Niche breadth predicts geographical range size: a general ecological pattern

The role of gut microbiota in a generalist, golden snub-nosed monkey, adaptation to geographical diet change

Changes in diet causing ecological stress pose a significant challenge to animal survival. In response, the gut microbiota, a crucial part of the host's digestive system, exhibits patterns of change reflective of alterations in the host's food component. The impact of temporal dietary shifts on gut microbiota has been elucidated through multidimensional modeling of both food component and macronutrient intake. However, the broad distribution of wild generalist and the intricate complexity of their food component hinder our capacity to ascertain the degree to which their gut microbiota assist in adapting to spatial dietary variations. We examined variation in patterns of the gut microbial community according to changes in diet and in a colobine monkey with a regional variable diet, the golden snub-nosed monkey (Rhinopithecus roxellana). Specifically, we analyse the interactions between variation in food component, macronutrient intake and the gut microbial community. We compared monkeys from four populations by quantifying food component and macronutrient intake, and by sequencing 16S rRNA and the microbial macro-genomes from the faecal samples of 44 individuals. We found significant differences in the diets and gut microbial compositions, in nutrient space and macronutrient intake among some populations. Variations in gut microbiota composition across distinct populations mirror the disparities in macronutrient intake, with a notable emphasis on carbohydrate. Geographical differences in the diet among of golden snub-nosed monkey populations will result in macronutrient intake variation, with corresponding differences in macronutrient intake driving regional differences in the compositions and abundances of gut microbiota. Importantly, the gut microbiota associated with core digestive functions does not vary, with the non-core gut microbiota fluctuating in response to variation in macronutrient intake. This characteristic may enable species heavily reliant on gut microbiota for digestion to adapt to diet changes. Our results further the understanding of the roles gut microbiota play in the formation of host dietary niches.

Colour polymorphism is prevalent on islands but shows no association with range size in web-building spiders

One of the most evident sources of phenotypic diversity within a population is colouration, as exemplified by colour polymorphism. This is relevant to a greater extent in animals with visually biased sensory systems. There is substantial evidence suggesting that different colour morphs can access a broader range of habitats or niches, leading to larger geographic range sizes. However, this hypothesis has been tested in few lineages, comprising species where colour is likely to be involved in sexual selection. Furthermore, some available evidence considers geographical variation as polymorphism, thus limiting our comprehension of how sympatric colour polymorphism can influence a species' geographic range. Through an extensive systematic literature review and a comparative analysis, we examined the relationship between colour polymorphism and range size or niche breadth in web-building spiders. We identified 140 colour polymorphic spider species, belonging mainly to the families Araneidae and Theridiidae. We found no evidence that colour polymorphic species differ significantly from non-polymorphic species in terms of range size and niche breadth, after accounting for phylogenetic relationships and other covariates. However, we did observe that colour polymorphic species were more likely to be found on islands compared to non-polymorphic species. Overall, our results indicate that the association between colour polymorphism and geographic range size may not exist among web-building spiders, or be as pronounced as in other lineages. This suggests that the strength of the association between colour polymorphism and ecological success might depend on the ecological role that colouration plays in each clade.

Synergistic co-evolution of rhizosphere bacteria in response to acidification amelioration strategies: impacts on the alleviation of tobacco wilt and underlying mechanisms

Soil acidification represents a severe threat to tobacco cultivation regions in South China, exacerbating bacterial wilt caused by Ralstonia solanacearum. The comprehension of the underlying mechanisms that facilitate the restoration of rhizosphere microbial communities in "healthy soils" is imperative for ecologically managing tobacco bacterial wilt. This study focuses on acidified tobacco soils that have been subjected to continuous cultivation for 20 years. The experimental treatments included lime (L), biochar (B), and a combination of lime and biochar (L+B), in addition to a control group (CK). Utilizing rhizosphere biology and niche theory, we assessed disease suppression effects, changes in soil properties, and the co-evolution of the rhizosphere bacterial community. Each treatment significantly reduced tobacco bacterial wilt by 16.67% to 20.14% compared to the control group (CK) (p < 0.05) and increased yield by 7.86% to 27.46% (p < 0.05). The biochar treatment (B) proved to be the most effective, followed by the lime-biochar combination (L+B). The key factors controlling wilt were identified through random forest regression analysis as an increase in soil pH and exchangeable bases, along with a decrease in exchangeable acidity. However, lime treatment alone led to an increase in soil bulk density and a decrease in available nutrients, whereas both biochar and lime-biochar treatments significantly improved these parameters (p < 0.05). No significant correlation was found between the abundance of Ralstonia and wilt incidence. Nonetheless, all treatments significantly expanded the ecological niche breadth and average variation degree (AVD), enhanced positive interactions and cohesion within the community, and intensified negative interactions involving Ralstonia. This study suggests that optimizing community niches and enhancing pathogen antagonism are key mechanisms for mitigating tobacco wilt in acidified soils. It recommends using lime-biochar mixtures as soil amendments due to their potential ecological and economic benefits. This study offers valuable insights for disease control strategies and presents a novel perspective for research on Solanaceous crops.

Climate change effects on the diversity and distribution of soybean true bugs pests

BACKGROUND

Climate change and pests are two major factors in the reduction of global soybean yields. The diversity and geographic distribution of soybean true bug pests vary across soybean production areas worldwide, and climate change impacts are different across species and regions. Therefore, we integrated spatial and temporal predictions at the global scale to predict the impact of global warming on the distribution of 84 soybean true bug pests by the maximum entropy niche model (MaxEnt) under present (1970-2000) and future (2041-2060) scenarios. We produced an ensemble projection of the potential distribution of pests and crop production areas to estimate how and where climate warming will augment the threat of soybean true bug pests to soybean production areas.

RESULTS

Our results indicated that Southeast North America, Central South America, Europe and East Asia were the regions with the higher richness of soybean true bug and the most vulnerable areas to invasion threats. Climate change would promote the expansion of the distribution range and facilitate pest movement pole wards, affecting more soybean cultivated areas located in mid-latitudes. Moreover, species with different distribution patterns responded differently to climate change in that large-ranged species tended to increase in occupancy over time, whereas small-ranged species tended to decrease.

CONCLUSION

This result indicates that some pests that have not yet become notable may have the chance to develop into serious pests in the future due to the expansion of their geographical range. Our findings highlight that soybean cultivated regions at mid-latitudes would face general infestations from soybean true bug pests under global warming. These results will further facilitate the formulation of adaptation planning to minimize local environmental impacts in the future. © 2024 Society of Chemical Industry.

Specialists regulate microbial network and community assembly in subtropical seagrass sediments under differing land use conditions

Microorganisms in the sediment play a pivotal role in the functioning and stability of seagrass ecosystems and their dynamics are influenced by the nutrient acquisition strategies of host plants. While the distinct impacts of microbial generalists and specialists on community dynamics are recognized, their distribution patterns and ecological roles within seagrass ecosystems remain largely unexplored. To address this issue, we conducted an analysis of community assembly processes and co-occurrence relationships of both microbial generalists and specialists within sediment profiles (0-100 cm) from seagrass habitats subjected to differing land use conditions. The results revealed that seagrasses in Yifeng Estuary experienced the large proportion of cultivated land and exhibited higher organic carbon content in the 0-20 cm surface sediment layer. Nitrogen-cycling bacteria were predominantly associated with seagrasses from Yifeng Estuary, whereas Vibrio spp. was more prevalent in seagrasses from Liusha Bay. Notably, seagrass Halophia beccarii (YHB) in Yifeng Estuary harbored higher niche breadths for both microbial generalist and specialist compared to Halodule uninervis (LHU) and Halophia ovalis (LHO) from Liusha Bay. Stochastic processes were pivotal in shaping seagrass sediment microbial communities, with a higher immigration rate observed in YHB, suggesting greater microbial turnover in this area. Additionally, YHB sediment presented lower drift and higher dispersal limitation among generalists compared to LHU and LHO, whereas the pattern was reversed among specialists. Specialists were found to play a crucial role in shaping microbial interactions within YHB sediment, with genera Halioglobus identified as keystone species in the network. The specialists were further found to significantly influence microbial β-diversity in seagrass sediment directly. Overall, our findings illustrated how microbial generalists and specialists were distributed in seagrass sediments in response to land use changes and provided new insights into the potential roles of microbial regulation in degraded seagrass ecosystems.

