Population Genetics and Conservation of the Rare and Endangered Florida-Endemic <i>Conradina glabra</i> (Lamiaceae)

Premise of research. Conradina glabra, or Apalachicola rosemary, is an endangered scrub mint narrowly endemic to a 1000-ha region of longleaf pine sandhill habitat east of the Apalachicola River in the Florida panhandle. Understanding genetic structure and diversity in this species is critical to informing conservation management, including accurate species counts and ex situ conservation efforts. Methodology. In this study, we assessed population genetic diversity, clonality, and population structure to better inform management decisions. We obtained 15,387 single-nucleotide polymorphisms from 562 individuals using the nextRAD sequencing approach. Pivotal results. Genetic diversity overall was low. Clustering methods demonstrate that two distinct clusters of individuals exist, representing six sandhills that are separated by steephead ravines. Individuals sampled within 2 m of each other showed evidence of clonality. Conclusions. When interpreted in the context of historic disturbances in the 1950s and 1980s, it is likely that this species was once more widespread and underwent two bottleneck events leading to the pattern of diversity and structure observed today. This species was described only in the 1960s, after the first major disturbance event, so the full historical extent of range and genetic diversity may never be known. All efforts should be made to preserve genetic diversity ex situ through seed or cuttings following best practices and the preservation of the Florida longleaf pine sandhill forest system.