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Key message: The first-order root traits are important for nutrients foraging for plants and their foraging strategies can be influenced by the changing of environmental variables. Fine roots are critical for soil resource acquisition by trees. Understanding root traits and their responses to varied environmental conditions is crucial for root resource foraging under environmental alternations. Data on eight first-order root traits including branching ratio, root diameter (RD), specific root length (SRL), specific root area (SRA), root tissue density (RTD), root carbon (C) concentration, root nitrogen (N) concentration, and arbuscular mycorrhizal colonization of roots (AM colonization) were collected along a large environmental gradient to quantify relationships between first-order root traits and environmental contributing factors in Chinese fir (Cunninghamia lanceolata) plantations of Subtropical China. High mean annual precipitation (MAP) significantly increased AM colonization but decreased root C concentration, resulting in shifting towards a conservative foraging strategy of the first-order roots. Soil pH showed positive correlations with AM colonization and root N concentration, but negative correlations with the branching ratio (number of first-order roots/second-order roots), indicating shifting towards an acquisitive foraging strategy when soil becomes more acidic. However, increased soil C: N and soil P resulted in lower root N, lower RTD, and thicker root diameter of the first-order roots. Our study provides evidence that harsh environmental conditions such as drought and acidity resulted in the growth of more root tips (first-order roots), consequently shifting towards an acquisitive foraging strategy. In contrast, locations with more abundant rainfall and more neutral and fertile soils caused thicker and fewer root tips with higher AM colonization, shifting towards a conservative foraging strategy. [ABSTRACT FROM AUTHOR]

Trait-based approaches are a common method for testing community assembly theory. However, most traitbased studies focus on interspecific trait variation across broad-scale climatic gradients and are lacking in extreme eliniates and vulnerable ecosystems. I his study investigated how variations in elevation, and the associated changes in abiotic variables, intluenced the functional traits of a high-altitude mountain shrub, Alpine Grevillea Grevillea australts, within the Victorian Alpine Region. Six sites of varying elevation were selected and variation iii a range of functional traits of G. austratis was measured: height, stem density, leaf dry matter content (LDMC), leaf thickness, and leaf size. Shrubs associated with lower elevations were taller, with lower stem density, thicker leaves and higher LDMC. At higher elevations, shrubs were shorter, had thinner leaves, lower LDMC and higher stem density. these findings suggest a shift in ecological strategy iii response to changing abiotic stressors, and describe the trade-off between coping with environmental variables and competition. (The Victorian Naturalist 140 (3), 2023,64-74). [ABSTRACT FROM AUTHOR]

The beta diversity among lakes is affected by natural environmental sorting, dispersal constraints, and anthropogenic disturbances. We hypothesized that fish beta diversity would increase towards lower latitudes and be higher in less disturbed lakes at within-region scale, but environmental disturbances could affect these patterns due to community homogenization or heterogenization (e.g., gain of exotic species) among lakes. We used generalized dissimilarity modeling to assess the relative importance of geographic distance, climate, and environmental heterogeneity on fish beta diversity across Denmark, Belgium/The Netherlands, and Spain. We also tested whether differences in beta diversity changed between lake types (e.g., clear vs. turbid lakes and lakes with vs. without exotics fish) within-region and across latitude. Beta diversity increased from Denmark to Spain and geographic distance and climate variability were the main drivers of community change across latitude, but the rate of change varied between lake types. At the within-region scale, factors such as turbidity, lake size, and presence of exotics had varying impacts on beta diversity (i.e., increasing, decreasing, or no effect) across the three regions. Our findings suggest that understanding the effects of environmental disturbances on beta diversity requires consideration of both biogeographic and local factors. [ABSTRACT FROM AUTHOR]

Adaptive genetic divergence occurs when selection imposed by the environment causes the genomic component of the phenotype to differentiate. However, genomic signatures of natural selection are usually identified without information on which trait is responding to selection by which selective agent(s). Here, we integrate whole‐genome sequencing with phenomics and measures of putative selective agents to assess the extent of adaptive divergence in threespine stickleback occupying the highly heterogeneous lake Mývatn, NE Iceland. We find negligible genome wide divergence, yet multiple traits (body size, gill raker structure and defence traits) were divergent along known ecological gradients (temperature, predatory bird densities and water depth). SNP based heritability of all measured traits was high (h2 = 0.42–0.65), indicating adaptive potential for all traits. Environment‐association analyses further identified thousands of loci putatively involved in selection, related to genes linked to, for instance, neuron development and protein phosphorylation. Finally, we found that loci linked to water depth were concurrently associated with pelvic spine length variation ‐ supporting the conclusion that divergence in pelvic spine length occurred in the face of gene flow. Our results suggest that whilst there is substantial genetic variation in the traits measured, phenotypic divergence of Mývatn stickleback is mostly weakly associated with environmental gradients, potentially as a result of substantial gene flow. Our study illustrates the value of integrative studies that combine genomic assays of multivariate trait variation with landscape genomics. [ABSTRACT FROM AUTHOR]

We investigated spatial patterns of evolutionary diversity along Neotropical Non‐Flooded Evergreen Forests (NEF). We addressed the following questions: (i) What are the main NEF evolutionary groups? (ii) How evolutionary diversity varies across NEF environmental gradients? Based on a phylogeny of 1248 tree genera distributed over 1824 NEF assemblages, we examined the evolutionary differentiation using UPGMA and evopca. We measured lineage diversity (ses.PD) and structure (ses.MPD and ses.MNTD) and tested their response to environmental gradients using linear models. Phylogenetic dissimilarity segregated NEF into 12 evolutionary groups that largely confirm groups obtained in our previous work based on floristic similarity. However, one discrepancy was the amalgamation of Amazon and northern Atlantic Forest assemblages, while the southern Atlantic Forest remained an isolated group. Furthermore, Mesoamerica, which had been recognized as a single group, here split into six evolutionary groups. We found greater lineage diversity as altitude and latitude increased and temperature decreased. Evolutionary groups with the highest mean values of lineage diversity were those composed of Mesoamerican cloud forests, which harbor a mixture of tropical and temperate lineages representing a confluence of South and North American floras. We found that variations in phylogenetic diversity in NEF are primarily related to the coexistence of lineages of temperate and tropical climates in the mountain and nebular environments of NEF, indicating the strong contribution of extratropical niche conservatism in structuring evolutionary diversity. [ABSTRACT FROM AUTHOR]

Context: Climate and soil factors play central roles in shaping grassland landscapes. However, an accurate assessment of how these factors influence grassland plant diversity has been scarce and difficult because soil properties are determined partly by climate factors, and diversity can be characterized in variety of ways. Objective: We aimed to explore how and to what extent climate and soil factors influence different components (richness vs. evenness) and levels (among- vs. within-species) of plant diversity. Methods: We used the linear and the structural equation models to examine the impacts of 16 soil and climate factors on the four diversity indices across 113 Qinghai-Tibetan grassland sites. Results: Species richness was negatively correlated with sunshine hours, temperature and soil pH, but positively with soil fertility and climate moisture (precipitation and relative humidity). By contrast, Pielou evenness and individual size inequality (ISI) were correlated positively with temperature, but negatively with soil fertility and climate moisture. The main factor affecting species richness and Shannon diversity directly (or indirectly through soil pH and total nitrogen content) was precipitation, whereas precipitation and temperature together governed ISI. Moreover, total soil nitrogen (or phosphorus) content was the significant factor increasing (or decreasing) ISI. Conclusion: Results suggest that moisture conditions, especially precipitation, are the main driver of landscape-scale biodiversity. We also highlight the importance of both direct and indirect climate impact on grassland community assembly through changing soil conditions. [ABSTRACT FROM AUTHOR]

