Patterns Of Species Richness Research Articles

Unraveling global species richness patterns of the Lysmatidae family: a multi-scale and multi-hypothesis ecological approach

While diversity gradients are well-explored in macroecology, factors shaping species richness at broad scales remain debated. We investigated the species richness of the decapod family Lysmatidae across 4 spatial scales: realm, province, ecoregion, and local (2° × 2° grid cells). We tested 4 ecological hypotheses: physiological stress (PSH), resource availability (RAH), habitat heterogeneity (HHH), and anthropogenic impact (AIH). Occurrence data (52 Lysmatidae species) and environmental variables (salinity, temperature, primary productivity, bathymetry, coral richness, anthropogenic impact index) were obtained from online databases and literature. Fifteen regression models, incorporating spatial filters, were tested to assess the hypotheses. The highest Lysmatidae species richness occurred in the Tropical Atlantic and Central Indo-Pacific realms. Richness varied with scale, with the highest values in the transition between the tropical and subtropical zones. Bathymetry was associated with Lysmatidae richness across all scales, especially at local and ecoregional scales, while coral richness was related to province and realm scales. HHH explained Lysmatidae richness patterns at the realm scale. Variables related to PSH and AIH were associated with richness at the ecoregion and province scales. Our study emphasized the importance of scale in biodiversity research, influencing richness patterns in Lysmatidae, and pointed to bathymetry, coral richness, and temperature range as the main drivers of richness. As this study showed a relationship between Lysmatidae richness, coral richness, and temperature at 3 spatial scales, this family may be susceptible to the effects of climate change, such as tropicalization of subtropical zones and defaunation of tropical ecosystems, including coral reefs.

Spatial pattern of woody plant species richness and composition in primary warm temperate evergreen forest in Kasugayama Hill, Japan

Plant species richness and composition are influenced by complex interactions between biotic and abiotic factors that operate on different spatial scales. Since spatial scales vary continuously in nature, it is expected that multiple factors simultaneously affect species richness and composition at an intermediate spatial scale (i.e., the mesoscale landscape level). Previous studies have shown that local topography and elevation are important factors for shaping intermediate spatial scale plant species richness; however, the relative importance of these factors has rarely been examined. Here, we used spatially explicit woody plant data to examine the factors that characterize the spatial pattern of primary evergreen forest biodiversity at the intermediate spatial scale. We found that the spatial pattern of species diversity in a predominantly warm temperate evergreen forest at the landscape level is mainly characterized by shifts in species composition along the elevation gradient. Our study also found that compositional shift along the elevational gradient was mainly caused by habitat specialization among congeneric species, suggesting that niche partitioning among closely-related species is a fundamentally important feature of the intermediate spatial scale species richness pattern. Furthermore, we found that specialization in a habitat of closely-related species can be established even within a limited environmental gradient. This suggests that biotic interactions among closely-related species may be an important factor driving habitat specialization, and biotic interactions may play an important role in shaping landscape-scale biodiversity patterns.

Elevational patterns of species richness and phylogenetic diversity in a Mediterranean island

Understanding the abiotic factors influencing biodiversity patterns on Earth is a crucial task for conservation scientists. At the regional level, meso-climate factors, primarily associated with elevational gradients, are of great importance. However, disentangling these factors can be challenging due to the influence of other variables, such as geological substrata. To address this issue and better understand elevational gradients, it is essential to study geologically homogeneous terrains, particularly in Mediterranean islands where such research is lacking. In this study, we investigated the distribution of plant species richness along the elevational gradient of the Limbara massif, which consists predominantly of granite rocks and ranks as the third-highest peak in Sardinia at 1,359 meters a.s.l. We employed generalized linear models to analyze richness patterns, considering various factors, including all plant species, functional species groups categorized by Raunkiær life forms, chorological groups of species, alien species and phylogenetic diversity. Our findings revealed a hump-shaped model of species richness along the elevational gradient, with lower elevations exhibiting the highest species richness. Additionally, endemic species richness increased with higher elevations, while alien species were predominantly found at lower elevations. These results indicate that the Limbara massif possesses a significant elevational gradient in species composition, likely reflecting a unique plant evolutionary history. Furthermore, we emphasize the importance of published floras as valuable sources of biodiversity data for such studies.

