Biology subjects

Langebrake, G.

Publications and source records attributed to Langebrake, G..

5 recordsLinked to original sources

bioRxiv2026

From migrants to residents: Genomic insights into adaptive strategies in European robins (Erithacus rubecula)

Bird migration evolved as an adaptation to seasonally changing habitats. Migratory behaviour can vary within the same species in case of partial migratory behaviour, i.e. one population (or individual) is migratory and another one is resident. Species that exhibit a wide variety of migratory phenotypes provide valuable systems to understand the evolutionary drivers behind different phenotypes and how populations adapt to habitats with distinct seasonality. The European robin (Erithacus rubecula) expresses migratory behaviour in central and northern areas of the species distribution range, whereas populations in the South and on the Macaronesian islands are predominantly resident, providing a suitable system to investigate these questions. We use high coverage whole genome re-sequencing data of 125 European robins to investigate how migration behaviour affects population structure and demography, and how it affects the selection landscape in the genome. Genetic structure in European robins coincides with migratory phenotype and geography and populations are characterised by distinct demographic histories. Our results suggest that both the continental resident population as well as the Macaronesian island populations have derived independently from an ancestral migratory population. Unexpectedly, tests for differential selection revealed extensive positive selection pressure acting across all chromosomes in the resident populations, while selective sweeps are largely absent from migrants. We speculate that this might be an analytical artifact due to mismatching timescales between what population genomics methods can detect and the scale on which migration behaviour likely evolved in the robin. We suggest that future studies on the genomics of migration should more focally account for different time scales on which these processes happen, such as including the wider phylogenomic background of the target species, to capture the full evolutionary history of migratory traits.

evolutionary biology↗

bioRxiv2026

Expression patterns and interaction profiles of heterotrimeric transducin subunits in the retina of the European robin ( Erithacus rubecula )

The heterotrimeric G-protein transducin (Gt) is mediating phototransduction in rod and cone cells of the vertebrate retina, but its expression patterns in migratory songbirds is unknown. We characterised Gt expression in the European robin, a night-migratory songbird known for its light-dependent magnetoreception. One well-supported hypothesis of magnetoreception involves radical-pair formation in the blue light receptor cryptochrome type 4a. The - and {gamma}-subunits of cone specific transducin have been identified as possible interaction partners of cryptochrome 4a. Therefore, we analysed the expression patterns of various G-protein subunits in bird photoreceptors by combining single cell RNA sequencing and immunohistochemistry. Protein-protein interaction was tested by pulldown, co-immunoprecipitation, and NanoBiT luminescence assays. G-protein subunits Gt{beta}1 and Gt{beta}3 are predominantly expressed in rods and cones, and Gt{gamma}T2 was the principal isoform in cones, whereas Gt{gamma}11 was associated with rods. In contrast, we did not detect Gt{gamma}10 expression in either photoreceptor type. Interaction assays demonstrated that all three {beta}{gamma} combinations; {beta}{gamma}T2, {beta}{gamma}10, and {beta}{gamma}11, can associate in vitro. These findings indicate that {beta}{gamma} dimer formation in vivo is likely constrained by the photoreceptor-specific expression of the respective subunits. The absence of Gt{gamma}10 expression in rods and cones does not support a role in photoreceptor-based magnetoreception.

Molecular Biology↗

bioRxiv2026

The road to nowhere: geolocation-by-genotype traces large-scale yellow-browed warbler vagrancy to central Siberia

Vagrant animals - individuals found far outside their normal range - offer powerful natural experiments for understanding migratory mechanisms. The yellow-browed warbler (Phylloscopus inornatus) provides perhaps the best-yet example, typically migrating from Siberia to South/Southeast Asia yet found in increasingly large numbers in Western Europe. This represents a strikingly unresolved evolutionary puzzle: why do so many migrants consistently move in almost the complete wrong direction? A critical first step toward solving this enigma is determining where these birds come from. If vagrants came from the proximal western range edge this would imply simple disorientation, whilst a more easterly origin could imply large-scale reverse misorientation. Here, we develop a geolocation-by-genotype algorithm for low-coverage whole-genome resequencing data collected from feathers. Our method identifies spatially informative SNPs; clusters them to account for covariance in allele frequency through space; and employs a bootstrapped maximum-likelihood framework to estimate spatial origin with uncertainty. Applied to more than 80 European-caught birds, our results place their origin in central Siberia (118{degrees}E; 89-134{degrees}E [95% CI]); over 2000km east of the western range edge. These results suggest mass misorientation in a near-reverse direction, and highlight the yellow-browed warbler as an exceptional system for probing the mechanism, ontogeny and evolution of migration.