Climate change is driving Baltic Sea shifts, with predictions for decrease in salinity and increase in temperature and light limitation. Understanding the responses of the spring phytoplankton community to these shifts is essential to assess potential changes in the Baltic Sea biogeochemical cycles and functioning. In this study we use a high-throughput well-plate setup to experimentally define growth and the light acquisition traits over gradients of salinity, temperature and irradiance for three dinoflagellates commonly occurring during spring in the Baltic Sea, Apocalathium malmogiense, Gymnodinium corollarium and Heterocapsa arctica subsp. frigida. By analysing the response of cell volume, growth, and light-acquisition traits to temperature and salinity gradients, we showed that each of the three dinoflagellates have their own niches and preferences and are affected differently by small changes in salinity and temperature. A. malmogiense has a more generalist strategy, its growth being less affected by temperature, salinity, and light gradients in comparison to the other tested dinoflagellates, with G. corollarium growth being more sensitive to higher light intensities. On the other hand, G. corollarium light acquisition traits seem to be less sensitive to changes in temperature and salinity than those of A. malmogiense and H. arctica subsp. frigida. We contextualized our experimental findings using data collected on ships-of-opportunity between 1993-2011 over natural temperature and salinity gradients in the Baltic Sea. The Apocalathium complex and H. arctica subsp. frigida were mostly found in temperatures

The ecological indicator values are the most common and sufficiently effective method of habitat assessment. The aim of our research review is to analyze current studies from 2020 to 2022 in which researchers have used Ellenberg indicator values to address a variety of problems. We limited the study to papers that are published in journals indexed by Scopus and Web of Science. The total number of records examined was 358. The number of records selected was 98. Visualization of the distribution of studies by country is based on the GeoCharts library. The results revealed that about half of the studies were conducted in Germany and Poland, and the most common objects were forests and grasslands. Almost half of the studies were devoted to ecological niches, habitat analysis, assessment of vegetation dynamics, and influence of various factors on plants. The analyzed articles are actively cited. In general, our research analysis revealed the effectiveness of Ellenberg indicator values for solving a wide range of urgent problems for a variety of plant communities, and different climate zones. The results of our research confirmed the advisability of actively using this approach. [ABSTRACT FROM AUTHOR]

Warming temperatures and advancing spring are affecting annual snow and ice cycles, as well as plant phenology, across the Arctic and boreal regions. These changes may be linked to observed population declines in wildlife, including barren‐ground caribou (Rangifer tarandus), a key species of Arctic environments. We quantified how barren‐ground caribou, characteristically both gregarious and migratory, synchronize births in time and aggregate births in space and investigated how these tactics are influenced by variable weather conditions. We analyzed movement patterns to infer calving dates for 747 collared female caribou from seven herds across northern North America, totaling 1255 calving events over a 15‐year period. By relating these events to local weather conditions during the 1‐year period preceding calving, we examined how weather influenced calving timing and the ability of caribou to reach their central calving area. We documented continental‐scale synchrony in calving, but synchrony was greatest within an individual herd for a given year. Weather conditions before and during gestation had contrasting effects on the timing and location of calving. Notably, a combination of unfavorable weather conditions during winter and spring, including the pre‐calving migration, resulted in a late arrival on the calving area or a failure to reach the greater calving area in time for calving. Though local weather conditions influenced calving timing differently among herds, warm temperatures and low wind speed, which are associated with soft, deep snow, during the spring and pre‐calving migration, generally affected the ability of female caribou to reach central calving areas in time to give birth. Delayed calving may have potential indirect consequences, including reduced calf survival. Overall, we detected considerable variability across years and across herds, but no significant trend for earlier calving by caribou, even as broad indicators of spring and snow phenology trend earlier. Our results emphasize the importance of monitoring the timing and location of calving, and to examine how weather during summer and winter are affecting calving and subsequent reproductive success. [ABSTRACT FROM AUTHOR]

Canopy gaps are openings in the forest canopy resulting from branch fall and tree mortality events. The geographical distribution of large canopy gaps may reflect underlying variation in mortality and growth processes. However, a lack of data at the appropriate scale has limited our ability to study this relationship until now.We detected canopy gaps using a unique LiDAR dataset consisting of 650 transects randomly distributed across 2500 km2 of the Brazilian Amazon. We characterized the size distribution of canopy gaps using a power law and we explore the variation in the exponent, α. We evaluated how the α varies across the Amazon, in response to disturbance by humans and natural environmental processes that influence tree mortality rates.We observed that South‐eastern forests contained a higher proportion of large gaps than North‐western, which is consistent with recent work showing greater tree mortality rates in the Southeast than the Northwest. Regions characterized by strong wind gust speeds, frequent lightning and greater water shortage also had a high proportion of large gaps, indicating that geographical variation in α is a reflection of underlying disturbance processes. Forests on fertile soils were also found to contain a high proportion of large gaps, in part because trees grow tall on these sites and create large gaps when they fall; thus, canopy gap analysis picked up differences in growth as well as mortality processes. Finally, we found that human‐modified forests had a higher proportion of large gaps than intact forests, as we would expect given that these forests have been disturbed.Synthesis. The proportion of large gaps in the forest canopy varied substantially over the Brazilian Amazon. We have shown that the trends can be explained by geographical variation in disturbance and growth. The frequency of extreme weather events is predicted to increase under climate change, and changes could lead to greater forest disturbance, which should be detectable as an increased proportion of large gaps in intact forests. [ABSTRACT FROM AUTHOR]

Clustering of species with similar niches or traits occurs in communities, but the mechanisms behind this pattern are still unclear. In the emergent neutrality model, species with similar niches and competitive ability self‐organise into clusters. In the hidden‐niche model, unaccounted‐for niche differences stabilise coexistence within clusters. Finally, clustering may occur through alliances of species that facilitate each other. We tested these hypotheses using population‐growth models that consider interspecific interactions parameterised for 35 species using field data. We simulated the expected community dynamics under different species‐interaction scenarios. Interspecific competition was weaker within rather than between clusters, suggesting that differences in unmeasured niche axes stabilise coexistence within clusters. Direct facilitation did not drive clustering. In contrast, indirect facilitation seemingly promoted species alliances in clusters whose members suppressed common competitors in other clusters. Such alliances have been overlooked in the literature on clustering, but may arise easily when within cluster competition is weak. [ABSTRACT FROM AUTHOR]

Plant defense against herbivores is multidimensional, and investment into different defense traits is intertwined due to genetic, physiological, and ecological costs. This relationship is expected to generate a trade‐off between direct defense and tolerance that is underlain by resource availability, with increasing resources being associated with increased investment in tolerance and decreased investment in direct resistance. We tested these predictions across populations of the shrub Artemisia californica by growing plants sourced from a latitudinal aridity gradient within common gardens located at the southern (xeric) and northern (mesic) portions of its distribution. We measured plant growth rate, resistance via a damage survey, and tolerance to herbivory by experimentally simulating vertebrate herbivory. Plants from more northern (vs. southern) environments were less resistant (received higher percent damage by vertebrate herbivores) and tended to be more tolerant (marginally significant) with respect to change in biomass measured 12 months after simulated vertebrate herbivory. Also, putative growth and defense traits paralleled patterns of resistance and tolerance, such that leaves from northern populations contained lower concentrations of terpenes and increased N, specific leaf area, and % water. Last, plant growth rate did not demonstrate clear clinal patterns, as northern populations (vs. southern populations) grew more slowly in the southern (xeric) garden, but there was no clinal relationship detected in the northern (mesic) garden. Overall, our findings support the prediction of lower resistance and higher tolerance in plant populations adapted to more resource‐rich, mesic environments, but this trade‐off was not associated with concomitant trade‐offs in growth rate. These findings ultimately suggest that plant adaptation to resource availability and herbivory can shape intraspecific variation in multivariate plant defenses. [ABSTRACT FROM AUTHOR]

