionally, significant differences in alpha and beta diversity were observed between nested and idiosyncratic sites. Furthermore, it was revealed that the nestedness of benthic diatom metacommunity in our study area were mostly influenced by local environmental variables. Our study contributes to the understanding of the significant nestedness observed in benthic diatom metacommunity in TIL, highlighting its relevance to biodiversity conservation efforts.