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The Mekong River is one of the largest rivers in the world and hosts the second greatest fish diversity in the world after the Amazon. However, despite the importance of this diversity and its associated biomass for human food security and the economy, different anthropogenic pressures threaten the sustainability of the Mekong River and fish diversity, including the intense damming of the main river. Both the increase in salt-water penetration into the Mekong Delta and the disrupted connectivity of the river may have serious impacts on the numerous freshwater and migratory species. To evaluate the potential of an eDNA approach for monitoring fish diversity, water was sampled at 15 sites along the salinity gradient in the Mekong Delta and along 1500 km of the main stream, from Vietnam to Thailand and Laos. A total of 287 OTUs were recovered, of which 158 were identified to the species level using both reference sequences available in GenBank and references obtained locally. Agglomerative hierarchical clustering and PCA identified up to three main species assemblages in our samples. If the transition from brackish to freshwater conditions represents the main barrier between two of these assemblages, more surprisingly, the two other assemblages were observed in the freshwater Mekong, with a spatial disjunction that did not match any biogeographic ecoregion or the Khone falls, the latter thought to be an important fish dispersion barrier. Between 60% and 95% of the freshwater species were potamodromous. This pioneer eDNA study in the Mekong River at this geographical and ecological scale clearly confirmed the potential of this approach for ecological and diversity monitoring. It also demonstrated the need to rapidly build an exhaustive Mekong fish barcode library to enable more accurate species’ assignment. More eDNA surveys can now be expected to better describe the ecological niche of different species, which is crucial for any models aimed at predicting the impact of future damming of the Mekong.

Trait matching between mutualistic species is usually expected to maintain mutualism, but empirical studies of trait complementarity and coadaptation in multi‐species assemblages—which represent the reality of most interactions in nature—are few. Here, we studied trait matching between the leafflower shrub Kirganelia microcarpa and three associated seed‐predatory leafflower moths (Epicephala spp.) across 16 populations. Behavioral and morphological observations suggested that two moths (E. microcarpa and E. tertiaria) acted as pollinators while a third (E. laeviclada) acted as a cheater. These species differed in ovipositor morphology but showed trait complementarity between ovipositor length and floral traits at both species level and population level, presumably as adaptations to divergent oviposition behaviors. However, this trait matching varied among populations. Comparisons of ovipositor length and floral traits among populations with different moth assemblages suggested an increase of ovary wall thickness where the locular‐ovipositing pollinator E. microcarpa and cheater E. laeviclada were present, while stylar pit depth was less in populations with the stylar pit‐ovipositing pollinator E. tertiaria. Our study indicates that trait matching between interacting partners occurs even in extremely specialized multi‐species mutualisms, and that although these responses vary, sometimes non‐intuitively, in response to different partner species. It seems that the moths can track changes in host plant tissue depth for oviposition. Moth ovipositor morphology matches with different floral traits, suggesting potential adaptation to divergent oviposition behaviors across populations. Floral traits vary similarly in response to locular oviposition by both one of the pollinator species and the cheater, suggesting the possibility of arms race dynamics between plants and insect pollinators or cheaters.

Aim: To predict Rhododendron diversity patterns and identify Rhododendron hotspots and priority areas for their conservation. Location: China. Methods: We predicted the distribution of 212 Rhododendron species by applying a spatially explicit species assemblage modelling (SESAM) framework on a 10 × 10 km grid across China. We evaluated Rhododendron diversity based on species richness, β-diversity and weighted endemism (also known as range-size rarity), and then identified hotspots formed by the top 1%, 5%, 25% and 50% of record-containing grid cells for each diversity metric separately and for the combination of the three diversity metrics. We determined the priority conservation areas for Rhododendrons by overlaying the hotspots with the map of the 2139 nature reserves existing in China, and calculated the percentage of hotspots that is protected. The same analysis was also applied to threatened Rhododendron species. Results: Rhododendron species richness, β-diversity and weighted endemism decrease within China from the south-west to the north-east, mainly along mountain ranges. In total, 12 general hotspots for Rhododendron species are detected, covering 1.4% of China's land area. Five separately discerned hotspots (i.e. southern Chongqing, south-eastern Tibet, north-western Yunnan, south-western Sichuan and northern Guangdong) comprising threatened Rhododendron species largely overlap (86.3%) with the general hotspots, and form priority areas for conservation. However, the remaining hotspots, especially southern Zhejiang and north-eastern Guizhou, need more protection. Main conclusions: To the best of our knowledge, this is the first comprehensive study of Rhododendron diversity patterns across the whole of China in terms of species richness, β-diversity and weighted endemism, thereby offering a sound basis for the conservation of Rhododendrons in China. We demonstrate that as much attention should be paid to the small hotspots in south-western and south-eastern China, as to the largest hotspot (i.e. Mt Hengduan), to achieve conservation of Rhododendrons.

