Global gradients in intraspecific variation in vegetative and floral traits are partially associated with climate and species richness

The study would not have been possible without the work of the TRY initiative on plant traits (http://www.try-db.org) and the BIEN database (http://bien.nceas.ucsb.edu/bien/). We thank all the BIEN and TRY contributors. Furthermore, we thank Benjamin Blonder, Melanie Harze, Ruben Milla, Clara Pladevall, Quentin Read, Marko Spasojevic, Alexia Totte, Evan R. Weiher, Ian Wright and Gerhard W. Zotz for providing additional information for their datasets. Additionally, we thank Franziska Schrodt and anonymous reviewers for constructive and thoughtful suggestions on earlier versions of this paper. Open Access funding was provided by Ulm University under the DEAL-agreement.Aim: Intraspecific trait variation (ITV) within natural plant communities can be large, influencing local ecological processes and dynamics. Here, we shed light on how ITV in vegetative and floral traits responds to large-scale abiotic and biotic gradients (i.e., climate and species richness). Specifically, we tested whether associations of ITV with temperature, precipitation and species richness were consistent with any of four hypotheses relating to stress tolerance and competition. Furthermore, we estimated the degree of correlation between ITV in vegetative and floral traits and how they vary along the gradients. Location: Global. Time period: 1975–2016. Major taxa studied: Herbaceous and woody plants. Methods: We compiled a dataset of 18,401 measurements of the absolute extent of ITV (measured as the coefficient of variation) in nine vegetative and seven floral traits from 2,822 herbaceous and woody species at 2,372 locations. Results: Large-scale associations between ITV and climate were trait specific and more prominent for vegetative traits, especially leaf morphology, than for floral traits. The ITV showed pronounced associations with climate, with lower ITV values in colder areas and higher values in drier areas. The associations of ITV with species richness were inconsistent across traits. Species-specific associations across gradients were often idiosyncratic, and covariation in ITV was weaker between vegetative and floral traits than within the two trait groups. Main conclusions: Our results show that, depending on the traits considered, ITV either increased or decreased with climate stress and species richness, suggesting that both factors can constrain or enhance ITV, which might foster plant-population persistence in stressful conditions. Given the species-specific responses and covariation in ITV, associations can be hard to predict for traits and species not yet studied. We conclude that consideration of ITV can improve our understanding of how plants cope with stressful conditions and environmental change across spatial and biological scales

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Reduced seed set under water deficit is driven mainly by reduced flower numbers and not by changes in flower visitations and pollination

Water deficit can alter floral traits with cascading effects on flower-visitor interactions and plant fitness. Water stress induction can diminish productivity, directly resulting in lower flower production and consequently seed set. Changes in floral traits, such as floral scent or reward amount, may in turn alter pollinator visitations and behavior and consequently can reduce pollination services resulting in lower reproduction output. However, the relative contribution of this indirect in comparison to the direct effects of changes in seed set are not fully understood. We manipulated water availability using rain-out shelters in a field experiment and measured effects on floral scent bouquet, morphology, phenology, flower-visitor interactions, pollination, and seed set. Plant individuals of Sinapis arvensis (Brassicaceae) were randomly assigned to one of three treatments: mean precipitation (= control), reduced mean precipitation, or drought period treatment. Our results show that decreasing water availability lowers the number of flowers and seed set. This indicates a direct link between water stress and seed set, as seed mass increases with increasing flower number. The indirect link of water stress via floral traits, pollinator visits, and pollination has weaker effects on seed set. However, floral traits remain relatively stable under decreased water availability, whereas plant growth and flower abundance decrease, potentially in order to allow investment in more resources in fewer flowers to maintain pollination success. Thus, plants are able to compensate for water stress and can maintain floral trait expression, such as a stable scent emission and bouquet, to retain pollinator attraction. These findings indicate that the direct link from water stress to seed set has a stronger impact on plants' reproductive success than the indirect link through altered floral trait expression and pollinator visits in a generalist plant species.Data are saved in a common data exchange format ".csv." Statistical anlyses were made with open source software R studio.Funding provided by: Deutsche ForschungsgemeinschaftCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001659Award Number: KU 3667/2-1- manipulation of water availability on wild mustard (Sinapis arvensis) using rain-out shelters - 3 treatments: well-watered, reduced watered, drought period; stem water potential was measured to conform plant's water stress and was used as the linear variable for further statistical analysis - "Foral_traits"-file: following parameters were measured once in three freshly open flowers per plant from a low, middle, and high position to avoid position and age effects: stamen, style, and calyx length, petal length and width, flower display size, and nectar volume. On two flowers per plant, we collected one anther each in order to count pollen grains by means of a microscope (after 3 weeks under treatment). For pollen and nectar collection, nearly open flowers were covered with mesh bags the day before collection in order to prevent access by flower visitors. The inflorescence size (greatest expansion) was measured once on five inflorescences per plant. Floral height (height of the highest flower) was measured weekly with a folding yardstick; means values were included in the data file and were used for statistical analyses - "Int_data"- file: plant-animal interactions were observed: each plant individual was observed daily; the number of visits by arthropods was recorded; the number of visits per day and per flower was calculated and used for further statistical analyses - "Scent_data"-filechemical (= floral scent) data were analyzed using a thermal desorption system coupled with a GC-MS; compounds were analyzed and identified using GCMSsolution package; compounds in flowers were compared with those found on blank controls; the amount of compounds was estimated by comparing peak areas with area of a standard (Octadecane C18); absolute compound amounts included in the data file - "Loggerdata"-file: raw data obtained from data loggers that were placed under each shelter; measured temperature and relative air humidity; one logger was placed next to the shelters and recorded temperature, relative air humidity, wind speed, photosynthetic active radiation PAR and air pressure - "Soil_humi_temp"-file: raw data of weekly measured soil humidity and soil temperature next to each plant individual using avolumetrix water content sensor (Hydrosense II, Campbell Scientific) and a simple thermometer (DET3R, Voltcraft) - "Plant_list"-file: file with individual plant informatio

