Biology subjects

Biedermann, P.

Publications and source records attributed to Biedermann, P..

3 recordsLinked to original sources

bioRxiv2025

The Invisible Heterogeneity of a Forest -- Beta Diversity of Volatiles

Forest structural heterogeneity affects biodiversity, yet how changes in forest structure influence the spatial patterns of forest chemical heterogeneity remains poorly understood. Volatile organic compounds (VOCs) create invisible chemical landscapes that influence forest ecosystem processes, but whether VOC {beta}-diversity patterns respond to silviculture or disturbance caused heterogeneity remains unknown. We quantified how enhanced structural beta complexity (ESBC) treatments affect VOC {beta}-diversity patterns and investigated potential drivers and ecological effects in temperate production forests. Using the experimental BETA-FOR framework, we sampled ambient forest air at the forest floor and 1 m heights across 234 forest patches in six German regions using Tenax/Carboxen adsorbent traps analyzed via TD-GCMS. Results from generalized linear beta regression models showed that {beta}-diversity of VOCs increased significantly at 1 m height in ESBC forests compared to control forests, but this increase was not significant at the forest floor. In contrast to studies on plants, fungi and animals, the main driver for increasing beta-diversity in VOCs was not the heterogeneity of canopy openness, but the amount of deadwood. Using saproxylic beetles as a test group, we found that saproxylic beetle community dissimilarity increased with VOC dissimilarity, but only for forest floor VOCs. Our finding adds a new component to the framework of habitat heterogeneity, the invisible gradient of volatile diversity utilized by many forest organisms. Furthermore, we provide the first evidence that enhancing the heterogeneity of forests, and particularly of the dead wood, increase not only the structural heterogeneity but also the volatile {beta}-diversity.

ecology↗

bioRxiv2025

Genomic Insights into the Evolution of Parental Care in Weevils

Parental care, a key step in the evolution of sociality, has evolved multiple times in insects, yet the molecular mechanisms underlying its emergence remain poorly understood. Weevils (Curculionidae) exhibit diverse parental care behaviours, from nest building to egg and larval attendance, making them an ideal system to investigate genomic changes associated with subsociality. We analysed 13 high-quality weevil genomes, encompassing independent origins of egg and larval attendance, to test two predictions: (1) the sheltering hypothesis, where parental care relaxes selection on traits critical for independent larval survival, and (2) the regulatory hypothesis, where behavioural shifts are driven by changes in transcriptional regulation. Gene family evolution analyses revealed significantly more convergent contractions, particularly in genes linked to transcriptional regulation and enzymatic activity, on branches where larval attendance evolved, consistent with functional gene loss under relaxed selection. Selection analyses identified over 400 genes under relaxed selection, especially those associated with transcriptional regulation and neural plasticity, further supporting hypothesis 1. In contrast, positive selection and intensified selection were rare but enriched for genes regulating gene expression, consistent with hypothesis 2. Together, these results suggest that parental care in weevils drives both simplification of larval traits through relaxed selection and convergent gene loss, and innovation in caregiving behaviours via adaptive changes in gene regulation. Significance statementParental care is a pivotal evolutionary innovation, yet its genetic basis in insects remains underexplored. By comparing genomes from weevil species with and without care behaviours, we reveal two key processes shaping the emergence of subsociality: relaxation of selection on genes linked to larval independence and adaptive evolution in genes regulating gene expression. This combination likely reflects reduced demands on protected larvae alongside fine-tuning of parental behaviours. Our findings highlight how simple social systems can evolve through both loss and innovation, offering a comparative framework for understanding social evolution across insects.

evolutionary biology↗

bioRxiv2024

Effects of selection for early dispersal on the ambrosia beetle Xyleborinus saxesenii and its fungal symbionts

Overlapping generations is a defining characteristic of advanced social life. In cooperative breeding societies, for example, temporary groups of mature offspring are formed that assist in the rearing of additional brood before the offspring disperse and reproduce independently. It is hypothesized that the number of helpers and their delayed dispersal period will determine the number of siblings that can be reared, thus resulting in an indirect fitness gain. The objective of this study, was to investigate the effect of artificial selection for early dispersal of mature offspring on the life history, behaviour and fungal symbionts in the cooperatively breeding ambrosia beetle Xyleborinus saxesenii. Two lineages of beetles were bred in the laboratory for five successive generations. In one group, dispersing females were selected at random to initiate the next generation, while in the other group, only early dispersers were selected. A number of life-history traits exhibited a pronounced response in the initial generation, subsequently recuperating to levels approximating those observed at the outset of the experiment. The laboratory rearing resulted in an increasing proportion of successful nests in both lineages. Additionally, the control lineage exhibited a reduction in lifespan and in productivity. Furthermore, significant differences were observed in the fungal communities from the third generation onwards. The results suggest that X. saxesenii has limited potential to respond to this selection pressure, potentially due to sibmating and resulting low genetic variability. Furthermore, the correlation between nest lifespan and productivity is a crucial factor in explaining philopatry and altruism in this species.

evolutionary biology↗