Biology subjects

Richter, R.

Publications and source records attributed to Richter, R..

At least 19 recordsLinked to original sources

bioRxiv2026

Constraints on the xylem safety-efficiency trade-off

The xylem safety-efficiency trade-off is a central paradigm in plant hydraulics, yet empirical support remains inconsistent. In this study, we highlight how this inconsistency may arise from variation in environmental and evolutionary constraints and from differences in observational scale. We analysed 38 diffuse-porous angiosperm and 24 conifer species grown in a common garden experiment to quantify the relationship between embolism resistance (P50) and specific hydraulic conductivity (Ks) across and within species, and its differences between three species groups differing in evolutionary ancestry and eco-hydrological strategy. When pooling over all species, we found evidence for a safety-efficiency trade-off both across and within species. However, this pattern was driven almost exclusively by the mesic broadleaved species. In contrast, the across-species pattern was suppressed in coniferous species due to the evolutionary constraints on efficiency posed by their tracheid-based wood anatomy, while there was no evidence for a trade-off on either level in hydrophilic broadleaved species, which evolved under conditions that pose reduced selective pressure on embolism resistance. Our results demonstrate that the safety-efficiency trade-off is not universal, but emerges only in specific ecological and evolutionary contexts, highlighting the importance of multi-scale analyses and constraint-based frameworks for interpreting plant hydraulic strategies.

plant biology↗

bioRxiv2026

Stomatal sensitivity to VPD across 38 tree species reflects past drought responses but is little explained by stomatal and leaf economic traits

Climate change is exposing trees to rising atmospheric water demand. Because stomata regulate plant water loss, understanding stomatal behaviour is critical. However, few comparative studies examine species-specific stomatal responses to atmospheric demand. Here, we quantify stomatal behaviour in 38 temperate tree species (27 broadleaved, 11 conifers) in a German research arboretum during a warm summer without soil drought. We measured the diurnal stomatal conductance (gs) of 787 leaves and modelled gs species-specific responses to leaf-to-air vapour pressure deficit (VPDL). Four descriptors of the gs-VPDL relationship were derived: maximum stomatal conductance (gmax), the VPDL that maximises gs, the VPDL associated with a 50% reduction in gs, and the stomatal closure rate. We relate these metrics to drought-induced shifts of carbon isotope ratios and to leaf functional traits. Large variation in stomatal behaviour exists, ranging from early-closure to VPDL-tolerant strategies. Species maintaining gs at higher VPDL also show weaker physiological responses to past drought. gmax is partly explained by leaf economic traits; other gs-VPDL descriptors are not related to stomatal anatomy and leaf economy. Our interspecific comparison reveals substantial variation in stomatal responses to atmospheric demand that is relevant to drought responses, but cannot be readily inferred from commonly measured leaf traits.

ecology↗

bioRxiv2026

Quantitative biophysical analysis of human septin hexamer and octamer self-assembly on model membranes

1Septins are GTP-binding cytoskeletal proteins that shape and compartmentalize the plasma membrane. Their complex interactome has made it difficult to understand the molecular factors that govern their assembly. Moreover, it is unclear whether human septin hexamers and octamers form distinct higher-order assemblies, especially at the plasma membrane. Here, we address this question by using label-free methods to probe binding and self-assembly of recombinant human septins on supported lipid bilayers. Quartz crystal microbalance with dissipation (QCM-D) monitoring revealed that septin-membrane binding is diffusion-limited and concentration-dependent. Hexamers and octamers showed distinct viscoelastic properties, suggestive of structural differences. Imaging by atomic force microscopy (AFM) revealed that septin hexamers formed aligned nematic filamentous networks, whereas septin octamers formed aligned curved structures including spirals. QCM-D and AFM measurements both showed that septins form double-layered filament networks. However, upon C-terminal truncation of the SEPT6 and SEPT7 subunits, hexamers no longer bound the membrane while octamers formed a single-layered network of filament spirals. Our findings reveal that human septin hexamers and octamers interact differently with membranes, providing a baseline to understand their functions in the cell. 2 Significance statementO_LISeptins are cytoskeletal proteins that control cell membrane shape and stiffness. It is poorly understood how septin oligomers, the basic building blocks of septin filaments, bind and assemble on membranes. C_LIO_LIWe used label-free biophysical assays to quantitatively compare the binding kinetics and self-assembly behavior of recombinant human septin hexamers and octamers on supported lipid bilayer membranes. C_LIO_LIOur findings reveal that human septin hexamers and octamers both form organized filamentous networks on membranes, but with different structural properties that may potentially translate into different biological functions. C_LI