Rhizospheric bacterial communities against microplastics (MPs): Novel ecological strategies based on the niche differentiation

Considerable amounts of microplastics (MPs) are stocked in plant rhizospheres, yielding adverse effects on rhizospheric microorganisms and threatening plant health. However, the adaptation of the rhizospheric microbiota for MPs remains largely unknown. Here, to evaluate the adaptive strategies of rhizospheric bacterial communities against MPs, we characterized the spatial dissimilarities in MPs properties and bacterial communities from mangrove non-rhizosphere to rhizosphere to root hair sediments. Consequently, two strategies were uncovered: (1) Bacterial communities showed significant niche differentiation induced by the increasingly enriched MPs evaluated by piecewise structural equation modeling (piecewise SEM), as increasing specialization (10.2 % to 19.4 % to 23.0 % of specialists) and decreasing generalization (10.4 % to 10.2 % to 8.7 % of generalists). (2) A self-remediation strategy of enhancing microbial plastic-degrading potentials was determined in bacterial communities, tightly coupled to the increase of specialists (linear regression analysis, R2 = 0.54, P < 0.001) and increasing MPs weathering degrees visualized by the scanning electron microscopy (SEM) from non-rhizosphere to rhizosphere to root hair regions. Our study provides a novel insight into the ecological strategies that rhizospheric microbes utilize against MPs, and broadens our knowledge of the interaction between soil microbes and global MPs pollution.

Climate and land use/land cover changes increasing habitat overlap among endangered crested ibis and sympatric egret/heron species

Climate and land use/land cover (LULC) changes have far-reaching effects on various biological processes in wildlife, particularly interspecific interactions. Unfortunately, interspecific interactions are often overlooked when assessing the impacts of environmental changes on endangered species. In this study, we examined niche similarities and habitat overlaps between wild Crested Ibis and sympatric Egret and Heron species (EHs) in Shaanxi, China, using Ecological niche models (ENMs). We aimed to forecast potential alterations in habitat overlaps due to climate and LULC changes. The results showed that although EHs possess a broader niche breadth compared to the Crested Ibis, they still share certain niche similarities, as indicated by Schoener's D and Hellinger's I values exceeding 0.5, respectively. Notably, despite varying degrees of habitat reduction, the shared habitat area of all six species expands with the changes in climate and LULC. We suggest that with the climate and LULC changes, the habitats of sympatric EHs are likely to suffer varying degrees of destruction, forcing them to seek refuge and migrate to the remaining wild Ibis habitat. This is primarily due to the effective conservation efforts in the Crested Ibis habitat in Yangxian County and neighboring areas. Consequently, due to the niche similarity, they will share and compete for limited habitat resources, including food and space. Therefore, we recommend that conservation efforts extend beyond protecting the Crested Ibis habitat. It is crucial to control human activities that contribute to LULC changes to safeguard the habitats of both Crested Ibis and other sympatric birds.

Genome size is positively correlated with extinction risk in herbaceous angiosperms

Angiosperms with large genomes experience nuclear-, cellular-, and organism-level constraints that may limit their phenotypic plasticity and ecological niche, which could increase their risk of extinction. Therefore, we test the hypotheses that large-genomed species are more likely to be threatened with extinction than those with small genomes, and that the effect of genome size varies across three selected covariates: life form, endemism, and climatic zone. We collated genome size and extinction risk information for a representative sample of angiosperms comprising 3250 species, which we analyzed alongside life form, endemism, and climatic zone variables using a phylogenetic framework. Genome size is positively correlated with extinction risk, a pattern driven by a signal in herbaceous but not woody species, regardless of climate and endemism. The influence of genome size is stronger in endemic herbaceous species, but is relatively homogenous across different climates. Beyond its indirect link via endemism and climate, genome size is associated with extinction risk directly and significantly. Genome size may serve as a proxy for difficult-to-measure parameters associated with resilience and vulnerability in herbaceous angiosperms. Therefore, it merits further exploration as a useful biological attribute for understanding intrinsic extinction risk and augmenting plant conservation efforts.

Generalism in species interactions is more the consequence than the cause of ecological success

Generalism in resource use is commonly considered a critical driver of population success, species distribution and extinction risk. This idea can be questioned as generalism may be a result rather than the cause of species abundance and range size. We tested these contrasting causal hypotheses focusing on host use in three databases encompassing approximately 44,000 mutualistic (hummingbird-plant), commensalistic (lichen-plant) and parasitic (flea-mammal) interactions in 617 ecological communities across the Americas and Eurasia. Across all interaction types, our analyses indicated that range size and abundance influence the probability of encountering hosts and set the arena for species to express generalism potentials or adapt to new hosts. Hence, our findings support the hypothesis that generalism is a consequence of species ecological success. This highlights the importance of ecological opportunity in driving species characteristics considered key for their survival and conservation.

Comparative phylogeography reveals dissimilar genetic differentiation patterns in two sympatric amphibian species

Global climate change is expected to have a profound effect on species distribution. Due to the temperature constraints, some narrow niche species could shift their narrow range to higher altitudes or latitudes. In this study, we explored the correlation between species traits, genetic structure, and geographical range size. More specifically, we analyzed how these variables are affected by differences in fundamental niche breadth or dispersal ability in the members of two sympatrically distributed stream-dwelling amphibian species (frog, Quasipaa yei; salamander, Pachyhynobius shangchengensis), in Dabie Mountains, East China. Both species showed relatively high genetic diversity in most geographical populations and similar genetic diversity patterns (JTX, low; BYM, high) correlation with habitat changes and population demography. Multiple clustering analyses were used to disclose differentiation among the geographical populations of these two amphibian species. Q. yei disclosed the relatively shallow genetic differentiation, while P. shangchengensis showed an opposite pattern. Under different historical climatic conditions, all ecological niche modeling disclosed a larger suitable habitat area for Q. yei than for P. shangchengensis; these results indicated a wider environment tolerance or wider niche width of Q. yei than P. shangchengensis. Our findings suggest that the synergistic effects of environmental niche variation and dispersal ability may help shape genetic structure across geographical topology, particularly for species with extremely narrow distribution.

Range size positively correlates with temperature and precipitation niche breadths but not with dietary niche breadth in triatomine insects, vectors of Chagas disease

Ecological theory predicts that species that can utilise a greater diversity of resources and, therefore, have wider niche breadths should also occupy larger geographic areas (the 'niche breadth-range size hypothesis'). Here, we tested this hypothesis for a blood-sucking group of insects of medical significance: the Triatominae (aka 'kissing bugs') (Hemiptera: Reduviidae). Given that niches can be viewed from different perspectives, we tested this hypothesis based on both dietary and climatic niches. We assembled the most complete dataset of triatomine feeding patterns to date by reviewing 143 studies from the literature up to 2021 and tested whether the niche breadth-range size hypothesis held for this group for both dietary and climatic components of the niche. Temperature and precipitation niche breadths were estimated from macro-environmental variables, while diet breadth was calculated based on literature data that used PCR and/or ELISA to identify different types of hosts as blood sources per triatomine species. Our results showed that temperature and precipitation niche breadths, but not dietary breadth, were positively correlated with range sizes, independent of evolutionary history among species. These findings support the predictions from the range size-niche breadth hypothesis concerning climate but not diet, in Triatominae. It also shows that support for the niche breadth-range size hypothesis is dependent upon the niche axis under consideration, which can explain the mixed support for this hypothesis in the ecological literature.

Anti-seasonal flooding drives substantial alterations in riparian plant diversity and niche characteristics in a unique hydro-fluctuation zone

Human-induced disturbances such as dam construction and regulation have led to widespread alterations in hydrological processes and thus substantially influence plant characteristics in the hydro-fluctuation zones (HFZs). To reveal utilization of limited resources and mechanisms of inter-specific competition and species co-existence of plant communities based on niche breadth and overlap under the different HFZs of the Three Gorges Reservoir (TGR) in China, we conducted a field investigation with 368 quadrats on the effects of hydrological alterations on plant diversity and niche characteristics. The results showed anti-seasonal flooding precipitated the gradual disappearance of the original diverse niches, resulting in the reduction of plant species richness and functional diversity and more obvious competition among plant species with similar resource requirements. Annuals, perennials and shrubs accounted for 71.23%, 27.39% and 1.37%, respectively, suggesting that annuals and flood-tolerant riparian herbs were favored under such novel flooding conditions. A consistent increase in species number, Shannon-Wiener diversity index and Simpson dominance index with altitude was inconsistent with hump-shaped diversity-disturbance relationship of the intermediate disturbance hypothesis, while the opposite trend was observed for the Pielou evenness index. This species distribution pattern might be caused by several synergetic attributes (e.g., the submergence depth, plant tolerant capacity to flooding, life form, dispersal mode and inter-specific competition). Vegetation types shifted from xerophytes to mesophytes and eventually to hygrophytes with the increasing flooding time in the HFZs. Hydrological alterations proved to be the paramount driver of vegetation distribution in the different HFZs. The niche analysis provided the first insights on the mechanisms of resource utilization and inter-specific competition, of which annuals could germinate quickly after soil drainage to achieve the greatest competitive advantages and occupy a larger niche space than other plants. Vegetation was still in the early stage of primary succession in the novel riparian forests. Therefore, vegetation restoration strategies should be biased towards herbaceous plants, due to annuals with better environmental adaptability, supplemented by shrubs and small trees. To establish a complete reference system for vegetation restoration, natural vegetation monitory plots in the different succession stages should be established in the different HFZs of the TGR, and their environmental conditions, community structures and inter-specific relationships further analyzed.