The present study is based on the identification of benthic diatoms sampled along the Coastal Central Constantine in northeastern of Algeria. Our work aims to address relationships between environmental variables and characterize the spatial and temporal distribution of the diatom flora. Diatoms and samples for physicochemical analysis were collected from 26 sampling sites between May 2017 and August 2018. The number of species accounted for was 109 species in the Safsaf watershed, 117 taxa in the Kebir and 129 species in the watershed of Guebli which was the most diversified catchment. The great majority of diatom taxa were cosmopolitan species. Naviculaceae were the most abundant (47.87%). Our results demonstrated the main environmental variables controlling the diatom distribution in all the watersheds, including conductivity, and pollution gradients highlighted in Canonical Correspondence Analyses (CCA). The results of the Shannon diversity index (H') showed that the species diversity observed in the sampled sites during summer is higher than that observed in spring and winter. During this season, mean Shannon diversity values were around H' = 4.49, 3.98, and 4.17, respectively, while species richness varied between 13 and 34 across the three watersheds. [ABSTRACT FROM AUTHOR]

Functional diversity and the contribution of functional traits in mangrove ecosystems dynamics in western Mexico remain unknown. In this study, we assessed functional variability and intraspecific trait variation in three different mangrove zones. We developed and tested the following hypothesis: (i) mangrove species vary along trait axes associated with plant size and leaf economics. (ii) there is intraspecific trait variation (ITV) in leaf traits related to economic aspects of plant function among mangrove zones. (iii) the presence of functional variation in plant traits among mangrove zones is related to physicochemical ground-water gradients. We used 65 permanent plots, distributed across three contrasting mangrove zones to assess morphological functional traits: leaf area, specific leaf area (SLA), leaf dry-matter content (LDMC), tree height (H) and wood density; in each permanent plot, we recorded: water salinity, dissolved oxygen, pH and temperature. We used Principal Component Analysis (PCA) to examine how mangrove and mangrove-associated species were assembled in the functional trait space; in order to identify ITV, we compared the mean functional trait values using general linear models (GLM) with the zone and species as fixed effects. We also tested for differences in functional composition by Community-Weighted Means (CWM) running GLM for each trait with mangrove zones as fixed effect. Finally, we ran a Redundancy Analysis (RDA) to identify interstitial water variables explaining functional composition. According to our GLM results, we found intraspecific variability in functional traits among the three mangrove zones; particularly LDMC varied the most among species inside the three zones. Regarding GLM results using CWM, traits such as SLA, LDMC and H were different among zones. Our findings suggested ITV among mangrove zones with spatial patterns related to interstitial water variables; mangrove species exhibited significant ITV mainly in SLA and LDMC; salinity and pH were relevant to the functional ecology in mangrove ecosystems. [ABSTRACT FROM AUTHOR]

Abstract Background The environment is a strong driver of genetic structure in many natural populations, yet often neglected in population genetic studies. This may be a particular problem in vagile species, where subtle structure cannot be explained by limitations to dispersal. Consequently, these species might falsely be considered quasi-panmictic and hence potentially mismanaged. A species this might apply to, is the buff-tailed bumble bee (Bombus terrestris), an economically important and widespread pollinator, which is considered to be quasi-panmictic at mainland continental scales. Here we aimed to (i) quantify genetic structure in 21+ populations of the buff-tailed bumble bee, sampled throughout two Eastern European countries, and (ii) analyse the degree to which structure is explained by environmental differences, habitat permeability and geographic distance. Using 12 microsatellite loci, we characterised populations of this species with Fst analyses, complemented by discriminant analysis of principal components and Bayesian clustering approaches. We then applied generalized dissimilarity modelling to simultaneously assess the informativeness of geographic distance, habitat permeability and environmental differences among populations in explaining divergence. Results Genetic structure of the buff-tailed bumble bee quantified by means of Fst was subtle and not detected by Bayesian clustering. Discriminant analysis of principal components suggested insignificant but still noticeable structure that slightly exceeded estimates obtained through Fst analyses. As expected, geographic distance and habitat permeability were not informative in explaining the spatial pattern of genetic divergence. Yet, environmental variables related to temperature, vegetation and topography were highly informative, explaining between 33 and 39% of the genetic variation observed. Conclusions In contrast to previous studies reporting quasi-panmixia in continental populations of this species, we demonstrated the presence of subtle population structure related to environmental heterogeneity. Environmental data proved to be highly useful in unravelling the drivers of genetic structure in this vagile and opportunistic species. We highlight the potential of including these data to obtain a better understanding of population structure and the processes driving it in species considered to be quasi-panmictic.

Abstract Warming temperatures and advancing spring are affecting annual snow and ice cycles, as well as plant phenology, across the Arctic and boreal regions. These changes may be linked to observed population declines in wildlife, including barren‐ground caribou (Rangifer tarandus), a key species of Arctic environments. We quantified how barren‐ground caribou, characteristically both gregarious and migratory, synchronize births in time and aggregate births in space and investigated how these tactics are influenced by variable weather conditions. We analyzed movement patterns to infer calving dates for 747 collared female caribou from seven herds across northern North America, totaling 1255 calving events over a 15‐year period. By relating these events to local weather conditions during the 1‐year period preceding calving, we examined how weather influenced calving timing and the ability of caribou to reach their central calving area. We documented continental‐scale synchrony in calving, but synchrony was greatest within an individual herd for a given year. Weather conditions before and during gestation had contrasting effects on the timing and location of calving. Notably, a combination of unfavorable weather conditions during winter and spring, including the pre‐calving migration, resulted in a late arrival on the calving area or a failure to reach the greater calving area in time for calving. Though local weather conditions influenced calving timing differently among herds, warm temperatures and low wind speed, which are associated with soft, deep snow, during the spring and pre‐calving migration, generally affected the ability of female caribou to reach central calving areas in time to give birth. Delayed calving may have potential indirect consequences, including reduced calf survival. Overall, we detected considerable variability across years and across herds, but no significant trend for earlier calving by caribou, even as broad indicators of spring and snow phenology trend earlier. Our results emphasize the importance of monitoring the timing and location of calving, and to examine how weather during summer and winter are affecting calving and subsequent reproductive success.

Abstract Despite growing knowledge on the distribution and functioning of dryland vegetation types, their internal biodiversity structure (i.e., subregions) is much less studied. In the delineation of subregions, the use of species occurrence or abundance data may reveal different aspects of metacommunity structure. We revisit the issue of the bioregionalization of the woody flora of the Caatinga, the largest block of the dry forest and woodland biome in Latin America, using abundance data. We also evaluated the drivers of the spatial distribution of plant subregions: historical, current environmental and human effects. Using a K-means partition on interpolated NMDS axes, we identified 10 abundance subregions. Aridity, topography and soil, biome stability since the Pleistocene, and historical indigenous effects were retained by a Multinomial Logistic regression model, and their combined fractions explained most of the abundance variability in subregions. The subregions we present may support spatialized conservation and management decisions in the lack of detailed local data. The present results confirm the Caatinga woody flora broad composition patterns uncovered using presence-absence data in previous studies. Additionally, we found larger subregions than those identified with presence and absence data, suggesting the existence of oligarchies of dominant species in distinct parts of the Caatinga biome.