biophysics↗

bioRxiv2026

Traversing the canopy: phenology-driven changes and within-canopy transport shape the phyllosphere microbiome in a temperate floodplain hardwood forest

O_LIPhyllosphere microbiomes are subject to microbial import from various sources and undergo substantial changes during phenological changes of plants. However, these processes are still poorly understood for forest canopies. We propose that phenology-driven changes in host properties, and rainwater-mediated, within-canopy transport shape the phyllosphere microbiome in temperate forests. Leaves and throughfall samples were collected from oak, ash and linden trees at top, mid, and bottom canopy positions at the Leipzig canopy crane facility (Germany) at time points representing early, mid and late phenological stages. Bacterial community composition was assessed by 16S rRNA gene amplicon sequencing. C_LIO_LIPhenological stages explained 19% of phyllosphere bacterial community variation, followed by tree species identity (12%) and canopy position (2%). Later phenological stages exhibited more homogeneous and functionally redundant phyllosphere communities along with a strong decline of plant pathogens and increasing potential for microbially mediated biocontrol mechanisms. Throughfall transported up to 1011 bacterial cells per litre with maximum bacterial fluxes at the canopy top. C_LIO_LIOur findings demonstrate that in temperate forests, phenology-driven effects on the phyllosphere microbiome are far more important than tree species specific effects. Extent and selectivity of throughfall-mediated mobilization may play a crucial role for the spatial heterogeneity of microbial communities in tree crowns. C_LI

ecology↗

bioRxiv2026

Sticker number modulates pyrenoid condensate assembly to support algal fitness

The valency of intrinsically disordered proteins underpins liquid-liquid phase separation (LLPS), yet how this parameter shapes condensate function and cellular fitness remains poorly understood. Here we exploit the algal pyrenoid-a minimal, two component LLPS system-to directly link condensate properties to physiological performance. Pyrenoid assembly is driven by a disordered, multivalent Linker protein that binds Rubisco at symmetry-related surface sites, with the number of binding motifs ("stickers") varying across species. Using Chlamydomonas reinhardtii, we systematically tuned sticker number from two to nine and examined effects on Rubisco condensation, pyrenoid architecture and CO2 fixation. Three stickers were sufficient for condensation in vitro, but at least four were required for pyrenoid assembly in vivo. Cryo-electron tomography and single-molecule tracking revealed that increasing sticker number enhances Rubisco packing and mobility, while time-resolved imaging and competition assays demonstrated that sticker number governs the kinetics of pyrenoid formation and determines cellular fitness under fluctuating carbon conditions. Our findings establish sticker number as an evolutionary tuning parameter that balances condensate formation, dynamics, and function, providing a quantitative framework for linking the molecular grammar of phase separation to biological fitness.

cell biology↗

bioRxiv2025

AngleCam V2: Predicting leaf inclination angles across taxa from daytime and nighttime photos