Drought-induced assembly of rhizosphere mycobiomes shows beneficial effects on plant growth

Beneficial interactions between plants and rhizosphere fungi can enhance plant adaptability during drought stress. However, harnessing these interactions will require an in-depth understanding of the response of fungal community assembly to drought. Herein, by using different varieties of wheat plants, we analyzed the drought-induced changes in fungal community assembly in rhizosphere and bulk soil. We demonstrated that drought significantly altered the fungal communities, with the contribution of species richness to community beta diversity increased in both rhizosphere and bulk soil compartments during drought stress. The stochastic processes dominated fungal community assembly, but the relative importance of deterministic processes, mainly homogeneous selection, increased in the drought-stressed rhizosphere. Drought induced an increase in the relative abundance of generalists in the rhizosphere, as opposed to specialists, and the top 10 abundant taxa that enriched under drought conditions were predominantly generalists. Notably, the most abundant drought-enriched taxon in rhizosphere was a generalist, and the corresponding Chaetomium strain was found capable of improving root length and activating ABA signaling in wheat plants through culture-based experiment. Together, these findings provide evidence that host plants exert a strong influence on rhizospheric fungal community assembly during stress and suggest the fungal communities that have experienced drought have the potential to confer fitness advantages to the host plants.

IMPORTANCE

We have presented a framework to integrate the shifts in community assembly processes with plant-soil feedback during drought stress. We found that environmental filtering and host plant selection exert influence on the rhizospheric fungal community assembly, and the re-assembled community has great potential to alleviate plant drought stress. Our study proposes that future research should incorporate ecology with plant, microbiome, and molecular approaches to effectively harness the rhizospheric microbiome for enhancing the resilience of crop production to drought.

Birds optimize fruit size consumed near their geographic range limits

Animals can adjust their diet to maximize energy or nutritional intake. For example, birds often target fruits that match their beak size because those fruits can be consumed more efficiently. We hypothesized that pressure to optimize diet-measured as matching between fruit and beak size-increases under stressful environments, such as those that determine species' range edges. Using fruit-consumption and trait information for 97 frugivorous bird and 831 plant species across six continents, we demonstrate that birds feed more frequently on closely size-matched fruits near their geographic range limits. This pattern was particularly strong for highly frugivorous birds, whereas opportunistic frugivores showed no such tendency. These findings highlight how frugivore interactions might respond to stressful conditions and reveal that trait matching may not predict resource use consistently.

Biogeographical distribution and community assembly of Myxococcota in mangrove sediments

BACKGROUND

Myxococcota, characterized by their distinct social lifestyles, are widely distributed micro-predators in global sediments. They can feed on a wide range of bacterial, archaeal, and fungal prey. Myxococcota are capable of producing diverse secondary metabolites, playing key roles in microbial food webs, and regulating the microbial community structures in different ecosystems. However, Myxococcota are rarely pure cultured due to the challenging and stringent culturing conditions. Their natural distribution, niche differentiation, and predator-prey relationships in a specific habitat are poorly understood.

RESULTS

In this study, we conducted a comprehensive analysis of the 16S rRNA gene sequence data from public databases and our collection. We compared the abundance, diversity, and distribution patterns of Myxococcota in various habitats, with a specific focus on mangroves. We found that Myxococcota accounted for 1.45% of the total prokaryotes in global sediments based on the abundance of 16S rRNA genes. Myxococcota are abundant and diverse in mangrove sediments. They tend to be more generalistic in mangroves than in other habitats due to their wide niche breadth. Besides, the deterministic processes (variable selection) influenced the assembly of mangrove Myxococcota communities significantly more than stochastic processes. Further, we determined that environmental factors explained a greater amount of total community variation in mangrove Myxococcota than geographical variables (latitude and sediment depth). In the end, through the analysis of microbial co-occurrence networks, Myxococcota emerges as a key component and functions as a connector in the mangrove microbial community.

CONCLUSIONS

Our study enhances comprehension of mangrove Myxococcota's biogeography, assembly patterns, driving factors, and co-occurrence relationships, as well as highlights their unique niche and ecological importance in mangrove sediments.

Assessing climate niche similarity between persian fallow deer (Dama mesopotamica) areas in Iran

The Persian fallow deer or Mesopotamian fallow Deer (Dama mesopotamica, Brook 1875), a species of significant ecological importance, had faced the threat of extinction in Iran. One conservation strategy involved the translocation of Persian deer to enclosed areas across Iran, where they were afforded protection from external threats and provided with essential care by human caretakers. While human caretakers diligently attend to their needs and mitigate external threats, climate variables may now become critical factors affecting population dynamics in enclosed areas. This study aims to assess the similarity in climate niches between the original area (Dez and Karkheh) of the Persian deer species and 11 newly enclosed areas. To achieve this, we employed climate data and ecological niche modeling (ENM) techniques to assess the variations in climate among 12 areas. We utilized the environmental equivalency test to determine whether the environmental spaces of area pairs exhibit significant differences and whether these spaces are interchangeable. Extrapolation analyses were also constructed in the next steps to explore climatic conditions in original fallow deer habitats that are non-analogous to those in other parts of Iran. Our results reveal significant disparities in climate conditions between the original and all translocated areas. Based on observations of population growth in specific enclosed areas where translocated deer populations have thrived, we hypothesize that the species may demonstrate a non-equilibrium distribution in Iran. Consequently, these new areas could potentially be regarded as part of the species' potential climate niche. Extrapolation analysis showed that for a significant portion of Iran, extrapolation predictions are highly uncertain and potentially unreliable for the translocation of Persian fallow deer. However, the primary objective of translocation efforts remains the establishment of self-sustaining populations of Persian deer capable of thriving in natural areas beyond enclosed areas, thus ensuring their long-term survival and contributing to preservation efforts. Evaluating the success of newly translocated species requires additional time, with varying levels of success observed. In cases where the growth rate of the species in certain enclosed areas falls below expectations, it is prudent to consider climate variables that may contribute to population declines. Furthermore, for future translocations, we recommend selecting areas with climate similarities to regions where the species has demonstrated growth rates.

Pushing the envelope: do narrowly and widely distributed Eucalyptus species differ in response to climate warming?

Contemporary climate change will push many tree species into conditions that are outside their current climate envelopes. Using the Eucalyptus genus as a model, we addressed whether species with narrower geographical distributions show constrained ability to cope with warming relative to species with wider distributions, and whether this ability differs among species from tropical and temperate climates. We grew seedlings of widely and narrowly distributed Eucalyptus species from temperate and tropical Australia in a glasshouse under two temperature regimes: the summer temperature at seed origin and +3.5°C. We measured physical traits and leaf-level gas exchange to assess warming influences on growth rates, allocation patterns, and physiological acclimation capacity. Warming generally stimulated growth, such that higher relative growth rates early in development placed seedlings on a trajectory of greater mass accumulation. The growth enhancement under warming was larger among widely than narrowly distributed species and among temperate rather than tropical provenances. The differential growth enhancement was primarily attributable to leaf area production and adjustments of specific leaf area. Our results suggest that tree species, including those with climate envelopes that will be exceeded by contemporary climate warming, possess capacity to physiologically acclimate but may have varying ability to adjust morphology.

Impacts of Climate Change on the Distribution of Suitable Habitats and Ecological Niche for Trollius Wildflowers in Ili River Valley, Tacheng, Altay Prefecture

Xinjiang in China is distinguished by its distinctive regional landscape and high ecological sensitivity. Trollius wildflowers represent a unique and iconic element of the mountain flower landscape in Xinjiang. However, their populations are predominantly distributed in mountainous areas, making them susceptible to climate change. Despite this, the impacts of climate change on the distribution of suitable habitats and ecological niche differentiation for Trollius wildflowers have rarely been quantified. Consequently, simulations were conducted using the R-optimized MaxEnt model to predict the suitable habitat distribution of Trollius wildflowers. This was based on the occurrence data and environmental variables for the four species of Trollius (T. altaicus, T. asiaticus, T. dschungaricus, and T. lilacinus) that exist in the study area. The simulation was conducted over a period of time, beginning with the past glacial period and extending to the present, and then to the future (2050s, 2070s, and 2090s) under multiple scenarios (SSP1-2.6, SSP3-7.0, SSP5-8.5). The simulation of suitable habitats enabled the measurement of the ecological niche breadth and differentiation. The results demonstrate that the model predictions are precisely accurate, with AUC values exceeding 0.9. Annual mean temperature (Bio1), isothermality (Bio3), and precipitation in the warmest quarter (Bio18) are the dominant climate variables, in addition to vegetation, elevation, and soil factors. The proportion of suitable habitats for Trollius wildflowers varies considerably over time, from 0.14% to 70.97%. The majority of habitat loss or gain occurs at the edges of mountains, while stable habitats are concentrated in the core of the mountains. The gravity center of suitable habitats also shifts with spatial transfer, with the shifts mainly occurring in a northeasterly-southwesterly direction. The SSP1-2.6 scenario results in the sustained maintenance of habitats, whereas the SSP3-7.0 and SSP5-8.5 scenarios present challenges to the conservation of habitats. The threshold of ecological niche breadth for Trollius wildflowers is subject to fluctuations, while the ecological niche differentiation also varies. The study aims to examine the evolution of the habitat and ecological niche of Trollius wildflowers in Xinjiang under climate change. The findings will provide theoretical support for delineating the conservation area, clarify the scope of mountain flower tourism development and protection of mountain flower resources, and promote the sustainable development of ecotourism and effective utilization of territorial space in Xinjiang.

