Species Diversity Research Articles

The diversity of ants in moderately isolated islands of Japan: towards understanding of factors affecting their colonisation success

ABSTRACT How species diversity is determined is an old question in community ecology but is not yet well understood. Island biotas offer opportunities to address this issue. Here, the ant fauna was studied in five moderately isolated islands of Japan and compared with those in reference regions on the nearby main islands to assess whether ants’ ecological characteristics affect their island colonisation success. Species that were more abundant in the reference regions were more frequently found on the islands, suggesting that ant communities on these islands are likely to have a nested subset structure. Species inhabiting both forests and open lands tended to occur more frequently in the study islands at least than those exclusively inhabiting forests, but this difference was not significant. In addition, nest sites and worker body size did not have significant effects on their occurrence in these islands. These results seem to suggest that the study islands as a whole offer various environments that support a variety of ant species with different ecological characteristics. It is suggested in this study that island size affects the species richness, as has often been reported.

ВОДНІ, ПРИБЕРЕЖНО-ВОДНІ ТА ЗАПЛАВНІ БІОТОПИ ТЕРИТОРІЇ РЛП «ЯЛІВЩИНА», ЇХ ВИДОВА РІЗНОМАНІТНІСТЬ ТА ЕКОЛОГО-ЦЕНОТИЧНІ ОСОБЛИВОСТІ

The article is devoted to the study of aquatic, coastal, and floodplain habitats within the territory of the RLP “Yalivshchyna”. It analyzes the species diversity of these habitats and provides data on the classification of biotopes in the RLP “Yalivshchyna”. A preliminary classification scheme, based on the results of original research and some bibliographic data, is presented. The analysis has revealed a significant diversity of aquatic ecosystems in the RLP “Yalivshchyna”, indicating the ecological stability and azonality of these systems within the park. The aquatic, coastal, and floodplain habitats within the study area are characterized by seven main categories (types), which exhibit significant floristic diversity, including 130 species of vascular plants belonging to 78 genera and 41 families. A notable feature of the studied habitats is the presence of a wide-ranging flora of most species due to their influence on water and floodplain systems. This results in the predominance of species characteristic of the Holarctic and Euro-Asian regions. From an ecological perspective, the biotopes of the Stryzhen River within the territory of the RLP “Yalivshchyna” are significantly represented by vascular plant species from limnophytic groups, and marsh and hygrophilic florogenetic complexes. This diversity is influenced by the overregulation of the Stryzhen riverbed, slow flow, and the formation of bottom sediments of varying thicknesses. The aquatic, coastal, and floodplain vegetation of the Stryzhen River is characterized by the presence of monodominant communities typical for this region, which exhibit limited species diversity, similar composition and structure of coenoses, and the influence of adventive species. An inventory of habitats in the channel and floodplain parts of the Stryzhen River was carried out, allowing for an assessment of the natural environment in accordance with modern approaches. The data obtained on these habitats allows for the determination of their hierarchical structure and identification of the stability level of each habitat. This, in turn, will facilitate the development of appropriate conservation strategies for these habitats in the future and can be used to maintain and preserve aquatic ecosystems, ensure the balanced use of natural resources, and support the sustainable development of the RLP “Yalivshchyna”.