animal behavior and cognition↗

bioRxiv2025

Migration patterns and hybridization within the Asian stonechat complex in response to a major geographical barrier

Long-distance avian migration is thought to be under strong natural selection. Facing geographical barriers, migrants display various patterns considered to be adaptive. For example, they may detour along either side around the barrier or cross it, requiring specialized behavioral adaptations. Variations within closely related taxa are excellent sources for understanding the evolutionary background of migration and how barriers are shaping migration routes. In Asia, some species are assumed to have a migratory divide in response to the major geographical barrier, the Qinghai-Tibet Plateau (QTP), including the stonechat taxa (Siberian Stonechat Saxicola maurus maurus and Amur Stonechat S. stejnegeri). As they detour along either side of the QTP, these taxa are believed to disfavor a crossing over the highland. However, the more southernly distributed Tibetan Stonechat (S. m. przewalskii) breeds on the QTP, suggesting adaptation to high elevation. To investigate migration patterns and the potentially associated genetic differences, we studied migration routes and population genetics of four populations around the assumed migratory divide in Russia and Mongolia, and of one from the QTP in China. Our results confirmed the existence of a migratory divide between maurus and stejnegeri, albeit with extensive hybridization. We observed both the hypothesized western and eastern routes, but also found individuals employing intermediate routes crossing the QTP, of which two-thirds were clear hybrids. Meanwhile, przewalskii followed a highland-crossing route and was genetically differentiated from maurus and stejnegeri. The diverse migration routes among Asian stonechats show differential responses towards the geographical barrier. The intermediate route may be associated with hybridization, and its conditional viability may facilitate gene flow between maurus and stejnegeri. The Asian stonechat complex thus offers great opportunities for novel research of the genetics and evolution of migration. The specific evolutionary background associated with inhabiting and crossing the QTP can offer new perspectives in this field. Teaser textMigratory divides can arise in birds because alternative routes around migratory barriers would select for behaviors to restrict hybridization. Hybrids of parental types that employ alternative routes are hypothesized to embark on intermediate routes that would expose them to suboptimal conditions, resulting in post-zygotic reproductive isolation. However, this hypothesis is challenged when a sister taxon actually breeds on the geographical barrier. This is the case in the Asian stonechat complex that breeds near or on the Qinghai-Tibet Plateau (QTP), the roof of the world. We demonstrated a migratory divide in central Siberia to Mongolia for race maurus and stejnegeri, yet showed also evidence for extensive hybridization. Hybrids migrated along a newly discovered intermediate route, seemingly viable and overlaps with the migration trajectory of race przewalskii over the eastern part of the QTP. The Asian migratory divide relative to the QTP thus provided new insights to the evolution of landbird migration.

evolutionary biology↗

bioRxiv2025

Cryptochrome 4b protein is likely irrelevant for the radical pair based magnetoreception in the European robin

Avian cryptochrome 4 (Cry4) protein is a putative magnetosensitive molecule facilitating precise long-distance navigation in migratory birds. Two splice variants of Cry4 were reported in European robin (Erithacus rubecula), namely ErCry4a and ErCry4b. It is known that ErCry4a protein exhibits electron transfer between the flavin adenine dinucleotide (FAD) cofactor and tryptophan residues that generates magnetically sensitive radical pairs for magnetoreception. However, little is known about the ErCry4b isoform. We therefore characterized the properties of ErCry4b to see whether it fulfills prerequisites to be a radical pair magnetic sensor molecule. Our results show that ErCry4b protein does not bind FAD in vitro. Computational structure simulations revealed that the FAD non-binding in ErCry4b is likely due to protein structure dynamics. Furthermore, ErCry4b protein abundance in the robin retina, cerebellum and liver is below the detection limit of immunoprecipitation assays coupled with mass spectrometry. Meanwhile, transcript analyses show that ErCRY4b mRNA abundance is 10 times less than ErCRY4b in the retina. In conclusion, ErCry4b does not fulfill the prerequisites to be a radical pair based magnetic sensing molecule due to the lack of FAD binding, and it might not even be expressed as a functional protein in the European robin.

biochemistry↗