Patterns and correlates of potential range shifts of bat species in China in the context of climate change

Climate change may diminish biodiversity; thus, it is urgent to predict how species' ranges may shift in the future by integrating multiple factors involving more taxa. Bats are particularly sensitive to climate change due to their high surface-to-volume ratio. However, few studies have considered geographic variables associated with roost availability and even fewer have linked the distributions of bats to their thermoregulation and energy regulation traits. We used species distribution models to predict the potential distributions of 12 bat species in China under current and future greenhouse gas emission scenarios (SSP1-2.6 and SSP5-8.5) and examined factors that could affect species' range shifts, including climatic, geographic, habitat, and human activity variables and wing surface-to-mass ratio (S-MR). The results suggest that Ia io, Rhinolophus ferrumequinum, and Rhinolophus rex should be given the highest priority for conservation in future climate conservation strategies. Most species were predicted to move northward, except for I. io and R. rex, which moved southward. Temperature seasonality, distance to forest, and distance to karst or cave were the main environmental factors affecting the potential distributions of bats. We found significant relationships between S-MR and geographic distribution, current potential distribution, and future potential distribution in the 2050s. Our work highlights the importance of analyzing range shifts of species with multifactorial approaches, especially for species traits related to thermoregulation and energy regulation, to provide targeted conservation strategies.

Combining camera trap surveys and IUCN range maps to improve knowledge of species distributions

Reliable maps of species distributions are fundamental for biodiversity research and conservation. The International Union for Conservation of Nature (IUCN) range maps are widely recognized as authoritative representations of species' geographic limits, yet they might not always align with actual occurrence data. In recent area of habitat (AOH) maps, areas that are not habitat have been removed from IUCN ranges to reduce commission errors, but their concordance with actual species occurrence also remains untested. We tested concordance between occurrences recorded in camera trap surveys and predicted occurrences from the IUCN and AOH maps for 510 medium- to large-bodied mammalian species in 80 camera trap sampling areas. Across all areas, cameras detected only 39% of species expected to occur based on IUCN ranges and AOH maps; 85% of the IUCN only mismatches occurred within 200 km of range edges. Only 4% of species occurrences were detected by cameras outside IUCN ranges. The probability of mismatches between cameras and the IUCN range was significantly higher for smaller-bodied mammals and habitat specialists in the Neotropics and Indomalaya and in areas with shorter canopy forests. Our findings suggest that range and AOH maps rarely underrepresent areas where species occur, but they may more often overrepresent ranges by including areas where a species may be absent, particularly at range edges. We suggest that combining range maps with data from ground-based biodiversity sensors, such as camera traps, provides a richer knowledge base for conservation mapping and planning.

Species-level correlates of land-use responses and climate-change sensitivity in terrestrial vertebrates

Land-use and climate change are major pressures on terrestrial biodiversity. Species' extinction risk and responses to human pressures relate to ecological traits and other characteristics in some clades. However, large-scale comparative assessments of the associations between traits and responses to multiple human pressures across multiple clades are needed. We investigated whether a set of ecological characteristics that are commonly measured across terrestrial vertebrates (ecological traits and geographic range area) are associated with species' responses to different land-use types and species' likely sensitivity to climate change. We aimed to test whether generalizable patterns in response to these pressures arise across both pressures and across vertebrate clades, which could inform assessments of the global signature of human pressures on vertebrate biodiversity and guide conservation efforts. At the species level, we investigated associations between land-use responses and ecological characteristics with a space-for-time substitution approach, making use of the PREDICTS database. We investigated associations between ecological characteristics and expected climate-change sensitivity, estimated from properties of species realized climatic niches. Among the characteristics we considered, 3 were consistently associated with strong land-use responses and high climate-change sensitivity across terrestrial vertebrate classes: narrow geographic range, narrow habitat breadth, and specialization on natural habitats (which described whether a species occurs in artificial habitats or not). The associations of other traits with species' land-use responses and climate-change sensitivity often depended on species' class and land-use type, highlighting an important degree of context dependency. In all classes, invertebrate eaters and fruit and nectar eaters tended to be negatively affected in disturbed land-use types, whereas invertebrate-eating and plant- and seed-eating birds were estimated to be more sensitive to climate change, raising concerns about the continuation of ecological processes sustained by these species under global changes. Our results highlight a consistently higher sensitivity of narrowly distributed species and habitat specialists to land-use and climate change, which provides support for capturing such characteristics in large-scale vulnerability assessments.

Quantitative evaluation of the global impacts of human land modification on raptors

Raptors are threatened by anthropogenic land modifications, but targeted quantitative assessment of these impacts is lacking. We conducted the first global quantitative evaluation of the impacts of human-modified land on raptors. We used eBird data from 2001 to 2020 on 425 raptor species and occupancy models to assess the impacts of human-modified land on raptor distribution. The mean spatiotemporal correlations of human settlement, cropland, and pasture with raptor occupancy probability were -0.048 (SE 0.031), -0.134 (0.032), and -0.145 (0.032), respectively. The mean sensitivity of raptor occupancy probability to settlement, cropland, and pasture was -5.760 (2.266), -3.128 (1.540), and -2.402 (1.551), respectively. The occupancy probability of raptors with a large body mass was more negatively correlated with cropland (phylogenetic generalized least squares regressions: slope = -0.052 [SE 0.022], t = -2.335, df = 1, 407, p = 0.020, λ = 0.006) and more positively correlated with pasture (slope = 0.047 [0.022], t = 2.118, df = 1, 407, p = 0.035, λ = 0.013). The occupancy probability of raptors with a more extensive range size was more positively correlated with cropland (slope = 0.002 [0.004], t = 0.399, df = 1, 407, p < 0.001, λ = 0.000). Raptors that prefer open habitats were more positively correlated with cropland (analysis of variance: F = 3.424, df = 2, p = 0.034, λ = 0.000) and pasture (F = 6.577, df = 2, p = 0.002, λ = 0.000). In Africa and South America, where raptor species are most abundant, raptor occupancy probability decreased over 20 years, most likely due to habitat fragmentation associated with human land modification. Although raptors with different ecological characteristics had different responses to human land modification, the impacts of settlement, cropland, and pasture on mean raptor occupancy probability were negative, regardless of space and time.

Alien range size, habitat breadth, origin location, and domestication of alien species matter to their impact risks

Invasive alien species are a major driver of biodiversity loss. Currently, the process of biological invasions is experiencing a constant acceleration, foreshadowing a future increase in the threat posed by invasive alien species to global biodiversity. Therefore, it is necessary to assess the impact risks of invasive alien species and related factors. Here, we constructed a dataset of negative environmental impact events to evaluate the impact risks of alien species. We collected information on 1071 established alien terrestrial vertebrates and then gathered negative environmental impacts for 108 of those species. Generalized linear mixed-effects model and phylogenetic generalized least-squares regression model were used to examine the characteristic (including life-history traits, characteristics related to distribution, and introduction event characteristics) correlates of species' impact risks at the global scale for 108 established alien terrestrial vertebrates (mammals, birds, reptiles and amphibians). Our results showed that a total of 3158 negative environmental impacts were reported for 108 harmful species across 71 countries worldwide. Factors associated with impact risks varied slightly among taxa, but alien range size, habitat breadth, origin location, and domestication were significantly correlated with impact risks. Our study aims to identify the characteristics of alien species with high-impact risks to facilitate urgent assessment of alien species and to protect the local ecological environment and biodiversity.

