<i>Reevesia</i> in a Warmer World: Mapping the Habitat Suitability of Its Two Representative Species ( <i>R. pubescens</i> and <i>R. thyrsoidea</i> ) in China

Climate change is altering the spatial distribution of species' suitable habitats. Congeneric species may exhibit divergent responses to climate change due to differences in their niches. A clear understanding of these differences is essential for the development of effective and targeted biodiversity conservation strategies. Here, we use the optimized maximum entropy model (MaxEnt) to simulate the current distributions of two congeneric species, <i>Reevesia pubescens</i> and <i>R. thyrsoidea</i>, and project their future distributions under different climate scenarios across China. Despite their close taxonomic relationship, the two species show distinct climatic preferences and distributional patterns. <i>R. pubescens</i> primarily occupies montane regions in southwestern China. Its distribution is most influenced by precipitation and temperature during the driest quarter, as well as precipitation seasonality. In contrast, <i>R. thyrsoidea</i> prefers lowland coastal areas in southeastern China. Its distribution responds more strongly to temperature stability and wet-season precipitation. Meanwhile, for both species, climatic factors, rather than terrain, are the dominant forces shaping their current distributions. Under future climate scenarios, both species are projected to expand their suitable habitats, although with different magnitudes and directions. <i>R. pubescens</i> shows moderate northward expansion under the low-emission scenario. However, under the high-emission scenario, this expansion is constrained, likely due to thermal limitations. <i>R. thyrsoidea</i> demonstrates robust expansion under both scenarios. Spatial overlap between the two species is expected to increase, especially by 2081-2100, suggesting potential areas for joint conservation. Our results highlight the importance of species-specific ecological strategies and underscore the role of climate adaptation in shaping future distributions, and provide valuable insights for conservation planning under climate change.