Geographic distribution of wild potato species.

The geographic distribution of wild potatoes (Solanaceae sect. Petota) was analyzed using a database of 6073 georeferenced observations. Wild potatoes occur in 16 countries, but 88% of the observations are from Argentina, Bolivia, Mexico, and Peru. Most species are rare and narrowly endemic: for 77 species the largest distance between two observations of the same species is <100 km. Peru has the highest number of species (93), followed by Bolivia (39). A grid of 50 × 50 km cells and a circular neighborhood with a radius of 50 km to assign points to grid cells was used to map species richness. High species richness occurs in northern Argentina, central Bolivia, central Ecuador, central Mexico, and south and north-central Peru. The highest number of species in a grid cell (22) occurs in southern Peru. To include all species at least once, 59 grid cells need to be selected (out of 1317 cells with observations). Wild potatoes occur between 38° N and 41° S, with more species in the southern hemisphere. Species richness is highest between 8° and 20° S and around 20° N. Wild potatoes typically occur between 2000 and 4000 m altitude.