Exploring invasiveness and versatility of used microhabitats of the globally invasive Gambusia holbrooki

Non-native species can lead to severe impacts on invaded ecosystems, including the decline of ecosystem function through deleterious impacts on species diversity. The successful establishment of non-native species in new environments is the first barrier a species must overcome, ultimately depending on its ability to either cope with or adapt to local site-specific conditions. Despite the widespread distribution and ecological consequences of many freshwater invaders, site-specific and climatic preferences are often unknown. This is also the case of the Eastern mosquitofish Gambusia holbrooki, a global invader considered as a pervasive threat to endemic species. Here, we determined the ecological features and preferred site-specific conditions of G. holbrooki in Türkiye, which spans a wide range of diverse biogeographically distinct ecosystems by surveying populations from 130 localities in 2016 and 2017. Gambusia holbrooki were detected by hand-net in 48 of these sites (19 lotic, 29 lentic). It showed a preference for shallow waters with medium sized rocks, and abundances differed spatially across a latitudinal gradient and was influenced predominantly by variations in pH. The only other factors predicting its presence were low current velocities and gravel substrate, highlighting its ecological versatility in utilising a wide range of microhabitats. Bioclimatic models suggest that G. holbrooki is found in areas with a wide average annual temperature ranging from 10 to 20 °C, but with temperature not being a limiting factor to its invasion. Gambusia holbrooki shows a preference for xeric freshwater ecosystems and endorheic basins, as well as temperate coastal rivers, temperate upland rivers, temperate floodplain rivers and wetlands, and tropical and subtropical coastal rivers. These results, particularly the wide occurrence with only few limiting factors, emphasise the invasion potential of mosquitofish and should substantiate the need for localised invasive species management and conservation efforts, particularly in smaller or insular areas where mosquitofish and endemic fish species co-exist.

Environmental and Biogeographic Drivers behind Alpine Plant Thermal Tolerance and Genetic Variation

In alpine ecosystems, elevation broadly functions as a steep thermal gradient, with plant communities exposed to regular fluctuations in hot and cold temperatures. These conditions lead to selective filtering, potentially contributing to species-level variation in thermal tolerance and population-level genetic divergence. Few studies have explored the breadth of alpine plant thermal tolerances across a thermal gradient or the underlying genetic variation thereof. We measured photosystem heat (Tcrit-hot) and cold (Tcrit-cold) thresholds of ten Australian alpine species across elevation gradients and characterised their neutral genetic variation. To reveal the biogeographical drivers of present-day genetic signatures, we also reconstructed temporal changes in habitat suitability across potential distributional ranges. We found intraspecific variation in thermal thresholds, but this was not associated with elevation, nor underpinned by genetic differentiation on a local scale. Instead, regional population differentiation and considerable homozygosity within populations may, in part, be driven by distributional contractions, long-term persistence, and migrations following habitat suitability. Our habitat suitability models suggest that cool-climate-distributed alpine plants may be threatened by a warming climate. Yet, the observed wide thermal tolerances did not reflect this vulnerability. Conservation efforts should seek to understand variations in species-level thermal tolerance across alpine microclimates.

Unveiling the overlooked microbial niches thriving on building exteriors

Rapid urbanization in the Asia-Pacific region is expected to place two-thirds of its population in concrete-dominated urban landscapes by 2050. While diverse architectural facades define the unique appearance of these urban systems. There remains a significant gap in our understanding of the composition, assembly, and ecological potential of microbial communities on building exteriors. Here, we examined bacterial and protistan communities on building surfaces along an urbanization gradient (urban, suburban and rural regions), investigating their spatial patterns and the driving factors behind their presence. A total of 55 bacterial and protist phyla were identified. The bacterial community was predominantly composed of Proteobacteria (33.7% to 67.5%). The protistan community exhibited a prevalence of Opisthokonta and Archaeplastida (17.5% to 82.1% and 1.8% to 61.2%, respectively). The composition and functionality of bacterial communities exhibited spatial patterns correlated with urbanization. In urban buildings, factors such as facade type, light exposure, and building height had comparatively less impact on bacterial composition compared to suburban and rural areas. The highest bacterial diversity and lowest Weighted Average Community Identity (WACI) were observed on suburban buildings, followed by rural buildings. In contrast, protists did not show spatial distribution characteristics related to facade type, light exposure, building height and urbanization level. The distinct spatial patterns of protists were primarily shaped by community diffusion and the bottom-up regulation exerted by bacterial communities. Together, our findings suggest that building exteriors serve as attachment points for local microbial metacommunities, offering unique habitats where bacteria and protists exhibit independent adaptive strategies closely tied to the overall ecological potential of the community.

Biodiversity responses to agricultural practices in cropland and natural habitats

Largely driven by agricultural pressures, biodiversity has experienced great changes globally. Exploring biodiversity responses to agricultural practices associated with agricultural intensification can benefit biodiversity conservation in agricultural landscapes. However, the effects of agricultural practices may also extend to natural habitats. Moreover, agricultural impacts may also vary with geographical region. We analyze biodiversity responses to landscape cropland coverage, cropping frequency, fertiliser and yield, among different land-use types and across geographical regions. We find that species richness and total abundance generally respond negatively to increased landscape cropland coverage. Biodiversity reductions in human land-use types (pasture, plantation forest and cropland) were stronger in tropical than non-tropical regions, which was also true for biodiversity reductions with increasing yield in both human and natural land-use types. Our results underline substantial biodiversity responses to agricultural practices not only in cropland but also in natural habitats, highlighting the fact that biodiversity conservation demands a greater focus on optimizing agricultural management at the landscape scale.

Tree species occurring in Amazonian wetland forests consistently show broader range sizes and niche breadths than trees in upland forests

Generally, species with broad niches also show large range sizes. We investigated the relationship between hydrological niche breadth and geographic range size for Amazonian tree species seeking to understand the role of habitat specialization to Amazonian wetlands and upland forests on the current distribution of tree species. We obtained 571,092 valid occurrence points from GBIF and SpeciesLink to estimate the range size and the niche breadth of 76% of all known Amazonian tree species (5150 tree species). Hydrological niche breadth was measured on different unidimensional axes defined by (1) total annual precipitation; (2) precipitation seasonality; (3) actual evapotranspiration; and (4) water table depth. Geographic range sizes were estimated using alpha-hull adjustments. General linear models were used to relate niche breadth to range size while contrasting tree species occurring and not occurring in wetlands. The hydrological niche breadth of Amazonian tree species varied mostly along the water table depth axis. The average range size for an Amazonian tree species was 751,000 km2 (median of 154,000 km2 and standard deviation of 1,550,000 km2). Niche breadth-range size relationships for Amazonian tree species were positive for all models, and the explanatory power of the models improved when including whether a species occurred in wetlands or in terrestrial uplands. Wetland species had steeper positive slopes for the niche breadth-range size relationship, and consistently larger range sizes for a given niche breadth. Amazonian tree species varied strongly in hydrological niche breadth and range size, but most species had narrow niche breadths and range sizes. Our results suggest that the South American riverscape may have been acting as a corridor for species dispersal in the Neotropical lowlands.

Exploring the potential effects of forest urbanization on the interplay between small mammal communities and their gut microbiota

Urbanization significantly impacts wild populations, favoring urban dweller species over those that are unable to adapt to rapid changes. These differential adaptative abilities could be mediated by the microbiome, which may modulate the host phenotype rapidly through a high degree of flexibility. Conversely, under anthropic perturbations, the microbiota of some species could be disrupted, resulting in dysbiosis and negative impacts on host fitness. The links between the impact of urbanization on host communities and their gut microbiota (GM) have only been scarcely explored. In this study, we tested the hypothesis that the bacterial composition of the GM could play a role in host adaptation to urban environments. We described the GM of several species of small terrestrial mammals sampled in forested areas along a gradient of urbanization, using a 16S metabarcoding approach. We tested whether urbanization led to changes in small mammal communities and in their GM, considering the presence and abundance of bacterial taxa and their putative functions. This enabled to decipher the processes underlying these changes. We found potential impacts of urbanization on small mammal communities and their GM. The urban dweller species had a lower bacterial taxonomic diversity but a higher functional diversity and a different composition compared to urban adapter species. Their GM assembly was mostly governed by stochastic effects, potentially indicating dysbiosis. Selection processes and an overabundance of functions were detected that could be associated with adaptation to urban environments despite dysbiosis. In urban adapter species, the GM functional diversity and composition remained relatively stable along the urbanization gradient. This observation can be explained by functional redundancy, where certain taxa express the same function. This could favor the adaptation of urban adapter species in various environments, including urban settings. We can therefore assume that there are feedbacks between the gut microbiota and host species within communities, enabling rapid adaptation.

