Ecological niche modeling reveals habitat differentiation and climatic vulnerability in two imperiled, sympatric southern Appalachian carnivorous plants

Understanding the habitat requirements of imperiled flora is critical for informing conservation horticulture practices, designing effective reintroduction strategies, and understanding how climate change will impact such species, especially in montane regions with high levels of environmental heterogeneity. In southern Appalachia, USA, the Mountain Sweet Pitcher Plant (Sarracenia rubra ssp. jonesii) and Mountain Purple Pitcher Plant (Sarracenia purpurea var. montana) inhabit overlapping ranges. These taxa rarely co-occur in the same mountain bogs, but frequently hybridize at sites where they do co-occur. We assessed patterns of climatic niche differentiation in these imperiled taxa to explore whether they naturally co-occur or may have been brought into secondary contact through human translocations. In addition, we constructed ecological niche models to evaluate the comparative availability of suitable habitat for each taxon under present and future climates. We find 1) evidence that the two taxa inhabit distinct niches, and 2) predict that current populations of Sarracenia rubra ssp. jonesii will experience climates markedly different from those it currently inhabits in the future, while suitable habitat for S. purpurea var. montana will remain comparatively stable in its current range. Our findings demonstrate that, despite high spatial overlap, these two related taxa exhibit divergent climatic niches, resulting in highly different management needs and conservation approaches. We raise concerns about the future of mountain bog plant assemblages, and the rare species they include, under climate change.