Extreme genetic structure in a relict cactus genus from campo rupestre landscapes: implications for conservation

Uebelmannia is a cactus genus represented by three microendemic species with patchy distributions in campo rupestre landscapes in the Espinhaco Range in eastern Brazil. It is one of the ten genera of Cactaceae listed as threatened with extinction due to habitat loss and illegal overcollection. Assessment of the genetic diversity and population structure of this threatened genus is crucial to provide guidelines for both in situ and ex situ conservation and management efforts. Here, we genotyped 12 microsatellite loci from samples covering the entire distribution of this genus (485 individuals from 20 localities) to investigate the genetic diversity, spatial population structure, and demography of Uebelmannia species. The results identified moderate-to-high levels of genetic diversity in Uebelmannia, comparable to the wide-range cacti from Cerrado biome. The results confirmed an extremely high population structure even at small geographic scales, with population clusters exhibiting high inbreeding and genetic signatures of a recent bottleneck. Based on this study, we suggest some conservation strategies, including in situ management for populations at the borders of protected areas and ex situ seed collection, for further management of this genus. Furthermore, the results suggest the use of a precautionary approach for translocation plans and highlight that effective conservation management of Uebelmannia should target genetically clustered populations instead of species or subspecies.