Biology subjects

Frajman, B.

Publications and source records attributed to Frajman, B..

5 recordsLinked to original sources

bioRxiv2026

Cross-ploidy hybridisation in Alpine woodrushes is associated with ecological additivity and scale-dependent niche divergence

O_LIHybridisation and whole-genome duplication (WGD) are widespread in plants, yet their ecological consequences remain challenging to predict. In allopolyploids, where both processes coincide, ecological divergence is typically evaluated against a null hypothesis of ecological additivity. However, this hypothesis has not been tested explicitly in the context of cross-ploidy hybridisation. C_LIO_LIWe assessed ecological additivity following cross-ploidy hybridisation in the Alpine woodrush Luzula alpina across multiple spatial resolutions. Integrating genomic data, environmental niche modelling, vegetation releves, and morphometric analyses, we characterised population structure and quantified ecological and morphological differentiation between the hybrid and its parental species. C_LIO_LIGenomic and morphometric evidence confirmed the hybrid origin of L. alpina. Patterns of niche evolution varied with spatial resolution. Climatic and edaphic data supported ecological additivity, whereas plot-level vegetation data revealed subtle but significant niche divergence accompanied by shifts in associated plant community composition. Postglacial population histories further suggest long-term persistence of hybrid and parental lineages in distinct refugia followed by differential recolonisation of the Alps. C_LIO_LIOur results indicate that cross-ploidy hybridisation in Alpine Luzula is predominantly associated with niche stability rather than pronounced ecological divergence. Importantly, the detection of divergence beyond ecological additivity depends on the spatial resolution of environmental data. C_LI

plant biology↗

bioRxiv2025

The conquest and diversification of leafy spurges across the Holarctic and beyond: biogeography and evolution of life-history of Euphorbia subgenus Esula

Euphorbia subgenus Esula is one of four main lineages within the megadiverse angiosperm genus Euphorbia. It comprises 490 species, including herbs, shrubs, dendroid shrubs, and succulents. The subgenus is a northern temperate lineage, most diverse in the Irano-Turanian and Mediterranean regions. We assembled the largest taxon sampling of subg. Esula to date (321 spp.), using DNA sequences from nuclear ITS and plastid ndhF regions, and updated previous phylogenetic analyses and sectional classification of the group. We used Bayesian methods to estimate divergence times and reconstruct ancestral ranges, characterising the tempo and mode of lineage diversification that shaped the present distribution and extant diversity of the subgenus. We tested whether changes in life-history (annual vs. perennial) played a role in the diversification and current elevational distribution of subg. Esula. Our results show that subg. Esula diverged from its sister clade in the Mid-Eocene and started to diversify in the Late Eocene. The Western Palearctic was inferred to be the ancestral area of the subgenus, where the first diversification events began 41 Mya. Expansion to other continents was dated as occurring in the last 10 million years. This coincided with an increase in the diversification rate and with clade-specific rate shifts coupled with changes from annual to perennial life-histories. We found a positive correlation between perenniality and high elevations. These results support that the recent rapid diversification of subg. Esula could be associated with an evolutionary shift to perenniality, allowing colonisation of montane habitats and global range expansion beyond the Western Palearctic.

evolutionary biology↗

bioRxiv2025

Spatiotemporal diversification of forest understorey species reveals the existence of multiple Pleistocene forest refugia in Central Europe

During Pleistocene cold stages, European temperate forests were not only restricted to refugia in the southern European peninsulas. Rather, there is increasing evidence for survival of trees also in isolated patches further north, termed "northern refugia". While their existence is undisputed, based on what is known from a handful of tree species, there is very limited knowledge about forest understoreys. Here, we fill this gap by examining the evolutionary histories of three Central European forest understorey species (FUS; Aposeris foetida, Cardamine trifolia, Hacquetia epipactis). To do so, we use a set of exploratory and explicit analyses utilizing genomic data and ecological niche models, and interpret these data following an a priori defined framework. We identify the northwestern Balkan Peninsula as the primary diversification center for the three species but found additional northern refugia in the Alps, the Carpathians, and the Apennines. Divergence times indicated pre-Last Glacial Maximum (LGM) diversification within each FUS, suggesting persistence of forest islands in Central Europe during Pleistocene cold stages rather than exclusively post-LGM colonization. We conclude that FUS thrived in scattered northern refugia. This refines our understanding of past forest dynamics and further supports widespread long-term persistence of forest patches in Central Europe during Pleistocene cold stages.

evolutionary biology↗

bioRxiv2022

Parallel adaptation to lower altitudes is associated with enhanced plasticity in Heliosperma pusillum (Caryophyllaceae)

High levels of phenotypic plasticity are thought to be inherently costly in stable or extreme environments, but enhanced plasticity may evolve as a response to novel environments and foster adaptation. Heliosperma pusillum forms pubescent montane and glabrous alpine ecotypes that diverged recurrently and polytopically (parallel evolution). The specific montane and alpine localities are characterized by distinct temperature conditions, available moisture and light. To disentangle the relative contribution of constitutive versus plastic gene expression to altitudinal divergence, we analyze the transcriptomic profiles of two parallely evolved ecotype pairs, grown in reciprocal transplantations at native altitudinal sites. In both ecotype pairs, only a minor proportion of genes appear constitutively differentially expressed between the ecotypes regardless of the growing environment. Both derived, montane populations bear comparatively higher plasticity of gene expression than the alpine populations that can be considered in this system as ancestor-proxies. Genes that change expression plastically and constitutively underlie similar ecologically relevant pathways, related to response to drought and trichome formation. Other relevant processes, such as photosynthesis, seem to rely mainly on plastic changes. The enhanced plasticity consistently observed in the montane ecotype likely evolved as a response to the newly colonized niche. Our findings confirm that directional changes in gene expression plasticity can shape initial stages of phenotypic evolution, likely fostering adaptation to novel environments. Significance StatementUnderstanding the importance of phenotypic plasticity for fast adaptation to stress is very timely for breeding and current environmental challenges. Our study of an alpine plant in the carnation family evidences an increased level of expression plasticity in early stages of adaptation to hotter and drier habitats.

evolutionary biology↗

bioRxiv2021

Polygenic routes lead to parallel altitudinal adaptation in Heliosperma pusillum (Caryophyllaceae)

Understanding how organisms adapt to the environment is a major goal of modern biology. Parallel evolution - the independent evolution of similar phenotypes in different populations - provides a powerful framework to investigate the evolutionary potential of populations, the constraints of evolution, its repeatability and therefore its predictability. Here, we quantified the degree of gene expression and functional parallelism across replicated ecotype formation in Heliosperma pusillum (Caryophyllaceae), and gained insights into the architecture of adaptive traits. Population structure analyses and demographic modelling support a previously formulated hypothesis of parallel polytopic divergence of montane and alpine ecotypes. We detect a large proportion of differentially expressed genes (DEGs) underlying divergence within each replicate ecotype pair, with a strikingly low amount of shared DEGs across pairs. Functional enrichment of DEGs reveals that the traits affected by significant expression divergence are largely consistent across ecotype pairs, in strong contrast to the non-shared genetic basis. The remarkable redundancy of differential gene expression indicates a polygenic architecture for the diverged adaptive traits. We conclude that polygenic traits appear key to opening multiple routes for adaptation, widening the adaptive potential of organisms.

evolutionary biology↗