O_LIUnderstanding how plants capture light and maintain their energy balance is crucial for predicting how ecosystems respond to environmental changes. By monitoring leaf inclination angle distributions (LIADs), we can gain insights into plant behaviour that directly influences ecosystem functioning. LIADs affect radiative transfer processes and reflectance signals, which are essential components of satellite-based vegetation monitoring. Despite their importance, scalable methods for continuously observing these dynamics across different plant species throughout day-night cycles are limited. C_LIO_LIWe present AngleCam V2, a deep learning model that estimates LIADs from both RGB and near-infrared (NIR) night-vision imagery. We compiled a dataset of over 4,500 images across 200 globally distributed species to facilitate generalization across taxa. Moreover, we developed a method to simulate pseudo-NIR imagery from RGB imagery to enable an efficient training of a deep learning model for tracking LIADs across day and night. The model is based on a vision transformer architecture with mixed-modality training using the RGB and the synthetic NIR images. C_LIO_LIAngleCam V2 achieved substantial improvements in generalization compared to AngleCam V1 (R2 = 0.62 vs 0.12 on the same holdout dataset). Phylogenetic analysis across 100 genera revealed no systematic taxonomic bias in prediction errors. Testing against leaf angle dynamics obtained from multitemporal terrestrial laser scanning demonstrated the reliable tracking of diurnal leaf movements (R2 = 0.61-0.75) and the successful detection of water limitation-induced changes over a 14-day monitoring period. C_LIO_LIThis method enables continuous monitoring of leaf angle dynamics using conventional cameras, enabling applications in ecosystem monitoring networks, plant stress detection, interpreting satellite vegetation signals, and citizen science platforms for global-scale understanding of plant structural responses. C_LI

ecology↗

bioRxiv2025

Above- and below-ground trait coordination across 90 angiosperm and gymnosperm tree species

Quantifying the variation in plant traits reveals the trade-offs involved in plant ecological strategies and is fundamental to understanding underlying plant fitness mechanisms. Thus, the ecological success of plant species in a certain habitat may depend on the coordinated performance of both leaves and roots. However, despite the growing interest in trait variation, it is still uncertain i) to what extent the leaf economics spectrum (LES) and root economics space (RES) hold across locally coexisting tree species and ii) whether leaf and fine-root traits are correlated. In a research arboretum, we simultaneously measured eight key traits in leaves and fine-roots on 270 individuals belonging to 90 tree species, encompassing both angiosperm and gymnosperm species. We find varied plant resource strategies associated with leaves and fine-roots for angiosperms and gymnosperms. We observe a clear LES for gymnosperms and a clear RES for angiosperms. Our results support the existence of a correlation between analogous leaf and fine-root traits across all species. However, varying trait coordination across clades indicates varying resource acquisition strategies above- and belowground, highlighting the need to consider large-scale phylogenetic relatedness to better understand plant fitness.

ecology↗

bioRxiv2024

Functional traits explain growth resistance to successive hotter droughts across a wide set of common and future tree species in Europe

O_LIIn many regions worldwide, forests suffer from climate change-induced droughts. The hotter drought in Europe in 2018 with the consecutive drought years 2019 and 2020 caused large-scale growth declines and forest dieback. We investigated if tree growth responses to the 2018-2020 drought can be explained by tree functional traits related to drought tolerance, growth, and resource acquisition. C_LIO_LIWe assessed growth resistance, that is, growth during drought compared to pre-drought-conditions, in 71 planted tree species using branch shoot increments. We leveraged gap-filled trait data related to drought tolerance (P50, stomata density and conductivity), growth and resource acquisition (SLA, LNC, C:N, Amax) and wood density from the TRY database to explain growth resistance for gymnosperms and angiosperms. C_LIO_LIWe found significantly reduced growth during drought across all species. Legacy effects further decreased growth resistance in 2019 and 2020. Gymnosperms showed decreasing growth resistance with increasing P50 and acquisitiveness, such as high SLA, LNC, and Amax. Similar results were found for angiosperms, however, with less clear pattern. Four distinct response types emerged: Sufferer, Late sufferer, Recoverer and Resisters, with gymnosperms predominately falling into the Sufferer and Late sufferer categories. C_LIO_LIOur study provides evidence for significant growth reductions and legacy effects in response to consecutive hotter droughts, which can be explained by functional traits across a wide set of tree species. The a posteriori classification into response types revealed the diversity of temporal responses to a prolonged drought. We conclude that high drought tolerance bolsters growth resistance, while acquisitive species suffer stronger under drought. C_LI

ecology↗

bioRxiv2024

Tree growth is better explained by absorptive fine roots than transport fine roots

