Phylogenetics, Niche Evolution, and Distribution Dynamics of Isatis Species Under Climate Change

Isatis is a vital medicinal genus within the Brassicaceae family, yet key knowledge gaps persist regarding its environmental drivers, niche evolution patterns, and climate change responses-hindering the conservation and utilization of its germplasm resources. To address these, this study integrated 229 occurrence records of six Isatis species and 144 environmental variables. Using an optimized MaxEnt model, we predicted their potential geographic distributions under current and future climate scenarios (SSP245 and SSP585) and analyzed their niche evolution patterns in a phylogenetic context. The results revealed that: (1) excellent model performance (all AUC > 0.92); (2) clear life-history-based ecological differentiation-annual short-lived plants (I. violascens, I. minima) were primarily constrained by precipitation seasonality, whereas biennial species (cultivated I. indigotica, wild I. costata) were more strongly associated with habitat indicators such as growing-season vegetation phenology; (3) complex niche evolution patterns rejecting strict conservatism-niche conservatism in closely related pairs (I. indigotica and I. costata) coexisting with niche convergence in distantly related annual ephemerals (I. violascens and I. minima); and (4) divergent future trajectories-suitable habitat for I. indigotica remains stable, while that for I. costata is projected to contract by ~18.5%. This study elucidates adaptive evolution in Isatis through the lens of life-history strategies and niche evolution, highlights the elevated extinction risk faced by wild relatives, and provides a scientific foundation for targeted conservation and sustainable utilization of this genus' germplasm resources.