Altitude acts as an environmental filter on phylogenetic composition, traits and diversity in bee communities

Wild Bee Diversity and Bee-Plant Interactions in Tropical and Temperate Forest Clearings in a Natural Protected Area in Central West Mexico

BACKGROUND

Bees rely on plants for nutrition and reproduction, making the preservation of natural areas crucial as pollinator reservoirs. Seasonal tropical dry forests are among the richest habitats for bees, but only 27% of their original extent remains in Mexico. In contrast, temperate forests harbor fewer bee species and face high deforestation rates, with 40% of their area converted to other land uses. This study aimed to estimate the α and β diversities of wild bees and compare bee-plant interaction networks between these two vegetation types.

METHODS

Wild bees and their interactions with plants were monitored for one year in four sites within the Área de Protección de Flora y Fauna Sierra de Quila. Two sites corresponded to seasonal tropical dry forest and two to temperate forest. α and β diversity, connectance, nestedness, web asymmetry, and niche overlap were analyzed.

RESULTS

Sierra de Quila harbors high bee diversity, with 155 species in tropical dry forest and 103 in temperate forest. Species turnover between vegetation types was high, although nine species used floral resources in both forests, connecting the interaction networks.

CONCLUSIONS

Sierra de Quila diverse habitats promote high bee diversity, with niche partitioning and low connectance facilitating coexistence across different vegetation types.

Strong habitat and seasonal phenology effects on the evolution of self-compatibility, clonality and pollinator shifts in Lachenalia (Asparagaceae: Scilloideae)

Plants employ a diversity of reproductive safeguarding strategies to circumvent the challenge of pollen limitation. Focusing on southern African Lachenalia (Asparagaceae: Scilloideae), we test the hypothesis that the evolution of reproductive safeguarding traits (self-compatibility, autonomous selfing, bird pollination and clonal propagation) is favoured in species occupying conditions of low insect abundance imposed by critically infertile fynbos heathland vegetation and by flowering outside the austral spring insect abundance peak. We trace the evolution of these traits and selective regimes on a dated, multi-locus phylogeny of Lachenalia and assess their evolutionary associations using ordinary and phylogenetic regression. Ancestral state reconstructions identify an association with non-fynbos vegetation and spring flowering as ancestral in Lachenalia, the transition to fynbos vegetation and non-spring flowering taking place multiple times. They also show that self-compatibility, autofertility, bird pollination and production of multiple clonal offsets have evolved repeatedly. Regression models suggest that bird pollination and self-compatibility are selected for in fynbos and in non-spring flowering lineages, with autofertility being positively associated with non-spring flowering. These patterns support the interpretation of these traits as reproductive safeguarding adaptations under reduced insect pollinator abundance. We find no evidence to support the interpretation of clonal propagation as a reproductive safeguarding strategy.

Elevation and Human Disturbance Interactively Influence the Patterns of Insect Diversity on the Southeastern Periphery of the Tibetan Plateau

The maintenance of biodiversity and ecological balance heavily relies on the diversity of insects. In order to investigate the impacts of elevation and human disturbance, as well as their interactions on insect diversity, we conducted an intensive survey of insects in the Hengduan Mountain Range, which is situated on the southeastern periphery of the Tibetan Plateau in China. A total of 50 line transects were established in this study to investigate the impact of elevation and human disturbance on insect diversity and distribution patterns. Designed insect surveys were conducted at various elevations and levels of human disturbance, and statistical methods such as generalized linear modeling and redundancy analysis were employed for data analysis. The results of this study indicated a negative correlation between insect diversity and elevation. Additionally, moderate disturbance was found to have a positive impact on insect diversity to some extent. The explanatory power of the model for the distribution of insect diversity could be improved if elevation and human disturbance were included as an interaction effect into the model, and there were differences in the effects of human disturbances on insect diversity at different elevation levels. The highest insect diversity was observed under low disturbance conditions below elevation of ~2200 m, whereas above this threshold, insect diversity was the highest under moderate disturbance compared to low disturbance. The response of different insect taxa to the interactions of elevation and human disturbance varied. The findings imply that when formulating strategies for managing insect diversity, it is crucial to thoroughly consider the interaction of environmental factors and disturbance response of individual insect taxa.

Floral and pollinator functional diversity mediate network structure along an elevational gradient

Elevational gradients in alpine ecosystems are well suited to study how plant and pollinator communities respond to climate change. In the Austrian Alps, we tested how the taxonomic and functional diversity of plants and their pollinators change with increasing elevation and how this affects plant-pollinator network structure. We measured the phenotypes of flowering plants and their pollinators and observed their interactions in 24 communities along an elevational gradient. To assess variation in floral and pollinator traits, we then quantified trait spaces (n-dimensional hypervolumes) occupied by flowers and pollinators in each community. To assess plant-pollinator network structure, we quantified the levels of complementary specialization (H2'), modularity and nestedness (weighted NODF) for each community. As elevation increased, most measures of diversity and network specialization either declined linearly or in an oscillating manner. Communities that exhibited higher pollinator functional diversity exhibited larger degrees of complementary specialization and modularity; and communities with greater floral and pollinator functional diversity and higher phylogenetic diversity were less nested. Altogether, the degree to which elevation, species diversity, functional diversity and network structure changed in conjunction suggests environmental effects on the functional and phylogenetic diversity of plants and pollinators and consequently network structure. Our results suggest that the effects of climate change on plant and pollinator community composition will impact plant-pollinator network structure and potentially pollination services at the community scale.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00035-024-00308-w.

The Megachilidae (Hymenoptera, Apoidea, Apiformes) of the Democratic Republic of Congo curated at the Royal Museum for Central Africa (RMCA, Belgium)

Natural history collections are a cornerstone of entomology, and the conservation of specimens is the essential prerequisite for the development of research into systematics, biogeography, ecology, evolution and other disciplines. Yet, specimens collected during decades of entomological research conducted in less developed countries across Sub-Saharan Africa on pests, beneficial insects and insect biodiversity in general have largely been exported to be permanently preserved in developed countries, mainly in Europe and the United States of America. This is particularly true for the Democratic Republic of the Congos (DRC) diverse wild bee fauna, which has been investigated throughout the colonial period by visiting or resident entomologists and missionaries who have then transferred their collected material primarily to Belgium as part of a wider legacy of scientific exploration and colonialism. Digitizing NHC is one way to mitigate this current bias, by making samples accessible to researchers from the target post-colonial countries as well as to the wider international scientific community. In this study, we compiled and digitized 6,490 specimens records relevant to 195 wild bee species grouped in 18 genera within the biodiverse family Megachilidae, essentially from the colonial era (i.e., mostly between 19051960, with additional records up to 1978), and curated at the Royal Museum for Central Africa in Belgium. We provide a detailed catalogue of all records with updated locality and province names, including 29 species only available as type specimens. We also explore the historical patterns of diversity and distribution across DRC, and we provide a list of the research entomologists involved. This study is an important first step that uses digital technologies to democratize and repatriate important aspects of DRCs natural heritage of insect biodiversity, to stimulate more contemporary field surveys and modern taxonomic revisions, as well as to identify and characterize research gaps and biodiversity shortfalls in some of the less-explored regions of Sub-Saharan Africa.