Recreational Assessment of Green Belt Forests of the Ulaanbaatar City

The classification of forest vegetation of the Tuul river basin within the green belt of the Ulaanbaatar city. Two associations (Linnaeo borealis–Pinetum sibiricae and Vaccinio vitis-idaeae–Laricetum sibiricae) were classified Vaccinio–Piceetea. Diagnostic signs and characteristics of the ecological and geographical peculiarities of the units were presented, anthropogenic transformation was assessed. To determine the models of succession processes, the series of permanent sample plots were established in the communities of the Linnaeo borealis–Pinetum sibiricae association, located at different distances from the city, in taxation units with unequal intensity of recreational load. Recreational forest assessment was calculated according to the approach by V.S. Romanov and L.N. Rozhkov (1974). In the Linnaeo borealis–Pinetum sibiricae association, large areas were occupied by moderately transformed communities. The Vaccinio vitis-idaeae–Laricetum sibiricae association is characterized by being weakly transformed forests. Different stages of anthropogenic pressure were formed serial communities, unequal in structure and species diversity. Serial plant communities of allogeneic succession were developed according to 2 models of geitogenesis — tolerance (Linnaeo borealis–Pinetum sibiricae ↔ Rhytidium rugosum; Linnaeo borealis-Pinetum sibiricae ↔ Chamaenerion angustifolium) and inhibition (Linnaeo borealis–Pinetum sibiricae ↔ Betula rotundifolia). A comprehensive assessment of the recreational potential was based on three indicators: natural conditions, air hygiene and landscaping. All activities aimed at increasing the recreational potential should contribute to the improvement of these indicators. A prerequisite for increasing the recreational forest assessment should be functional zoning of the territory with the allocation of infrastructure, walking and sanitary protective zones. Forest management is of great importance in increasing the recreational potential of forests. The forest management project for the organization of recreational forests should be aimed at the formation of sustainable and aesthetically attractive forest plantations.

Predictions of Carbon Stock in the Southern Moscow Region Forests Under Different Forest Use Scenarios

The results of forest simulation modelling of the dynamics of carbon pools and fluxes in forest ecosystems under different forest management scenarios were considered on the example of the Dankovsky forest enterprise (south of the Moscow region, subzone of coniferous-broadleaved mixed forests). The impact of such changes in forest management practices, as the reserve regime, the reduction in the proportion of forest lands as a result of residential development, and zoning of the territory with an emphasis on increasing the recreational use of forests on the carbon balance was analysed. In computational experiments, a set of Russian models was used: the dynamic model of a forest stand FORRUS-S, the model of soil organic matter dynamics Romul_Hum, the model of the hydrothermal regime of soils SCLISS. Calculations were performed for a time period of 100 years at the forestry unit level, and were also aggregated at the level of the entire forestry district. The diversity of types of forest growth conditions (FGC), together with the species diversity and the initial different ages of stands, determined significant variations of the calculated indicators of forest stands’ production, the quantity and quality of plant litter entering the soil. For all cases, model estimates of changes in carbon reserves occurred in the forest stands within the initial 40–60 years with a subsequent decrease in the calculated values. Under the conservation scenario, an increase in the organic substances reserves in forest litter and soil was observed: for FGCs C2 and C3, an increase over 100 years was approximately 5–10 kg m–2, for the remaining FGCs — at the level of 2–3 kg m–2 in terms of carbon. Under the economic use scenarios, a relative “levelling” of forest enterprise area towards the lower end of the spectrum was shown in terms of soil carbon reserves. The maximum ecosystem carbon stock was calculated for FGC C2 and C3, the minimum — for A5 and C4. Depending on the scenario, over 100 years, the total net sequestration of carbon by the forests of the Dankovsky forest enterprise (with a total area of forested land of 6836 ha) was estimated within the range of 0.15–0.57 Tg.

Unveiling ophiuroid biodiversity across North Atlantic habitats via an integrative perspective

The depths of the North Atlantic Ocean host a species-rich fauna providing heterogeneous habitats from thermal vent fields to cold-water coral reefs. With the increasing threat of destruction of deep-sea habitats due to human impacts, such as demersal fishing and the beginning of deep-sea mining, an analysis of the diversity and distribution of species is crucial for conservation efforts. Brittle stars occur in high biomasses, contributing to the biodiversity of the seafloor. Specimens were collected during several scientific expeditions to gain a more detailed insight into the brittle star diversity in the North Atlantic Ocean. An integrative approach to identify the species with DNA barcoding (mtCOI) in combination with morphological studies revealed 24 species. Most species have been previously identified in the North Atlantic, but sequences for 13 species are newly added to public repositories. Additionally, the MALDI-TOF-MS proteomic analysis was successfully applied for 197 specimens with known COI barcodes. Results are congruent with other molecular species delimitations demonstrating the functionality of proteomics for the identification of brittle stars. This dataset significantly expands our understanding of the taxonomic and genetic diversity of brittle stars and contributes to publicly available data. It emphasizes the importance of considering habitat heterogeneity for large scale patterns of biodiversity.

