Population genomic of Huidobria fruticosa

The Atacama Desert is a biodiversity hotspot of neo-endemic radiations for which long-term aridity and complex physiographic processes form a unique environmental setting. Current species assemblages are mainly concentrated in highly patchy lomas formations, and plant populations occurring in these are often geographically isolated from each other. Despite a common consensus on long-term aridity in the Atacama, climatological and geological evidence points to repeated changes in climate, making the Atacama Desert an ideal system for studying population genetic processes in highly unstable habitats. We analyze the genetic structure within and among populations of Huidobria fruticosa, a paleo-endemic lineage of the Atacama Desert. We shed new light on its biogeographic history, broadening our understanding of the evolution of life in extreme aridity, and increasing our knowledge of plant evolution in response to a changing environment. We analysed SNP data obtained from genotyping-by-sequencing of 354 individuals in 21 populations, which represents the largest SNP data set so far analyzed for plant populations in the Atacama Desert. Our results suggest that, despite being an ancient lineage, current populations of Huidobria have been strongly affected by abiotic processes acting over the last 2 million years. We interpret our data to indicate phases of aridity during the Pleistocene causing strong population substructure.