Simple Summary: Thermal tolerance can help understand species' response to climate change, but regional scale data is missing. We filled this gap by investigating intraspecific variations in the critical thermal maximum (CTmax) of Rana uenoi tadpoles collected from rice paddies and Bufo sachalinensis tadpoles collected from lakes, over a five-degree latitudinal gradient. We found a positive relationship between latitude and CTmax in R. uenoi tadpoles, although they did not display specific thermoregulatory behaviors. In contrast, none of the abiotic factors were related to CTmax in B. sachalinensis, but the tadpoles swam closer to the water surface when water temperature increased. Thus, R. uenoi displays a physiological adaptive response while B. sachalinensis behaviorally thermoregulate. This is important as species specific responses to climate change have to be understood for their conservation. Although thermal tolerance along geographical gradients gives an insight into species' response to climate change, current studies on thermal tolerance are strongly skewed towards global-scale patterns. As a result, intraspecific variations are often assumed to be constant, despite a lack of evidence. To understand population-specific responses to thermal stress, we investigated the presence of intraspecific variations in the critical thermal maximum (CTmax) of tadpoles in two anuran species, Rana uenoi and Bufo sachalinensis. The study was conducted across a five-degree latitudinal gradient in the Republic of Korea. We exposed the tadpoles to increasing temperatures and recorded the CTmax for 270 R. uenoi individuals from 11 sites, collected in rice paddies, and for 240 B. sachalinensis individuals from ten sites, collected in reservoirs. We also recorded the swimming performance and behavior of the tadpoles when placed in an experimental apparatus during CTmax measurements. We then used linear regressions to determine the relationship between abiotic factors and CTmax. In R. uenoi, we found a positive relationship between latitude and CTmax, but the tadpoles did not display specific thermoregulatory behaviors. In B. sachalinensis, none of the abiotic factors such as climate and geographic coordinates were related to CTmax, but we detected a tendency to swim close to the water surface when water temperature was increasing. For R. uenoi, we tentatively relate the CTmax variability across the latitudinal gradient to a physiological adaptive response associated with habitat characteristics that are assumed to be fluctuating, as the species inhabits small water bodies prone to drying out. In the case of B. sachalinensis, the behavior observed may be linked to oxygen depletion and thermoregulation, as it may buffer temperature changes in the absence of physiological adjustment. These findings suggest that intra-specific variations in CTmax are greater than generally accounted for, and thermal conditions of natural environments are important for understanding thermal tolerance in ectothermic species. Our results highlight that species' specific responses to climate warmings need to be studied to better protect species against climate change. [ABSTRACT FROM AUTHOR]

Invasive alien species continue to spread and proliferate in waterways worldwide, but environmental drivers of invasion dynamics lack assessment. Knowledge gaps are pervasive in the Global South, where the frequent heavy human‐modification of rivers provides high opportunity for invasion. In southern Africa, the spatio‐temporal ecology of a widespread and high‐impact invasive alien snail, Tarebia granifera, and its management status is understudied. Here, an ecological assessment was conducted at seven sites around Nandoni Reservoir on the Luvuvhu River in South Africa. The distribution and densities of T. granifera were mapped and the potential drivers of population structure were explored. T. granifera was widespread at sites impacted to varying extents due to anthropogenic activity, with densities exceeding 500 individuals per square meter at the most impacted areas. T. granifera predominantly preferred shallow and sandy environments, being significantly associated with sediment (i.e., chlorophyll‐a, Mn, SOC, SOM) and water (i.e., pH, conductivity, TDS) variables. T. granifera seemed to exhibit two recruitment peaks in November and March, identified via size‐based stock assessment. Sediment parameters (i.e., sediment organic matter, sediment organic carbon, manganese) and water chemistry (i.e., pH, total dissolved solids, conductivity) were found to be important in structuring T. granifera populations, with overall snail densities highest during the summer season. We provide important autecological information and insights on the distribution and extent of the spread of T. granifera. This may help in the development of invasive alien snail management action plans within the region, as well as modelling efforts to predict invasion patterns elsewhere based on environmental characteristics. [ABSTRACT FROM AUTHOR]

Availability of suitable roosting sites influences distribution of wild turkeys (Meleagris gallopavo) across the landscape. In semi‐arid environments, roosts are limited to riparian corridors capable of supporting trees large enough to provide suitable roost sites. Gould's wild turkeys (M. g. mexicana) are spatially restricted to mountainous semi‐arid areas of southwestern United States and Mexico, and information on their distribution and habitat use is limited. We evaluated roost site selection and fidelity of Gould's wild turkeys relative to environmental gradients and forested land cover during 2016–2017 in southeastern Arizona, USA. We monitored 51 global positioning system (GPS)‐tagged individuals and collected 7,954 night roost locations. We quantified specific roost site characteristics at 274 unique roost locations. Gould's wild turkeys roosted in forested communities dominated by mature pine (Pinus spp.) and oak (Quercus spp.), and exhibited substantive roost site fidelity. Roost sites were selected at moderate elevations (range = 1,254–2,894 m), and were predominately on north‐facing slopes with slight incline (<11°), suggesting little plasticity in selection of roost sites. Conserving habitat with topography and vegetative structure similar to those described in our study is likely to improve ongoing restoration and management of Gould's wild turkeys. [ABSTRACT FROM AUTHOR]

Tropical estuarine environments have been rapidly changing due to deforestation and urbanization. To understand the unique water properties of pristine tropical estuaries and utilize information for future conservation and management, spatial and temporal variations in basic water properties were measured in the Brunei estuary (Brunei Bay and Brunei River) on Borneo, where most of the estuary is still rimmed with humid primary forests such as mangroves. The vertical section profiles of the estuarine water showed a clear gradient of salinity, pH, and dissolved oxygen (DO) from the upstream Brunei River to Brunei Bay. In the Brunei River, a clear halocline and pycnocline were observed at a 1–4 m depth in the dry season (May and July), and a pH and DO minimum layer was also observed at a 1–2 m depth, indicating the supply of acidic, oxygen-depleted freshwater from the surrounding forests. In the wet season (January), the surface water pH was much lower than that in the dry season and was the lowest recorded for estuaries in Southeast Asia. This low pH is most likely caused by aerobic and/or anaerobic microbial processes in the surrounding wetlands and forests. These findings showed the unique environmental gradients of the fundamental water properties in this tropical estuary, which is supported by ambient primary forest and mudflat ecosystems. For the sustainable management of tropical estuarine ecosystems, it is important to monitor and maintain this gradient of water quality, while also conserving the surrounding terrestrial ecosystem. [ABSTRACT FROM AUTHOR]

Abandoned agricultural areas (i.e. oldfields) represent an opportunity for natural vegetation recovery, increasing soil carbon sequestration and lessening the impacts of climate change and desertification. Ecological succession in oldfields can be hampered by the harsh conditions of semiarid and arid ecosystems, and hence, restoration actions may be needed in some contexts to reactivate the ecosystem functioning. Fleshy-fruited shrubs are indicators of progression in the ecological succession, which can shift notably across environmental gradients, making difficult to obtain robust conclusions at regional scales. Other poorly studied aspects at such scales (agricultural legacy, structural features and local landscape effects) add to this knowledge gap. Here, we study the species-specific natural colonization patterns of fleshy-fruited shrubs in semiarid oldfields across environmental gradients in the Southeast of the Iberian Peninsula taking into account specific traits of plants. We used Hierarchical Modelling of Species Communities (HMSC) to test the influence of the time since the abandonment and the past land-use history of the oldfields, and the effect of local structural factors, such as the presence of remnant trees and natural patches of vegetation, on the shrub recolonization patterns. We found that altitude and lithology conditioned the structure of shrub communities, allowing the selection of different focal species for making recommendations for restoration. Time since abandonment was not relevant for the colonization process. The persistence of remnant trees in the oldfields showed a positive effect on the occurrence of several shrub species. Close sources of propagules (terrace edges and/or natural vegetation patches) benefited the occurrence of certain species mainly at lower altitudes. Traits of species (growth form, root depth, dispersal mode, fruit length and water content) helped to explain the performance of species along the environmental gradients. We identified the main drivers of natural colonization of fleshy-fruited shrubs in semiarid oldfields across environmental gradients, providing ecological knowledge to guide scientists and practitioners to develop nature-based restoration frameworks. Different management actions are recommended according to the environmental gradient., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Abstract Studies on ecological communities often address patterns of species distribution and abundance, but few consider uncertainty in counts of both species and individuals when computing diversity measures. We evaluated the extent to which imperfect detection may influence patterns of taxonomic, functional, and phylogenetic diversity in ecological communities. We estimated the true abundance of fruit‐feeding butterflies sampled in canopy and understory strata in a subtropical forest. We compared the diversity values calculated by observed and estimated abundance data through the hidden diversity framework. This framework evaluates the deviation of observed diversity when compared with diversities derived from estimated true abundances and whether such deviation represents a bias or a noise in the observed diversity pattern. The hidden diversity values differed between strata for all diversity measures, except for functional richness. The taxonomic measure was the only one where we observed an inversion of the most diverse stratum when imperfect detection was included. Regarding phylogenetic and functional measures, the strata showed distinct responses to imperfect detection, despite the tendency to overestimate observed diversity. While the understory showed noise for the phylogenetic measure, since the observed pattern was maintained, the canopy had biased diversity for the functional metric. This bias occurred since no significant differences were found between strata for observed diversity, but rather for estimated diversity, with the canopy being more clustered. We demonstrate that ignore imperfect detection may lead to unrealistic estimates of diversity and hence to erroneous interpretations of patterns and processes that structure biological communities. For fruit‐feeding butterflies, according to their phylogenetic position or functional traits, the undetected individuals triggered different responses in the relationship of the diversity measures to the environmental factor. This highlights the importance to evaluate and include the uncertainty in species detectability before calculating biodiversity measures to describe communities.

