Evidence of flowering time advance in blue lupin (Lupinus angustifolius) in the last decades revealed by herbarium data and citizen science databases

Rapid adaptation to climate change in plants manifests through genetic modifications, epigenetic changes, or species-microbiome interactions, with short-living species having a greater potential for adaptation. The integration of historical collection data with modern databases improves our ability to study plant phenology and distribution shifts in response to global change. This study evaluates changes in the flowering phenology and vernalization requirements of Lupinus angustifolius populations across the Iberian Peninsula, assessing the effectiveness of diverse data sources. Using herbarium specimens and field photographs, we compiled flowering data and estimated flowering peaks. Thermal time and vernalization requirements were estimated using recorded flowering stages and high-resolution climate data. Analyses revealed a progressive advancement in L. angustifolius flowering in the last 60 years. Latitude and elevation emerged as significant influencing factors, with greater shifts observed at lower latitudes and elevations. Notably, plants now flower with fewer vernalization days, and higher thermal time, particularly at lower elevations. The adaptive responses of plants to global change are intricate and dynamic. Phenological advancement in flowering appears to be a key strategy for coping with environmental alterations, facilitating survival and reproduction through the interplay of genotype, phenotype, and environment, as well as existing genetic diversity. In this context, historical records and long-term monitoring prove invaluable for assessing the efficacy and pace of these adaptive processes. To improve our understanding of plant adaptation in the context of climate change, it is essential to synthesize diverse data sources and maintain ongoing collection efforts.