Biogeographic diversification inNolana(Solanaceae), a ubiquitous member of the Atacama and Peruvian Deserts along the western coast of South America

Abstract

Abstract The present paper reconstructs the biogeographic diversification forNolanaL.f. (Solanaceae), a genus of 89 endemic species largely restricted to fog‐dependent desertlomasformations of coastal Peru and Chile. Previous efforts have reconstructed a phylogenetic estimate forNolanausing a combination of molecular markers. Herein, we expand on those results to examine hypotheses of biogeographic origins and diversification patterns.Nolanaoccupies habitats within a continuous coastal desert and forms a terrestrial archipelago of discrete “islands” unique in size, topography, and species composition. Each locality contains at least oneNolanaspecies and many contain multiple species in sympatry. The genus has a Chilean origin, with the basal clades confined to Chile with wide geographic and ecological distributions. Peru contains two strongly supported clades, suggesting two introductions with subsequent radiation. A Chilean clade of shrubby, small‐flowered species appears to have had its origins from the same ancestors of the second line that radiated in Peru and northern Chile.Nolana galapagensisis endemic to the Islas Galápagos, with origins traced to Peruvian taxa with a divergence time of 0.35 mya. Rates of diversification over the past 4.02 mya inNolana, in one of the driest habitats on Earth, suggest rapid adaptive radiation in several clades. Success inNolanamay be attributed to characters that confer a competitive advantage in unpredictable and water‐dependent environments, such as succulent leaf anatomy and ecophysiology, and the reproductive mericarp unique toNolana. The processes affecting or shaping the biota of western South America are discussed.