Inferring the ecological and evolutionary determinants of community genetic diversity

Understanding the relative contributions of ecological and evolutionary processes to the structuring of ecological communities is needed to improve our ability to predict how communities may respond to future changes in an increasingly human-modified world. Metabarcoding methods make it possible to gather population genetic data for all species within a community, unlocking a new axis of data to potentially unveil the origins and maintenance of biodiversity at local scales. Here, we present a new eco-evolutionary simulation model for investigating community assembly dynamics using metabarcoding data. The model makes joint predictions of species abundance, genetic variation, trait distributions and phylogenetic relationships under a wide range of parameter settings (e.g. high speciation/low dispersal or vice versa) and across a range of community states, from pristine and unmodified to heavily disturbed. We first demonstrate that parameters governing metacommunity and local community processes leave detectable signatures in simulated biodiversity data axes. Next, using a simulation-based machine learning approach we show that neutral and non-neutral models are distinguishable and that reasonable estimates of several model parameters within the local community can be obtained using only community-scale genetic data, while phylogenetic information is required to estimate those describing metacommunity dynamics. Finally, we apply the model to soil microarthropod metabarcoding data from the Troodos mountains of Cyprus, where we find that communities in widespread forest habitats are structured by neutral processes, while high-elevation and isolated habitats act as an abiotic filter generating non-neutral community structure. We implement our model within the ibiogen R package, a package dedicated to the investigation of island, and more generally community-scale, biodiversity using community-scale genetic data.

Community metabarcoding reveals the relative role of environmental filtering and spatial processes in metacommunity dynamics of soil microarthropods across a mosaic of montane forests

Disentangling the relative role of environmental filtering and spatial processes in driving metacommunity structure across mountainous regions remains challenging, as the way we quantify spatial connectivity in topographically and environmentally heterogeneous landscapes can influence our perception of which process predominates. More empirical data sets are required to account for taxon- and context-dependency, but relevant research in understudied areas is often compromised by the taxonomic impediment. Here we used haplotype-level community DNA metabarcoding, enabled by stringent filtering of amplicon sequence variants (ASVs), to characterize metacommunity structure of soil microarthropod assemblages across a mosaic of five forest habitats on the Troodos mountain range in Cyprus. We found similar β diversity patterns at ASV and species (OTU, operational taxonomic unit) levels, which pointed to a primary role of habitat filtering resulting in the existence of largely distinct metacommunities linked to different forest types. Within-habitat turnover was correlated to topoclimatic heterogeneity, again emphasizing the role of environmental filtering. However, when integrating landscape matrix information for the highly fragmented Quercus alnifolia habitat, we also detected a major role of spatial isolation determined by patch connectivity, indicating that stochastic and niche-based processes synergistically govern community assembly. Alpha diversity patterns varied between ASV and OTU levels, with OTU richness decreasing with elevation and ASV richness following a longitudinal gradient, potentially reflecting a decline of genetic diversity eastwards due to historical pressures. Our study demonstrates the utility of haplotype-level community metabarcoding for characterizing metacommunity structure of complex assemblages and improving our understanding of biodiversity dynamics across mountainous landscapes worldwide.

DNA-based networks reveal the ecological determinants of plant-herbivore interactions along environmental gradients

Understanding the ecological rules structuring the organization of species interactions is a prerequisite to predicting how ecosystems respond to environmental changes. While the ecological determinants of single networks have been documented, it remains unclear whether network ecological rules are conserved along spatial and environmental gradients. To address this gap, we reconstructed 48 plant-herbivore interaction networks along six elevation gradients in the Central European Alps in Switzerland, using DNA metabarcoding on orthoptera faeces. We developed hypotheses on the ecological mechanisms expected to structure interaction networks, based on plant phylogeny, plant abundance, leaf toughness, leaf nitrogen content and plant metabolomics. We show that plant phylogenetic relationships and species abundance have the greatest explanatory power regarding the structure of the ecological networks. Moreover, we found that leaf nitrogen content is a key determinant of interactions in warmer environments, while phenolic compounds and tannins are more important in colder environments, suggesting that determinants of species interactions can shift along environmental gradients. With this work, we propose an approach to study the mechanisms that structure the way species interact with each other between bioregions and ecosystems.

Effects of ENSO events on the intensity, seasonality, and diversity of reproductive phenology of Miconia (Melastomataceae) species in tropical rainforest

We evaluated the phenology and reproductive phenological diversity of three sympatric species of Miconia in a gallery forest in the Chapada Diamantina mountains, Bahia, Brazil. The reproductive phenophases (bud, flower, immature fruit, and mature fruit) of M. alborufescens (N=38), M. holosericea (N=46), and M. prasina (N=44) were evaluated monthly, between June/2008 and June/2015. The Fournier index was used to assess the intensities of the reproductive phenophases; synchrony and seasonality were analyzed using circular statistics and the Rayleigh (Z) test. The Frideman and Wilcoxon tests were used to verify interannual variations in phenological patterns. Reproductive phenological diversity was measured by calculating the Shannon-Wiener index; ANOVA tested possible differences in the means of diversity among the different years. The reproductive phenophases of the studied Miconia species occurred sequentially (M. alborufescens, then M. holoserica, followed by M. prasina), in the transition between the dry and rainy seasons, with little overlap between them. In general, the species showed seasonal and synchronic phenological patterns, with some variations that coincided with El Niño and/or La Niña events, e.g., demonstrating changes in the periodicity, synchrony, and intensity of their phenophases. The intensity of fruiting, for example, showed increases during La Niña years. Reproductive phenological diversity appears to respond to climate changes resulting from El Niño events and periods of prolonged drought, with high Shannon-Wiener index values. The results also suggest that the effects of global climatic phenomena (El Niño and La Niña) that alter regional climatic seasonality can also cause variations in the reproductive phenological rhythms of the Miconia species studied.

