Biology subjects

Wierzbicka, A.

Publications and source records attributed to Wierzbicka, A..

5 recordsLinked to original sources

bioRxiv2026

Connectivity, genetic diversity and adaptive potential of an endangered beetle: genomic evidence for veteran tree management

Habitat fragmentation and destruction in old-growth forests represents a primary threat to specialist species, frequently resulting in the erosion of genetic diversity. The Hermit Beetle, Osmoderma barnabita, is a protected relic of primeval forests and an obligate saproxylic specialist whose larval development depends exclusively on the wood-mould of hollow trees. This study provides the first high-resolution, genome-wide assessment of O. barnabita across seven Polish forest complexes using double-digestion Restriction-site Associated DNA sequencing data from 49 individuals. Following rigorous quality control and reference bias assessment, we evaluate contemporary population structure. To distinguish between evolutionary processes, we isolated 2,920 putatively adaptive outliers from the neutral background, evaluating both neutral and adaptive genomic signals. The analyses revealed four distinct genetic clusters, confirming that the Polish metapopulation is severely subdivided. Crucially, the westernmost population in the Lower Silesian Forest emerged as the most divergent evolutionary unit (FST up to 0.360), suggesting potential hybrid origin or long-term isolation. We observed a striking linear correlation (R2=0.986) between neutral diversity and adaptive potential, indicating that genetic drift in small and isolated forest fragments is actively depleting the variation required for long-term persistence of this species. Our findings demonstrate significant gene flow restriction across all sites, suggesting that current conservation frameworks fail to encompass these highly differentiated lineages. To mitigate this genetic vulnerability, we recommend reclassifying these clusters as independent Management Units and Evolutionary Significant Units. Maintaining forest continuity and protecting local micro-habitats are essential to prevent further isolation and preserve the genomic integrity of this saproxylic flagship species.

evolutionary biology↗

bioRxiv2026

Metric-dependent genomic diversity reveals phylogenetic and ecological structure in saproxylic beetles

Abstract 1. Comparative studies can reach different conclusions when genomic-diversity metrics use different denominators. 2. We analysed standardized ddRAD-seq data from 759 individuals, 149 species-by-site population records and 26 saproxylic beetle species across eight Polish forest complexes. 3. Species identity and sampling hierarchy explained most population-level variation. Deciduous-associated species had higher variant-site expected heterozygosity than conifer-associated species. 4. All-position nucleotide diversity showed stable phylogenetic signal, whereas occurrence tier and exploratory forest-management and protection contrasts showed no consistent associations. 5. Genomic-diversity metrics are not interchangeable; comparative assessments should report their denominator and test lineage sensitivity.

evolutionary biology↗

bioRxiv2026

Beyond deadwood volume: structural heterogeneity and species-specific dispersal shape saproxylic beetle genetics

Many rare saproxylic (deadwood-dwelling) beetles are among Europes most threatened insects, yet the relative importance of local microhabitat quality versus broad-scale landscape connectivity in shaping their genetic integrity remains poorly understood. We evaluated environmental drivers for 13 saproxylic beetle species--rare old-growth specialists, common taxa, and economically significant pests--across eight major forest complexes in Poland, using double digest restriction-site associated DNA sequencing (ddRAD-seq) paired with plot-level structural inventories and estimated effective migration surfaces (EEMS) modelling. A beta generalized linear mixed model identified deadwood diversity as the only significant within-species predictor of observed heterozygosity ({beta} = 0.041, 95% CI 0.0227-0.0586, p < 10-); total deadwood volume, forest age, time since logging, stump density, and veteran tree density were not significant. Management-category contrasts in observed heterozygosity (Ho) and the inbreeding coefficient (Fis) were non-significant after Tukey adjustment. Predictor x ecological-tier interactions did not differ detectably between rare and common species for five of six structural predictors; time since last logging was the exception ({chi}{superscript 2} = 4.56, p = 0.033). EEMS patterns differed among species and fell into three broad groups: regional lineage barriers, asymmetrical corridors, and surfaces close to isolation- by-distance expectations. These results associate plot-level heterozygosity with deadwood diversity and show that regional gene-flow patterns cannot be generalised across saproxylic beetles. Conservation planning should therefore combine local deadwood restoration with species-specific assessment of landscape connectivity.

evolutionary biology↗

bioRxiv2025

Geography and forest naturalness as drivers of genetic diversity in saproxylic beetles

Understanding how geography and forest management shape genetic diversity is pivotal for the conservation of saproxylic beetles, the key indicators of forest ecosystem integrity. Using a multi-species Double Digest Restriction-site Associated DNA sequencing approach, we analyzed genome-scale SNP variation in 12 saproxylic beetle species (rare and common, incl. pests) differing in abundance, ecology, and mobility across central European forests, with respect to both geographic location and forest status. Analyses of distance-based redundancy test, molecular variance, and population structure consistently revealed that geography is the main determinant of genetic differentiation, with clear east-west clustering in several species. Forest status represented in four levels (commercial not protected, nature reserve, primeval not protected, and primeval protected) exerted a secondary but detectable effect in a subset of taxa, especially among rare and habitat-specialized species. For these species, populations from primeval protected sites showed distinct genetic structure compared to those from commercial stands. Our results highlight that regional connectivity, maintaining gene flow across a large spatial scale, should be prioritized in conservation planning, complemented by the protection of primeval forest refugia and the maintenance of structural complexity in commercial forests. By integrating high-resolution genomic data with geographical and management context, this study provides actionable insights into the processes shaping genetic structure in forest-dependent insects and underscores the importance of incorporating genetic monitoring into sustainable forest biodiversity management.

genetics↗

bioRxiv2020

Cortical inactivation does not block response enhancement in the superior colliculus

Repetitive visual stimulation is successfully used in a study on the visual evoked potential (VEP) plasticity in the visual system in mammals. Practicing visual tasks or repeated exposure to sensory stimuli can induce neuronal network changes in the cortical circuits and improve the perception of these stimuli. However little is known about the effect of visual training at the subcortical level. In the present study, we extend the knowledge showing positive results of this training in the rats superior colliculus (SC). In electrophysiological experiments, we showed that a single training session lasting several hours induces a response enhancement both in the primary visual cortex (V1) and in the SC. Further, we tested if collicular responses will be enhanced without V1 input. For this reason, we inactivated the V1 by applying xylocaine solution onto the cortical surface during visual training. Our results revealed that SCs response enhancement was present even without V1 inputs and showed no difference in amplitude comparing to VEPs enhancement while the V1 was active. These data suggest that the visual system plasticity and facilitation can develop independently but simultaneously in different parts of the visual system.

neuroscience↗