Abstract Boreal peatlands are critical ecosystems globally because they house 30%–40% of terrestrial carbon (C), much of which is stored in permafrost soil vulnerable to climate warming‐induced thaw. Permafrost thaw leads to thickening of the active (seasonally thawed) layer and alters nutrient and light availability. These physical changes may influence community‐level plant functional traits through intraspecific trait variation and/or species turnover. As permafrost thaw is expected to cause an efflux of carbon dioxide (CO2) and methane (CH4) from the soil to the atmosphere, it is important to understand thaw‐induced changes in plant community productivity to evaluate whether these changes may offset some of the anticipated increases in C emissions. To this end, we collected vascular plant community composition and foliar functional trait data along gradients in aboveground tree biomass and active layer thickness (ALT) in a rapidly thawing boreal peatland, with the expectation that changes in above‐ and belowground conditions are indicative of altered resource availability. We aimed to determine whether community‐level traits vary across these gradients, and whether these changes are dominated by intraspecific trait variation, species turnover, or both. Our results highlight that variability in community‐level traits was largely attributable to species turnover and that both community composition and traits were predominantly driven by ALT. Specifically, thicker active layers associated with permafrost‐free peatlands (i.e., bogs and fens) shifted community composition from slower‐growing evergreen shrubs to faster‐growing graminoids and forbs with a corresponding shift toward more productive trait values. The results from this rapidly thawing peatland suggest that continued warming‐induced permafrost thaw and thermokarst development alter plant community composition and community‐level traits and thus ecosystem productivity. Increased productivity may help to mitigate anticipated CO2 efflux from thawing permafrost, at least in the short term, though this response may be swamped by increase CH4 release.

ABSTRACT Distributions of aquatic macrophyte species are commonly associated with water chemistry characteristics. However, other environmental factors that can lead to the occurrence of aquatic plants in lotic ecosystems, such as dynamic habitats linked to the surrounding landscape, have been underestimated. This study aims to evaluate landscape features that may influence the occurrence of species of euhydrophyte aquatic macrophytes in a tropical river basin. We assessed the occurrence of the following seven species: Egeria densa, Cabomba furcata, Potamogeton pusillus, Potamogeton polygonus, Utricularia foliosa, Pistia stratiotes and Salvinia molesta. We also measured environmental variables related to three spatial scales, local (limnological), channel and riparian landscape, along 25.5 Km of the Itanhaém River basin (São Paulo, Brazil). We found that local (limnological) and channel characteristics were important variables in determining the occurrence of aquatic macrophyte species while the landscape scale had little influence on species composition. Channel depth and margin slope were especially relevant abiotic variables in explaining the occurrence of four of the species but not P. pusillus, P. polygonus and U. foliosa. Our results highlight the importance of channel morphology for understanding aquatic plant occurrence and community composition in tropical rivers.

Understanding the relationship between vegetation and the environment is critical to manage bog ecosystems. However, information on how environmental factors influence the species composition and diversity in the ombrotrophic bog of Northeast China is lacking. Here, we investigated species compositions and environmental characteristics (water level, water conductivity, soil moisture content, bulk density, pH, organic carbon, total nitrogen, total phosphorous) from five sample sites along the water level gradients (the water level is below the surface, near the surface, and above the surface). Plant communities presented a patchy distribution pattern along the environmental gradients and could be divided into five types of communities. Moreover, the distribution of plant communities was mainly determined by water level, water conductivity, soil moisture content, pH, and organic carbon, which significantly explained 32.2%, 30.9%, 29.7%, 29.1%, and 22.5% of the variation in floristic composition. Among these factors, water level was the dominant factor influencing the distribution of plant communities. The partial least squares path model analysis showed that water level could influence plant diversity through different pathways, which could directly affect plant diversity and indirectly affect by changing water chemistry and soil properties. Additionally, soil pH contributed most to the indirect effects of water level on plant diversity. Thus, this study highlighted the high dependence of plant communities on water level and environmental factors driven by water level in ombrotrophic bogs, which provided some valuable implications for regional vegetation restoration and plant community stability.

This study was carried out from December 2018 to November 2019 to examine the distribution and abundance of harmful algal species (HAS) in the central Bonny estuary. Seven sampling stations were established with ArcGIS tool. Microalgae species were sampled with 20 mm mesh plankton net. Nutrients were analyzed in the laboratory using the APHA 4500 Method, while physicochemical characteristics were determined in situ. Results revealed that environmental gradients were adequate to support life in that part of the estuary except for phosphate (2.90 ± 0.22-9.48 ± 1.06 mg l-1). A total of 31 HASs categorized into 17 genera and three classes were determined: Bacillariophyceae (29 species), Chlorophyceae and Cyanophyceae (one species each). Navicula amphibola had the highest density (4.713 103 cells l-1) while Pinnularia divergens recorded the lowest density (0.00049 103 cells l-1). Total density values decreased across seasons with 9.157 103 cells l-1 in dry season and 8.907 103 cells l-1 in wet season. Checklist of species across stations showed that five species were distributed across the seven stations, while two were found only in Station 2 and 7. Diversity indices revealed Shannon’s index ranged between 3.17 and 3.25 and species evenness ranged between 0.78 and 0.88, while Margalef range value (3.09-3.31) was considered moderately stable. Therefore, there is a need for proper management practices which could help to reduce the level of nutrient discharge into the central Bonny estuary.

The beta diversity among lakes is affected by natural environmental sorting, dispersal constraints, and anthropogenic disturbances. We hypothesized that fish beta diversity would increase towards lower latitudes and be higher in less disturbed lakes at within-region scale, but environmental disturbances could affect these patterns due to community homogenization or heterogenization (e.g., gain of exotic species) among lakes. We used generalized dissimilarity modeling to assess the relative importance of geographic distance, climate, and environmental heterogeneity on fish beta diversity across Denmark, Belgium/The Netherlands, and Spain. We also tested whether differences in beta diversity changed between lake types (e.g., clear vs. turbid lakes and lakes with vs. without exotics fish) within-region and across latitude. Beta diversity increased from Denmark to Spain and geographic distance and climate variability were the main drivers of community change across latitude, but the rate of change varied between lake types. At the within-region scale, factors such as turbidity, lake size, and presence of exotics had varying impacts on beta diversity (i.e., increasing, decreasing, or no effect) across the three regions. Our findings suggest that understanding the effects of environmental disturbances on beta diversity requires consideration of both biogeographic and local factors.