Patterns in Wing Morphology and Fluctuating Asymmetry in Eulaema nigrita along an Altitudinal Gradient in the Brazilian Rupestrian Grassland

Mountain ecosystems experience abrupt abiotic changes that represent environmental filters for many organisms, shaping their phenotypic expressions. However, little is known about the morphological and symmetric adjustments of native bees along altitudinal gradients. We evaluated the changes on wing morphology, wing size, and vein fluctuating asymmetry (FA) of Eulaema nigrita Lepeletier (Apidae: Euglossini) associated with climatic variables along an altitudinal gradient in the rupestrian grassland (known also as campo rupestre or rupestrian field) of Serra do Cipó, Brazil. Seven sampling points along the altitudinal gradient were selected and distributed among 800 and 1400 m.a.s.l., and then, 40 individuals of E. nigrita were collected per each altitudinal point to determine the FA levels and the morphological changes using geometric morphometric techniques. We found that the wing size of E. nigrita decreased with increasing altitude. At the highest altitudes, the levels of FA of the wing veins were greater compared to bees from lower altitudes. We detected significant changes in wing morphology along the altitudinal gradient; bees of lower altitudes showed longer and wider wings than bees of higher altitudes, which had narrower and less elongated wings. Our results show a set of morphological adjustments and phenotypic expressions in E. nigrita associated with the variation in environmental conditions along the altitudinal gradient. We highlight the importance of environmental variables as insect-stressor factors, and that FA and geometric morphometric can be excellent tools for monitoring and evaluating environmental stresses.

An elevational gradient in floral traits and pollinator assemblages in the Neotropical species Costus guanaiensis var. tarmicus in Peru

Different populations of plant species can adapt to their local pollinators and diverge in floral traits accordingly. Floral traits are subject to pollinator-driven natural selection to enhance plant reproductive success. Studies on temperate plant systems have shown pollinator-driven selection results in floral trait variation along elevational gradients, but studies in tropical systems are lacking. We analyzed floral traits and pollinator assemblages in the Neotropical bee-pollinated taxon Costus guanaiensis var. tarmicus across four sites along a steep elevational gradient in Peru. We found variations in floral traits of size, color, and reward, and in the pollinator assemblage along the elevational gradient. We examined our results considering two hypotheses, (1) local adaptation to different bee assemblages, and (2) the early stages of an evolutionary shift to a new pollinator functional group (hummingbirds). We found some evidence consistent with the adaptation of C. guanaiensis var. tarmicus to the local bee fauna along the studied elevational gradient. Corolla width across sites was associated with bee thorax width of the local most frequent pollinator. However, we could not rule out the possibility of the beginning of a bee-to-hummingbird pollination shift in the highest-studied site. Our study is one of the few geographic-scale analyses of floral trait and pollinator assemblage variation in tropical plant species. Our results broaden our understanding of plant-pollinator interactions beyond temperate systems by showing substantial intraspecific divergence in both floral traits and pollinator assemblages across geographic space in a tropical plant species.

Community dynamics of bumblebee across elevation gradients and habitat mosaics in Chitwan Annapurna Landscape, Nepal

The species composition of bumblebees (Bombus species) across the elevation gradients in Chitwan-Annapurna Landscape (CHAL) was studied from April to November 2019. We performed opportunistic surveys to collect the bumblebee specimens. The walking transects were followed in the accessible places along the Kaligandaki, Marshyandi, and Budhigandaki river basins in different habitats (e.g., agricultural, forest, grassland and home garden). We identified 16 Bombus species from the sampling areas. The highest relative abundance was of B. haemorrhoidalis (20%), followed by B. festivus (20%) and B. eximius (19%). The least abundant species were B. branickii, B. miniatus, B. novus, and B. pressus with 1% relative abundance of each. We examined the effects of elevation on bumblebee richness and found a significant relationship. The Highest species richness was detected in the mid-elevation. Likewise, the highest species richness and diversity were found in the forest habitat in Gorkha site (n = 12, Shannon index H' = 2.18) followed by the grassland habitat of the Mustang site (n = 11, Shannon index H' = 2.10). Whereas, comparatively, species diversity was higher in habitats of the Gorkha site comparing Manang and Mustang. The elevation gradients create immense variations in microclimatic conditions and vegetation dynamics, which influence bumblebee abundance, species richness and diversities in different habitats in the study area. The mid-elevation range (2000-3000 m asl) of CHAL exhibited the highest species richness probably due to the higher availability of pollinator-dependent flowering plants in this range. The landcover composition and anthropogenic activities along the elevation gradient is the governing factor for the species composition, distribution and diversity of bumblebees in CHAL. We recommend to decision-makers for formulating their conservation strategies under a socio-ecological framework.

Anthropogenic impacts on multiple facets of macroinvertebrate α and β diversity in a large river-floodplain ecosystem

Anthropogenic disturbances have become one of the primary causes of biodiversity decline in freshwater ecosystems. Beyond the well-documented loss of taxon richness in increasingly impacted ecosystems, our knowledge on how different facets of α and β diversity respond to human disturbances is still limited. Here, we examined the responses of taxonomic (TD), functional (FD) and phylogenetic (PD) α and β diversity of macroinvertebrate communities to human impact across 33 floodplain lakes surrounding the Yangtze River. We found that most pairwise correlations between TD and FD/PD were low and non-significant, whereas FD and PD metrics were instead positively and significantly correlated. All facets of α diversity decreased from weakly to strongly impacted lakes owing to the removal of sensitive species harboring unique evolutionary legacies and phenotypes. By contrast, the three facets of β diversity responded inconsistently to anthropogenic disturbance: while FDβ and PDβ showed significant impairment in moderately and strongly impacted lakes as a result of spatial homogenization, TDβ was lowest in weakly impacted lakes. The multiple facets of diversity also responded differently to the underlying environmental gradients, re-emphasizing that taxonomic, functional and phylogenetic diversities provide complementary information on community dynamics. However, the explanatory power of our machine learning and constrained ordination models was relatively low and suggests that unmeasured environmental features and stochastic processes may strongly contribute to macroinvertebrate communities in floodplain lakes suffering from variable levels of anthropogenic degradation. We finally suggested guidelines for effective conservation and restoration targets aimed at achieving healthier aquatic biotas in a context of increasing human impact across the 'lakescape' surrounding the Yangtze River, the most important being the control of nutrient inputs and increased spatial spillover effects to promote natural metasystem dynamics.