Spatial patterns of vascular plant species richness in Poland: Relations among species group richness and hot spot distribution

Knowledge of spatial patterns of species richness (SR) is highly relevant for theoretical research in ecology and the development of conservation plans. In Poland, despite a long tradition of botanical surveys, vascular plant SR has not been mapped, nor have the correlations in richness among different plant species groups been explored at the entire country scale. Here, we used a recently published data set to examine spatial patterns and relationships among the joined SR of vascular plant species, including native species, archaeophytes, neophytes, and species with high conservation value (i.e., red-list species). The basic spatial unit employed was a 10 × 10 km grid from the Atlas of Distribution of Vascular Plants in Poland (ATPOL). We found that SR of native species and archaeophytes, neophytes, and red-list species were positively correlated. The main patterns of SR and the percentage of particular groups in the joined SR were based on three components: (1) gradient of overall SR, (2) invasion level, and (3) peculiarity of flora in some regions resulting from the high number and proportion of rare species that often have high conservation value (red-list species). In general, northeastern Poland was species-poor, while the Carpathian Mountain range, the uplands in southern Poland, and some parts of Wisła River valley had the highest SR concentrations. e location of SR hotspots usually did not overlap with the existing national parks system. The correlations among native SR, high conservation value species, and neophyte SR suggest that biological invasions are among the most important threats to vascular plant diversity in Poland. Finally, despite likely biases in SR assessments, we demonstrated that the presented maps seem to reflect general ecological gradients influencing vascular plant distribution in Poland.

Climate Futures for Lizards and Snakes in Western North America May Result in New Species Management Issues.

We assessed changes in fundamental climate-niche space for lizard and snake species in western North America under modeled climate scenarios to inform natural resource managers of possible shifts in species distributions. We generated eight distribution models for each of 130 snake and lizard species in western North America under six time-by-climate scenarios. We combined the highest-performing models per species into a single ensemble model for each scenario. Maps were generated from the ensemble models to depict climate-niche space for each species and scenario. Patterns of species richness based on climate suitability and niche shifts were calculated from the projections at the scale of the entire study area and individual states and provinces, from Canada to Mexico. Squamate species' climate-niche space for the recent-time climate scenario and published known ranges were highly correlated (r = 0.81). Overall, reptile climate-niche space was projected to move northward in the future. Sixty-eight percent of species were projected to expand their current climate-niche space rather than to shift, contract, or remain stable. Only 8.5% of species were projected to lose climate-niche space in the future, and these species primarily occurred in Mexico and the southwestern U.S. We found few species were projected to lose all suitable climate-niche space at the state or province level, although species were often predicted to occupy novel areas, such as at higher elevations. Most squamate species were projected to increase their climate-niche space in future climate scenarios. As climate niches move northward, species are predicted to cross administrative borders, resulting in novel conservation issues for local landowners and natural resource agencies. However, information on species dispersal abilities, landscape connectivity, biophysical tolerances, and habitat suitability is needed to contextualize predictions relative to realized future niche expansions.

A Novel Web-Based Approach for Monitoring Biodiversity.

Understanding complexities in biodiversity is one of the fundamental goals of ecology and its monitoring is significant for ecosystem sustainability, maintenance, and conservation. However, biodiversity monitoring needs improvement to handle complex datasets and their analyses. This study attempts to understand these ecological complexities quickly, efficiently, and easily. The aim is to provide an alternative to ecologists, researchers, instructors, and stakeholders for biodiversity monitoring with the flexibility to visualize and customize outputs without software knowledge. A novel web-based technique is applied to monitor the biodiversity of a complex mountain ecosystem using a national database. The species-environment relationships of different vegetation types across a mountain ecosystem's elevation gradient are investigated using open-source climatic, physiographic, and socioeconomic variables. The proposed interactive tool to monitor biodiversity and understand its complexities is designed to visualize the data structure, summary, correlations, and sampling effectiveness quickly and easily. Plant species richness patterns and life forms (herb, shrub, and tree) across elevational gradients are investigated. We highlight the preliminary investigation of the data structure and their spatial distribution and apply the multicollinearity test to select variables for modeling. The drop-down menu helps users browse different datasets and select those datasets for instant visualization. Preliminary investigations on interactions between variables and species richness of vegetation types along elevation gradient interactively displayed with options to select variables, plant richness, and an elevational range. Species-environment relationships are investigated using multiple modeling protocols, and results are interactively displayed with options to download in different file formats and colors at the click of a button. This visualization tool helps to understand ecosystem structure, species richness patterns and species-environment relationships easily and efficiently. The R-codes used in this tool are reproducible and can be implemented with multiple datasets to monitor ecosystems.

