Biology subjects

Meyer, S. T.

Publications and source records attributed to Meyer, S. T..

7 recordsLinked to original sources

bioRxiv2025

Why they occur here but not there - a case study of Great Spotted Woodpeckers in the city of Munich

O_LIMany animal species can occur in the urban environment. The factors determining whether a particular species can live in a particular place in the city are, however, often not known. Such knowledge is needed to be able to design a built environment that is suitable for species. C_LIO_LIThe Great Spotted Woodpecker, Dendrocopos major, breeds in self-made cavities in trees and regularly occurs in cities. Here, we used a number of approaches to elucidate the factors that influence the occurrence of woodpeckers in the build-up area of the city. C_LIO_LIWe studied the occurrence of D. major on 103 squares in Munich, Germany and linked their presence to a number of square features such as square size, position in the city, tree occurrences, and a number of other variables. We also observed the presence of woodpecker cavities and undertook behavioural observations to study tree use. C_LIO_LIWoodpeckers were observed on 60% of the squares. A random forest model showed that the number of humans on squares negatively affected woodpecker occurrence, while a number of tree-related variables, such as tree density, tree diversity, the number of old trees (>60 cm DBH), and the sum of DBH of trees on the square, positively affected occurrence. Some other variables were also important, such as the amount of green in the surroundings and the distance to the city centre. C_LIO_LINests were found only in trees with a DBH>20 cm, and there was a distinct preference for larger trees, whereby a range of species was accepted. Behavioural observations showed that woodpeckers used a wide variety of trees, including small ones. Particular species and trees with a DBH>20 cm are preferred. C_LIO_LIOur study shows that humans can design public places for the presence of the Great Spotted Woodpecker by providing a locally high abundance of trees of different species with total DBH close to 25m. Trees in the surroundings and the presence of softwood trees with >40 cm will make it more likely that woodpeckers will use such sites in the city. C_LI Statement on inclusionOur study brings both established scientists with permanent faculty positions with Ph.D.-students and students of the 2nd year of their B.Sc.-studies or 1st or 2nd year of their M.Sc.-studies for whom this work is the first experience in the publication of scientific results. Students were particularly encouraged to contribute to question and hypothesis development as well as analysis and interpretation.

ecology↗

bioRxiv2025

Plant diversity shapes plant volatile emission differently at the species and community level

Studies have investigated the interactions between plants through competition and resource sharing to understand the mechanisms behind the positive effects of plant diversity on productivity. Volatile organic compounds (VOCs) are important info-chemicals in plant-plant interactions, but they have so far rarely been considered in this context. Here, we measured VOC emissions at both community and species levels (Plantago lanceolata) in experimental plant communities of varying diversity (The Jena Experiment) to understand the role of VOCs in driving biodiversity-ecosystem functioning relationships. We show that plant diversity determines the release of plant VOCs at both levels. At the community level, plant species richness directly enhanced VOC emission and increased VOC richness both directly and indirectly by altering herbivore damage and LAI. At the species level, plant diversity did not directly affect the VOC emissions of P. lanceolata but indirectly affected it by influencing the VOC emissions from the surrounding community. Plantago lanceolata individuals in communities with high concentrations of green leaf volatiles decreased their VOC emission, while those in communities with high concentrations of terpenoids increased their VOC diversity. Our results provide first evidence that plant diversity shapes community-level plant VOC emission and thus influences focal plant VOC emission inside the community.

ecology↗

bioRxiv2025

Plant diversity promotes aboveground arthropods and associated functions despite arthropod loss over time