The environmental conditions of endemism hotspots shape the functional traits of mammalian assemblages

Endemic (small-ranged) species are distributed non-randomly across the globe. Regions of high topography and stable climates have higher endemism than flat, climatically unstable regions. However, it is unclear how these environmental conditions interact with and filter mammalian traits. Here, we characterize the functional traits of highly endemic mammalian assemblages in multiple ways, testing the hypothesis that these assemblages are trait-filtered (less functionally diverse) and dominated by species with traits associated with small range sizes. Compiling trait data for more than 5000 mammal species, we calculated assemblage means and multidimensional functional metrics to evaluate the distribution of traits across each assemblage. We then related these metrics to the endemism of global World Wildlife Fund ecoregions using linear models and phylogenetic fourth-corner regression. Highly endemic mammalian assemblages had small average body masses, low fecundity, short lifespans and specialized habitats. These traits relate to the stable climate and rough topography of endemism hotspots and to mammals' ability to expand their ranges, suggesting that the environmental conditions of endemism hotspots allowed their survival. Furthermore, species living in endemism hotspots clustered near the edges of their communities' functional spaces, indicating that abiotic trait filtering and biotic interactions act in tandem to shape these communities.

Saccharomycotina yeasts defy long-standing macroecological patterns

The Saccharomycotina yeasts ("yeasts" hereafter) are a fungal clade of scientific, economic, and medical significance. Yeasts are highly ecologically diverse, found across a broad range of environments in every biome and continent on earth; however, little is known about what rules govern the macroecology of yeast species and their range limits in the wild. Here, we trained machine learning models on 12,816 terrestrial occurrence records and 96 environmental variables to infer global distribution maps at ~1 km2 resolution for 186 yeast species (~15% of described species from 75% of orders) and to test environmental drivers of yeast biogeography and macroecology. We found that predicted yeast diversity hotspots occur in mixed montane forests in temperate climates. Diversity in vegetation type and topography were some of the greatest predictors of yeast species richness, suggesting that microhabitats and environmental clines are key to yeast diversity. We further found that range limits in yeasts are significantly influenced by carbon niche breadth and range overlap with other yeast species, with carbon specialists and species in high-diversity environments exhibiting reduced geographic ranges. Finally, yeasts contravene many long-standing macroecological principles, including the latitudinal diversity gradient, temperature-dependent species richness, and a positive relationship between latitude and range size (Rapoport's rule). These results unveil how the environment governs the global diversity and distribution of species in the yeast subphylum. These high-resolution models of yeast species distributions will facilitate the prediction of economically relevant and emerging pathogenic species under current and future climate scenarios.

The relationship between niche breadth and phylogenetic characteristics of eight species of rhubarb on the Qinghai-Tibet Plateau, Asia

The relationship between spatial distribution and phylogeny has been widely debated in recent decades. To understand biogeographic and evolutionary history relationships and to explore the interspecific similarities and phylogenetic correlations of niche characteristics, we collected and recorded all distribution points for eight species of rhubarb on the Qinghai-Tibet Plateau, used different methods to describe the ecological niche, and explored the relationship between phylogeny, ecological niche, and distribution range. The results reveal that: (1) the ranges of optimal environmental variables for species with close kinship are not exactly the same, ecologically similar species are not necessarily sister species, and the overlap of rhubarb has no significant correlation with phylogeny. Therefore, the impact of ecological dimensions on species formation is greater than that of geographical latitude for the eight species of rhubarb. (2) Among the eight species of rhubarb, the breadth of ecological niche is positively correlated with the current suitable habitat area and negatively correlated with fluctuations in future suitable habitat area. In the future, except for Rheum tanguticum and Rheum palmatum, the suitable planting areas for the other six species of rhubarb will decrease as greenhouse gas emissions concentrations and time increase. Therefore, species with smaller ecological niches are at a greater risk of habitat loss compared to species with larger ecological niches. (3) In both existing and future distribution prediction models of rhubarb, we observed that both the widely distributed Rheum spiciforme and the niche narrow Rheum nobile, all eight species of rhubarb are present in the Hengduan Mountains, based on our analysis, we propose that the Hengduan Mountains should be regarded as a priority conservation area for rhubarb, to preserve the species' biodiversity. Our study lays the groundwork for identifying evolutionary trends in ecological specialization.

Comparative epigenetic and genetic spatial structure in Mediterranean mountain plants: a multispecies study

Changes in epigenetic states can allow individuals to cope with environmental changes. If such changes are heritable, this may lead to epigenetic adaptation. Thus, it is likely that in sessile organisms such as plants, part of the spatial epigenetic variation found across individuals will reflect the environmental heterogeneity within populations. The departure of the spatial epigenetic structure from the baseline genetic variation can help in understanding the value of epigenetic regulation in species with different breadth of optimal environmental requirements. Here, we hypothesise that in plants with narrow environmental requirements, epigenetic variability should be less structured in space given the lower variability in suitable environmental conditions. We performed a multispecies study that considered seven pairs of congeneric plant species, each encompassing a narrow endemic with habitat specialisation and a widespread species. In three populations per species we used AFLP and methylation-sensitive AFLP markers to characterise the spatial genetic and epigenetic structures. Narrow endemics showed a significantly lower epigenetic than genetic differentiation between populations. Within populations, epigenetic variation was less spatially structured than genetic variation, mainly in narrow endemics. In these species, structural equation models revealed that such pattern was associated to a lack of correlation between epigenetic and genetic information. Altogether, these results show a greater decoupling of the spatial epigenetic variation from the baseline spatial genetic pattern in endemic species. These findings highlight the value of studying genetic and epigenetic spatial variation to better understand habitat specialisation in plants.

Recent range shifts of moths, butterflies, and birds are driven by the breadth of their climatic niche

Species are altering their ranges as a response to climate change, but the magnitude and direction of observed range shifts vary considerably among species. The ability to persist in current areas and colonize new areas plays a crucial role in determining which species will thrive and which decline as climate change progresses. Several studies have sought to identify characteristics, such as morphological and life-history traits, that could explain differences in the capability of species to shift their ranges together with a changing climate. These characteristics have explained variation in range shifts only sporadically, thus offering an uncertain tool for discerning responses among species. As long-term selection to past climates have shaped species' tolerances, metrics describing species' contemporary climatic niches may provide an alternative means for understanding responses to on-going climate change. Species that occur in a broader range of climatic conditions may hold greater tolerance to climatic variability and could therefore more readily maintain their historical ranges, while species with more narrow tolerances may only persist if they are able to shift in space to track their climatic niche. Here, we provide a first-filter test of the effect of climatic niche dimensions on shifts in the leading range edges in three relatively well-dispersing species groups. Based on the realized changes in the northern range edges of 383 moth, butterfly, and bird species across a boreal 1,100 km latitudinal gradient over c. 20 years, we show that while most morphological or life-history traits were not strongly connected with range shifts, moths and birds occupying a narrower thermal niche and butterflies occupying a broader moisture niche across their European distribution show stronger shifts towards the north. Our results indicate that the climatic niche may be important for predicting responses under climate change and as such warrants further investigation of potential mechanistic underpinnings.

Soil organic carbon loss decreases biodiversity but stimulates multitrophic interactions that promote belowground metabolism

Soil organic carbon (SOC) plays an essential role in mediating community structure and metabolic activities of belowground biota. Unraveling the evolution of belowground communities and their feedback mechanisms on SOC dynamics helps embed the ecology of soil microbiome into carbon cycling, which serves to improve biodiversity conservation and carbon management strategy under global change. Here, croplands with a SOC gradient were used to understand how belowground metabolisms and SOC decomposition were linked to the diversity, composition, and co-occurrence networks of belowground communities encompassing archaea, bacteria, fungi, protists, and invertebrates. As SOC decreased, the diversity of prokaryotes and eukaryotes also decreased, but their network complexity showed contrasting patterns: prokaryotes increased due to intensified niche overlap, while that of eukaryotes decreased possibly because of greater dispersal limitation owing to the breakdown of macroaggregates. Despite the decrease in biodiversity and SOC stocks, the belowground metabolic capacity was enhanced as indicated by increased enzyme activity and decreased enzymatic stoichiometric imbalance. This could, in turn, expedite carbon loss through respiration, particularly in the slow-cycling pool. The enhanced belowground metabolic capacity was dominantly driven by greater multitrophic network complexity and particularly negative (competitive and predator-prey) associations, which fostered the stability of the belowground metacommunity. Interestingly, soil abiotic conditions including pH, aeration, and nutrient stocks, exhibited a less significant role. Overall, this study reveals a greater need for soil C resources across multitrophic levels to maintain metabolic functionality as declining SOC results in biodiversity loss. Our researchers highlight the importance of integrating belowground biological processes into models of SOC turnover, to improve agroecosystem functioning and carbon management in face of intensifying anthropogenic land-use and climate change.

