Climate Change Reveals Contrasting Vulnerability: Asymmetric Range Shifts of Two Dianthus Species in the Irano-Anatolian Biodiversity Hotspot

Maryam Behroozian

The Irano-Anatolian biodiversity hotspot harbors exceptional plant richness and endemism but faces severe threats from climate change. We used MaxEnt-based ecological niche models to evaluate the current and future distributions of two closely related species, Dianthus floribundus and Dianthus szowitsianus. Models were projected for mid-century (2041–2070) and late-century (2071–2100) under SSP3-7.0 and SSP5-8.5 scenarios. Temperature-related predictors, particularly annual mean temperature (bio1) and temperature seasonality (bio4), were the dominant drivers, yet the species showed markedly different responses to future climates. D. floribundus, characterized by a narrow thermal niche, is predicted to undergo severe habitat contraction (up to 60%) and pronounced elevational and latitudinal shifts toward northern high-elevation refugia, consistent with the “escalator to extinction” paradigm for cold-adapted mountain taxa. In contrast, D. szowitsianus displayed broader climatic tolerance and ecological plasticity, maintaining most of its core range while expanding into newly suitable habitats, with projected gains exceeding 50%. These asymmetric outcomes highlight the species-specific nature of climate change impacts even among closely related endemics and forecast a decoupling of historical assemblages, with potential consequences for montane community structure and species interactions. Moreover, the reduction of overlap between the two species and the limited representation of persistent habitats within current protected areas underscore the urgent need for forward-looking conservation strategies. Our findings emphasize that conserving montane biodiversity in global hotspots requires species-focused vulnerability assessments, identification of future refugia, and adaptive management frameworks to mitigate differential risks and preserve endemic diversity under climate change.