Biology subjects

Rasmann, S.

Publications and source records attributed to Rasmann, S..

10 recordsLinked to original sources

bioRxiv2026

Glacier retreat reshapes trophic networks: interaction turnover outpaces species turnover over space-time

As glaciers retreat worldwide, newly exposed terrains are rapidly colonized by plants and their associated animal communities. Although plant-animal interactions are key for biodiversity maintenance and ecosystem functioning, the ecological processes underlying the assembly and development of trophic interactions over space-time remain poorly understood. Here, we investigated the trophic niche structure of plant-arthropod interactions along a 140-year primary succession at Mont Mine glacier foreland (Switzerland). Using arthropod gut-content DNA metabarcoding, we reconstructed trophic interactions at the food web level, revealing numerous previously undetected links among 284 arthropod taxa feeding on 263 plant taxa. Trophic niche overlap among arthropods increased following glacier retreat, indicating decreasing resource partitioning and suggesting increased resource competition. Trophic niche breadth became narrower and diet species richness declined, indicating increased trophic specialization. Notably, changes in trophic interactions occurred more rapidly than shifts in species diversity or community composition of plants and arthropods. These results demonstrate that glacier retreat reorganizes trophic networks beyond simple species turnover, reshaping biotic interactions during ecosystem development. Our findings highlight trophic interactions as sensitive indicators of biodiversity change and suggest that the stability of emerging food webs may be strongly affected as glaciers vanish worldwide.

ecology↗

bioRxiv2026

Photorhabdus metabolites reshape soil microbial communities and promote plant growth and insect resistance

Photorhabdus bacteria are potent insect-killing microbes associated with entomopathogenic nematodes and offer opportunities for environmentally benign pest control. They can be applied as foliar sprays or soil drenches without their nematode vector, resulting in massive amounts of Photorhabdus cells and their (toxic) metabolites introduced into the soil. However, their effects beyond the target organisms are unknown. To fill this knowledge gap, we investigated the soil legacy effects of Photorhabdus cells and their metabolites on soil microbial communities, plant performance and resistance to herbivores. To this end, we first conditioned soils with i) mechanically killed (MK) or Photorhabdus-infected insect larvae, ii) aqueous extracts of MK or Photorhabdus-infected insect larvae, iii) cell-free Photorhabdus supernatants, iv) autoclaved soil complemented with live soil previously conditioned with MK or Photorhabdus-infected insect larvae. We then grew maize plants in these soils and measured plant biomass, profiled soil microbial communities and plant metabolites, and evaluated plant resistance against two pest insects Diabrotica balteata and Spodoptera frugiperda. We found that conditioned soils increased plant biomass by 10-26% relative to controls and significantly altered soil bacterial and nematode communities, and to a lesser extent, fungal communities. Re-inoculating conditioned soil microbiota into autoclaved soils recreated the plant growth-promoting effects, indicating microbial-mediated mechanisms. Additionally, plants grown in soils conditioned with Photorhabdus-infected insect cadavers were often more resistant to herbivorous insect attack, in a strain-specific manner. On average, D. balteata and S. frugiperda larvae gained 10-20% and 10-59% less weight, respectively, when fed on plants grown in conditioned soils than on plants grown in control soils. The plant metabolic profiles of plant leaves and roots also varied with resistance levels. We conclude that Photorhabdus metabolites modulate soil microbial communities towards a structure that enhances plant growth and triggers systemic responses against herbivores.

microbiology↗

bioRxiv2025

The role of peripheral regions in shaping the phylogeography of the Bear s ear complex across the Alps

AimPeripheral regions of the Alps are often overlooked in molecular studies, yet they may play a major role in shaping the current distribution of species and genetic lineages. LocationEurope TaxonAngiosperms (Primulaceae: Primula) MethodsBy focusing on the bears ear (Primula auricula) complex as model species, we used genetic inferences for population genetic structure and performed genetic reconstructions, species delimitations and divergence time estimates in order to get a detailed view of its molecular evolution and current genetic structuring across the Alps sensu lato. ResultsThe Lombardian Alps and the southern eastern Alps are genetically distinct in the vicinity of the Adige valley. The northern and western Alps and their peripheries constitute a third clade and are separated by the siliceous central Alps. Within the latter, an additional cluster made of singular populations from the Devoluy and Vercors regions is retrieved, likely reflecting a strong founder effect rather than an ancient divergence. Main conclusionsThe biogeographic history P. auricula sensu lato pinpoints the importance of the peripheral regions in a phylogeographic context. Populations from northern peripheral regions exhibit long-lasting isolation and in situ survival during glaciations, followed by recolonization into the central Alpine massif.

