Mudrak, O. | bioRxiv Science

bioRxiv2026

Climate-driven in-situ trait variation in an annual ruderal grass across Europe

O_LIPlant functional traits link environmental conditions to plant performance and adaptation. Growing evidence shows that in-situ intraspecific trait variation can be as important as differences between species, yet large intraspecific datasets measured in situ are rare. While most studies focused on plant morphological traits, contents of elemental nutrients in the seeds received much less attention so far. C_LIO_LIWe conducted a large-scale in-situ study of the widespread ruderal grass Hordeum murinum. We sampled 2070 individuals from 207 populations from a large part of the native range in Europe and Northern Africa. In-situ, we measured seed ripening phenology and morphological traits, and analyzed the content of elemental nutrients in the seeds. C_LIO_LIWe found that Hordeum murinum grew larger, produced seeds later, and had heavier seeds in colder and wetter areas. Plants in denser vegetation were taller with heavier seeds but formed fewer spikes. Seed nutrient content generally declined with seed weight and was mainly driven by climate. Soil conditions had only minor effects on plant traits and seed nutrients. Population identity explained much of the variation, indicating a possible genetic component. C_LIO_LISynthesis: Our findings provide a comprehensive view of Hordeum murinum responding to environmental gradients across its European distribution. Climatic variables, especially temperature, are key drivers for reproductive success and seed nutrient content, while local environments, such as biotic pressures, are more critical for growth-related traits. These patterns indicate that H. murinum modulates its growth and reproductive investment along environmental gradients, balancing phenology, stress tolerance, and limited competitive capacity. C_LI

ecology↗

bioRxiv2025

Trait Convergence Dominates Community Assembly Across Contrasting Himalayan Habitats: Integrating Above- and Belowground Strategies With Phylogenetic Structure

Understanding the mechanisms that structure plant communities is fundamental for predicting biodiversity responses to global change. Functional trait-based approaches can reveal assembly processes by linking species adaptations to community-level patterns, with convergence typically signalling strong environmental filtering and divergence reflecting niche partitioning or competitive exclusion. In extreme environments such as cold, arid mountains, it remains unclear whether persistence is driven primarily by abiotic filtering (low temperatures) or by competition for scarce resources (soil moisture, nutrients) that promotes niche differentiation. Disentangling these mechanisms requires an integrated framework combining multidimensional trait data with phylogenetic structure, enabling separation of adaptive responses from evolutionary constraints in shaping community composition. We analysed community assembly across 482 sites in six contrasting Himalayan habitats: salt marshes, wet grasslands, shrublands, steppes, screes, and alpine tundra, spanning 3,700-5,850 m. Using community-weighted means (CWM) and standardized effect sizes (SES) for 13 above- and belowground traits, including leaf morphology, stem anatomy, clonality, root carbohydrates, and nutrient storage, alongside a multi-locus phylogeny of all species, we linked functional and phylogenetic structure with species richness. Most communities showed strong functional convergence (negative SES) in stress-tolerant traits (e.g., high Leaf Dry Matter Content, Root Phosphorus Content, and Root Non-structural Carbohydrates), particularly in species-poor habitats such as salt marshes and alpine tundra. Divergence (positive SES) was more common in species-rich wet grasslands and steppes, where milder conditions likely facilitate niche differentiation. Phylogenetic overdispersion frequently accompanied functional convergence, indicating repeated evolution of similar trait syndromes in distantly related lineages under shared environmental constraints. Assembly processes had contrasting effects across traits: in alpine and scree communities, conservative traits converged while clonality and {delta}15N diverged, suggesting parallel action of filtering and differentiation; in nutrient-enriched systems, convergence in Specific Leaf Area coincided with divergence in root traits, highlighting trait-specific responses to stress and competition. We conclude that environmental filtering dominates Himalayan community assembly but is frequently modulated by niche differentiation. The consistent decoupling between functional and phylogenetic diversity demonstrates that only by integrating multidimensional trait data with phylogeny can we disentangle adaptation from evolutionary constraint and robustly predict biodiversity responses to environmental change.

ecology↗