This study examines the complex feedback mechanisms that regulate a positive relationship between species richness and productivity in a longleaf pine-wiregrass woodland. Across a natural soil moisture gradient spanning wet-mesic to xeric conditions, two large scale manipulations over a 10-yr period were used to determine how limiting resources and fire regulate plant species diversity and productivity at multiple scales. A fully factorial experiment was used to examine productivity and species richness responses to N and water additions. A separate experiment examined standing crop and richness responses to N addition in the presence and absence of fire. Specifically, these manipulations addressed the following questions: (1) How do N and water addition influence annual aboveground net primary productivity of the midstory/overstory and ground cover? (2) How do species richness responses to resource manipulations vary with scale and among functional groups of ground cover species? (3) How does standing crop (including overstory, understory/midstory, and ground cover components) differ between frequently burned and fire excluded plots after a decade without fire? (4) What is the role of fire in regulating species richness responses to N addition? This long-term study across a soil moisture gradient provides empirical evidence that species richness and productivity in longleaf pine woodlands are strongly regulated by soil moisture. After a decade of treatment, there was an overall species richness decline with N addition, an increase in richness of some functional groups with irrigation, and a substantial decline in species richness with fire exclusion. Changes in species richness in response to treatments were scale-dependent, occurring primarily at small scales (≤10 m²). Further, with fire exclusion, standing crop of ground cover decreased with N addition and non-pine understory/midstory increased in wet-mesic sites. Non-pine understory/midstory standing crop increased in xeric sites with fire exclusion, but there was no influence of N addition. This study highlights the complexity of interactions among multiple limiting resources, frequent fire, and characteristics of dominant functional groups that link species richness and productivity.

To understand the impact of soil properties and land use systems on earthworm diversity in the biodiversity-rich Eastern Ghats Highlands of India, the present study was carried out in six land use systems i.e., moist deciduous forest, dry deciduous forest, fallow land, cropland, compost pit, and, sewage soil. The study area has been divided into 10 × 10 km2 grids and 25% grids were randomly selected for sampling from April to December 2022. A total of 16 species of earthworms under 14 genera and 8 families were recorded, out of which 15 species are new records for the region. The most taxonomically rich family was the Megascolecidae. The most abundant species are endogeic followed by epigeic and anecic. Based on Hill numbers, the highest values of Shannon index (1D = 9.89) and Simpson diversity (2D = 9.14) were found for the fallow land. Earthworm abundance showed a significant difference among six land use systems [F (5,84) = 3.256, p < 0.05] and seasons [F (2,87) = 46.463, p < 0.01]. Furthermore, earthworms showed a significant positive relationship with moisture (r = 0.538, p < 0.01), organic carbon (r = 0.560, p < 0.01), available Nitrogen (r = 0.525, p < 0.01), and clay content (r = 0.535, p < 0.01), whereas negatively correlated with sand content (r = − 0.513, p < 0.01) of soil. Cropland showed high species richness, and fallow land exhibited increased diversity due to elevated moisture, moderate edaphic factors, and proximity to pristine forests. The presence of a high number of native species urges their conservation in this region through land management.

Joshi, N.; Arya, P.C., and Saulnier-Talbot, E., 2025. Benthic foraminifera as useful bioindicators of heavy metal and organic enrichment in northern temperate coastal zones: A comprehensive review. Journal of Coastal Research, 41(3), 516–535. Charlotte (North Carolina), ISSN 0749-0208. Benthic foraminifera are known to respond to naturally occurring and anthropogenically induced stresses. A considerable body of literature exists describing the effects that contamination by heavy metal and organic enrichment has on these organisms in coastal environments. This review of the literature on the subject since 1980 shows that these types of contamination are reflected through changes in the physiology, abundance, and community structure of foraminifera, confirming them as useful bioindicators of environmental quality in the geographical context of the north temperate zone. Based on this analysis of the literature, results show that metal enrichment leads to deformations and altered foraminiferal test chemistry, whereas organic enrichment tends to mostly affect foraminiferal abundance and community structure, with little evidence for morphological effects. Additionally, anthropogenic activities can degrade and even destroy the ecological niches occupied by foraminifera, as evidenced by the disappearance of symbiont-bearing taxa with increasing organic contamination. This review highlights the usefulness of the ecological responses of foraminifera in assessing the current and long-term state of ecosystems in temperate benthic coastal environments, especially in the context of increased heavy metal and organic contamination by anthropogenic activities.