O_LIQuantifying plant trait variation yields insights into trade-offs inherent in the ecological strategies of plants and is the basis for a trait-based prediction of plant performance and ecosystem functioning. Although the interest in root traits has increased in recent years, we still have limited knowledge of i) whether functionally different fine roots--absorptive versus transport roots--have similar trait coordination and ii) how they help to explain plant performance, such as growth. C_LIO_LIWe measured traits of 25 European broadleaved tree species growing in a research arboretum to study i) the coordination of root traits within absorptive and transport fine roots and ii) the degree of trait-tree growth relationships. To do so, we combined a suite of morphological (root diameter, specific root length and root tissue density) and anatomical (cortex to stele ratio and arbuscular mycorrhizal colonization rate) traits for each of the absorptive and transport roots and also leaf traits (leaf mass per area, dry matter content and toughness). C_LIO_LIDespite remarkable differences in average trait values between absorptive and transport roots, our study shows that trait coordination within absorptive and transport roots is relatively equivalent. Our results also show that, for the traits we studied, tree growth is better explained by absorptive root traits than by transport root traits and is higher in species with a thinner root diameter. This suggests that variation primarily in absorptive roots affects the uptake of soil-based resources like nutrients and water and directly influences tree growth. C_LIO_LIThe significant relationship between absorptive roots and tree growth and the lack of such a relationship for transport roots highlights that roots mostly involved with resource absorption are more important in explaining tree growth than roots involved in transport. C_LI

ecology↗

bioRxiv2024

Forest growth resistance and resilience to the 2018-2020 drought depend on tree diversity and mycorrhizal type

O_LIThe frequency of consecutive drought years is predicted to increase due to climate change. These droughts have strong negative impacts on forest ecosystems. Mixing tree species is proposed to increase the drought resistance and resilience of tree communities. However, this promising diversity effect has not yet been investigated under extreme drought conditions and in the context of complementary mycorrhizal associations and their potential role in enhancing water uptake. C_LIO_LIHere, we investigate whether tree diversity promotes growth resistance and resilience to extreme drought and whether drought responses are modulated by mycorrhizal associations. We used inventory data (2015 - 2021) of a young tree diversity experiment in Germany, manipulating tree species richness (1, 2, 4 species) and mycorrhizal type (communities containing arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) tree species, or both). For all tree communities, we calculated basal area increment (BAI) in the periods before, during, and after the drought and used the concepts of resistance and resilience to quantify growth responses to drought. C_LIO_LIWe found strong growth declines during the extreme 2018-2020 drought for most of the tree communities. Contrary to our hypothesis, we did not find that tree species richness per se can buffer the negative impacts of extreme drought on tree growth. However, while for EM communities, drought resistance, and resilience decreased with tree species richness, they increased for AM communities and communities comprising both mycorrhizal types. We highlight that among various tree species mixtures, only those with mixed mycorrhizal types outperformed their respective monocultures during and after drought. Further, under extreme drought, the community tends to segregate into "winner" and "loser" tree species in terms of diversity, indicating a potential intensification of competition. C_LIO_LIWhile we cannot disentangle the underlying mechanisms, or clarify the role of mycorrhiza during drought, our findings suggest that mixtures of mycorrhizal types within tree communities could help safeguard forests against increasing drought frequency. C_LIO_LISynthesis: Drought resistance and resilience of tree communities depend on tree diversity and mycorrhizal association types. Mixing tree species with diverse mycorrhizal types holds promise for forest restoration in the face of climate change. C_LI