Diversity of Thrips Species Associated with Soybean Grown in Different Plant Arrangements at Various Phenological Stages

Changes in crop seeding density may affect the presence of phytophagous organisms, whose development is closely associated with host plants. The main objective of this study was to evaluate the abundance and species composition of thrips (Thysanoptera) collected in soybean plants of two different varieties cultivated in different plant arrangements (row spacing, seed density) at different phenological stages. The research was carried out at two locations in southwest Poland between 2015 and 2018. The herbivores that inhabited the plants were caught using an entomological net. The experiments were conducted using a complete block design with four replications. A total of 20 species of thrips were identified and their dietary specialization was determined with an emphasis on the possibility of feeding on Fabaceae plants. Thrips tabaci, Aeolothrips intermedius, and T. fuscipes were the dominant species within the collected material. The general linear model revealed no significant changes in the number of thrips caused by the row spacing, seed density or soybean variety. The significant factor was the phenological stage. The number of thrips increased significantly during the flowering period and shortly after flowering, making them an important threat to the plants. Therefore, it is crucial to develop innovative pest management strategies tailored to effective soybean cultivation to mitigate potential pest-related challenges.

Studies on Relative Abundance and Diversity of Insect Fauna in Cotton in Rajendranagar, Telangana, India

The accurate documentation of insects is crucial for studying biodiversity and population dynamics. Given the resilience of the majority of insect species, proper sampling necessitates the utilization of suitable strategies for capturing specific insects. However, the diversity and types of insect species present in major crops cultivated in Rajendranagar remain poorly understood. Consequently, a comprehensive investigation of the diversity of different insect species in cotton crop was conducted during the period from September 2021 to February 2022 at College Farm. A total of 10,233 individuals from 47 families and 10 orders were documented. Among the orders, Hemiptera recorded the highest number of 4,256 individuals followed by Coleoptera (2,567), while the minimum number of individuals was observed in the order Neuroptera (12). Notably, the order Hemiptera exhibited the highest Shannon-Weiner index value (H = 1.78) and species richness (R = 0.963). However, evenness was found to be highest in Orthoptera (e = 0.826). Furthermore, the order Hemiptera displayed the highest relative abundance (RA) with a value of 41.59%, whereas Neuroptera exhibited the lowest relative abundance with a value of 0.12%.

Wolbachia strain diversity in a complex group of sympatric cryptic parasitoid wasp species

BackgroundMaternally-inherited symbionts can induce pre-mating and/or post-mating reproductive isolation between sympatric host lineages, and speciation, by modifying host reproductive phenotypes. The large parasitoid wasp genus Cotesia (Braconidae) includes a diversity of cryptic species, each specialized in parasitizing one to few related Lepidoptera host species. Here, we characterized the infection status of an assemblage of 21 Cotesia species from 15 countries by several microbial symbionts, as a first step toward investigating whether symbionts may provide a barrier to gene flow between these parasitoid host lineages.ResultsThe symbiotic microbes Arsenophonus, Cardinium, Microsporidium and Spiroplasma were not detected in the Cotesia wasps. However, the endosymbiotic bacterium Wolbachia was present in at least eight Cotesia species, and hence we concentrated on it upon screening additional DNA extracts and SRAs from NCBI. Some of the closely related Cotesia species carry similar Wolbachia strains, but most Wolbachia strains showed patterns of horizontal transfer between phylogenetically distant host lineages.ConclusionsThe lack of co-phylogenetic signal between Wolbachia and Cotesia suggests that the symbiont and hosts have not coevolved to an extent that would drive species divergence between the Cotesia host lineages. However, as the most common facultative symbiont of Cotesia species, Wolbachia may still function as a key-player in the biology of the parasitoid wasps. Its precise role in the evolution of this complex clade of cryptic species remains to be experimentally investigated.

