Anthropocene refugia in Patagonia: A macrogenetic approach to safeguarding the biodiversity of flowering plants

Intraspecific genetic diversity (IGD), the fundamental dimension of biodiversity, is scarcely considered in the context of anthropogenic impact at regional and global scales. Here, encouraged by the knowledge about the effect of past climate changes that shaped IGD at the community level, we evaluated how current land use and future climate changes may erode mechanisms underlying genetic diversity and species richness of the native flora of the Patagonian steppe, a cold desert that covers 827,446 km(2) in the southern cone of South America. About 36% of the Patagonian steppe could serve as Anthropocene refugia, with only 1.8% being protected areas at present. Moreover, 63% of the areas with the highest species richness and endemism, and 37% with the highest genetic diversity are outside the refugia areas. Human-driven changes threaten plant biodiversity mainly in northern Patagonia. We provide the first broad assessment of climate change and land-use effects on IGD for the Patagonian steppe. The conservation of the detected high genetic diversity and species-rich areas with moderate land use and projected low climate anomaly should be prioritized, whereas high-risk areas, those for which a high climatic anomaly is projected, deserve monitoring and mitigation policies. This approach which includes IGD as a biodiversity metric may be useful for other endangered ecoregions in the world, with promising results for biodiversity conservation.