Patterns and drivers of soil surface-dwelling Oribatida diversity along an altitudinal gradient on the Changbai Mountain, China

Distribution patterns of biodiversity and environmental interactions are dominant themes in ecology. In montane ecosystems, biodiversity is closely associated with altitudinal gradients. However, studies of biodiversity in montane ecosystems are focused on plants and vertebrates, with relatively less on invertebrates. Here, the present study used a Vortis arthropod suction sampler to explore the biodiversity patterns of soil surface-dwelling Oribatida and their drivers along an altitudinal gradient (600, 800, 1600, 2000, and 2300 m) from typical temperate forests, evergreen coniferous forests, subalpine birch forests to alpine tundra on the north slope of Changbai Mountain, Northeast China. Trichoribates berlesei, Platynothrus peltifer, and Oribatula tibialis were the dominant soil surface-dwelling species on Changbai Mountain. Generally, alpha diversity and beta diversity of soil surface-dwelling Oribatida decreased with the rising altitude, with a peaking density value at 2000 m. The result of beta diversity showed that the structures of community were more influenced by the species turnover component than the nestedness component. Nonmetric multidimensional scaling (NMDS) ordination showed that the community structure of soil surface-dwelling Oribatida varied significantly along the altitudinal gradient. The variance partitioning showed that the elevation and climatic conditions determined the soil surface-dwelling Oribatida community. Spatial filtering represented by geographic and elevation distances was particularly associated with soil surface-dwelling Oribatida community variation between altitudes on Changbai Mountain. However, the variation of the Oribatida community between adjacent altitudes was only associated with geographic distance. Our study provides supportive evidence for the biodiversity analyzing of soil surface-dwelling Oribatida in montane ecosystems along an altitudinal gradient.

Cuticular hydrocarbons of alpine bumble bees (Hymenoptera: Bombus) are species-specific, but show little evidence of elevation-related climate adaptation

Alpine bumble bees are the most important pollinators in temperate mountain ecosystems. Although they are used to encounter small-scale successions of very different climates in the mountains, many species respond sensitively to climatic changes, reflected in spatial range shifts and declining populations worldwide. Cuticular hydrocarbons (CHCs) mediate climate adaptation in some insects. However, whether they predict the elevational niche of bumble bees or their responses to climatic changes remains poorly understood. Here, we used three different approaches to study the role of bumble bees’ CHCs in the context of climate adaptation: using a 1,300 m elevational gradient, we first investigated whether the overall composition of CHCs, and two potentially climate-associated chemical traits (proportion of saturated components, mean chain length) on the cuticle of six bumble bee species were linked to the species’ elevational niches. We then analyzed intraspecific variation in CHCs of Bombus pascuorum along the elevational gradient and tested whether these traits respond to temperature. Finally, we used a field translocation experiment to test whether CHCs of Bombus lucorum workers change, when translocated from the foothill of a cool and wet mountain region to (a) higher elevations, and (b) a warm and dry region. Overall, the six species showed distinctive, species-specific CHC profiles. We found inter- and intraspecific variation in the composition of CHCs and in chemical traits along the elevational gradient, but no link to the elevational distribution of species and individuals. According to our expectations, bumble bees translocated to a warm and dry region tended to express longer CHC chains than bumble bees translocated to cool and wet foothills, which could reflect an acclimatization to regional climate. However, chain lengths did not further decrease systematically along the elevational gradient, suggesting that other factors than temperature also shape chain lengths in CHC profiles. We conclude that in alpine bumble bees, CHC profiles and traits respond at best secondarily to the climate conditions tested in this study. While the functional role of species-specific CHC profiles in bumble bees remains elusive, limited plasticity in this trait could restrict species’ ability to adapt to climatic changes.

High species turnover and unique plant-pollinator interactions make a hyperdiverse mountain

We studied α- and β-diversity of pollinators, flowering plants and plant-pollinator interactions along the altitudinal gradient of Mt. Olympus, a legendary mountain and biodiversity hotspot in Central Greece. We explored 10 study sites located on the north-eastern slope of the mountain, from 327 to 2596 m a.s.l. Insect surveys were conducted once a month using hand netting (years 2013, 2014 and 2016), and they were combined with recordings of flowering plant diversity (species richness and flower cover). We then calculated α- and β-diversity of pollinators, plants in flower and plant-pollinator interactions, and explored their demographic response along the altitudinal gradient. Alpha diversity of pollinators, plants and plant-pollinator interactions were altitude dependent; α-diversity of all pollinators, bees, non-bumblebee bees, bee flies and butterflies showed linear declines with altitude, whereas those of hoverflies and bumblebees showed unimodal patterns. Beta diversity and its turnover component of all pollinators, hoverflies, bees, bumblebees, non-bumblebee bees, butterflies and plants showed linear increases, whereas those of bee flies and of plant-pollinator interactions varied independently from the pairwise altitudinal difference. The high dissimilarity and uniqueness of pollination networks, which is probably a result of the high biodiversity and endemism of Mt. Olympus, is driven by species turnover and the formation of new interactions between new species. Contrasting to the monotonic decline of the remaining groups, the unimodal patterns of hoverfly and bumblebee α-diversity are probably the effect of a higher tolerance of these groups to high-altitude environmental conditions. Our findings highlight that the high turnover of species and of pollination interactions along the altitudinal gradient are the mainstay of hyperdiverse mountains, a fact that conveys important historical, ecological and conservational implications.

Changes in bee functional traits at community and intraspecific levels along an elevational gradient in a Mexical-type scrubland

Understanding the causes of morphological variation of organisms along climatic gradients has been a central challenge in ecological research. We studied the variation of community weighted mean (CWM) and two functional diversity metrics (Rao-Q and functional richness) computed for five morphological traits of wild bees (Hymenoptera: Apoidea) related to thermal performance (namely body size, relative appendage length and hairiness), at community and interspecific levels, along an elevation gradient in a Mexical-type scrubland. At the community level we found a decreasing CWM of body size pattern with increasing elevation which is consistent with the species-energy theory (and contrary to Bergmann's rule). We also found an increase in the CWM of relative tibia length, which is contrary to Allen's rule. Additionally, we found an increase in the CWM of relative hair length towards high levels of elevation, which would be consistent with the hypothesis that hairiness plays an important role as thermal insulation. We found that functional diversity was larger at low elevations with respect to high elevation for body size and hair length, which could imply that highland communities were more sensitive towards environmental changes than lowland communities. Overall, at intraspecific level, most of species showed no pattern for any of the traits along the elevation gradient. Future research should provide further evidence on the possible behavioral or physiological mechanisms behind it.