Influence of Bacterial Fertilizers on the Structure of the Rhizospheric Fungal Community of Cereals South of Western Siberia

The general lack of knowledge on the conditions of Western Siberia (Omsk region) and the taxonomic diversity of zonal soils determines the relevance of these studies. The research was carried out in order to study the effect of complex biologics on the taxonomic diversity of the fungal component of the microbiome of the rhizosphere of cereals and the phytosanitary condition of crops in the southern forest-steppe (meadow-chernozem soil) and subtaiga (gray forest soil) zones of the Omsk Irtysh region (Western Siberia). This work was carried out in 2022–2023, using laboratory studies in combination with field experiments and metagenomic and statistical analyses. The objects of research were varieties of cereals and grain forage crops of Omsk selection: soil microorganisms. The scheme of the experiment involved the study of the following options: varieties of cereals (factor A): spring soft wheat—Omsk 42, Omsk 44, Tarskaya 12; durum wheat—Omsk coral; barley—Omsk 101; oats—Siberian hercules; bacterial preparation for seed inoculation (factor B) without the drug—Mizorin and Flavobacterin. The sampling of the plant rhizosphere for metagenomic analysis was carried out during the earing phase (July). For the first time, the taxonomic composition of the fungal community was determined based on the analysis of amplicon libraries of fragments of ribosomal operons of ITS2 fungi during colonization of crop roots by nitrogen-fixing bacteria in various soil and climatic zones of the Omsk region. The fungal component of the microbiome was analyzed in two zones of the Omsk region (southern forest-steppe and subtaiga). The five dominant phyla of soil fungi were located in the following decreasing series: Ascomycota (about 70%) > Mortierellomycota (about 7%) > Basidiomycota (about 5%) > Mucoromycota (3%) > Chytridiomycota (1%). The five main genera of fungi inhabiting the rhizosphere of cereals are located in a decreasing row: Giberella (6.9%) > Mortierella (6.6%) > Chaetomium (4.8%) > Cladosporium (3.8%) > Rhizopus (3.3%). The predominantly positive effect of biologics of associative nitrogen fixation on the fungal community of the soil (rhizosphere) of experimental sites located in different soil and climatic zones has been established. During seed bacterization, the growth of saprotrophic fungal genera was noted in relation to the control variants Pseudogymnoascus, Chloridium, Clonostachys, Trihoderma, etc., and the fungicidal properties of bacterial strains introduced into the soil were actively manifested relative to phytopathogenic fungi of the genera Alternaria, Blumeria, Fusarium, etc. According to the results of determining the number of infectious structures of Rhizoctonia solani, it was found that the population of the soil with viable cells of this pathogen was 1–3 pcs/g (below the threshold of harmfulness, PV 20 pcs/g of soil), which indicates a favorable phytosanitary situation with respect to the pathogen. The fungicidal effect of the applied bacterial fertilizers on Rhizoctonia solani could not be detected. The number of Bipolaris sorokiniana varied depending on the drug used. In the conditions of the southern forest-steppe zone of the Omsk region (meadow-chernozem soil), the greatest fungicidal effect was noted in Flavobacterin application variants on wheat of the Omsk 42 variety, durum wheat of the Omsk coral variety, and barley; the decrease in conidia relative to the control was 73, 35, and 29%, respectively. In the subtaiga zone of the Omsk Irtysh region (gray forest soil), as in the southern forest-steppe zone, pre-sowing bacterization of seeds with Flavobacterin led to a decrease in Bipolaris sorokiniana in the rhizosphere of wheat of the Omsk 42 variety by 18%, and oats by 27%, to control. The use of the drug Mizorin in some variants of the experiment led to an insignificant decrease in the harmful fungus or had no effect at all.

Fortunefuroic Acid J from Keteleeria hainanensis and Its Dual Inhibitory Effects on ATP-Citrate Lyase and Acetyl-CoA Carboxylase.