genetics↗

bioRxiv2024

Odor-based real-time detection and identification of pests and diseases attacking crop plants

Early detection of crop pests and diseases can enable timely, targeted interventions, and help reduce pesticide use. Plants under biotic stress are known to rapidly emit characteristic blends of volatile compounds that could potentially serve as early and attacker-specific cues for precise pest monitoring. Here, we evaluated the feasibility of this approach using two complementary, state-of-the-art sensing technologies: a handheld nanomechanical membrane-based sensor array and chemical ionization time-of-flight mass spectrometry. Under laboratory conditions, with enclosed headspace sampling, both technologies readily distinguished undamaged maize plants from plants infested by caterpillars or infected with a fungal pathogen. Under semi-controlled outdoor open-air conditions, where volatile concentrations were strongly diluted, the membrane-based sensor no longer retained discriminatory power, whereas mass spectrometry predicted herbivory status with more than 90% accuracy using one-second measurements. Finally, in an initial field trial based on simulated herbivory, a compact, field-deployable, real-time mass spectrometer distinguished damaged from undamaged maize plants with highly encouraging performance under real field conditions. Together, these results demonstrate the potential of odor-based detection of pest attacks in maize and identify real-time mass spectrometry as a promising tool for crop monitoring, while pinpointing challenges that remain to be addressed for translation to practical field applications.

plant biology↗

bioRxiv2024

plantMASST - Community-driven chemotaxonomic digitization of plants

Understanding the distribution of hundreds of thousands of plant metabolites across the plant kingdom presents a challenge. To address this, we curated publicly available LC-MS/MS data from 19,075 plant extracts and developed the plantMASST reference database encompassing 246 botanical families, 1,469 genera, and 2,793 species. This taxonomically focused database facilitates the exploration of plant-derived molecules using tandem mass spectrometry (MS/MS) spectra. This tool will aid in drug discovery, biosynthesis, (chemo)taxonomy, and the evolutionary ecology of herbivore interactions.

plant biology↗

bioRxiv2023

Leaf metabolic traits reveal hidden dimensions of plant form and function

The plant metabolome encompasses the biochemical mechanisms through which evolutionary and ecological processes shape plant form and function1,2. However, while the metabolome should thus be an important component of plant life-history variation3, we know little about how it varies across the plant kingdom. Here, we use the plant functional trait concept4 - a powerful framework for describing plant form and function5-7 - to interpret leaf metabolome variation among 457 tropical and 339 temperate plant species. Distilling metabolite chemistry into five discriminant metabolic functional traits reveals that plants vary along two major axes of leaf metabolic specialization - a leaf chemical defense spectrum and an expression of leaf longevity. These axes are qualitatively consistent for tropical and temperate species, with many trait combinations being viable. However, axes of leaf metabolic specialization vary orthogonally to life-history strategies described by widely used functional traits5-7, while being at least equally important to them. Our findings question classical trait6 and plant defense8 theory that predicts relationships between the leaf chemical phenotype, plant productivity, and pace of life. Moreover, we show that metabolic functional traits describe unique dimensions of plant life-history variation that are complementary to, and independent from, those captured by existing plant functional traits.

ecology↗

bioRxiv2020

Within-species floral odor variation is maintained by spatial and temporal heterogeneity in pollinator communities