Seasonal changes in altitudinal patterns of bird species richness in a temperate low-elevation mountain

Mountain environments change rapidly over short distances along altitudinal gradients, providing an ideal system for exploring the mechanisms that shape biodiversity gradients. Species richness is the most studied diversity metric in mountains, and altitudinal patterns and their shaping mechanisms have been investigated worldwide. Although the altitudinal patterns of species richness in breeding bird assemblages have been extensively studied, less attention has been paid to seasonal changes in patterns between winter and summer. Furthermore, the effects of severe climate in high-elevation areas on seasonal changes in the altitudinal pattern of species richness in insular mountains remain unclear. We investigated changes in the pattern between the breeding and wintering seasons using field and literature surveys in Mount Tsukuba (877 m a.s.l.), central Japan. Temperatures at the middle elevations of the slope are relatively higher than those at the foot of the mountain in winter. The mountain is covered with forests up to its summit. We found that the altitudinal pattern of species richness was the low-plateau during the wintering season. Low-elevation areas were havens for wintering species, whereas high-elevation areas were impoverished in wintering species. Conversely, there was no association between elevation and species richness during the breeding season. Our study suggests that the relaxation of severe climates in high-elevation areas during winter and verdant forests in the highlands during summer are critical mechanisms driving seasonal changes in the altitudinal pattern of species richness. Furthermore, we highlight that comprehensive monitoring, including wintering seasons, is essential for detecting the changes in the diversity patterns of mountain bird assemblages due to the shift in the peak of wintering species richness under ongoing climate change.

Structure of Reef Fish Families (Butterflyfishes and Angelfishes) at Isolated Oceanic Reefs in the Indian Ocean: Christmas Island and the Cocos (Keeling) Islands

There has been substantial research on the factors that structure reef fish assemblages, but this has mostly focused on nearshore or continental reefs. This study examines patterns of abundance and species composition for two iconic groups of coral reef fishes, angelfishes (family Pomacanthidae) and butterflyfishes (family Chaetodontidae) at two isolated, oceanic reefs in the Indian Ocean: Christmas Island and the Cocos (Keeling) Islands. Six explanatory variables were investigated to determine whether large-scale physical factors are more important than fine-scale biotic factors in structuring reef fish communities on oceanic islands. For angelfishes, depth was the factor that most explained patterns in abundance (explaining 46.5% of the variation), species richness (44.8%) and composition (15.3%), with both abundance and species richness being greater at 20 m than at 5 m. Differences in species composition were greater between depths than between islands. For butterflyfishes, variation in abundance and species richness was best explained by the difference in aspect or exposure among sites, though abundance and composition also differed significantly between Christmas Island and the Cocos (Keeling) Islands. Large-scale variation in the structure of these reef fish assemblages could not be explained based on differences in habitat diversity, or coral and algal cover. This study indicates that large-scale physical factors (island location, exposure, depth) are more important than fine-scale biotic factors in structuring reef fish assemblages on oceanic islands.

Diversity pattern of Symplocos tree species in China under climate change scenarios: Toward conservation planning

Symplocos, a genus rich in endemic and keystone species in China's subtropical forests, plays a vital role in maintaining biodiversity. Climate change impacts on Symplocos trees affect ecosystem composition, dynamics, and functions. This study delves into the potential ramifications of climate change on the distribution and richness of Symplocos species across China under different climatic conditions. A comprehensive analysis was conducted using occurrence records of 29 species of Symplocos, focusing on habitat suitability modeling and spatial analysis, to demonstrate the possible effects of climate change on the distribution and diversity patterns of Symplocos species in China. Environmental data, including bioclimatic variables, were collected, and the future climate scenarios were projected using the combined average of the two global climate models. Four modeling algorithms were applied in an ensemble species distribution models to assess the distribution of Symplocos species and decipher the pattern of species richness and endemism. The results indicate high accuracy and performance of the models with a mean AUC of 0.94 and TSS of 0.77, particularly the random forest. The analysis identified key bioclimatic variables influencing Symplocos species distribution, with precipitation patterns (precipitation of driest month and precipitation of warmest quarter) and temperature variability (temperature mean diurnal range) playing significant roles. Predictions suggest a reduction in Symplocos species richness over the next six decades, particularly in southern and southwestern China, with potential gains in other regions. Overall, this study highlights the vulnerability of Symplocos species to climate change and underscores the importance of proactive conservation efforts and forest plantations to mitigate future loss in Symplocos species diversity.