A previously undescribed triterpenoid (fortunefuroic acid J, 1) was isolated from the endangered conifer Keteleeria hainanensis, along with 20 other known terpenoids. Compound 1 is characterized by an unusual 3,4-seco-9βH-lanost-3-oic acid motif, featuring a rare furoic acid moiety in its lateral chain. The structure elucidation of this compound was achieved through a combination of spectroscopic and computational methods. The C-15 epimers of 15-methoxypinusolidic acid (15R-8 and 15S-9) were successfully separated and identified for the first time. Compound 1 demonstrated dual inhibitory effects against ATP-citrate lyase (ACL, IC50: 0.92 μM) and acetyl-CoA carboxylase 1 (ACC1, IC50: 10.76 μM). Compounds 2 and 11 exclusively inhibited ACL, exhibiting IC50 values of 2.64 and 6.35 μM, respectively. Compound 1 is classified among the fortunefuroic acid-type compounds, previously isolated from K. fortunei, distinguished by the presence of a rare furoic acid moiety in their lateral chain. The chemotaxonomic significance of the 9βH-lanost-26-oic acids in Keteleeria was briefly discussed. These findings highlight the importance of conserving plant species diversity, thereby enhancing the exploration of structurally diverse compounds and potential avenues for developing new therapeutics targeting ACL/ACC1-associated diseases.

Effect of lactic acid bacteria inoculation on the aflatoxin B1 contamination and the diversity of yeast communities in Aspergillus flavus-contaminated experimental corn silage

AbstractThe present work aimed to study the yeast communities of whole crop corn silages (CS) that were previously contaminated with aflatoxin-producing Aspergillus flavus (CSCA). In addition, the effect of lactic acid bacterium (LAB) inoculation on the aflatoxin B1 (AFB1) content, genotoxicity, yeast load, and diversity of yeast communities were also investigated. In A. flavus contaminated silages, after two months, the AFB1 content was 40% lower with LAB inoculation, also a lower level of genotoxicity was determined. The number of yeasts cultured from the initial mixture of chopped whole crop corn was 4.8 × 107 CFU g−1 wet mass, while only 2.4 × 106 CFU g−1 from the CSCA and 7.1 × 105 CFU g−1 from the LAB-inoculated CSCA could be cultured. Based on 144 randomly isolated strains, the yeast community of the initial mixture consisted of 8 species. In contrast, the yeast community of CSCA consisted only of 4 species determined by 132 randomly selected isolates. LAB-inoculated CSCA consisted also of 4 species based on 158 randomly isolated strains. Saccharomyces cerevisiae and Pichia kudriavzevii proved to be predominant in the CSCA, while S. cerevisiae and Meyerozyma guilliermondii were the most abundant in the LAB-inoculated CSCA. The species richness was also confirmed by alpha diversity values (1.827, 1.188, and 1.123 as Shannon's indices for CS, CSCA, and LAB-inoculated CSCA, respectively). In response to LAB inoculation, the species diversity decreased considerably.

Biodiversity as a Tool in the Assessment of the Conservation Status of Coastal Habitats: A Case Study from Calabria (Southern Italy)

The Mediterranean coasts are threatened by human activities that alter habitats structure and functionality, modifying vegetation and causing the loss of typical species. The definition of the conservation status of coastal habitats is essential to preserve these fragile environments through planned policies. This study aims to assess the conservation status of the habitats of community interest (sensu EEC Directive 43/92) through the analysis of biodiversity and correlating it with urbanisation. A total of 73 vegetation relevés were carried out, so allowing 13 revealing different habitats to be identified. The total plant species diversity per habitat was measured by means of the H-index, also used to assess naturalness (N), differently considering native, alien, and disturbance species. To correlate the N index with distance from urban centres, a statistical analysis was performed. The analysis showed the highest values of H+ were found in habitats 2240, 2110, 2260, and 2230, while lowest values were observed in habitats 2270* and 2240. The habitats 2270* and 2240, the closest to urban centres, have a lower naturalness score than habitats 1420, 2120, 2250*, and 2270*, where higher naturalness scores have been found and therefore lower levels of disturbance. The criteria and methods discussed in this study can be used in coastal management in order to identify the most sensitive habitats and implement an effective conservation strategy.