Arthropods comprise the majority of terrestrial biodiversity and play key roles in ecosystem functioning. Biodiverse grasslands support many arthropods, yet such ecosystems have declined due to land conversion and management changes. While restoration aims to conserve species-rich grasslands, long-term effects of plant richness on arthropod communities and associated functions remain underexplored. We addressed this gap by quantifying arthropods, herbivory, and predation over 13 years (2010-2022) across 80 grassland plots with varying plant richness. We examined (1) temporal trends in arthropod communities, herbivory and predation and whether changes depended on plant richness, (2) whether plant richness effects varied or strengthened over time, and (3) whether arthropod changes affected associated functions. Arthropod metrics declined over time across all plant richness levels, with average losses mainly being more pronounced in species-poor mixtures. Plant richness consistently had a positive effect on arthropods and their functions, although this effect varied between years without a consistent temporal trend. Notably, temporal changes in arthropod community metrics did not predict shifts in associated functions. Our findings highlight the dynamic interplay between plant richness and arthropods. From a conservation perspective, we can conclude that diversification in grasslands- the increase in plant diversity- directly supports arthropods and associated functions. Additionally, first trends indicate that the maintenance and protection of diverse semi-natural grasslands over a long period might mitigate the arthropod loss driven by environmental changes. In other words, diverse grasslands may buffer against the ongoing arthropod loss, though this effect may take years to become apparent. This again emphasizes the long-term nature of conservation efforts.

ecology↗

bioRxiv2024

BirdNET is as good as experts for acoustic bird monitoring in a European city

BirdNET has become a leading tool for recognising bird species in audio recordings. However, its applicability in ecological research has been questioned over the sometimes large number of species falsely identified. Using species-specific confidence thresholds has been identified as a powerful approach to solving this issue. However, determining these thresholds is time and resource-consuming. While optimising the parameter setting of the algorithm could be an alternative strategy, the effect of parameter settings on the algorithms performance is not well understood. Here, we compared the species identification of BirdNET against expert identification using an acoustic dataset comprising 930 minutes of recordings collected in Munich, Germany. The performance of BirdNET was evaluated using three performance metrics: precision, recall, and F1-score. The metrics were calculated using 24 combinations of the parameters: week, sensitivity, and overlap at four temporal aggregations (pooling of data across time intervals) to also test the effects of recording length. We found that BirdNET closely matched expert identification, particularly when given more data (higher temporal aggregation, F1 score = 0.84) and when including the parameters week of the year, a suitable sensitivity, and an overlap of one to two seconds. Thus, while there are still limitations, using appropriate parameter settings and recording durations, BirdNET yields results comparable to experts without the need for time-consuming estimation of species-specific thresholds. This approach offers reliable presence-absence data in a fast and efficient way while species-specific thresholds are not readily available.

ecology↗

bioRxiv2024

Rampant transcription replication conflict creates therapeutic vulnerability in extrachromosomal DNA containing cancers

Extrachromosomal DNA (ecDNA) presents a major challenge for precision medicine, contributing to poor survival for patients with oncogene-amplified tumours. EcDNA renders tumours resistant to targeted treatments by facilitating massive transcription of oncogenes and rapid genome evolution. At present, there are no ecDNA- specific treatments. Here we show that enhancing transcription replication conflict enables targeted elimination of ecDNA-containing cancers, exposing an actionable vulnerability. Stepwise analyses of ecDNA transcription reveal landscapes of pervasive RNA transcription and associated single-stranded DNA, leading to excessive transcription replication conflicts and replication stress (RS) compared to chromosomal loci. Nucleotide incorporation onto growing DNA strands is markedly slower on ecDNA, and RS is significantly higher in ecDNA-containing tumours regardless of cancer type or oncogene cargo. Replication Protein A2 phosphorylated on serine 33, a mediator of DNA damage repair that binds single-stranded DNA, shows elevated localization on ecDNA in a transcription dependent manner, along with increased DNA double strand breaks, and activation of the S-phase checkpoint kinase, CHK1. Genetic or pharmacological CHK1 inhibition abrogates the DNA replication check point, causing extensive and preferential tumour cell death in ecDNA-containing tumours as they enter S-phase. To exploit this vulnerability, we develop a highly selective, potent, and bioavailable oral CHK1 inhibitor, BBI-2779, and demonstrate that it preferentially kills ecDNA-containing tumour cells. In a gastric cancer model containing FGFR2 on ecDNA, BBI-2779, suppresses tumour growth and prevents ecDNA-mediated acquired resistance to the pan-FGFR inhibitor infigratinib, resulting in potent and sustained tumour regression in mice. These results reveal transcription-replication conflict as an ecDNA-generated vulnerability that can be targeted as an ecDNA-directed therapy and suggest that synthetic lethality of excess can be exploited as a strategy for treating cancer.