Landscape changes in tropical environments result in long-lasting and complex changes in biodiversity that involve several biological responses (e.g., loss of species diversity and functional diversity). Both taxonomic and functional diversity might respond differently to land-use change, and this response might also vary depending on several factors, such as the taxonomic group or landscape context. Even though each level of diversity expresses different properties of the community structure, studies characterizing the species community in human-dominated landscapes have often only focused on patterns involving taxonomic diversity. Here, we evaluated different descriptors of taxonomic (i.e., richness, diversity, and dominance) and functional entropy (i.e., richness, diversity, and redundancy) and the taxonomic and functional composition of ants in a forest cover gradient (%) in 16 highly fragmented tropical humid forest landscapes in Mexico. We found that all descriptors of taxonomic diversity decreased along a gradient of forest loss. Furthermore, functional redundancy was the only component of functional diversity that was positively associated with forest cover (%). These findings suggest an ecological backup of functions provided by species in landscapes with higher forest cover, protecting these landscapes against habitat disturbance or species loss. We also observed that landscapes with larger forest cover were inhabited by ant species with larger interocular distances and smaller femurs, which could allow predator ants the exploitation of ground cracks and higher mobility in leaf-litter microhabitats. Our results highlight the importance of the primary forest as a reservoir of the taxonomic and functional diversity of ants in highly fragmented tropical rainforest landscapes. [ABSTRACT FROM AUTHOR]

Environmental variation within a species' range can create contrasting selective pressures, leading to divergent selection and novel adaptations. The conservation value of populations inhabiting environmentally marginal areas remains in debate and is closely related to the adaptive potential in changing environments. Strong selection caused by stressful conditions may generate novel adaptations, conferring these populations distinct evolutionary potential and high conservation value under climate change. On the other hand, environmentally marginal populations may be genetically depauperate, with little potential for new adaptations to emerge. Here, we explored the use of ecological niche models (ENMs) linked with common garden experiments to predict and test for genetically determined phenotypic differentiation related to contrasting environmental conditions. To do so, we built an ENM for the alpine plant Silene ciliata in central Spain and conducted common garden experiments, assessing flowering phenology changes and differences in leaf cell resistance to extreme temperatures. The suitability patterns and response curves of the ENM led to the predictions that: (1) the environmentally marginal populations experiencing less snowpack and higher minimum temperatures would have delayed flowering to avoid risks of late‐spring frosts and (2) those with higher minimum temperatures and greater potential evapotranspiration would show enhanced cell resistance to high temperatures to deal with physiological stress related to desiccation and heat. The common garden experiments revealed the expected genetically based phenotypic differentiation in flowering phenology. In contrast, they did not show the expected differentiation for cell resistance, but these latter experiments had high variance and hence lower statistical power. The results highlight ENMs as useful tools to identify contrasting putative selective pressures across species ranges. Linking ENMs with common garden experiments provides a theoretically justified and practical way to study adaptive processes, including insights regarding the conservation value of populations inhabiting environmentally marginal areas under ongoing climate change. [ABSTRACT FROM AUTHOR]

Variation in plant sex ratios is often attributable to sex‐specific mortality in heterogeneous environments that differentially limit male and female plant reproduction. Yet sexual dimorphism and plastic responses to environmental heterogeneity are common and may co‐vary with variation in sex ratios. Here, we show that the sex ratio and the degree of sexual dimorphism for a number of plant traits varied along climatic and elevation gradients in three wind‐pollinated dioecious species, Rumex lunaria, Urtica dioica and Salix helvetica. Some of the observed sex‐specific responses to climatic variation are consistent with greater sensitivity of females to water scarcity, but most responses rather point to the greater sensitivity of males to ecological stress, consistent with larger male reproductive effort, as has been commonly reported for wind‐pollinated plants. In contrast, we found no evidence for variation in either sex ratios or sexual dimorphism expected under sexual selection. Interestingly, sex ratios and sexual dimorphism varied both along distinct and the same ecological axes of variation, suggesting that the evolution of sexual dimorphism in the measured traits was not sufficient to prevent sex‐specific mortality. [ABSTRACT FROM AUTHOR]

Analysing the effects of environmental variation on species assemblages is a key topic in community ecology. However, the outcome may strongly depend on the focal species group. Moths have often been used as the target in ecological studies due to their fast response to environmental change. Yet, some moth subgroups might be more sensitive than others to reflect environmental differences, depending on their functional and physiological characteristics.We investigated which moth subsets are especially suitable to mirror responses to subtle variation in vegetation. We analysed the susceptibility of different subsets to local weather conditions and inter‐annual fluctuations. Finally, we checked for the importance of including abundance information. We analysed moth communities (392 species, 23.870 individuals) at 60 sites within two Mediterranean forest reserves and investigated relationships between community composition and environment of (1) all moths (with and without taking abundances into account), and of subsets comprising only (2) small‐sized species, (3) host‐plant specialists, (4) moss, lichen and detritus feeding species, (5) 'microlepidoptera', (6) 'macro‐moths' and (7) random subsets of 50, 100 and 200 species.Incidence data performed similarly to abundance data in matrix regression models. Host plant specialists responded especially sensitive to small‐scaled variation in vegetation composition. Macro‐moth samples in contrast were highly prone to local weather conditions and to inter‐annual abundance fluctuations. Accordingly, a focus on host‐specialists and micro‐moths is the best way to analyse relationships between shallow environmental gradients and insect communities. [ABSTRACT FROM AUTHOR]

Predation affects community structure and functioning within marine habitats. Predator–prey interactions can change through space and time. Documenting how these interactions change is essential to improve our understanding of food web dynamics and to enhance our ability to manage preferred species. In this study, our goals were to determine whether the density of subtidal oysters (Crassostrea virginica) differed spatially by looking at three separate restored oyster sanctuaries within Pamlico Sound (North Carolina, USA), whether oyster density changed over an interval of 16 months, and whether oyster density was related to the presence of different‐sized predators by using an experimental approach. Multiple exclusion treatments were used in situ to exclude, selectively, different predator guilds from consuming oysters. Predator densities were also measured both within experimental treatments and on the restored oyster reefs by using multiple survey techniques. We found that oyster abundance differed among the four sample dates over the 16‐month study and differed among the three sites. Mud crabs—one of the smallest predators measured—had the greatest predator biomass per unit of area, but the presence of other predators was largely site‐dependent. Oyster abundance was affected by the exclusion of all predators, but this was dependent on sample date and location, which may suggest that mud crabs were the only predator to reduce oyster abundance in this study. In addition, large predators may have affected small predators, such as mud crabs and oyster drills, which were more abundant in treatments where large predators were excluded. The strongest evidence for top‐down effects on oyster reefs occurred at one of the three field sites at the first and final sampling time, suggesting that predator effects are complex, as well as spatially and temporally variable. Field experiments that assess variables through time and at multiple locations are needed as this information could improve the success of oyster reef conservation and restoration efforts. [ABSTRACT FROM AUTHOR]

Simple Summary: Mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddisflies (Trichoptera) (EPT) are aquatic insects that are well known to the general public and are commonly used as indicators of environmental quality in water management. Knowledge of how EPT communities react to human-induced gradients in real environments can be important, for example, during the assessment of the implications of newly planned or currently active human disturbances for natural or cultural landscapes. We sampled a stream ecosystem affected by mining and smelting industries and communal wastewaters with pronounced concentrations of cadmium, lead, and zinc, as well as high levels of pesticides, pharmaceuticals, illegal drugs, and sewage-derived organic matter. Changes in other environmental factors such as increases in temperature were also studied at the affected sites. The abundance and species richness of stoneflies fell rapidly at the study sites. The richness of mayfly families also declined, from four to one, even though overall mayfly abundance was not affected. Conversely, the abundances of caddisflies were higher at the affected sites, and their richness did not decrease. This study will provide feedback for ecotoxicologists who perform better controlled and manipulated tests in laboratories, although any such test results are limited by simple artificial environments. Abundances of EPT larvae sampled in a Central European locality affected by mining and smelting, as well as by the continual inflow of treated communal wastewaters (WWs), were recorded. High concentrations of trace metals in water (maximum 1200 µg·L–1 for zinc) and sediments (maximum 140,000 mg·kg–1 in dry weight for lead) were found at the most contaminated sites. The highest loads of pesticides, pharmaceuticals, and illegal drugs were found under the WW effluent. Other associated factors such as the physicochemical parameters of the water and alterations to microhabitats were also evaluated and taken into account. Although EPT richness was lower at affected sites, abundances did not fall. Stoneflies were dominant at unaffected sites, while caddisflies dominated at affected sites. Only baetid mayflies were detected at the sites contaminated by trace metals and WWs; ephemerellid, heptageniid, and leptophlebiid mayflies were absent from these sites. The site contaminated by trace metals was also inhabited by numerous limnephilid caddisflies, in which limb malformations were detected in up to 11.8% of all specimens of a single taxon. Downstream from the entrance of the WWs, the locality was dominated by hydropsychid caddisflies. The increasing prevalence of predator or passive filter-feeding strategies in these EPT communities was significantly related to increasing water conductivity and acute ecosystemic exposure to 'poorly treated' WWs. [ABSTRACT FROM AUTHOR]