ecology↗

bioRxiv2023

Tree diversity increases forest temperature buffering

Global warming is increasing the frequency and intensity of climate extremes. Forests may buffer such extreme events by creating their own microclimate below their canopy via cooling hot and insulating against cold macroclimate air temperatures. This buffering capacity of forests may be increased by tree diversity and may itself maintain forest functioning and biodiversity. However, despite its relevance for many ecosystem processes, the effect of tree diversity on temperature buffering is largely unexplored. Here, we show that tree species richness consistently increases forest temperature buffering across daily, monthly, and annual scales over six years. This finding is based on data from a large-scale tree diversity experiment covering a species richness gradient of 1 to 24 tree species. We found that species richness strengthened both components of forest temperature buffering: the attenuation of hot and of cold macroclimate air temperatures, with the cooling effect being more pronounced. The buffering effect of tree species richness was mediated by canopy density and structural diversity, assessed as leaf area index and stand structural complexity index, respectively. Safeguarding and planting diverse forests may thus mitigate negative effects of global warming and climate extremes on ecosystem functions and communities below the tree canopy.

ecology↗

bioRxiv2022

Rapid reduction of Paraoxonase expression followed by inactivation across semiaquatic mammals suggests adaptive benefit of gene loss

Convergent adaptation to the same environment by multiple lineages frequently involves rapid evolutionary change at the same genes, implicating these genes as important for environmental adaptation. Such adaptive molecular changes may yield either change or loss of protein function; loss of function can eliminate newly deleterious proteins or reduce energy necessary for protein production. We previously found a striking case of recurrent pseudogenization of the Paraoxonase 1 (Pon1) gene among aquatic mammal lineages - Pon1 became a pseudogene with genetic lesions, such as stop codons and frameshifts, at least four times independently in aquatic and semiaquatic mammals. Here, we assess the landscape and pace of pseudogenization by studying Pon1 sequences, expression levels, and enzymatic activity across four aquatic and semiaquatic mammal lineages: pinnipeds, cetaceans, otters, and beavers. We observe in beavers and pinnipeds an unexpected reduction in expression of Pon3, a paralog with similar expression patterns but different substrate preferences. Ultimately, in all lineages with aquatic/semiaquatic members, we find that preceding any coding level pseudogenization events in Pon1, there is a drastic decrease in expression, followed by relaxed selection, thus allowing accumulation of disrupting mutations. The recurrent loss of Pon1 function in aquatic/semiaquatic lineages is consistent with a benefit to Pon1 functional loss in aquatic environments. Accordingly, we examine diving and dietary traits across pinniped species as potential driving forces of Pon1 functional loss. We find that loss is best correlated with diving activity and likely results from changes in selective pressures associated with hypoxia and hypoxia-induced inflammation.

evolutionary biology↗

bioRxiv2022

Flower patterns improve foraging efficiency in bumblebees independent of nectary guidance

Colourful patterns on flowers are thought to benefit both pollinators and the plants they visit, by increasing the plants pollination success via an improved foraging efficiency of its pollinators. This increased efficiency is thought to result from a guidance effect of the flower patterns, correspondingly termed nectar guides, which indicate the position of the nectary to visiting pollinators. While it is well established that flower patterns play an important role in flower choice, the mechanisms underlying their function for flower-visiting insects remain poorly understood. In this study, we quantified the contributions of patterns to all phases of flower interaction in the buff-tailed bumblebee (Bombus terrestris). We analysed their flight paths, as well as landing positions and walking tracks on artificial flowers with different pattern types. We reveal that flower patterns improved the overall foraging efficiency of the bees by up to 30%, by guiding their approach flight, landing positions, and departure decisions. Surprisingly, these effects were not related to nectary guidance. Since we conducted the experiments with experienced foragers, which represent the majority of insect pollinators active in nature, the newly described nectary-independent guidance effects of flower patterns are of fundamental importance to plant-pollinator interactions under natural conditions.

ecology↗

bioRxiv2021

Vegetation characteristics control sediment and nutrient retention on but not underneath vegetation in floodplain meadows