Context Human disturbance has transformed ecosystems globally, yet studies of the ecological impact of landscape modification are often confounded. Non-random patterns of land clearing cause differing vegetation types and soil productivity between fragments in modified landscapes and reference areas—like national parks—with which they are compared. Objectives We sought to explore the influence of land modification on herpetofauna and small mammal communities using multiple biodiversity measures—species richness and diversity, individual species abundance, and community composition. We also aimed to investigate the role of traits such as diet, habitat breadth, and litter size in moderating species responses to land modification. Methods We established 100 sampling sites to survey herpetofauna and small mammals in 11 fragments in an agricultural landscape compared to 11 ecologically equivalent ‘pseudo-fragments’ in a nearby national park in south-eastern Australia. We selected pairs of fragments and pseudo-fragments of the same size and vegetation type, and used identical survey methods to sample pairs simultaneously, thereby controlling for numerous confounding factors, such as differing vegetation type, weather, and survey effort. Results Species richness and diversity were similar between fragments and pseudo-fragments. Despite this, we found community composition differed markedly—driven by the varying responses of individual species—indicating a shift in fauna communities associated with land modification. Fossorial habit, omnivorous diet, and broad habitat requirements led to higher abundance in fragments whilst arboreality, carnivorous diet, and narrow habitat requirements led to higher abundance in pseudo-fragments. Conclusions Although fragments hold similar numbers of species to continuous areas, they contain distinct and novel communities, and sustain high abundances of some species. These diverse communities are dominated by native species, including threatened species, and their distinctive composition is shaped by traits conducive to persistence amidst land modification. These novel communities may provide a reservoir of resilience in the face of environmental change and should be viewed as complementary to conservation areas.

Aim: This study investigated how human activities and local environmental variables shape tree assemblages (species composition in a defined location), comparing their effects on edible and inedible tree species. Three hypotheses were tested: (1) Environmental filtering impacts spatial beta-diversity more than dispersal limitation; (2) human activities significantly influence regional tree beta-diversity; and (3) predictors of beta-diversity differ between edible and inedible species. Location: Tropical forest in Nigeria and Cameroon in West and Central Africa. Methods: Tree data were collected between 2002 and 2019 from 66 forest plots. Species were categorised as edible and inedible by humans using interviews and online databases. Pairwise beta-diversity (partitioned into total beta-diversity and turnover) between plots was analysed using Generalised Dissimilarity Models (GDMs) with geographical distance, plot-specific variables (forest composition, climate, elevation, stem density, human influence indicators), and human influence indicators (distance to closest human presence [DCHP], and nearest anthropogenic edges [DNAE]) as predictors.

The functional traits of organisms within multispecies assemblages regulate biodiversity effects on ecosystem functioning. Yet how traits should assemble to boost multiple ecosystem functions simultaneously (multifunctionality) remains poorly explored. In a multibiome litter experiment covering most of the global variation in leaf trait spectra, we showed that three dimensions of functional diversity (dispersion, rarity, and evenness) explained up to 66% of variations in multifunctionality, although the dominant species and their traits remained an important predictor. While high dispersion impeded multifunctionality, increasing the evenness among functionally dissimilar species was a key dimension to promote higher multifunctionality and to reduce the abundance of plant pathogens. Because too-dissimilar species could have negative effects on ecosystems, our results highlight the need for not only diverse but also functionally even assemblages to promote multifunctionality. The effect of functionally rare species strongly shifted from positive to negative depending on their trait differences with the dominant species. Simultaneously managing the dispersion, evenness, and rarity in multispecies assemblages could be used to design assemblages aimed at maximizing multifunctionality independently of the biome, the identity of dominant species, or the range of trait values considered. Functional evenness and rarity offer promise to improve the management of terrestrial ecosystems and to limit plant disease risks.

With the intensification of human activities, preserving animal populations is a contemporary challenge of critical importance. In this context, the umbrella species concept is appealing because preserving a single species should result in the protection of multiple co-occurring species. Practitioners, though, face the task of having to find suitable umbrellas to develop single-species management guidelines. In North America, boreal forests must be managed to facilitate the recovery of the threatened boreal caribou (Rangifer tarandus). Yet, the effect of caribou conservation on co-occurring animal species remains poorly documented. We tested if boreal caribou can constitute an effective umbrella for boreal fauna. Birds, small mammals, and insects were sampled along gradients of post-harvest and post-fire forest succession. Predictive models of occupancy were developed from the responses of 95 species to characteristics of forest stands and their surroundings. We then assessed the similarity of species occupancy expected between simulated harvested landscapes and a 90 000-km2 uncut landscape. Managed landscapes were simulated based on three levels of disturbance, two timber-harvest rotation cycles, and dispersed or aggregated cut-blocks. We found that management guidelines that were more likely to maintain caribou populations should also better preserve animal assemblages. Relative to fragmentation or harvest cycle, we detected a stronger effect of habitat loss on species assemblages. Disturbing 22%, 35%, and 45% of the landscape should result, respectively, in 80%, 60%, and 40% probability for caribou populations to be sustainable; in turn, this should result in regional species assemblages with Jaccard similarity indices of 0.86, 0.79, and 0.74, respectively, relative to the uncut landscape. Our study thus demonstrates the value of single-species management for animal conservation. Our quantitative approach allows for the evaluation of management guidelines prior to implementation, thereby providing a tool for establishing suitable compromises between economic and environmental sustainability of human activities.