Patterns of Species Richness and Its Endemism of Beetles in the Beijing–Tianjin–Hebei Region of China

The Beijing–Tianjin–Hebei region lies between the Mongolia-Xinjiang Zoogeographic Region and the Central China Zoogeographic Region in China, harboring relatively rich biodiversity. This study specifically examined the species diversity, richness and endemic areas of beetles in this area. By analyzing 5965 detailed distribution records of 2047 beetle species in the Beijing–Tianjin–Hebei region, the species richness maps were created with a grid size of 0.5°. Additionally, two methods, parsimony analysis of endemism (PAE) and endemicity analysis (EA) were applied to detect areas of endemism (AOEs) with different grid sizes (0.1°, 0.25° and 0.5°), resulting in the identification of three AOEs in the southern mountainous areas of the Taihang Mountains, Yanshan Mountains, and Xiaowutai Mountains. It also verified that AOEs are consistent with the hypothesis that endemic areas are predominantly located in mountain ranges, as proposed by previous related studies. These findings highlight the importance of complex topography and stable climate in shaping AOEs and conserving biodiversity.

Effects of the interaction between Linnean and Darwinian shortfalls on diversification gradients

It is now widely recognized that broad-scale patterns in species richness, particularly the Latitudinal Diversity Gradients (LDGs), are driven by complex interactions among ecological, evolutionary, and historical processes. However, even if it is now possible to better evaluate evolutionary explanations for LDGs based on speciation and diversification rates estimated from phylogenies, a subtle interaction between such estimates and the geographic structure of the Linnean shortfall, forming the Latitudinal Taxonomy Gradient (LTG), was recently recognized. Here, we expand on previous simulation results and show that a relatively small geographical bias in the Linnean shortfall, adding less than 20% of new species phylogenetically correlated with previously described ones in the southern (richer) region, would be enough to change the patterns in diversification rates, based on different methods (tip rates DR and GeoSSE). Further investigations of the magnitude of LTG and new empirical modeling of problems in species delimitation are thus necessary to evaluate the robustness of the estimates of the diversification gradients to biased knowledge and taxonomic uncertainty, allowing a better understanding of the evolutionary dynamics underlying LDGs. Geographical patterns in the Linnean shortfall, creating Latitudinal Taxonomy Gradients (LTGs), may jeopardize robust estimates of diversification gradients and our understanding of processes underlying diversity patterns. Simulations show that a relatively small geographic bias in the Linnean shortfall, adding new undiscovered species phylogenetically close to the known ones, is sufficient to invert patterns in diversification rates estimated by two distinct methods. A more comprehensive assessment of the magnitude of diversification gradients in respect to the LTGs is necessary to evaluate the robustness of our understanding of LDGs. Empirical modeling of species delimitation quality and simulations adding small branches in the phylogenies, mitigating simultaneously both Linnean and Darwinian shortfalls, may provide more consistent evidence for drivers of LDGs accounting for taxonomic uncertainty.

Accumulation of pathogens in soil microbiome can explain long-term fluctuations of legumes in a grassland community.

All plant populations fluctuate in time. Apart from the dynamics imposed by external forces such as climate, these fluctuations can be driven by endogenous processes taking place within the community. In this study, we aimed to identify potential role of soil-borne microbial communities in driving endogenous fluctuations of plant populations. We combined a unique, 35-yr long abundance data of 11 common plant species from a species-rich mountain meadow with development of their soil microbiome (pathogenic fungi, arbuscular mycorrhizal fungi and oomycetes) observed during 4 yr of experimental cultivation in monocultures. Plant species which abundance fluctuated highly in the field (particularly legumes) accumulated plant pathogens in their soil mycobiome. We also identified increasing proportion of mycoparasitic fungi under highly fluctuating legume species, which may indicate an adaptation of these species to mitigate the detrimental effects of pathogens. Our study documented that long-term fluctuations in the abundance of plant species in grassland communities can be explained by the accumulation of plant pathogens in plant-soil microbiome. By contrast, we found little evidence of the role of mutualists in plant population fluctuations. These findings offer new insights for understanding mechanisms driving both long-term vegetation dynamics and patterns of species coexistence and richness.