Taxonomic, Functional, and Phylogenetic Diversity of Bats in Urban and Suburban Environments in Southern México

Urbanization is one of the leading causes of habitat loss, which has increased significantly in tropical regions in recent years, leading to the loss of species, their ecological functions, and evolutionary history. To determine the effect of urbanization on the diversity of bat communities in urban and suburban environments, we analyzed the α and β taxonomic, functional, and phylogenetic diversities at four sites along urbanization gradients surrounding a rapidly expanding city (Oaxaca City) in southern Mexico. We recorded bats using conventional techniques such as mist nets and acoustic monitoring. We calculated the diversity of bats in four sites with different urbanization conditions: urban (1), suburban (1), and rural (2). To assess the degree of total differentiation and components of bat turnover and nestedness between sites, we calculated the β taxonomic, functional, and phylogenetic diversities. A total of 33 bat species were recorded. The highest taxonomic and functional diversity was observed in the Center of Oaxaca (the site with the highest level of urbanization). In contrast, the highest phylogenetic diversity was found in the West (the site with the lowest level of urbanization). The total β taxonomic diversity was higher than the functional and phylogenetic diversity. Regarding the contributions of turnover and nestedness, turnover made a more significant contribution than nestedness to the taxonomic and phylogenetic β diversity. In contrast, functional nestedness contributed more to the functional β diversity than turnover. Tadarida brasiliensis, Desmodus rotundus, Sturnira hondurensis, and S. parvidens were recorded in all three urbanization conditions. In the most urbanized site, four Myotis species were recorded: M. fortidens, M. keaysi, M. thysanodes, and M. velifer. We suggest that the analysis of different dimensions of diversity is essential and should be considered to strengthen conservation strategies; moreover, we suggest the preservation of native vegetation mosaics and water bodies within the city to maintain bat diversity.

Mixed-charge hyperbranched polymer nanoparticles with selective antibacterial action for fighting antimicrobial resistance

The escalating menace of antimicrobial resistance (AMR) presents a profound global threat to life and assets. However, the incapacity of metal ions/reactive oxygen species (ROS) or the indiscriminate intrinsic interaction of cationic groups to distinguish between bacteria and mammalian cells undermines the essential selectivity required in these nanomaterials for an ideal antimicrobial agent. Hence, we devised and synthesized a range of biocompatible mixed-charge hyperbranched polymer nanoparticles (MCHPNs) incorporating cationic, anionic, and neutral alkyl groups to effectively combat multidrug-resistant bacteria and mitigate AMR. This outcome stemmed from the structural, antibacterial activity, and biocompatibility analysis of seven MCHPNs, among which MCHPN7, with a ratio of cationic groups, anionic groups, and long alkyl chains at 27:59:14, emerged as the lead candidate. Importantly, owing to inherent differences in membrane potential among diverse species, alongside its nano-size (6 - 15 nm) and high hydrophilicity (Kow = 0.04), MCHPN7 exhibited exceptional selective bactericidal effects over mammalian cells (selectivity index > 564) in vitro and in vivo. By inducing physical membrane disruption, MCHPN7 effectively eradicated antibiotic-resistant bacteria and significantly delayed the emergence of bacterial resistance. Utilized as a coating, MCHPN7 endowed initially inert surfaces with the ability to impede biofilm formation and mitigate infection-related immune responses in mouse models. This research heralds the advent of biocompatible polymer nanoparticles and harbors significant implications in our ongoing combat against AMR. Statement of SignificanceThe escalating prevalence of antimicrobial resistance (AMR) has been acknowledged as one of the most significant threats to global health.Therefore, a series of mixed-charge hyperbranched polymer nanoparticles (MCHPNs) with selective antibacterial action were designed and synthesized. Owing to inherent differences in membrane potential among diverse species and high hydrophilicity (Kow = 0.04), the optimal nanoparticles exhibited exceptional selective bactericidal effects over mammalian cells (selectivity index >564) and significantly delayed the emergence of bacterial resistance. Importantly, they endowed surfaces with the ability to impede biofilm formation and mitigate infection-related immune responses.Furthermore, the above findings focus on addressing the problem of AMR in Post-Pandemic, which will for sure attract attention from both academic and industry research.