Modelling species interactions in diverse communities traditionally requires a prohibitively large number of species‐interaction coefficients, especially when considering environmental dependence of parameters. We implemented Bayesian variable selection via sparsity‐inducing priors on non‐linear species abundance models to determine which species interactions should be retained and which can be represented as an average heterospecific interaction term, reducing the number of model parameters. We evaluated model performance using simulated communities, computing out‐of‐sample predictive accuracy and parameter recovery across different input sample sizes. We applied our method to a diverse empirical community, allowing us to disentangle the direct role of environmental gradients on species' intrinsic growth rates from indirect effects via competitive interactions. We also identified a few neighbouring species from the diverse community that had non‐generic interactions with our focal species. This sparse modelling approach facilitates exploration of species interactions in diverse communities while maintaining a manageable number of parameters. [ABSTRACT FROM AUTHOR]

Abstract Spatial environmental gradients can promote adaptive differences among conspecific populations as a result of local adaptation or phenotypic plasticity. Such divergence can be opposed by various constraints, including gene flow, limited genetic variation, temporal fluctuations, or developmental constraints. We focus on the constraint that can be imposed when some populations are found in locations characterized by low levels of an essential nutrient. We use scales of wild fish to investigate phenotypic effects of spatial variation in a potentially limiting nutrient—calcium. If scale calcium (we use “scalar” calcium for consistency with the physiology literature) simply reflects environmental calcium availability, we expect higher levels of scalar calcium in fish from calcium‐rich water, compared to fish from calcium‐poor water. To consider this “passive response” scenario, we analyzed scalar calcium concentrations from three native fish species (Lepomis gibbosus, Percina caprodes, and Perca flavescens) collected at multiple sites across a dissolved calcium gradient in the Upper St. Lawrence River. Contradicting the “passive response" scenario, we did not detect strong or consistent relationships between scalar calcium and water calcium. Instead, for a given proportional increase in water calcium across the wide environmental gradient, the corresponding proportional change in scalar calcium was much smaller. We thus favor the alternative “active homeostasis” scenario, wherein fish from calcium‐poor water are better able to uptake, mobilize, and deposit calcium than are fish from calcium‐rich water. We further highlight the importance of studying functional traits, such as scales, in their natural setting as opposed to only laboratory studies.

Abstract Predation affects community structure and functioning within marine habitats. Predator–prey interactions can change through space and time. Documenting how these interactions change is essential to improve our understanding of food web dynamics and to enhance our ability to manage preferred species. In this study, our goals were to determine whether the density of subtidal oysters (Crassostrea virginica) differed spatially by looking at three separate restored oyster sanctuaries within Pamlico Sound (North Carolina, USA), whether oyster density changed over an interval of 16 months, and whether oyster density was related to the presence of different‐sized predators by using an experimental approach. Multiple exclusion treatments were used in situ to exclude, selectively, different predator guilds from consuming oysters. Predator densities were also measured both within experimental treatments and on the restored oyster reefs by using multiple survey techniques. We found that oyster abundance differed among the four sample dates over the 16‐month study and differed among the three sites. Mud crabs—one of the smallest predators measured—had the greatest predator biomass per unit of area, but the presence of other predators was largely site‐dependent. Oyster abundance was affected by the exclusion of all predators, but this was dependent on sample date and location, which may suggest that mud crabs were the only predator to reduce oyster abundance in this study. In addition, large predators may have affected small predators, such as mud crabs and oyster drills, which were more abundant in treatments where large predators were excluded. The strongest evidence for top‐down effects on oyster reefs occurred at one of the three field sites at the first and final sampling time, suggesting that predator effects are complex, as well as spatially and temporally variable. Field experiments that assess variables through time and at multiple locations are needed as this information could improve the success of oyster reef conservation and restoration efforts.

Plant-plant facilitation is widely studied to increase productivity and resource utilization in cereal-legume intercropping system. However, physiological and ecological mechanisms driving interspecific interaction shift along the environmental gradients is largely unknown. To clarify this issue, we first tested plant-plant facilitation along with four phosphorus (P) gradients in maize-grass pea intercropping system. Results illustrated a progressive transition of seed yield-based facilitation from mutually facilitated (+/+) to maize facilitated but grass pea as facilitator (+/-) along with low to high P gradients. Secondly, above trend was evidently enhanced when combining with drought stress gradients, in which severe drought amplified facilitative effects, whereas the magnitude of facilitation was relatively weak under well-watered condition. Interestingly, biomass-based facilitation transition did not synchronize with seed-based one, in which occurred in a broader threshold range of water and P gradients. Specifically, total yield, biomass, N and P uptake increased by 0.5%, 4.1%, 1.8% and 2.9% under the sufficient P and water availability, whereas these indicators increased by 25.3%, 18.5%, 20.5% and 21.4% in P and water deficient soils. And the total net effect was positive under all the environmental conditions. Rhizosphere interaction plays a crucial role in facilitation judgment, and the driving mechanism was associated with soil acidification and microbial community promotion under P-deficient condition. Under low soil moisture and available P, soil acidification and lower rhizosphere soil pH of intercropped maize were observed. Rhizosphere phosphatase secretion were significantly activated in P-deficient soils and accelerated the mineralization of soil organophosphorus, and the microbial biomass P was improved for stronger facilitation. Taken together, our findings confirmed the P and water driven facilitation shift along with stress gradients and highlighted the roles of rhizosphere interaction in affecting species diversity advantage. In conclusion, our work provided a relatively full picture for plant facilitation evaluation and more accurate management regarding intercropping productivity.

The natural territory disturbance, losses, and degradation are real and alarming threats to the ecosystem. The population of butterflies remains arbitrary in prairie residuals and linear range habitats. Such environments are low, isolated, and sub-quality than intact prairies - biodiversity losses associated with ecosystems regulating services and supporting services. Therefore, the present study was conducted on environmental variables and soil gradient and its effects on butterfly colonies in tehsil Tangi, Charsadda, Khyber Pakhtunkhwa, Pakistan. A total of 506 specimens of butterflies and soil samples were collected from different localities randomly. Butterflies were collected with aerial nets, searching, and picking method, and taken to the laboratory for identification and recording concerning each location every two weeks from August 2014 to May 2015. The similarity index among individuals was 246 (47%), while among species 45.5 (8.62%) and Catopsilia pyranthe were at (35/122; 14/30; 7/14; 6.91/24.11) position, similarly in dissimilarity index, Catopsilia ponoma was at (58/122; 19/30; 9/14; 11.460/24.11) position. The density revealed that the Danauas chrysippus was the most abundant species 122/506. Similarly, among environmental gradients, silt associated considerably with pH, wilting point (Wp), field capacity (Fc), bulk density (Bd), saturated hydraulic conductivity (Shy) and available water (Aw) (p≈0.000), sand with pH, Wp, Fc and Bd (p≈0.000), pH with Wp, Fc and Bd (p≈0.000), Wp with Fc, Bd, and Aw (p≈0.000), Fc with Bd and Aw (p≈0.000). We concluded that low latitude and altitude, excessive amounts of insecticides and pesticides show a significant impact on butterflies' diversity.