A decadal-scale qualitative comparison of lotic Odonata nymph surveys in northwestern Pennsylvania, USA, reveals possible assemblage restructuring

Detecting long-term changes to Odonata assemblages requires repeated sampling at fixed locations over decadal periods. However, few such biomonitoring efforts exist for Odonata, especially at low taxonomic resolution and immature life stages. We repeated a survey of Odonata nymphs conducted nearly thirty years ago in ten streams from a northern Pennsylvania forest reserve to qualitatively explore assemblage-scale changes and identify streams supporting species of conservation concern. Our survey collected five more species among all sites than the original survey, reflecting a 15% increase in richness despite a reduced sampling effort. Rank abundances of many species changed substantially between surveys. Some, such as Calopteryx maculata, fell in rank while other species like Boyeria vinosa and Phanogomphus lividus that were rare in 1994 became the most numerically dominant. We did not detect patterns in species richness or changes in richness between surveys along gradients of unconventional natural gas extraction or timber harvest among streams. The fraction of species deemed vulnerable or imperiled within Pennsylvania grew from 22 to 38% between surveys, highlighting the regional conservation value of protected area we sampled. Our sampling methodology precludes population estimates or quantitative community comparisons due to the sampling design and inconsistencies in the literature used for identification between surveys. However, the substantial differences in rank-abundance among species between surveys suggests potential long-term changes in these lotic Odonata assemblages. The collective findings presented here emphasize the high value of data from repeated surveys with species-level taxonomic resolution.

Island area and diet predict diversity and distribution of bats in a Pacific Northwest archipelago

Abstract The island biogeography theory predicts that species richness in islands and island-like systems is the ultimate result of island isolation and area. Species with high dispersal capabilities are predicted to be less affected by these factors because of their capacity to move more efficiently between islands or habitats, and here we test this idea in bats, the only mammals capable of flight. We conducted mist net and acoustic surveys across 21 islands in the San Juan Archipelago (Washington State, United States) and adjacent northwest mainland to: (i) investigate the effects of island area, distance from mainland, and habitat on bat diversity; and (ii) evaluate whether differences in morphological (body mass, forearm length, wing loading) and ecological (dietary niche breadth, foraging guild) traits among species influence their prevalence across islands. We found that island size strongly influenced patterns of species richness, with larger islands having a greater number of bat species. However, neither island distance from mainland nor any measure of habitat availability was a significant predictor of species richness at the scale of this study. Additionally, we found that dietary niche breadth, as opposed to any morphological trait, best predicted the prevalence of species across the islands. Our results suggest that species with more specialized diets may be more vulnerable to habitat fragmentation, and provide insight into how geographic and ecological factors affect the diversity of insular bat communities, adding to growing knowledge about the role of species traits as mediators of their responses to large-scale landscape structure.

Airborne DNA reveals predictable spatial and seasonal dynamics of fungi

Fungi are among the most diverse and ecologically important kingdoms in life. However, the distributional ranges of fungi remain largely unknown as do the ecological mechanisms that shape their distributions1,2. To provide an integrated view of the spatial and seasonal dynamics of fungi, we implemented a globally distributed standardized aerial sampling of fungal spores3. The vast majority of operational taxonomic units were detected within only one climatic zone, and the spatiotemporal patterns of species richness and community composition were mostly explained by annual mean air temperature. Tropical regions hosted the highest fungal diversity except for lichenized, ericoid mycorrhizal and ectomycorrhizal fungi, which reached their peak diversity in temperate regions. The sensitivity in climatic responses was associated with phylogenetic relatedness, suggesting that large-scale distributions of some fungal groups are partially constrained by their ancestral niche. There was a strong phylogenetic signal in seasonal sensitivity, suggesting that some groups of fungi have retained their ancestral trait of sporulating for only a short period. Overall, our results show that the hyperdiverse kingdom of fungi follows globally highly predictable spatial and temporal dynamics, with seasonality in both species richness and community composition increasing with latitude. Our study reports patterns resembling those described for other major groups of organisms, thus making a major contribution to the long-standing debate on whether organisms with a microbial lifestyle follow the global biodiversity paradigms known for macroorganisms4,5.