Variations in Functional Richness and Assembly Mechanisms of the Subtropical Evergreen Broadleaved Forest Communities along Geographical and Environmental Gradients

Linking functional trait space and environmental conditions can help to understand how species fill the functional trait space when species increase along environmental gradients. Here, we examined the variations in functional richness (FRic) and their correlations with key environmental variables in forest communities along latitudinal, longitudinal, and elevational gradients, by measuring seven functional traits of woody plants in 250 forest plots of 0.04 ha across five locations in the subtropical evergreen broadleaved forests (SEBLF) of China. On this basis, we explored whether environmental filtering constrained the functional volume by using a null model approach. Results showed that FRic decreased with increasing elevation and latitude, while it increased with increasing longitude, mirroring the geographical gradients in species richness. FRic was significantly related to precipitation of driest quarter, soil pH, and total phosphorus. Negative SES.FRic was prevalent (83.2% of the communities) in most SEBLF communities and was negatively related to mean diurnal range. Our study suggested that the geographical variation in the functional space occupied by SEBLF communities was affected mainly by climate and soil conditions. The results of the null model revealed that niche packing was dominant in SEBLF communities, highlighting the importance of environmental filtering in defining functional volume within SEBLF communities.

Body Size and Symmetry Properties of Termite Soldiers Under Two Intraspecific Competition Scenarios

Single-piece nesting termites live and forage in the same piece of wood throughout their life, which limit their colony size. In certain species, more than one colony thrive in a given piece of wood (multicolonial substrate) and intraspecific competition become important in this limited resource, as has been reported in Zootermopsis nevadensis (Hagen, 1858) and Neotermes chilensis (Blattodea: Kalotermitidae) (Blanchard, 1851). The effects of such competition have been described mainly at population and colony levels rather than at the individual level. In eusocial insects such as termites, intraspecific competition constitutes a stress factor imposed to a colony as a whole and should also cause developmental instability in soldiers produced under such conditions. Investment in the production of soldiers involves a trade-off between colony maintenance costs and defense benefits. Hence, we hypothesize that body size and fluctuating asymmetry, two indicators of developmental instability, will increase when two or more colonies of N. chilensis share a piece of wood (high intraspecific competition scenario). Our results showed that soldiers developing in multicolonial substrates were indeed larger and more asymmetric than soldiers developing in unicolonial substrates. The large body size in a soldier could improve its chance to win a physical contest with a non-nestmate opponent; thus, despite the high cost to produce large soldiers in small colonies, larger soldier production could be an adaptative strategy to avoid being outcompeted. However, the effects of deviations from perfect symmetry on soldier performance are not clear.

Contrasting patterns of richness, abundance, and turnover in mountain bumble bees and their floral hosts

Environmental gradients generate and maintain biodiversity on Earth. Mountain slopes are among the most pronounced terrestrial environmental gradients, and the elevational structure of species and their interactions can provide unique insight into the processes that govern community assembly and function in mountain ecosystems. We recorded bumble bee-flower interactions over three years along an 1400 m elevational gradient in the German Alps. Using nonlinear modeling techniques, we analyzed elevational patterns at the levels of abundance, species richness, species β-diversity, and interaction β-diversity. While floral richness exhibited a mid-elevation peak, bumble bee richness increased with elevation before leveling off at the highest sites, demonstrating the exceptional adaptation of these bees to cold temperatures and short growing seasons. In terms of abundance, though, bumble bees exhibited divergent species-level responses to elevation, with a clear separation between species preferring low vs. high elevations. Overall interaction β-diversity was mainly caused by strong turnover in the floral community, which exhibited a well-defined threshold of β-diversity rate at the tree line ecotone. Interaction β-diversity increased sharply at the upper extreme of the elevation gradient (1800-2000 m), an interval over which we also saw steep decline in floral richness and abundance. Turnover of bumble bees along the elevation gradient was modest, with the highest rate of β-diversity occurring over the interval from low- to mid-elevation sites. The contrast between the relative robustness bumble bee communities and sensitivity of plant communities to the elevational gradient in our study suggests that the strongest effects of climate change on mountain bumble bees may be indirect effects mediated by the responses of their floral hosts, though bumble bee species that specialize on high-elevation habitats may also experience significant direct effects of warming.

The patterns of co-occurrence variation are explained by the low dependence of bark beetles (Coleoptera: Scolytinae and Platypodinae) on hosts along altitude gradients

Background

Separation of biotic and abiotic impacts on species diversity distribution patterns across a significant climatic gradient is a challenge in the study of diversity maintenance mechanisms. The basic task is to reconcile scale-dependent effects of abiotic and biotic processes on species distribution models. Here, we used a hierarchical modeling method to detect the host specificities of bark beetles (Scolytinae and Platypodinae) with their dependent tree communities across a steep climatic gradient, which was embedded within a relatively homogenous spatial niche.

Results

Species turnover of both trees and bark beetles have an opposite pattern along the climatic proxy (represented by the elevation gradients) at the regional scale, but not at local spatial scales. This pattern confirmed the hypothesis wherein emphasis was on influences of macro-climate on local biotic interactions between trees and hosted bark beetle communities, whereas local biotic relations, represented by host specificity dependence, were regionally conserved.

Conclusions

At a confined spatial scale, cross-taxa comparisons of β-diversity highlighted the importance of simultaneous impacts from both extrinsic factors related to geography and environment, and intrinsic factors related to organism characteristics. The effects of tree abundance and phylogeny diversity on bark beetle diversity were, to a large extent, indirect, operating via changes in bark beetle abundance through spatial and temporal dynamics of resources distribution. Tree host dependence, which was considered and represented by host specificities, plays a minor role on the hosted beetle community in this concealed wood decomposing interacting system.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12983-022-00455-y.

Drivers of Collembola assemblages along an altitudinal gradient in northeast China

Altitudinal changes in the diversity of plants and animals have been well documented; however, soil animals received little attention in this context and it is unclear whether their diversity follows general altitudinal distribution patterns. Changbai Mountain is one of few well-conserved mountain regions comprising natural ecosystems on the Eurasian continent. Here, we present a comprehensive analysis of the diversity and community composition of Collembola along ten altitudinal sites representing five vegetation types from forest to alpine tundra. Among 7834 Collembola individuals, 84 morphospecies were identified. Species richness varied marginally significant with altitude and generally followed a unimodal relationship with altitude. By contrast, the density of Collembola did not change in a consistent way with altitude. Collembola communities changed gradually with altitude, with local habitat-related factors (soil and litter carbon-to-nitrogen ratio, litter carbon content, and soil pH) and climatic variables (precipitation seasonality) identified as major drivers of changes in Collembola community composition. Notably, local habitat-related factors explained more variation in Collembola assemblages than climatic variables. The results suggest that local habitat-related factors including precipitation and temperature are the main drivers of changes in Collembola communities with altitude. Specifically, soil and litter carbon-to-nitrogen ratio correlated positively with Collembola communities at high altitudes, whereas soil pH correlated positively at low altitudes. This documents that altitudinal gradients provide unique opportunities for identifying factors driving the community composition of not only above- but also belowground invertebrates.

