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Hagen, S. B.

Publications and source records attributed to Hagen, S. B..

3 recordsLinked to original sources

Synchrony Genetics: Linking Ecological Mechanisms to Genetic Structure A framework for genetic inference in ecologically coupled systems

Spatial synchrony, correlated population dynamics across space, is a defining feature of ecological dynamics, shaping outbreaks, cycles, and waves across ecosystems. Yet its genetic consequences remain poorly resolved because classical population-genetic models assume demographic independence and equilibrium conditions that synchronised populations systematically violate. Here I introduce Synchrony Genetics, a general framework that treats ecological coupling as the causal process and spatial synchrony as only one observable manifestation of that coupling. The framework links the three canonical ecological coupling mechanisms, environmental (Moran-type) coupling, dispersal-driven coupling, interaction-mediated coupling, alone or in combination, to their characteristic genetic signatures. Under this view, genetic structure is not a static property of populations or a proxy for equilibrium connectivity, but an emergent indicator of how populations are ecologically coupled across space. These expectations are synthesised in a Prediction Matrix that maps coupling mechanisms to diagnostic contrasts across widely used genetic metrics, enabling mechanism attribution from genetic data alone or in combination with demographic information. By reframing genetic patterns as evidence of coupling mechanisms rather than equilibrium processes, Synchrony Genetics provides a mechanistic foundation for interpreting genetic data in spatially coherent systems where dispersal, demographic covariance, and ecological interactions jointly shape genetic signatures. More broadly, the framework establishes a new baseline for genetic inference in systems where ecological coupling violates demographic independence, repositioning genetic structure as mechanistic evidence of how populations are linked across space.

ecology↗

A relic at risk: Genomic evidence for an early-diverging domesticated lineage in Norwegian farmhouse yeast

The use of Saccharomyces cerevisiae to ferment alcoholic beverages is an ancient tradition, with genetic evidence indicating origins in Neolithic Asia, although the domestication process of the species is not fully understood. Kveik is a group of traditional yeasts used in farmhouse brewing in western Norway preserved through generations of rural brewing practice. While recent studies have highlighted the distinctiveness of kveik, its precise phylogenetic position, genetic diversity, and domestication history remain unclear. We performed whole-genome sequencing on 64 isolates from 25 traditional brewing cultures from Western Norway selected using cultural heritage criteria, and generated telomere-to-telomere (T2T) assemblies for selected strains. Phylogenomic and population genetic analyses reveal that kveik strains form a paraphyletic and early diverging group with respect to other domesticated S. cerevisiae strains. Most strains exhibit low diversity among isolates from the same brewing culture, strong geographic clustering, and little evidence of gene-flow or admixture. Mitochondrial genomes and Ty1 retrotransposon profiles corroborate this distinct lineage history. We further show that previously reported signals of gene flow between kveik and Asian fermentation strains are likely artifacts caused by population structure and selection. Divergence time estimates suggest that the common ancestor of beer, kveik, and other liquid-phase fermenting strains originated from ancestral populations 4,000 to 8,000 years ago. Our genomic resource sheds light on yeast evolution and domestication. Kveik likely comprises some of the oldest domesticated lineages in continuous use until today, connecting intangible cultural heritage to an early genetic origin. Significance statementYeast has been used to brew beer and ferment food for thousands of years, but we still do not fully understand how and where the different domesticated strains we are using today arose. We sequenced the largest collection of Norwegian farmhouse yeasts (kveik) to date, from cultures used by rural traditional brewers for generations. Our genetic analyses show that kveik forms a distinct and early branch among European brewing yeasts. This shows that historical traditions have created unique local types of yeast and helps us better understand and preserve the diversity of domesticated yeasts.

genomics↗

Arctic evergreening - encroaching allelopathy in a management blind spot

O_LIOngoing Arctic greening can increase productivity and reindeer pasture quality in the tundra. However, greening may also entail proliferation of unpalatable species, with distinct consequences for pastoral socio-ecological systems (SES). C_LIO_LIWe show extensive greening across 20 reindeer districts in northern Norway between 2003 and 2020. The allelopathic, evergreen dwarf-shrub crowberry biomass increased by 60%, contrasted by smaller increases of deciduous dwarf-shrubs and stagnating forb and graminoid biomass. C_LIO_LIWe found evidence, although uncertain, of a negative relationship between biomass and reindeer densities, but only among forbs, the least abundant plant group. C_LIO_LIOur results challenge the management decision-making, which aims at sustainable pasture management, but which assumes stationary density-dependent relationships. Changes in temporal vs. spatial relationships should be included as management criteria, to avoid mismanaging a SES in transition. C_LIO_LILarge-scale shift towards increased allelopathy may undermine the resource base of a key Arctic herbivore and pastoral SES. C_LI

ecology↗