Format: ORAL

Caroline Iacuaniello 1, Christa Horn 1, Joyce Maschinski 2, Stephanie Steele 1, Katie Heineman 2

1 San Diego Zoo Wildlife Alliance, Plant Conservation 2 Center for Plant Conservation

San Diego County, USA is a hotspot of plant biological diversity. Many rare plant species are severely threatened by habitat fragmentation in this rapidly developing population center. Dudleya brevifolia is a diminutive, deciduous succulent that is an edaphic endemic with 6 known extant occurrences all located within a five-mile radius. The range of this species genetic diversity, both within and between occurrences, the degree of inbreeding, and the possibility of outbreeding depression was not previously known. Our study set out to genotype representative individuals from five of six known occurrences in order to inform management practices. We sought to understand 1) whether the distinct occurrences were genetically similar or different from one another, and 2) whether there was evidence of inbreeding due to fragmentation between populations. This information will help land managers decide if seed from more robust populations might be appropriate for supplementing smaller populations in augmentation projects. Genomic data indicated that individuals separated into three distinct clusters corresponding closely with geographic localities. Further analysis showed moderate differentiation (Fst) exists between the more distant populations, while slightly higher than expected heterozygosity (He) and low inbreeding (Fis) were seen across all sites. Based on this data, we suggest managing the clusters as populations where seed from occurrences within each cluster might be used to augment each other as needed.