The Effects of Climate Change on the Distribution Pattern of Species Richness of Endemic Wetland Plants in the Qinghai-Tibet Plateau.

Wetland ecosystems in the Qinghai-Tibet Plateau (QTP), the region with the richest biodiversity and the most important ecological barrier function at high altitudes, are highly sensitive to global change, and wetland plants, which are important indicators of wetland ecosystem structure and function, are also threatened by wetland degradation. Therefore, a comprehensive study of changes in the geographical distribution pattern of plant diversity, as well as species loss and turnover of wetlands in the QTP in the context of global climate change is of great importance for the conservation and restoration of wetland ecosystems in the QTP. In this study, species turnover and loss of 395 endemic wetland plants of the QTP were predicted based on the SSP2-4.5 climate change scenarios. The results showed that there were interspecific differences in the effects of climate change on the potential distribution of species, and that most endemic wetland plants would experience range contraction. Under the climate change scenarios, the loss of suitable wetland plant habitat is expected to occur mainly in parts of the southern, north-central and north-western parts of the plateau, while the gain is mainly concentrated in parts of the western Sichuan Plateau, the Qilian Mountains, the Three Rivers Source Region and the northern Tibetan Plateau. Overlaying the analysis of priority protected areas with the established protected areas in the QTP has resulted in the following conservation gaps: the eastern Himalayan region, midstream of the Yarlung Zangbo River, the transition zone between the northern Tibetan Plateau and the Hengduan Mountains, Minshan-Qionglai mountain, Anyemaqen Mountains (southeast) to Bayankala (southeast) mountains, the southern foothills of the Qilian Mountains and the northern Tibetan Plateau region. In the future, the study of wetland plant diversity in the QTP and the optimisation of protected areas should focus on the conservation gaps. This study is of great importance for the study and conservation of wetland plant diversity in the QTP, and also provides a scientific basis for predicting the response of wetland plants to climate change in the QTP.

Knowledge shortfalls and the effect of wildfires on biodiversity conservation in Guanajuato, Mexico

Knowledge of shortfalls could modify the geographic distribution patterns and limit the actions to conserve the biodiversity, even in the taxa best known. In addition, forest fires also could modify those patterns, but the potential effects of both factors have not been tested. Our aim was to analyze the effect of the Linnean and Wallacean shortfalls in the first evaluation of wildfire impacts on 22 amphibian and 13 mammal species distributed in Guanajuato, Mexico. We evaluated those shortfalls using the non-parametric estimator Chao2 and the Qs estimator and through maps of species richness patterns. To evaluate the effects of wildfires, we produced a fire recurrence map and quantified the burned area within species distributions and in 24 Protected Natural Areas (PNA) in the state. The Linnean shortfall showed some species missing to record in Guanajuato for both taxa, while the Wallacean shortfall showed poor quality of knowledge. Fire recurrence was high within 5 PNA. The richness patterns affected by fires covered nearly 17% of the surface of Guanajuato. Improving the knowledge of biogeographical patterns could provide better tools to stakeholders to decrease the negative impact of fires within PNA.

Historical and contemporary climate jointly determine angiosperm plant diversity patterns across east Eurasia