ABEJAS EN SISTEMAS AGRÍCOLAS: REVISIÓN DE LA DIVERSIDAD TAXONÓMICA Y FUNCIONAL, Y PERSPECTIVAS DE INVESTIGACIÓN

Las abejas son insectos de gran importancia ecológica ya que son responsables de procesos como la polinización en ambientes naturales y agrícolas, contribuyendo a la salud y resiliencia de los ecosistemas. Se hizo una revisión para abordar las dimensiones taxonómica y funcional de la diversidad de abejas en cultivos de palma, papa, café, granadilla, gulupa y maracuyá. Se realizó la búsqueda de información en bases de datos usando palabras claves y operadores boléanos. Se construyeron curvas análogas a las de acumulación de especies y se realizó un análisis de complementariedad, para evaluar la diversidad taxonómica. Se utilizó un análisis de conglomerados para identificar tipos funcionales y se evaluó la riqueza funcional de cada cultivo. Se encontraron 19 publicaciones de abejas asociadas a cultivos, con registros de 116 especies. El cultivo de palma presentó la mayor riqueza con 48 especies, seguido de papa (44) y café (41). Se identificaron 11 tipos funcionales, donde el más representativo fue el de abejas con corbícula, eusociales, que anidan en cualquier cavidad (ScEuCc). La riqueza funcional fue mayor en el café (3,33), seguido de papa (2,83) y gulupa (2,00). La alta diversidad de abejas en agroecosistemas parece estar relacionada con la cercanía de cada cultivo a fragmentos de bosque, de acuerdo a las publicaciones analizadas. Los agroecosistemas podrían ofrecer un recurso alternativo a las abejas al permitirles combatir la disminución de sus hábitats, por lo que sugerimos ampliar las investigaciones de los beneficios de los cultivos agrícolas sobre las abejas y viceversa.

Pollination generalization and reproductive assurance by selfing in a tropical montane ecosystem

Pollination and reproduction are important processes for understanding plant community dynamics. Information regarding pollination and reproduction is urgent for threatened ecosystems, such as tropical montane ecosystems. In tropical mountains, pollination patterns are expected to conform to the reproductive assurance theory (due to low pollinator activity) and old, climatically buffered and infertile landscapes (OCBIL) theory (due to restricted plant range size). For 82 plant species of the Itatiaia National Park (including endemic and endangered species), we evaluated at least one of the following features: pollinator identity, flower color and size, flowering phenology, and pollinator dependence. Most plant species (ca. 60%) were pollinated by two or more functional groups of pollinators (generalized pollination), with high importance of flies as pollinators. There was low pollinator activity overall (less than one visit per flower per hour). Notably, the invasive honeybee Apis mellifera L. performed half of the visits to this entire plant community, suggesting an impact on the native pollinator fauna and consequently on the native flora. Most endemic plants were generalized with white and small flowers, while endangered species were pollination-specialized with colorful and large flowers. Thus, endangered species are susceptible to changes in pollinator fauna. Flowering seasonality reflected the importance of climatic constraints in this environment. One-third of the plant species were autogamous. Our data suggest that pollinator scarcity may have promoted reproductive assurance strategies such as generalization and pollinator independence. Our community-level study highlighted consistent pollination patterns for tropical mountains and emphasized threats for specialized endangered species.

Variations in Plant Richness, Biogeographical Composition, and Life Forms along an Elevational Gradient in a Mediterranean Mountain

Despite the increasing interest in elevational patterns in biodiversity, few studies have investigated variations in life forms and biogeographical composition, especially in the Mediterranean biome. We investigated elevational patterns in species richness, biogeographical composition (chorotypes) and life forms (Raunkiaer classification) along an elevational gradient in a Mediterranean mountain (Central Italy). We found a general hump-shaped pattern of species richness, which can be explained by harsher conditions at the lowest and highest elevations. This pattern is distinctly related to prevalence at mid elevations of species with European and Euro-Asiatic distribution, which are favored by a temperate climate. Phanerophytes and geophytes (which are mainly associated with woods) were concentrated at mid elevations where woodlands prevail. Hemicryptophytes increased with elevation, consistently with their ability to cope with high altitude climatic conditions. Mediterranean species declined with elevation because they are negatively affected by decreasing temperatures. Chamaephytes showed a U-shaped pattern, suggesting they are able to cope with arid and cold conditions at the extremes of the gradient. Endemics increased with elevation because of their association with mountainous areas as key places for endemism evolution. These results illustrate how elevational patterns in species richness, biogeographical composition and life forms are interrelated and demonstrate reciprocal insights for understanding current vegetation settings.

Diversity Patterns of Dung Beetles along a Mediterranean Elevational Gradient

Most studies of biodiversity-elevational patterns do not take species abundance into consideration. Hill numbers are a unified family of indices that use species abundance and allow a complete characterization of species assemblages through diversity profiles. Studies on dung beetle responses to elevation were essentially based on species richness and produced inconsistent results because of the non-distinction between different habitats and the use of gradients dispersed over wide areas. We analyzed dung beetle diversity in a Mediterranean mountain (central Italy) for different habitats (woodlands vs. grasslands) and taxonomic groups (scarabaeids and aphodiids). Scarabaeids were the most abundant. Since scarabaeids are able to construct subterranean nests, this indicates that the warm and dry summer climatic conditions of high elevations favor species capable of protecting their larvae from desiccation. Dung beetles were more abundant and diversified in grasslands than in woodlands, which is consistent with their preference for open habitats. In the woodlands, diversity increased with increasing elevation because of increasing tree thinning, whereas, in the grasslands, diversity decreased with elevation because of increasingly harsher environmental conditions. These results indicate a trade-off in the beetle response to elevation between the positive effects of increasing the availability of more suitable habitats and the decrease of optimal environmental conditions.

Ecology: What Affects the Distribution of Global Bee Diversity

Despite being the most important pollinators in the world, how bees are distributed and the main drivers of their diversity have never been assessed at a global scale. A new study has brought together global data sets to answer these questions.