Habitat fragmentation differentially affects invasive and native plant diversity in a human-dominated wetland island system

Managing invasive species requires identifying the factors that determine alien species invasion success. This study investigates how anthropogenic and biogeographical factors influence alien plant invasion in the Sanyang Wetlands, a human-dominated island system in Wenzhou City, China. Specifically, we analyzed whether human activities (e.g., habitat heterogeneity, proportion of road area, and cultivation) and island characteristics (e.g., island area, isolation) affect the diversity of native and invasive plant species similarly. We also assessed the applicability of the equilibrium theory of island biogeography to invasive plant species diversity and examined how these factors affect invasive plant species with different dispersal syndromes (anemochore, zoochore, and autochore). We found that both invasive and native species richness positively correlate with island area, habitat heterogeneity, and proportion of road area. However, although native species richness was negatively correlated with isolation, invasive species richness was not. The diversity and composition of invasive species with different dispersal syndromes were determined by different variables; for example, the composition and diversity of zoochores was increased by habitat heterogeneity, while anemochore species richness was increased by the proportion of road area, whereas anemochore species composition was influenced by distance to the nearest island. We conclude that habitat fragmentation differentially affects invasive and native plant diversity, aligning with the predictions of the equilibrium theory of island biogeography only for native species but not for invasive species. Our findings indicate that tailoring habitat attributes and regulating human activities could be effective strategies for mitigating the spread of invasive species in fragmented landscapes.

The fate of sulfamethoxazole in microcosms of the macrophyte Schoenoplectus californicus and its impact on microbial communities

Sulfamethoxazole is a widely used antibiotic frequently found as an environmental pollutant. It can alter microbial communities and increase antibiotic resistance, becoming a public health risk. Constructed wetlands have the potential for removing sulfamethoxazole from polluted waters, but the role of different macrophytes in this process is not well understood. We investigated the fate of sulfamethoxazole and its effect on bacterial communities in microcosms containing Schoenoplectus californicus, an altitude-tolerant macrophyte. Within the first ten hours after introducing sulfamethoxazole (initial concentration 5 mg/L) to the microcosms, the concentration in the liquid phase significantly differed between microcosms with and without S. californicus. However, over the long term (15 and 30 days post-addition), the removal percentage (around 75%) in the liquid phase was not significantly influenced by S. californicus, indicating that sediments might be primarily responsible for removing the antibiotic. The presence of S. californicus promoted algae growth in the microcosms, and we determined that algae contributed to sulfamethoxazole removal from the liquid phase, likely through adsorption. Additionally, we characterized bacterial communities in the microcosm sediments via nanopore sequencing to identify changes following sulfamethoxazole addition. The relative abundance of Proteobacteria increased from 37-46% to 48-99% with the addition of the antibiotic. Conversely, the relative abundance of cyanobacteria decreased significantly after sulfamethoxazole was added (from 17-35% to less than 2%), suggesting it may serve as a biological marker for sulfamethoxazole pollution. In addition, the functional profile of the community was estimated from taxonomic diversity using PICRUST.

Phylogeographic analysis reveals multiple origins of the desert shrub Reaumuria songarica in northern Xinjiang, involving homoploid and tetraploid hybrids.

Hybrid speciation plays an important role in species diversification. The establishment of reproductive isolation is crucial for hybrid speciation, and the identification of diverse types of hybrids, particularly homoploid hybrid species, contributes to a comprehensive understanding of this process. Reaumuria songarica is a constructive shrub widespread in arid Central Asia. Previous studies have inferred that the R. songarica populations in the Gurbantunggut Desert (GuD) originated from homoploid hybridizations between its eastern and western lineages and may have evolved into an incipient species. To further elucidate the genetic composition of different hybrid populations and to determine the species boundary of this hybrid lineage, we investigated the overall phylogeographic structure of R. songarica based on variation patterns of five cpDNA and one nrITS sequences across 32 populations. Phylogenetic analyses demonstrated that within the GuD lineage, the Wuerhe population evolved directly from ancestral lineages, whereas the others originated from hybridizations between the eastern and western lineages. PCoA and genetic barrier analysis supported the subdivision of the GuD lineage into the southern (GuD-S) and northern (GuD-N) groups. Populations in the GuD-S group had a consistent genetic composition and the same ancestral female parent, indicating that they belonged to a homoploid hybrid lineage. However, the GuD-N group experienced genetic admixture of the eastern and western lineages on nrITS and cpDNA, with some populations inferred to be allopolyploid based on ploidy data. Based on cpDNA haplotypes, BEAST analyses showed that the GuD-S and GuD-N groups originated after 0.5 Ma. Our results suggest that multiple expansions and contractions of GuD, driven by Quaternary climatic oscillations and the Kunlun-Yellow River tectonic movement, are important causes of the complex origins of R. songarica populations in northern Xinjiang. This study highlights the complex origins of the Junggar Basin flora and the underappreciated role of hybridization in increasing its species diversity.