Sediment and nutrient retention are essential ecosystem functions that floodplains provide and that improve river water quality. During floods, the floodplain vegetation retains sediment, which settles on plant surfaces and the soil underneath plants. Both sedimentation processes require that flow velocity is reduced, which may be caused by the topographic features and the vegetation structure of the floodplain. However, the relative importance of these two drivers and their key components have rarely been both quantified. In addition to topographic factors, we expect vegetation height and density, mean leaf size and pubescence, as well as species diversity of the floodplain vegetation to increase the floodplains capacity for sedimentation. To test this, we measured sediment and nutrients (carbon, nitrogen and phosphorus) both on the vegetation itself and on sediment traps underneath the vegetation after a flood at 24 sites along the River Mulde (Germany). Additionally, we measured biotic and topographic predictor variables. Sedimentation on the vegetation surface was positively driven by plant biomass and the height variation of the vegetation, and decreased with the hydrological distance (total R2=0.56). Sedimentation underneath the vegetation was not driven by any vegetation characteristics but decreased with hydrological distance (total R2=0.42). Carbon, nitrogen and phosphorus content in the sediment on the traps increased with the total amount of sediment (total R2=0.64, 0.62 and 0.84, respectively), while C, N and P on the vegetation additionally increased with hydrological distance (total R2=0.80, 0.79 and 0.92, respectively). This offers the potential to promote sediment and especially nutrient retention via vegetation management, such as adapted mowing. The pronounced signal of the hydrological distance to the river emphasises the importance of a laterally connected floodplain with abandoned meanders and morphological depressions. Our study improves our understanding of the locations where floodplain management has its most significant impact on sediment and nutrient retention to increase water purification processes.

ecology↗

bioRxiv2021

Cumulative growth and stress responses to the 2018-2019 drought in a European floodplain forest

Droughts increasingly threaten the worlds forests and their potential to mitigate climate change. In 2018-2019, Central European forests were hit by two consecutive hotter drought years, an unprecedented phenomenon that is likely to occur more frequently with climate change. Here, we examine tree growth and physiological stress responses (increase in carbon isotope composition; {Delta}{delta}13C) to this consecutive drought based on tree-rings of dominant tree species in a Central European floodplain forest. Tree growth was not reduced for most species in 2018, indicating that water supply in floodplain forests can partly buffer meteorological water deficits. Drought stress responses in 2018 were comparable to former single drought years but the hotter drought in 2018 induced drought legacies in tree growth while former droughts did not. We observed strong decreases in tree growth and increases in {Delta}{delta}13C across all tree species in 2019, which are likely driven by the cumulative stress both consecutive hotter droughts exerted. Our results show that consecutive hotter droughts pose a novel threat to forests under climate change, even in forest ecosystems with comparably high levels of water supply.

ecology↗

bioRxiv2021

Climate, latitude, and land cover predict flying insect biomass across a German malaise trap network

O_LIAmong the many concerns for biodiversity in the Anthropocene, recent reports of flying insect loss are particularly alarming, given their importance as pollinators and as a food source for many predators. Few insect monitoring programs cover large spatial scales required to provide more generalizable estimates of insect responses to global change drivers. C_LIO_LIWe ask how climate and surrounding habitat affect flying insect biomass and day of peak biomass using data from the first year of a new standardized distributed monitoring network at 84 locations across Germany comprising spatial gradient of land-cover types from protected to urban areas. C_LIO_LIFlying insect biomass increased linearly with monthly temperature across Germany. However, the effect of temperature on flying insect biomass flipped to negative in the hot months of June and July when local temperatures most exceeded long-term averages. C_LIO_LILand-cover explained little variation in insect biomass, but biomass was lowest in forested sites. Grasslands, pastures and orchards harbored the highest insect biomass. The date of peak biomass was primarily driven by surrounding land-cover type, with grasslands especially having earlier insect biomass phenologies. C_LIO_LIStandardized, large-scale monitoring is pivotal to uncover underlying processes of insect decline and to develop climate-adapted strategies to promote insect diversity. In a temperate climate region, we find that the benefits of temperature on flying insect biomass diminish in a German summer at locations where temperatures most exceeded long-term averages. These results highlighting the importance of local adaptation in climate change-driven impacts on insect communities. C_LI

ecology↗

bioRxiv2020

Strong reduction of the chain rigidity of hyaluronan by selective binding of Ca2+ ions