Changes in the structure and composition of the 'Mexical' scrubland bee community along an elevational gradient

'Mexical' scrubland is a sclerophyllous evergreen Mediterranean-like vegetation occurring in the leeward slopes of the main Mexican mountain ranges, under tropical climate. This biome occupies an elevational range approximately from 1900 to 2600 meters above sea level, which frequently is the upper-most part of the mountains range. This puts it at risk of extinction in a scenario of global warming in which an upward retraction of this type of vegetation is expected. The Mexical remains one of the least studied ecosystems in Mexico. For instance, nothing is known about pollinator fauna of this vegetation. Our main objective is to make a first insight into the taxonomic identity of the bee fauna that inhabits this biome, and to study how it is distributed along the elevational gradient that it occupies. Our results highlight that elevation gradient negatively affects bee species richness and that this relationship is strongly mediated by temperature. Bee abundance had no significant pattern along elevational gradient, but shows a significant relationship with flower density. Interestingly, and contrary to previous works, we obtained a different pattern for bee richness and bee abundance. Bee community composition changed strongly along elevation gradient, mainly in relation to temperature and flower density. In a global warming scenario, as temperatures increases, species with cold preferences, occupying the highest part of the elevation gradient, are likely to suffer negative consequences (even extinction risk), if they are not flexible enough to adjust their physiology and/or some life-story traits to warmer conditions. Species occupying mid and lower elevations are likely to extend their range of elevational distribution towards higher ranges. This will foreseeably cause a new composition of species and a new scenario of interactions, the adjustment of which still leaves many unknowns to solve.

Low bee visitation rates explain pollinator shifts to vertebrates in tropical mountains

Evolutionary shifts from bee to vertebrate pollination are common in tropical mountains. Reduction in bee pollination efficiency under adverse montane weather conditions was proposed to drive these shifts. Although pollinator shifts are central to the evolution and diversification of angiosperms, we lack experimental evidence of the ecological processes underlying such shifts. Here, we combine phylogenetic and distributional data for 138 species of the Neotropical plant tribe Merianieae (Melastomataceae) with pollinator observations of 11 and field pollination experiments of six species to test whether the mountain environment may indeed drive such shifts. We demonstrate that shifts from bee to vertebrate pollination coincided with occurrence at high elevations. We show that vertebrates were highly efficient pollinators even under the harsh environmental conditions of tropical mountains, whereas bee pollination efficiency was lowered significantly through reductions in flower visitation rates. Furthermore, we show that pollinator shifts in Merianieae coincided with the final phases of the Andean uplift and were contingent on adaptive floral trait changes to alternative rewards and mechanisms facilitating pollen dispersal. Our results provide evidence that abiotic environmental conditions (i.e. mountain climate) may indeed reduce the efficiency of a plant clade's ancestral pollinator group and correlate with shifts to more efficient new pollinators.

Species and functional diversity - A better understanding of the impact of urbanization on bee communities

We examined site patterns in bee species for diversity and functional diversity in urban, suburban and rural areas. We sampled bees from all three habitat types and compiled a database of functional traits for each species. While species diversity decreased with urbanization, as expected, components of functional diversity showed differences between urban and suburban habitats. Functional dispersion (FDis) increased significantly in suburban areas as compared to urban sites, while functional divergence (FDiv) and functional redundancy (Fred) were higher in urban areas. Functional richness (FRic) and evenness (FEven) were not affected by urbanization. Moreover, assemblages in highly urbanized environments have a substantially different functional composition. Solitary species, cleptoparasites, soil nesters, bees with trophic specialization, and those with a short flight period turned out to be more sensitive to urbanization changes. This study highlights the importance of examining functional diversity in assessing human-induced biodiversity loss and its impacts on ecosystem functioning in urbanized areas. These results have significant implications for improving our understanding of the mechanisms of suburban community ecology and conserving bees in urban habitats.

Decline of parasitic and habitat-specialist species drives taxonomic, phylogenetic and functional homogenization of sub-alpine bumblebee communities

The ongoing biodiversity crisis is characterised not only by an elevated extinction rate but also can lead to an increasing similarity of species assemblages. This is an issue of major concern, as it can reduce ecosystem resilience and functionality. Changes in the composition of pollinator communities have mainly been described in intensive agricultural lowland areas. In this context, using a replicated survey of historical and recent bumblebee diversity, we aimed here to test how documented changes in climate and land use influenced the potential homogenization of sub-alpine bumblebee communities in southern Norway. We assessed the change in community composition in terms of taxonomic, phylogenetic and functional (β-)diversity, and estimated the impact of various species traits in probabilities of species gains and losses. Overall, we found a strong reduction in functional diversity, but no change in phylogenetic diversity over time. The β-diversity decreased, especially at high elevations, and this pattern was consistent for taxonomic, phylogenetic and functional β-diversity. The spatial distribution, measured as the average site occupancy, decreased in habitat-specialist species. This was explained by both a higher risk of species loss and a lower probability of species gain for habitat-specialist and parasitic species than for generalist and social species. These findings demonstrate that a narrow niche breadth may contribute to a higher extinction risk in bumblebee species. This non-random impact of disturbance on species may lead to large-scale biotic homogenisation of communities, a pattern that can be detected by investigating biodiversity changes at different scales and across its multiple facets.

Cryptic species and hidden ecological interactions of halictine bees along an elevational gradient

Changes of abiotic and biotic conditions along elevational gradients represent serious challenges to organisms which may promote the turnover of species, traits and biotic interaction partners. Here, we used molecular methods to study cuticular hydrocarbon (CHC) profiles, biotic interactions and phylogenetic relationships of halictid bees of the genus Lasioglossum along a 2,900 m elevational gradient at Mt. Kilimanjaro, Tanzania. We detected a strong species turnover of morphologically indistinguishable taxa with phylogenetically clustered cryptic species at high elevations, changes in CHC profiles, pollen resource diversity, and a turnover in the gut and body surface microbiome of bees. At high elevations, increased proportions of saturated compounds in CHC profiles indicate physiological adaptations to prevent desiccation. More specialized diets with higher proportions of low-quality Asteraceae pollen imply constraints in the availability of food resources. Interactive effects of climatic conditions on gut and surface microbiomes, CHC profiles, and pollen diet suggest complex feedbacks among abiotic conditions, ecological interactions, physiological adaptations, and phylogenetic constraints as drivers of halictid bee communities at Mt. Kilimanjaro.

