Endemism, projected climate change, and identifying species of critical concern in the Scrub Mint clade (Lamiaceae)

Abstract

Recent studies have revealed that narrow endemics, particularly those native to the North American Coastal Plain, are experiencing range contractions due to human development and anthropogenic-driven climate warming. We model how the projected distributions of a group of scrub-adapted plant species with similar evolutionary histories change in response to warming climates. The Scrub Mint clade (Lamiaceae) (SMC), which comprises 24 species in Dicerandra, Conradina, Stachydeoma, Piloblephis, and Clinopodium, including federally or state-listed threatened and endangered species, occurs in the scrub and sandhill biomes of the North American Coastal Plain. Georeferenced occurrence points were used to develop species distribution models (SDMs) to assess both present and predicted future ranges of all SMC species under future climate change. Future SDMs show that suitable environments for 67% of the SMC species would cover reduced geographical areas than at present. This loss of habitat is most pronounced in species of the Florida peninsula but is also prevalent in species found farther north. We use SDMs to identify the most at-risk species and geographic areas. Narrowly endemic species were more susceptible to habitat loss than those species with wider ranges. Using a large dataset and modeling habitat suitability at this regional scale, we demonstrate that scrub-adapted species are highly vulnerable to habitat reduction as a result of climate change.