Floral odor is a complex trait that mediates many biotic interactions, including pollination. While high intraspecific floral odor variation appears to be common, the ecological and evolutionary drivers of this variation are often unclear. Here, we investigated the influence of spatially and temporally heterogeneous pollinator communities on floral odor variation in Arum maculatum (Araceae). Through Europe-wide field surveys, we identified high floral odor diversity and shifts in the dominant pollinator species within several A. maculatum populations compared to pollinator data from the same sites ten years ago. Using common-garden experiments, we further confirmed that inflorescences from native and foreign pollinator backgrounds were equally efficient at attracting local pollinators. The substantial within-population floral odor variation we observed may therefore be advantageous when facing temporally heterogeneous pollinator communities. We propose spatio-temporal heterogeneity in pollinators as one potential mechanism maintaining diverse floral odor bouquets in angiosperms.

ecology↗

bioRxiv2019

Genotypic Variation in Below- to Aboveground Systemic Induction of Glucosinolates Mediates Plant Fitness Consequences under Herbivore Attack

Plants defend themselves against herbivore attack by constitutively producing toxic secondary metabolites, as well as by inducing them during herbivore feeding. Induction of secondary metabolites can cross plant tissue boundaries, such as from root to shoot. However, whether the potential for plants to systemically induce secondary metabolites from roots to shoots shows genetic variability, and thus, potentially, is under selection conferring fitness benefits to the plants is an open question. To address this question, we induced 26 maternal plant families of the wild species Cardamine hirsuta belowground (BG) using the wound-mimicking phytohormone jasmonic acid (JA). We measured resistance against a generalist (Spodoptera littoralis) and a specialist (Pieris brassicae) herbivore species, as well as the production of glucosinolates (GSLs) in plants. We showed that BG induction increased AG resistance against the generalist but not against the specialist, and found substantial plant family-level variation for resistance and GSL induction. We further found that the systemic induction of several GSLs tempered the negative effects of herbivory on total seed set production. Using a widespread natural system, we thus confirm that BG to AG induction has a strong genetic component, and it can be under positive selection by increasing plant fitness. We suggest that natural variation in systemic induction is in part dictated by allocation trade-offs between constitutive and inducible GSL production, as well as natural variation in AG and BG herbivore attack in nature.

ecology↗

bioRxiv2018

Variable Effects on Growth and Defence Traits for Plant Ecotypic Differentiation and Phenotypic Plasticity along Elevation Gradients

Along ecological gradients, ecotypes generally evolve as the result of local adaptation to a specific environment to maximize organisms fitness. Alongside ecotypic differentiation, phenotypic plasticity, as the ability of a single genotype to produce different phenotypes under different environmental conditions, can also evolve for favouring increased organisms performance in different environments. Currently, there is a lack in our understanding of how varying habitats may contribute to the differential contribution of ecotypic differentiation and plasticity in growth versus defence traits. Using reciprocal transplant-common gardens along steep elevation gradients, we evaluated patterns of ecotypic differentiation and phenotypic plasticity of two coexisting but unrelated plant species, Cardamine pratensis and Plantago major. For both species, we observed ecotypic differentiation accompanied by plasticity in growth related traits. Plants grew faster and produced more biomass when placed at low elevation. In contrast, we observed fixed ecotypic differentiation for defence and resistance traits. Generally, low elevation ecotypes produced higher chemical defences regardless of the growing elevation. Yet, some plasticity was observed for specific compounds, such as indole glucosinolates. We speculate that ecotypic differentiation in defence traits is maintained by costs of chemical defence production, while plasticity in growth traits is regulated by temperature driven growth response maximization.

ecology↗

bioRxiv2018

Evolutionary dynamics of specialization in herbivorous stick insects

Understanding the evolutionary dynamics underlying herbivorous insect mega-diversity requires investigating the ability of insects to shift and adapt to different host plants. Feeding experiments with nine related stick insect species revealed that insects retain the ability to use ancestral host plants after shifting to novel hosts, with host plant shifts generating fundamental feeding niche expansions. These expansions were not accompanied by expansions of the realized feeding niches however, as species on novel hosts are generally ecologically specialized. For shifts from angiosperm to chemically challenging conifer hosts, generalist fundamental feeding niches even evolved jointly with strong host plant specialization, indicating that host plant specialization is more likely driven by species interactions than by constraints imposed by plant chemistry. By coupling analyses of plant chemical compounds, fundamental and ecological feeding niches in multiple insect species, we provide novel insights into the evolutionary dynamics of host range expansion and contraction in herbivorous insects.

evolutionary biology↗