Landscape patterns are pivotal in the realms of land use planning and ecological development, yet there remains a dearth of comprehensive research pertaining to the prediction of changes in landscape pattern characteristics. Within this study, we adopt the PLUS-CA-Markov and Fragstats models to forecast landscape patterns on the Tibetan Plateau spanning the period from 2030 to 2050. Through qualitative and quantitative analyses, we explore the spatiotemporal characteristics of landscape pattern changes between 2000 and 2050, concurrently identifying correlations among landscape pattern indices. Moreover, acknowledging the distinctive environmental gradients encompassing the plateau, notably elevation, slope, temperature, and precipitation, we investigate their implications on landscape pattern changes. Our findings indicate that: (1) Grassland degradation exhibited the utmost severity between 2000 and 2020, primarily attributed to overgrazing and climate-induced glacial melt. In contrast, cropland, forest, and water showcased divergent trends from 2020 to 2050 when compared to the preceding two decades, indicative of the efficacy of climate change control measures. (2) The distribution of landscape patterns on the Tibetan Plateau exhibited a considerable level of instability, marked by a decline in aggregation, reduced diversity and complexity, and amplified ecological connectivity between 2000 and 2020, signifying a partial amelioration in ecological quality. Between 2020 and 2050, landscape aggregation decreased alongside landscape fragmentation and the number of connectivity paths, signifying a discernible degradation of the plateau's ecosystem. (3) The most significant trade-off relationship was observed between landscape division index and largest patch index, while the synergistic relationship between landscape shape index and mean shape index was more pronounced. (4) Landscape aggregation, division, and largest patch index demonstrated non-linear quadratic trends in relation to elevation and temperature. Landscape shape index and patch density exhibited irregular non-linear effects. Largest patch index was predominantly influenced by slope, whereas division index was most affected by precipitation. • Simulating the spatiotemporal dynamics of landscape patterns on the Tibetan Plateau. • Evident future degradation of the ecosystem on the Tibetan Plateau. • Notable tradeoff effect between landscape division index and largest shape index. • Nonlinear impact of landscape pattern indices in response to environmental gradients. [ABSTRACT FROM AUTHOR]

Dispersal has three major effects on adaptation. First, gene flow mixes alleles adapted to different environments, potentially hindering (swamping) adaptation. Second, it brings in other variants and inflates genetic variance: this aids adaptation to spatially (and temporally) varying environments but if selection is hard, it lowers the mean fitness of the population. Third, neighbourhood size, which determines how weak genetic drift is, increases with dispersal--when genetic drift is strong, increase of the neighbourhood size with dispersal aids adaptation. In this note, I focus on the role of dispersal in environments that change gradually across space, and when local populations are quite small such that genetic drift has a significant effect. Using individual-based simulations, I show that in small populations, even leptokurtic dispersal benefits adaptation by reducing the power of genetic drift. This has implications for management of fragmented or marginal populations: the beneficial effect of increased dispersal into small populations is stronger than swamping of adaption under a broad range of conditions, including a mixture of local and long-distance dispersal. However, when environmental gradient is steep, heavily fat-tailed dispersal will swamp continuous adaptation so that only patches of locally adapted subpopulations remain. This article is part of the theme issue 'Species' ranges in the face of changing environments (Part II)'. [ABSTRACT FROM AUTHOR]

Aim: Plant functional traits are broadly used to quantify and predict impacts of climate change on vegetation. However, high intraspecific trait variation can bias mean values when few measurements are available. Here, we determine the extent of individual leaf trait variation and covariation across a highly heterogeneous environmental gradient for a widely distributed subtropical pine. We demonstrate the implications of trait variation for characterising species by assessing data availability and variability across the Pinus genus. Location: Central Mountain Range, Taiwan. Taxon Pinus taiwanensis Hayata (Pinaceae). Methods: We measured eight functional traits suggested to reflect plant strategies: needle length, area, thickness, dry and fresh mass, stomatal row density (SD), leaf dry matter content (LDMC) and specific leaf area (SLA). We examined trait variation in response to climatic and physiographic factors across an elevational gradient of 495–3106 m a.s.l. using linear mixed effects models (LMMs). Intraspecific trait covariation was explored using principal component analyses (PCAs) and LMMs. Descriptive statistics were calculated for Pinus records in the global TRY plant trait database. Results: Intraspecific variability among traits was high (CV 20%–44%) and predictable with elevation (generally p < 0.05, with declining needle size and LDMC with elevation and increasing SD). However, 41%–92% of variance was un‐explained by topography. Sixty‐five percent of variation was explained by two trait covariation axes, with predictable changes with elevation (p < 0.001). Pinus data availability in TRY was low. Across traits, only 12.5%–53% of species had sufficient sample sizes for intraspecific analyses. Main conclusions: We show substantial trait variation for a single species, here likely driven by temperature differences and additional biotic and abiotic drivers across the elevational range. Improved understanding of the extent and implications of intraspecific variability is necessary for reliable quantifications and predictions of the impacts of environmental change, especially in understudied, hyper‐diverse ecosystems such as tropical forests. [ABSTRACT FROM AUTHOR]

Thermal springs provide natural laboratories to test the responses of biological communities to various stressors. To date, little is known about how water temperature and chemistry influence the microalgal assemblages in these ecosystems, especially in the circum-Mediterranean area. In this study, we assessed the environmental drivers of benthic diatom assemblages collected from different substrates in 8 thermo-mineral springs of Sardinia, Italy, with a focus on temperature and conductivity. A total of 205 diatom species (67 genera) were found, of which 12 (8 genera) were centric and 193 (59 genera) were pennate. Composition of diatom assemblages was associated with temperature, pH, conductivity, bicarbonates (HCO3−), and sulfates (SO42−). Multivariate analyses also confirmed differences in species composition, richness, diversity, and evenness of diatom assemblages from groups of springs distinguished by temperature and conductivity gradients. We found higher species richness, diversity, and evenness in hyperthermal (water temperature = 52.7−71.5°C) and medium-mineral springs (conductivity = 590−1193 µS/cm). Our results indicate that thermal springs are not always inhospitable environments for diatoms. Springs with high water temperatures hosted rich and diverse diatom assemblages, likely thanks to their ecotonal nature and a combination of multiple local factors. [ABSTRACT FROM AUTHOR]

A new approach for visual fish survey in reservoirs using underwater drones (remotely operated vehicle- ROV) is presented. The ROV was applied to identify abiotic gradients and to compare fish assemblages on the steep slopes in a tropical reservoir. The tested hypothesis is that fish are concentrated in the littoral zone due to the better physicochemical and habitat conditions, compared to deep and hypoxic layers. Twelve species were recorded (seven native, five exotic), with all species occurring in the littoral zone, seven species in the transition, and four in the profundal zone. A greater fish abundance and richness was found in the littoral zone corroborating the main hypothesis. The littoral zone was dominated by exotic cichlids (Cichla spp., Coptodon rendalli), while native catfish (Loricariichthys castaneus, Pimelodella lateristriga) occupied deeper areas. The fish distribution seems to be driven by local factors, such as oxygen availability and habitat structure. The preference for the littoral zone by alien cichlids may have led to the extirpation/decrease of native characids and induced catfishes to occupy deep habitats. Underwater drones can be a valuable tool for the simultaneous collection of abiotic/biotic data, especially in deep reservoirs with complex habitats, resulting in advances in the environmental monitoring. [ABSTRACT FROM AUTHOR]

Spatial variation in species interactions (interaction β‐diversity) and its ecological drivers are poorly understood, despite their relevance to community assembly, conservation and ecosystem functioning. We investigated effects of wildfire severity on patterns and four proximate ecological drivers of interaction β‐diversity in plant–bee communities across three localities in the northern Rocky Mountains (Montana, USA). Wildfires decreased interaction β‐diversity but increased interaction frequency (number of visits) and richness (number of links). After controlling for interaction frequency and richness, standardized effect sizes of interaction β‐diversity were highest following mixed‐severity wildfires, intermediate following high‐severity wildfires and lowest in unburned landscapes, suggesting that wildfire increases spatial aggregation of plant–bee interactions. Moreover, higher effect sizes in burned landscapes were largely determined by turnover in the species composition of both trophic levels rather than by interaction rewiring (spatial turnover in local species interactions not due to species turnover). The underrepresented level of rewiring indicated spatial consistency in post‐disturbance patterns of interactions among co‐occurring species. Together, our findings suggest that wildfire alters the β‐diversity of mutualistic species interactions via linked assembly of plant–bee communities and provide insights into how environmental change alters complex networks of species interactions. [ABSTRACT FROM AUTHOR]