Mechanisms underlying large‐scale spatial patterns of species richness are one of the central issues in ecology. Although contemporary climate, evolutionary history, and historical climate change have been proposed as drivers of species richness patterns, variation in the relative importance of different factors remains a major challenge. Here, using newly compiled distribution data with a spatial resolution of 100 × 100 km for 43 023 angiosperms plant species in east Eurasia, we mapped species richness patterns for plants with different growth forms (i.e. woody versus herbaceous) and range sizes (i.e. wide‐ranged versus narrow‐ranged species), and compared the relative importance of the four hypotheses in explaining these patterns, i.e. freezing tolerance hypothesis, historical climate change hypothesis, Janzen's hypothesis (predicting that climate seasonality and topography determine species richness patterns), and diversification rate hypothesis. We found that species richness of all angiosperm plants presented a clear latitudinal gradient and was highest in southwestern China and Central Asian mountains. Notably, species richness patterns and their dominant drivers differed between species groups. Historical climate change was the dominant driver for richness patterns of all and herbaceous species. The freezing tolerance hypothesis dominated the drivers for all woody species, while Janzen's hypothesis dominated narrow‐ranged woody and herbaceous species. Our study suggests that different hypotheses contribute to large‐scale plant richness patterns via their effects on different plant groups. Our results did not support the diversification rate hypothesis, but demonstrated the high importance of historical climate change to plant diversity in east Eurasia, providing new perspectives on the mechanisms of plant diversity patterns in this continent.

Diversification in birds is promoted by plant diversity, topographic heterogeneity and stable paleoclimate

AbstractAimsLong‐term climate stability, contemporary climate and environmental heterogeneity have been linked to bird diversity patterns through their direct impacts on diversification rate, as well as through their indirect effects on plant species richness, which could also directly and indirectly affect bird diversity. This study aimed to quantitatively assess whether these potential drivers could indirectly affect bird species richness through their direct effects on the diversification rate in birds in eastern Asia.LocationMainland China.TaxonBirds.MethodsUsing the distribution data of 1127 bird species across 320 prefecture cities in China and a phylogenetic tree of these bird species, we analysed the distribution patterns of bird species richness and diversification rate of all birds, passerine birds and non‐passerine birds, respectively. We also investigated their relationships with long‐term climate stability, contemporary climate, elevation range and plant diversity using ordinary least squares regression model and simultaneous autoregressive model. In addition, structural equation model was used to analyse whether these drivers could indirectly affect bird species richness through their direct effects on bird diversification rate.ResultsThe results showed that bird species richness and diversification rate were highest in southwestern China. Additionally, diversification rate for passerine birds was higher than non‐passerine birds and all birds. Regression analyses revealed that plant species richness was the variable most associated with bird species richness and diversification rate across the three groups. Notably, results from structural equation model indicated that plant species richness, elevation range and glacial–interglacial climate change can indirectly influence bird species richness by directly affecting diversification rates.Main ConclusionsThese findings emphasize the importance of considering diversification rate when understanding the geographic distribution patterns of bird diversity. The direct and indirect effects of plant species richness, elevation range and glacial–interglacial climate change on bird diversity highlight the crucial role of mountain regions with higher plant diversity and stable paleoclimate in forming and maintaining biodiversity.

Current and future patterns of vascular plant species richness across a forest–grassland–desert transect in East Asia

AbstractQuestionsRapid climate change has profoundly altered the spatial distribution of terrestrial plants especially in arid and semi‐arid biomes. However, it remains poorly documented how climate shapes the current and future patterns of plant diversity within and across these vulnerable vegetation types.LocationParts of Mongolia, southeastern Russia, and northern China (94.78°–126.78°E, 34.60°–54.27°N).MethodsUsing a random forest model trained by a comprehensively compiled database on vascular plant species richness (i.e., the number of species within a defined plot area) and corresponding climate variables, soil conditions and vegetation types (forest, grassland, desert), we assessed the current pattern of vascular plant species richness across a typical forest–grassland–desert transect in East Asia. We further predicted future changes in vascular plant species richness under three climate scenarios (SSP1‐2.6, SSP3‐7.0, and SSP5‐8.5).ResultsVascular plant species richness generally showed a decrease from northeast to southwest across the transect, mainly explained by spatial variations in growing‐season precipitation and the minimum temperature of the coldest month. More than half of the transect area will likely experience a loss in vascular plant species richness in 2041–2070 under all three scenarios. The decrease in vascular plant species richness will likely occur in a smaller area under the low‐emission scenario (SSP1‐2.6). We also predict distinct changes in vascular plant species richness for different vegetation types, including a slight increase in forests but an overall decrease in both grasslands and deserts.ConclusionsOur findings suggest a dominant role of growing‐season precipitation in shaping the spatiotemporal patterns of vascular plant species richness across the forest–grassland–desert transect and highlight a risk of plant diversity loss in the regional dryland ecosystems in response to future climate change.