Biology subjects

Siebert, U.

Publications and source records attributed to Siebert, U..

5 recordsLinked to original sources

bioRxiv2026

Contemporary hybridization and localized genomic differentiation between grey seal subspecies

Grey seals are divided into two subspecies, Halichoerus grypus grypus in the Baltic Sea and H. grypus atlantica in the North Atlantic Ocean. Historically, intense hunting caused local extinctions of grey seals across their range and promoted geographical isolation of the subspecies. However, recent population recovery and recolonization have renewed their overlap in a contact zone in Danish and Swedish waters. Here, using whole-genome sequencing data from 119 individuals, we investigate the demographic history of grey seals, the divergence of the subspecies, and genomic signatures of local adaptation and potential hybridization in the contact zone. We estimate that divergence began approximately 10,000 years ago, with gene flow ceasing 2000 years ago. We detect peaks of high genetic differentiation near genes with putative functions in osmo- and thermoregulation, consistent with salinity and temperature differences between the Baltic Sea and the North Atlantic. As evidence of the geographic isolation breaking up, we report a hybrid individual in the southwest Baltic contact zone, with Baltic maternal and Atlantic paternal ancestry, and identify a migrant of Baltic origin in the North Sea. Our study illustrates how local environmental variation and long-term hunting pressure have contributed to divergence between mammal subspecies over a short evolutionary timescale, with recent population recovery, recolonization and hybridization reshaping gene flow dynamics. Broadly, our work emphasizes the importance of studying evolutionary processes amid anthropogenic influences, including both disturbances and conservation successes, where demographic fluctuations, range shifts, altered gene flow, and adaptation to changing environments interact in complex, potentially consequential ways.

evolutionary biology↗

bioRxiv2026

From the lung to the muscle: Systemic insights from an integrative MultiOmics analysis of harbour porpoises in poor respiratory health

Harbour porpoises (Phocoena phocoena) in the North and Baltic Seas are increasingly impacted by anthropogenic pressures, including underwater noise, fisheries and pollution. These pressures correlate with declining population health, particularly affecting the respiratory system. Growing pathological lesions, partly resulting from high prevalence of parasitic infestations and subsequent diseases, can impair tissue function and oxygen supply to distant end-organs. In this study, we applied an integrative MultiOmics approach (proteomics, metabolomics, lipidomics) to analyse the lungs and muscles of 12 wild harbour porpoises with compromised respiratory health. Our aim was to identify dysregulated biological pathways across omics layers to advance insights into adaptive physiological responses and to define disease-associated molecular signatures that could assist health assessments. Our analysis revealed pronounced immune system and antioxidative responses in the lungs and muscles, indicated by enhanced immunoglobulins, plasmalogens and glutathione-related proteins. In the lungs, high cardiolipin levels and reduced collagen suggest impaired tissue structure and function, while tissue maintenance processes were elevated in the muscle. Both tissues exhibited metabolic alterations suggestive of energetic imbalance, including increased purine metabolism in the lung and decreased lipid metabolism in the muscle. Several dysregulated molecules were shared across tissues, pointing to pathophysiological effects. The proposed disease-associated molecular signatures included the protein SLC25A4, the metabolite O-phosphoethanolamine and the lipid TG O-16:0_16:0_20:4 for the lung, and the protein SPEG, the metabolite pipecolic acid, and the lipid BMP 18:1_22:6 in the muscle. Our findings elucidate the complexity of molecular mechanisms linking anthropogenic and environmental stressors with vulnerability and resilience in a marine sentinel species. Furthermore, this study highlights the potential of integrative omics to define disease-related marker panels, thereby supporting ongoing and future health monitoring and conservation efforts.

systems biology↗

bioRxiv2020

Form, function, and divergence of a generic fin shape in small cetaceans

Tail flukes as well as the dorsal fin are the apomorphic traits of cetaceans appeared during evolutionary process of adaptation to the aquatic life. Both appendages present a generic wing-like shape associated with lift generation and low drag. Variability of the form of appendages was studied in seven species of cetaceans having different body size, external morphology, and specialization. Hydrodynamic performance of the fin cross-sections was examined with the CFD software and compared with similar engineered airfoils. Affinity of hydrodynamic design of both appendages was found in a wing-like planform and cross-sectional design optimized for lift generation. Distinctions in the planform and cross-sections were found related with the fin specialization in thrust production or swimming stability control. Cross-sectional design of the dorsal fin was found to be optimized for the narrow range of small angles of attack. Cross-sections of tail flukes were found to be more stable for higher angles of attack and had gradual stall characteristics that is associated with their propulsive efficiency as oscillating foils. The results obtained are the evidence of divergent evolutionary pathways of a generic wing-like shape of the fins of cetaceans under specific demands of thrust production and swimming stability control.

evolutionary biology↗

bioRxiv2020

An approach to stress assessment during hunting: Cortisol levels of wild boar (Sus scrofa) during drive hunts

Only little is known about the effect of stress (both short-term and long-term) on wildlife species. To get an idea of stress in wildlife, we investigated the cortisol level of wild boar during drive hunts in Lower Saxony, Germany. Cortisol as one of the main stress hormone in mammals is considered to have negative impacts on the animals well-being if expressed excessively (repeatedly over a longer period). We analysed serum cortisol levels of 115 samples using a radioimmunoassay and compared sampling month, hunting grounds, age classes and sexes, as well as possible correlations between cortisol level and weight and pregnancy status of female wild boar. We found that cortisol levels during these drive hunts exhibit wide variation. The mean cortisol level was 411.16 nmol/L with levels ranging from 30.60 nmol/L (minimum) to 1,457.92 nmol/L (maximum). Comparing age groups and sexes, we found significant differences between the sexes, with females having a higher cortisol levels than males. After grouping age groups and sexes together, we also found significant differences based on the age-sex group. We found no correlation between cortisol levels and weight, but significantly higher cortisol levels in pregnant females compared to non-pregnant females. No differences were found between sampling months and locations, respectively. These results show the impact of drive hunts on stress in wild boar; nevertheless, this impact of drive hunts as performed in most parts of Central Europe seems to be not as high as imagined. Still, we need more information about cortisol levels and stress in (hunted) wildlife species.

animal behavior and cognition↗

bioRxiv2020

High syphilis seropositivity in European brown hares, Lower Saxony, Germany

Treponema paraluisleporidarum infects lagomorphs and is a close relative of the human syphilis-bacterium Treponema pallidum. There is paucity of information on the epidemiology of hare syphilis and its relationship to rabbit- and human-infecting Treponema. We have found a high seropositivity (405/734) for Treponema paraluisleporidarum-infection in hares of Lower Saxony, Germany.

ecology↗