Areas of endemism in the Patagonian Steppe

Abstract In this study we quantify and analyse the distribution of vascular plants endemic to the Patagonian Steppe, one of the world’s largest and oldest temperate rangelands. We found that nearly 30% of the flora is endemic to the steppe vegetation. The steppe in its entirety constitutes a large Area of Endemism (AE), but most of the endemic species are concentrated in smaller, nested or partially overlapping AEs. Endemism peaks in the Neuquén AE followed by a second peak in the Santa Cruz AE, both located in the transition zone with the Andean foothills. Both areas are widely recognized as Pliocene-Pleistocene refugia in phylogeographic studies, but the high endemic Neuquén AE may be a much older species cradle and long-standing refugium according to published diversifications studies of forest species within the area. Other, smaller AEs were identified in the central, arid parts of the steppe and along the Atlantic coast, with many of these areas corresponding to known biogeographic breaks and refugia. Effective conservation of the Patagonian Steppe flora should focus on protecting the species-rich Neuquén and Santa Cruz AEs, as well as establishing an arid corridor through the central steppe to preserve genetic resilience against future climate change.