The positive effects of the alpine cushion plant Arenaria polytrichoides on insect dynamics are determined by both physical and biotic factors

Cushion plants' significant role for alpine biodiversity has been demonstrated in particular through their positive effects on plant diversity. However, their effects on higher trophic levels (e.g. insects) remain largely unclear. In this study, by field sampling in the Hengduan Mountains (HDM) in southwestern China, we evaluated the effects of an alpine gynodioecious cushion species, Arenaria polytrichoides (Carophyllaceae), on insect richness, abundance and population dynamics at two different elevations (4427 m vs. 4732 m) separately at two time periods (day vs. night) and in two growing seasons (early vs. late). The results showed that the total insect diversity decreases from low to high elevation sites. Some insect species were exclusively detected within A. polytrichoides cushions, leading to an increase in local insect richness from 7% to 35%. The positive effects of cushions on insect diversity could be attributed to unique biotic properties provided by cushions. Firstly, the effects were determined by the sexual dimorphism of the cushion with hermaphroditic cushions supporting higher insect diversity than female cushions. This could be because hermaphroditic cushions provide more resources, such as nectar and pollen grains, for insects than female cushions. Secondly, the cushions' associated beneficiary plants can also provide extra resources for attracting more insects, but this effect was mediated by the micro-environmental conditions. Finally, the magnitude of cushions' positive effects on insect dynamics were stronger under higher than under lower environmental stress. This study confirmed that facilitation by A. polytrichoides cushions in HDM plays an important role in constructing the alpine insect community and further regulating its dynamics. Moreover, the positive effects of cushions on insect dynamics increase with increasing environmental stress. Therefore, the distribution range of insects would quite possibly be expanded into higher elevation under future climate changes, which will induce new challenges for the local alpine ecosystems.

Latitudinal and elevational patterns of phylogenetic structure in forest communities in China's mountains

The phylogenetic structure incorporates both ecological and evolutionary processes to explain assembly of a local community. The "phylogenetic niche conservatism" (PNC) hypothesis suggests that distributions of species along environmental gradients reflect both ancestral traits and ecological fitness of individual species The temperature is generally regarded to change in similar ways along both latitudinal and elevational gradients but with different historical contingence. Therefore, comparing the latitudinal and elevational patterns of phylogenetic structure of communities is of help to depict the effects of ecological and evolutionary processes in shaping the community assembly. In this study, we explored the latitudinal, elevational and climatic patterns of phylogenetic structure of 569 angiosperm tree communities from 38 mountains across China. We found a larger mean abundance-weighted net relatedness index (NRI) than the presence/absence-based NRI; and the NRI decreased when the species pool downscaled from the full pool to county-level pool. The mean family age and phylogenetic species evenness decreased with latitude, and increased with temperature of the coldest month and precipitation; whilst NRI increased with latitude, and decreased with mean temperature of the coldest month. In most mountains, NRI, mean family age and phylogenetic species evenness showed non-significant trends along the elevational gradient. Our results support the main predictions of PNC for the latitudinal gradient, i.e., species tend to be more phylogenetically related to each other and clades are younger in temperate environments, compared to those in tropical environments. We suggested that independent species pools and abundance should be incorporated in analysis to fully represent the phylogenetic structure of communities.

Contrasting responses of above- and below-ground herbivore communities along elevation

Above- and below-ground herbivory are key ecosystem processes that can be substantially altered by environmental changes. However, direct comparisons of the coupled variations of above- and below-ground herbivore communities along elevation gradients remain sparse. Here, we studied the variation in assemblages of two dominant groups of herbivores, namely, aboveground orthoptera and belowground nematodes, in grasslands along six elevation gradients in the Swiss Alps. By examining variations of community properties of herbivores and their food plants along montane clines, we sought to determine whether the structure and functional properties of these taxonomic groups change with elevation. We found that orthoptera decreased in both species richness and abundance with elevation. In contrast with aboveground herbivores, the taxonomic richness and the total abundance of nematode did not covary with elevation. We further found a stronger shift in above- than below-ground functional properties along elevation, where the mandibular strength of orthoptera matched a shift in leaf toughness. Nematodes showed a weaker pattern of declined sedentary behavior and increased mobility with elevation. In contrast to the direct exposal of aboveground organisms to the surface climate, conditions may be buffered belowground, which together with the influence of edaphic factors on the biodiversity of soil biota, may explain the differences between elevational patterns of above- and below-ground communities. Our study emphasizes the necessity to consider both the above- and below-ground compartments to understand the impact of current and future climatic variation on ecosystems, from a functional perspective of species interactions.

Using functional traits to model annual plant community dynamics

Predicting the response of biological communities to changes in the environment or management is a fundamental pursuit of community ecology. Meeting this challenge requires the integration of multiple processes: habitat filtering, niche differentiation, biotic interactions, competitive exclusion, and stochastic demographic events. Most approaches to this long-standing problem focus either on the role of the environment, using trait-based filtering approaches, or on quantifying biotic interactions with process-based community dynamics models. We introduce a novel approach that uses functional traits to parameterize a process-based model. By combining the two approaches we make use of the extensive literature on traits and community filtering as a convenient means of reducing the parameterization requirements of a complex population dynamics model whilst retaining the power to capture the processes underlying community assembly. Using arable weed communities as a case study, we demonstrate that this approach results in predictions that show realistic distributions of traits and that trait selection predicted by our simulations is consistent with in-field observations. We demonstrate that trait-based filtering approaches can be combined with process-based models to derive the emergent distribution of traits. While initially developed to predict the impact of crop management on functional shifts in weed communities, our approach has the potential to be applied to other annual plant communities if the generality of relationships between traits and model parameters can be confirmed.

Asynchrony among insect pollinator groups and flowering plants with elevation

Mountains influence species distribution through differing climate variables associated with increasing elevation. These factors determine species niche ranges and phenology. Although the distribution patterns of some specific insect groups relative to elevation have been determined, how differing environmental conditions across elevation zones differentially influence the phenology of various insect groups is largely unknown. This is important in this era of rapid climate change. We assess here how species composition and seasonal peaks in abundance among different insect pollinator groups and flowering plants differ across four floristically distinct elevation zones up a sentinel mountain subject to strong weather events. We sampled insect pollinators in four major groups (bees, wasps, beetles and flies) over two spring seasons. Pollinator species composition across all elevation zones tracks flowering plant species composition. In terms of abundance, beetles were the dominant group across the three lower zones, but declined greatly in the summit zone, where flies and bees were more abundant. Bee abundance peaked earlier than the other groups across all four elevation zones, where there were significant peaks in abundance. Bee abundance peaked earlier than flowering plants at the middle zone and slightly later than flowering plants at the base zone, suggesting a mismatch. We conclude that, while elevation shapes species distribution, it also differentially influences species phenology. This may be of great significance in long-term assessment of species distribution in sensitive mountain ecosystems.