Niche differentiation, reproductive interference, and range expansion

Understanding species distributions and predicting future range shifts requires considering all relevant abiotic factors and biotic interactions. Resource competition has received the most attention, but reproductive interference is another widespread biotic interaction that could influence species ranges. Rubyspot damselflies (Hetaerina spp.) exhibit a biogeographic pattern consistent with the hypothesis that reproductive interference has limited range expansion. Here, we use ecological niche models to evaluate whether this pattern could have instead been caused by niche differentiation. We found evidence for climatic niche differentiation, but the species that encounters the least reproductive interference has one of the narrowest and most peripheral niches. These findings strengthen the case that reproductive interference has limited range expansion and also provide a counterexample to the idea that release from negative species interactions triggers niche expansion. We propose that release from reproductive interference enables species to expand in range while specializing on the habitats most suitable for breeding.

Climate match is key to predict range expansion of the world's worst invasive terrestrial vertebrates

Understanding the determinants of the range expansion of invasive alien species is crucial for developing effective prevention and control strategies. Nevertheless, we still lack a global picture of the potential factors influencing the invaded range expansion across taxonomic groups, especially for the world's worst invaders with high ecological and economic impacts. Here, by extensively collecting data on 363 distributional ranges of 19 of world's worst invasive terrestrial vertebrates across 135 invaded administrative jurisdictions, we observed remarkable variations in the range expansion across species and taxonomic groups. After controlling for taxonomic and geographic pseudoreplicates, model averaging analyses based on generalized additive mixed-effect models showed that species in invaded regions having climates more similar to those of their native ranges tended to undergo a larger range expansion. In addition, as proxies of propagule pressure and human-assisted transportation, the number of introduction events and the road network density were also important predictors facilitating the range expansion. Further variance partitioning analyses validated the predominant role of climate match in explaining the range expansion. Our study demonstrated that regions with similar climates to their native ranges could still be prioritized to prevent the spread of invasive species under the sustained global change.

Maximum temperatures determine the habitat affiliations of North American mammals

Addressing the ongoing biodiversity crisis requires identifying the winners and losers of global change. Species are often categorized based on how they respond to habitat loss; for example, species restricted to natural environments, those that most often occur in anthropogenic habitats, and generalists that do well in both. However, species might switch habitat affiliations across time and space: an organism may venture into human-modified areas in benign regions but retreat into thermally buffered forested habitats in areas with high temperatures. Here, we apply community occupancy models to a large-scale camera trapping dataset with 29 mammal species distributed over 2,485 sites across the continental United States, to ask three questions. First, are species' responses to forest and anthropogenic habitats consistent across continental scales? Second, do macroclimatic conditions explain spatial variation in species responses to land use? Third, can species traits elucidate which taxa are most likely to show climate-dependent habitat associations? We found that all species exhibited significant spatial variation in how they respond to land-use, tending to avoid anthropogenic areas and increasingly use forests in hotter regions. In the hottest regions, species occupancy was 50% higher in forested compared to open habitats, whereas in the coldest regions, the trend reversed. Larger species with larger ranges, herbivores, and primary predators were more likely to change their habitat affiliations than top predators, which consistently affiliated with high forest cover. Our findings suggest that climatic conditions influence species' space-use and that maintaining forest cover can help protect mammals from warming climates.

Applying the concept of niche breadth to understand urban tree mortality in the UK

Accelerated climate change has raised concerns about heightened vulnerability of urban trees, spurring the need to reevaluate their suitability. The urgency has also driven the widespread application of climatic niche-based models. In particular, the concept of niche breadth (NB), the range of environmental conditions that species can tolerate, is commonly estimated based on species occurrence data over the selected geographic range to predict species response to changing conditions. However, in urban environments where many species are cultivated out of the NB of their natural distributions, additional empirical evidence beyond presence and absence is needed not only to test the true tolerance limits but also to evaluate species' adaptive capacity to future climate. In this research, mortality trends of Acer and Quercus species spanning a 21-year period (2000-2021) from tree inventories of three major UK botanic gardens - the Royal Botanic Gardens, Kew (KEW), Westonbirt, the National Arboretum (WESB), and the Royal Botanic Garden Edinburgh (RBGE) - were analyzed in relation to their NB under long-term drought stress. As a result, Acer species were more responsive to drought and heat stress. For Acer, positioning below the lower limits of the precipitation of warmest quarter led to an increase in the probability of annual mortality by 1.2 and 1.3 % at KEW and RBGE respectively. In addition, the mean cumulative mortality rate increased corresponding to an increase in the number of niche positions below the lower limits of the selected bioclimatic variables. On the other hand, Quercus species in general exhibited comparable resilience regardless of their niche positions. Moreover, Mediterranean oaks were most tolerant, with cumulative mortality rates that were lower than those of native oaks in the UK. These findings further highlight the importance of incorporating ecological performance and recognizing species-specific adaptive strategies in climatic niche modeling.

Impacts of climate change and habitat loss on the distribution of the endangered crested capuchin monkey (Sapajus robustus)

The crested capuchin monkey (Sapajus robustus) is endemic to the Atlantic Forest and its transition areas within Cerrado in Brazil. The species is currently threatened by habitat loss and has been classified as endangered by the IUCN Red List of Threatened Species since 2015. We used ecological niche models built with MaxEnt to predict the potential impact of climate change on the distribution of this species. The models were projected onto the reference climate, considering six climate scenarios (three Global Climate Models and two Representative Concentration Pathways) from IPCC for 2050 and 2070. We showed that while the amount of suitable area is expected to change little across the species' range in most evaluated climate scenarios, climatic conditions may significantly deteriorate by 2070 in the pessimistic scenario, especially in currently warmer and dryer areas to the west. As seen on other capuchin monkeys, the potential use of tools by crested capuchins may increase the chances of the species adaptation to novel harsher environmental conditions. The major negative impacts across the species range also include habitat loss and fragmentation so that the conservation of the species relies on the protection of the forest remnants in the center of its distribution, which can harbor populations of the species in current and future climate scenarios.

Local niches explain coexistence in environmentally-distinct contact zones between Western Mediterranean vipers

Species' ecological niches are frequently analysed to gain insights into how anthropogenic changes affect biodiversity. Coping with these changes often involves shifts in niche expression, which can disrupt local biotic interactions. Secondary contact zones, where competition and ecological segregation commonly occur, are ideal for studying the ecological factors influencing species' niches. In this study, we investigated the effect of climate and landscape factors on the ecological niches of two viper species, Vipera aspis and Vipera latastei, across three contact zones in northern Iberia, characterized by varying levels of landscape alteration. Using niche overlap tests, ecological niche models and spatial analyses we observed local variation in the expression of the species' niches across the three contact zones, resulting from the different abiotic and biotic conditions of each area. Rather than spatial niche segregation, we observed high niche overlap, suggesting niche convergence. A pattern of asymmetrical niche variation was identified in all contact zones, driven by species' climatic tolerances and the environmental conditions of each area. V. aspis generally exhibited a wider niche, except in the southernmost zone where the pure Mediterranean climate favored V. latastei. Human-induced landscape changes intensified niche asymmetry, by favoring the most generalist V. aspis over the specialist V. latastei, increasing habitat overlap, and likely competition. This study presents a comprehensive analysis of niche expression at range margins, anticipating a heightened impact of landscape changes in V. latastei. The methodological framework implemented here, and our findings, hold significant relevance for biodiversity management and conservation in human-impacted areas.

Distribution and co-occurrence patterns of charophytes and angiosperms in the northern Baltic Sea

The distribution data of 11 soft substrate charophyte and angiosperm species were analyzed. Our study aimed to elucidate the co-occurrence patterns among these sympatric macrophyte species and quantify their distribution areas. The central hypothesis of this study proposed that the observed co-occurrence patterns among the studied species deviate from what would be expected by random chance. Macrophyte occurrence data was derived from an extensive field sampling database. Environmental variables available as georeferenced raster layers including topographical, hydrodynamic, geological, physical, chemical, and biological variables were used as predictor variables in the random forest models to predict the spatial distribution of the species. Permutation tests revealed statistically significant deviations from random co-occurrence patterns. The analysis demonstrated that species tended to co-occur more frequently within their taxonomic groups (i.e., within charophytes and within angiosperms) than between these groups. The most extensive distribution overlap was observed between Chara aspera Willd. and Chara canescens Loisel., while Zostera marina L. exhibited the least overlap with the other species. The mean number of co-occurring species was the highest in Chara baltica (Hartman) Bruzelius while Z. marina had the largest share of single-species occurrences. Based on the distribution models, Stuckenia pectinata (L.) Börner had the largest distribution area.