The biological functions of natural polyelectrolytes are strongly influenced by the presence of ions, which bind to the polymer chains and thereby modify their properties. Although the biological impact of such modifications is well-recognized, a detailed molecular picture of the binding process and of the mechanisms that drive the subsequent structural changes in the polymer is lacking. Here, we study the molecular mechanism of the condensation of calcium, a divalent cation, on hyaluronan, a ubiquitous polymer in human tissues. By combining two-dimensional infrared spectroscopy experiments with molecular dynamics simulations, we find that calcium specifically binds to hyaluronan at millimolar concentrations. Because of its large size and charge, the calcium cation can bind simultaneously to the negatively charged carboxylate group and the amide group of adjacent saccharide units. Molecular dynamics simulations and single-chain force spectroscopy measurements provide evidence that the binding of the calcium ions weakens the intra-molecular hydrogen-bond network of hyaluronan, increasing the flexibility of the polymer chain. We also observe that the binding of calcium to hyaluronan saturates at a maximum binding fraction of ~10-15 mol %. This saturation indicates that the binding of Ca2+ strongly reduces the probability of subsequent binding of Ca2+ at neighboring binding sites, possibly as a result of enhanced conformational fluctuations and/or electrostatic repulsion effects. Our findings provide a detailed molecular picture of ion condensation, and reveal the severe effect of a few, selective and localized electrostatic interactions on the rigidity of a polyelectrolyte chain. TOC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=74 SRC="FIGDIR/small/277194v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@d0e95borg.highwire.dtl.DTLVardef@1886d60org.highwire.dtl.DTLVardef@1c4c4aborg.highwire.dtl.DTLVardef@14bcf0d_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2020

Molecular phylogeny and historical biogeography of andrenine bees (Hymenoptera: Andrenidae)

The mining bee subfamily Andreninae (Hymenoptera: Andrenidae) is a widely distributed and diverse group of ground-nesting solitary bees, including numerous species known as important pollinators. Most of the species diversity of Andreninae is concentrated in the mainly Holarctic genus Andrena, comprising ca. 1500 described species. The subfamily and especially the genus have remained relatively neglected by recent molecular phylogenetic studies, with current classifications relying largely on morphological characters. We sampled ultraconserved element (UCE) sequences from 235 taxa, including all andrenine genera and 98 out of 104 currently recognized Andrena subgenera. Using 419,858 aligned nucleotide sites from 1009 UCE loci, we present a comprehensive molecular phylogenetic analysis of the subfamily. Our analysis supports the recognition of seven distinct genera in the Andreninae: Alocandrena, Ancylandrena, Andrena, Cubiandrena, Euherbstia, Megandrena, and Orphana. Within the genus Andrena, present-day subgeneric concepts revealed high degrees of paraphyly and polyphyly, due to heavy morphological character homoplasy, necessitating a thorough, extensive revision of the higher classification of the genus. Our results also show that the MRCA of Andrena+Cubiandrena dispersed from the New World to the Palaearctic probably during the Eocene- early Oligocene, followed by 10-14 Neogene dispersal events from the Palaearctic to the Nearctic and 1-6 Neogene dispersals back into the Palaearctic, all within the genus Andrena. HighlightsO_LIA phylogeny is presented for the bee subfamily Andreninae based on UCE sequences C_LIO_LIThe Eastern Mediterranean subgenus Cubiandrena is sister to all remaining Andrena C_LIO_LIMany Andrena subgenera exhibit paraphyly or polyphyly, requiring recircumscription C_LIO_LIAt least 11 Old World-New World exchange events have occurred within Andrena C_LI

evolutionary biology↗