cancer biology↗

bioRxiv2020

Obesity control by SHIP inhibition requires pan-paralog inhibition and an intact eosinophil compartment

Previously a small molecule SHIP inhibitor, K118, was shown to reverse high-fat diet induced obesity and improve blood glucose regulation in obese mice. K118 treatment was also found to increase the frequency and number of IL-4 producing eosinophils in the visceral fat as well two potent immunoregulatory myeloid cell populations: M2-polarized macrophages and myeloid derived suppressor cells (MDSC) suggesting an immune regulatory mechanism. However, the cell(s) or SHIP paralog that should be targeted to improve metabolic regulation was not defined. Here we extend our understanding of how chemical inhibition of SHIP paralogs improves metabolic regulation during excess caloric intake. Here we compare SHIP inhibitors in an obesity prevention model and find that selective inhibitors for SHIP1 or SHIP2 lack the ability to prevent weight gain and body fat accumulation during increased caloric intake. Surprisingly, only pan-SHIP1/2 inhibitors can prevent diet-induced obesity. We confirm that both SHIP1 and SHIP2 must be targeted by showing that dual treatment with the SHIP1 and SHIP2 selective inhibitors can reduced adiposity caused by excess caloric consumption. We also show that pan-SHIP1/2 inhibitors of two different chemical classes can control diet-induced obesity and improve blood glucose regulation. Intriguingly, we find that both classes of pan-SHIP1/2 inhibitors require an intact eosinophil compartment to prevent diet-related fat accumulation demonstrating pan-SHIP1/2 inhibitors act via the VAT innate immune compartment to control adiposity However, improved blood glucose regulation by pan-SHIP1/2 inhibition is not dependent upon eosinophils, indicating a separate mechanism of action for diet-related loss of glucose regulation.

immunology↗

bioRxiv2019

The results of biodiversity-ecosystem functioning experiments are realistic

A large body of research shows that biodiversity loss can reduce ecosystem functioning, thus providing support for the conservation of biological diversity1-4. Much of the evidence for this relationship is drawn from biodiversity-ecosystem functioning experiments (hereafter: biodiversity experiments), in which biodiversity loss is simulated by randomly assembling communities of varying species diversity, and ecosystem functions are measured5-9. This random assembly has led some ecologists to question the relevance of biodiversity experiments to real-world ecosystems, where community assembly may often be non-random and influenced by external drivers, such as climate or land-use intensification10-18. Despite these repeated criticisms, there has been no comprehensive, quantitative assessment of how experimental and real-world plant communities really differ, and whether these differences invalidate the experimental results. Here, we compare data from two of the largest and longest-running grassland biodiversity experiments globally (Jena Experiment, Germany; BioDIV, USA) to related real-world grassland plant communities in terms of their taxonomic, functional, and phylogenetic diversity and functional-trait composition. We found that plant communities of biodiversity experiments have greater variance in these compositional features than their real-world counterparts, covering almost all of the variation of the real-world communities (82-96%) while also containing community types that are not currently observed in the real world. We then re-analysed a subset of experimental data that included only ecologically-realistic communities, i.e. those comparable to real-world communities. For ten out of twelve biodiversity-ecosystem functioning relationships, biodiversity effects did not differ significantly between the full dataset of biodiversity experiments and the ecologically-realistic subset of experimental communities. This demonstrates that the results of biodiversity experiments are largely insensitive to the inclusion/exclusion of unrealistic communities. By bridging the gap between experimental and real-world studies, these results demonstrate the validity of inferences from biodiversity experiments, a key step in translating their results into specific recommendations for real-world biodiversity management.

ecology↗