Species-level drivers of avian centrality within seed-dispersal networks across different levels of organisation

Bird-plant seed-dispersal networks are structural components of ecosystems. The role of bird species in seed-dispersal networks (from less [peripheral] to more connected [central]), determines the interaction patterns and their ecosystem services. These roles may be driven by morphological and functional traits as well as evolutionary, geographical and environmental properties acting at different spatial extents. It is still unknown if such drivers are equally important in determining species centrality at different network levels, from individual local networks to the global meta-network representing interactions across all local networks. Using 308 networks covering five continents and 11 biogeographical regions, we show that at the global meta-network level species' range size was the most important driver of species centrality, with more central species having larger range sizes, which would facilitate the interaction with a higher number of plants and thus the maintenance of seed-dispersal interactions. At the local network level, body mass was the only driver with a significant effect, implying that local factors related to resource availability are more important at this level of network organisation than those related to broad spatial factors such as range sizes. This could also be related to the mismatch between species-level traits, which do not consider intraspecific variation, and the local networks that can depend on such variation. Taken together, our results show that the drivers determining species centrality are relative to the levels of network organisation, suggesting that prediction of species functional roles in seed-dispersal interactions requires combined local and global approaches.

Variation in abundance and habitat use of the critically endangered Microcebus gerpi across its fragmented range

A link between the abundance of species and their degree of ecological specialization has previously been suggested within the primate order. Many species of lemurs were only recently described and even basic ecological data are not yet available for them. We investigated the habitat use, abundance, and habitat characteristics of the critically endangered Microcebus gerpi and evaluated potential impacts of vegetation structure and human disturbances on variations in its abundance. We determined abundance by systematic nocturnal surveys along 13 transects that were also used for characterizing the vegetation structure in seven study sites that were widely distributed within its range. Although M. gerpi occurred in all studied lowland rainforest and littoral forest fragments in central eastern Madagascar and therefore has a higher ecological plasticity and wider distribution than previously thought, its actual Area of Occupancy is very small (339.78 km2 ) due to an extreme degree of habitat fragmentation throughout its range. M. gerpi occurred with a mean encounter rate of 3.04 individuals/km but abundance varied substantially between sites (0.75-4.5 individuals/km). Statistical modeling revealed that the cover of small- to medium-sized trees had a positive impact on the abundance of M. gerpi, whereas a composite disturbance score (CDS), formed on the basis of information on the prominence of fires, cattle, charcoal production and wood extraction inside and around the forest, had a negative impact on abundance. These results suggest that M. gerpi is slightly less threatened than expected because of its larger geographic range, but also that it responds negatively to human disturbances. These findings raise strong conservation concerns and question the long-term viability of the remaining small and isolated populations of this arboreal solitary forager.

Uncovering the processes of microbial community assembly in the near-surface sediments of a climate-sensitive glacier-fed lake

Glacier-fed lakes are characterized by cold temperatures, high altitudes, and nutrient-poor conditions. Despite these challenging conditions, near-surface sediments of glacier-fed lakes harbor rich microbial communities that are critical for ecosystem functioning and serve as a bridge between aquatic ecology and the deep subsurface biosphere. However, there is limited knowledge regarding the microbial communities and their assembly processes in these sediments, which are highly vulnerable to climate change. To fill this knowledge gap, this study systematically analyzed environmental variables, microbial communities, diversity, co-occurrence relationships, and community assembly processes in the near-surface sediments of a glacier-fed lake in the Tibetan Plateau. The results revealed distinct vertical gradients in microbial diversity and subcommunities, highlighting the significant influence of selection processes and adaptive abilities on microbial communities. Specifically, specialists played a crucial role within the overall microbial communities. Microbial assembly was primarily driven by homogeneous selection, but its influence declined with increasing depth. In contrast, homogenizing dispersal showed an opposite pattern, and the bottom layer exhibited heterogeneous selection and undominated processes. These patterns of microbial assembly were primarily driven by environmental gradients, with significant contributions from processes associated to ammonium and organic matter deposition, as well as chemical precipitation in response to a warming climate. This study enhances our understanding of the microbial communities and assembly processes in the near-surface sediments of glacier-fed lakes and sheds light on geo-microbiological processes in climate-sensitive lacustrine sediments.

Contrasting range changes of terrestrial orchids under future climate change in China

Climate change has impacted the distribution and abundance of numerous plant and animal species during the last century. Orchidaceae is one of the largest yet most threatened families of flowering plants. However, how the geographical distribution of orchids will respond to climate change is largely unknown. Habenaria and Calanthe are among the largest terrestrial orchid genera in China and around the world. In this paper, we modeled the potential distribution of eight Habenaria species and ten Calanthe species in China under the near-current period (1970-2000) and the future period (2081-2100) to test the following two hypotheses: 1) narrow-ranged species are more vulnerable to climate change than wide-ranged species; 2) niche overlap between species is positively correlated with their phylogenetic relatedness. Our results showed that most Habenaria species will expand their ranges, although the climatic space at the southern edge will be lost for most Habenaria species. In contrast, most Calanthe species will shrink their ranges dramatically. Contrasting range changes between Habenaria and Calanthe species may be explained by their differences in climate-adaptive traits such as underground storage organs and evergreen/deciduous habits. Habenaria species are predicted to generally shift northwards and to higher elevations in the future, while Calanthe species are predicted to shift westwards and to higher elevations. The mean niche overlap among Calanthe species was higher than that of Habenaria species. No significant relationship between niche overlap and phylogenetic distance was detected for both Habenaria and Calanthe species. Species range changes in the future was also not correlated with their near current range sizes for both Habenaria and Calanthe. The results of this study suggest that the current conservation status of both Habenaria and Calanthe species should be adjusted. Our study highlights the importance of considering climate-adaptive traits in understanding the responses of orchid taxa to future climate change.

The role of thermal tolerance in determining elevational distributions of four arthropod taxa in mountain ranges of southern Asia

Understanding the role of thermal tolerances in determining species distributions is important for assessing species responses to climate change. Two hypotheses linking physiology with species distributions have been put forward-the climatic variability hypothesis and the climatic extreme hypothesis. The climatic variability hypothesis predicts the selection of individuals with broad thermal tolerance in more variable climatic conditions and the climatic extreme hypothesis predicts the selection of individuals with extreme thermal tolerance values under extreme climatic conditions. However, no study has tested the predictions of these hypotheses simultaneously for several taxonomic groups along elevational gradients. Here, we related experimentally measured critical thermal maxima, critical thermal minima and thermal tolerance breadths for 15,187 individuals belonging to 116 species of ants, beetles, grasshoppers, and spiders from mountain ranges in central and northern Pakistan to the limits and breadths of their geographic and temperature range. Across all species and taxonomic groups, we found strong relationships between thermal traits and elevational distributions both in terms of geography and temperature. The relationships were robust when repeating the analyses for ants, grasshoppers, and spiders but not for beetles. These results indicate a strong role of physiology in determining elevational distributions of arthropods in Southern Asia. Overall, we found strong support for the climatic variability hypothesis and the climatic extreme hypothesis. A close association between species' distributional limits and their thermal tolerances suggest that in case of a failure to adapt or acclimate to novel climatic conditions, species may be under pressure to track their preferred climatic conditions, potentially facing serious consequences under current and future climate change.

Thermal niche breadth and their relationship with sturnira bat species diversification

The interaction between climatic conditions and the ability of organisms to maintain homeostasis regulates the distribution of species on the planet. However, its influence on macroevolutionary dynamics is not well understood. It has been suggested that diversification rates will be different in lineages with narrow thermal niches (specialists) to diversification rates in generalist lineages, but the evidence for this is elusive. Here, we tested this hypothesis by using the most diverse (in species richness and geographic range variation) tropical bat genus within the Phyllostomidae family. We estimated the realized thermal niche breadth of Sturnira species from their geographic range and categorized them as generalists, cold specialists, or warm specialists. We compared dynamic evolutionary models that differ in 1) niche breadth evolution, 2) parental niche breadth inheritance, and 3) whether niche breadth evolution is associated with shifts in diversification rates. Our best-performing model indicates that most Sturnira species arose as specialists in warm climates and that over time, their niche breadth broadens, and just a subset of those species becomes specialists in cold environments. We found that the evolution of realized thermal niche breadth causes fluctuations in per-lineage rates of diversification, where warm specialists boast the highest speciation rates. However, we found no evidence of these changes in niche neither triggering nor being a result of speciation events themselves; this suggests that diversification events in Sturnira could instead depend on allopatric speciation processes such as the development of geographic barriers.

Into the microbial niche

The environmental niche concept describes the distribution of a taxon in the environment and can be used to understand community dynamics, biological invasions, and the impact of environmental changes. The uses and applications are still restricted in microbial ecology, largely due to the complexity of microbial systems and associated methodological limitations. The development of shotgun metagenomics and metatranscriptomics opens new ways to investigate the microbial niche by focusing on the metabolic niche within the environmental space. Here, we propose the metabolic niche framework, which, by defining the fundamental and realised metabolic niche of microorganisms, has the potential to not only provide novel insights into habitat preferences and the metabolism associated, but also to inform on metabolic plasticity, niche shifts, and microbial invasions.