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

PREMISE: Understanding the habitat requirements of imperiled flora is critical for informing ex situ conservation 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 subsp. 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. METHODS: 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. RESULTS: Sarracenia purpurea var. montana inhabits higher elevation habitats than Sarracenia rubra subsp. jonesii, and these differences in elevation correspond with differences in climatic niche. Under the most likely future climate scenario, models predicted that habitat matching the climatic niche of Sarracenia rubra subsp. jonesii will decline in area by 95% by 2080, while habitat matching the climatic niche of Sarracenia purpurea var. montana will increase in area by 13%. CONCLUSIONS: 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.