Biology subjects

Gruenert, U.

Publications and source records attributed to Gruenert, U..

3 recordsLinked to original sources

bioRxiv2026

Long-term stomatal and leaf trait dynamics in invasive knotweeds in Europe - insights from 160 years of herbarium records

O_LIStomata and leaf traits are key regulators of plant water use efficiency and are expected to have changed in response to rising atmospheric CO2 concentrations and climate warming over the past centuries. However, long-term data documenting such changes are rare. C_LIO_LIWe leveraged herbarium collections to track changes in stomatal characteristics and leaf traits in 656 individuals of invasive Japanese knotweed and its hybrid Bohemian knotweed collected across their European range and spanning 160 years of invasive spread. C_LIO_LIWe found that several functional traits including stomatal density and maximum anatomical stomatal conductance did not show significant changes over time but that plants adjusted their stomatal size and shape over time, and that these changes were associated with increased atmospheric CO2 levels. Interestingly, Reynoutria japonica showed increases in stomatal size and stomatal elongation, while the hybrid R. x bohemica showed a reduction in stomatal size. Traits also varied systematically with climates of origin. Plants from warmer origins with higher evaporative demands during the growing season had thicker leaves, lower SLA, smaller stomata and higher stomatal density, indicating more conservative water-use strategies. Stomatal density and gas exchange capacity co-varied with leaf structural traits, and there was a trade-off between stomatal size and number. Overall, "fast" leaf economic traits were associated with "slow" physiological traits. C_LIO_LIOur results suggest that stomatal anatomical plasticity may enhance climate resilience by maintaining a stable maximum gas exchange capacity across environmental gradients. Herbarium collections provide a unique resource for reconstructing plant responses to historical environmental changes and understanding intraspecific trait variation. C_LI

ecology↗

bioRxiv2026

Using herbarium genomics to understand the history of a global plant invasion

Invasive plants are dynamic eco-evolutionary systems characterized by rapid spread and evolutionary change. Herbarium genomics offers a powerful way to study these processes across broad spatial and temporal scales. We generated low-coverage shotgun-sequencing data from 152 herbarium specimens of the invasive Japanese knotweed species complex (Reynoutria), collected across its native range in Japan and China, and its introduced ranges in Europe and North America, spanning 200 years of global spread. Introduced populations of R. japonica, R. japonica var. compacta and R. sachalinensis showed reduced genetic diversity compared to native populations and were genetically most similar to Japanese specimens, indicating Japan as the source of all three introductions. European and North American R. japonica were genetically highly similar and closely related to local R. x bohemica hybrids, suggesting that these hybrids originated post-introduction, through hybridization and subsequent introgression from the R. japonica parent. A few R. x bohemica hybrids in the UK and France shared a multilocus lineage with R. sachalinensis, indicating an independent but ecologically less successful hybridization event involving introgression from R. sachalinensis. A genetically distinct R. x bohemica from Japan was closely related to a Japanese R. sachalinensis specimen, suggesting that hybridization also occurs in the native range. Introduced R. japonica has remained genetically uniform for [~]200 years reflecting long-term founder effects. The dominance of a single R. japonica lineage supports the general-purpose genotype hypothesis and the importance of vegetative reproduction in its spread. Herbarium genomics thus uncovers the origin and global spread of Japanese knotweed, providing direct molecular evidence of long-term plant invasions.

evolutionary biology↗

bioRxiv2025

Dissolved inorganic carbon driven dynamics of calcite shell formation in 12 strains of the freshwater algae Phacotus lenticularis (Chlorophyta)

This article explores the close relationship between dissolved inorganic carbonate ion concentration (DIC) and the calcification state of Phacotus lenticularis, a globally abundant freshwater phytoplankton that is responsible for a significant part of modern lake carbonate production during bloom formation. We cultured 12 freshly isolated P. lenticularis strains under an ecologically relevant range of DIC (0.2 to 12 mmol l-1 total scale) for 14 days. From this experiment we gained information on responses in shell formation and growth that highlight strong lower boundaries in morphometric calcite shell variables with regards to DIC. All P. lenticularis strains showed reduced shell thickness by up to 60 % and dissolved calcite crystals structures at declining DIC < 4 mmol l-1. Increasing DIC > 4 mmol l-1 had no significant effect on shell thickness and crystal length in the culture experiments. We found a significant preadaptation of all 12 strains to ambient DIC concentrations measured in their lake of origin, but no dependence of growth rates up to a lethal DIC of > 10 mmol l-1. The simulation experiments illustrate the close relationship between shell function and dissolved inorganic carbonate ion concentration in lakes and highlight the need of continued research of important roles in biogenic carbon transformation and storage in a future world.

ecology↗