Land-use stress alters cuticular chemical surface profile and morphology in the bumble bee Bombus lapidarius.

Pollinators and other insects are currently undergoing a massive decline. Several stressors are thought to be of importance in this decline, with those having close relationships to agricultural management and practice seemingly playing key roles. In the present study, we sampled Bombus lapidarius L. workers in grasslands differing in their management intensity and management regime across three different regions along a north-south gradient in Germany. We analyzed the bees with regard to (1) their cuticular hydrocarbon profile (because of its important role in communication in social insects) and amount of scent by using gas chromatography and (2) the size of each individual by using wing distances as a proxy for body size. Our analysis revealed changes related to land-use intensity and temperature in the cuticular scent profile of bumble bees. Decreasing body size and increasing total scent amount were explained by an interaction of land-use intensity and study region, but not by land-use intensity alone. Thus, land-use intensity and temperature influence intracolonial communication and size, both of which can have strong effects on foraging. Land management and climate are therefore probably detrimental for colony maintenance and the reproductive success of bumble bees

Interconnectedness of the Grinnellian and Eltonian niche in regional and local plant-pollinator communities

Understanding the causes and consequences of coexistence and thus biodiversity is one of the most fundamental endeavors of ecology, which has been addressed by studying species requirements and impacts conceptualized as their Grinnellian and Eltonian niches. However, different niche types have been mostly studied in isolation and thus potential covariation between them remains unknown. Here we quantified the realized Grinnellian niche (environmental requirements), the fundamental (morphological phenotype) and realized Eltonian niche (role in networks) of plant and pollinator taxa at a local and regional scale to investigate the interconnectedness of these niche types. We found a strong and scale-independent co-variation of niche types suggesting that taxa specialized in environmental factors are also specialized in their position in trait spaces and their role in bipartite networks. The integration of niche types thus will help to detect the true causes for species distributions, interaction networks, as well as the taxonomic and functional diversity of communities.(VLID)461537

Floral traits are associated with the quality but not quantity of heterospecific stigmatic pollen loads

Abstract Background In flowering communities, plant species commonly share pollinators and therefore plant individuals receive heterospecific pollen (HP). However, the patterns of HP transfers can deviate from patterns of plant-pollinator visitations. Although flower-visitor interactions are known to be mediated by floral traits, e.g. floral size or nectar tube depth, the explanatory power of these traits for HP transfer patterns remains elusive. Here, we have explored pollen transfer patterns at three sites in Southern Germany on three dates (early, mid and late summer). At the plant level, we tested whether flower abundance and floral traits are correlated with HP reception and donation. At the community level, we determined whether flower and bee diversity are correlated with network modularity and whether floral traits explain the module affiliation of plant species. We collected the stigmas of flowering plant species, analysed HP and conspecific pollen (CP) loads and measured floral traits, flower and bee diversity. Results Our results show that the degree and intensity of HP reception or donation at the plant level do not correlate with floral traits, whereas at the community level, the module affiliation of who is sharing pollen with whom is well-explained by floral traits. Additionally, variation in network modularity between communities is better explained by plant diversity and abundance than by bee diversity and abundance. Conclusions Overall, our results indicate that floral traits that are known to mediate flower-visitor interactions can improve our understanding of qualitative HP transfer but only provide limited information about the quantity of HP transfer, which more probably depends on other floral traits, flower-visitor identity or community properties

Local and Landscape Effects on Carrion-Associated Rove Beetle (Coleoptera: Staphylinidae) Communities in German Forests

Intensification of anthropogenic land use is a major threat to biodiversity and thus to essential ecosystem services provided by insects. Rove beetles (Coleoptera: Staphylinidae), which react sensitively to habitat changes, are species-rich colonizers of vertebrate cadavers and contribute to the important ecosystem service of carrion decomposition. The unveiling of anthropogenic and environmental drivers that modify carrion-associated rove beetle communities should improve our understanding of the plasticity of cadaver decay. We report the presence of 80 rove beetle species on 65 decomposing piglet cadavers at forest sites characterized by a gradient of management intensity across three geographic regions in Germany. Local and landscape drivers were revealed that shape beetle abundance, diversity, and community composition. Forest management and regions affect rove beetle abundance, whereas diversity is influenced by local habitat parameters (soil pH, litter cover) and regions. The community composition of rove beetles changes with management intensification by promoting generalist species. Regarding single species, Philonthus decorus and Anotylus mutator are linked to unmanaged forests and Ontholestes tessellatus to highly used forest stands. The spatial information provided about carrion-associated rove beetle communities in German forests is not only of carrion-ecological but also of forensic entomological interest