Construction of landscape ecological network based on MCR risk assessment Model: A case study of Liaoning Province, China

Numerous disorderly expansions of impervious surfaces have resulted from the ongoing urbanization process, eroding the ecological security pattern and exacerbating ecological risks, subsequently leading to a progressive deterioration in its integrity. The tension between the expansion of ecological space and urban spatial expansion is becoming increasingly acute. Exploring the connection between ecological risks in urban landscapes is important for effectively managing regional ecological risks and optimizing patterns of regional ecological security. However, previous studies focus on selecting ecological sources in an ecological network and ignore how ecological resilience is impacted by factors such as species diversity, ecological structure complexity, etc. Based on remote sensing images of Liaoning Province in 2000, 2010, and 2020, the study used the landscape core index as the main indicator of ecological risk assessment, constructed a landscape ecological risk assessment model, and analyzed the spatiotemporal evolution of landscape ecological risk over the past 20 years. The impact of landscape ecological risk on ecological resistance was further explored, and the landscape ecological risk results in 2020 were used as one of the resistance factors to construct a multi-indicator comprehensive resistance surface. After identifying important ecological sources, an ecological network based on the minimum cumulative resistance model (MCR) was constructed, the optimal path connecting important ecological source areas was determined, and the distribution pattern characteristics of the internal ecological network in Liaoning Province were revealed. The findings indicate a general shift in ecological risks from high to low, following a distribution pattern of “high in the east and low in the west”. Additionally, the study identified 8 ecological sources and established 28 ecological corridors, spanning a total length of roughly 8160 km. This study aims to furnish a scientific foundation for developing an ecological security pattern network and optimizing the landscape pattern within Liaoning Province.

Effect of the ten-year fishing ban on change of phytoplankton community structure: Insights from the Gan River.

The Yangtze River is one of the largest riverine ecosystems in the world and is a biodiversity hotspot. In recent years, this river ecosystem has undergone rapid habitat deterioration due to anthropogenic disturbances, leading to a decrease in freshwater biodiversity. Owing to these anthropogenic impacts, the Chinese government imposed a "Ten-year fishing ban" (TYFB) in the Yangtze River and its tributaries. Ecological changes associated with this decision have not been documented to evaluate the level of success. This study evaluates the success of the TYFB by analyzing the changes in phytoplankton communities and comparing them to periods before the TYFB was imposed. A total of 325 phytoplankton species belonging to 7 phyla and 103 genera dominated by Chlorophyceae and Bacillariophyceae were identified. Species diversity according to the Shannon-Wiener ranged between 1.19 and 3.00. The results indicated that phytoplankton diversity increased, while both density and biomass decreased after the TYFB. The health of the aquatic ecosystem appeared to have improved after the TYFB, as indicated by the phytoplankton-based index of biotic integrity. Significant seasonal and spatial differences were found among the number of species, density, and biomass of phytoplankton, where these differences were correlated with pH, water depth, chlorophyll-a, permanganate index, transparency, copper, ammonia nitrogen, and total phosphorus based on redundancy analysis. Results from this study indicate that the TYFB played an important role in the restoration of freshwater ecosystem in the Yangtze River and its tributaries.

Species Diversity and Distribution of Freshwater Fish in The Mekong River, Northeast of Thailand

Species Diversity and Distribution of Freshwater Fish in The Mekong River, Northeast of Thailand