J Syst Evol ›› 2009, Vol. 47 ›› Issue (5): 457-476.DOI: 10.1111/j.1759-6831.2009.00040.x

• Reviews & Research Articles • Previous Articles     Next Articles

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

1 Michael O. DILLON 2 Tieyao TU 3 Lei XIE 4 Victor QUIPUSCOA SILVESTRE 3,5 Jun WEN*   

  1. 1 ( Department of Botany, The Field Museum, 1400 South Lake Shore Drive, Chicago, IL 60605, USA)
    2 ( South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China)
    3 ( Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China)
    4 ( Departamento de Bot醤ica, Universidad Nacional de San Agust韓, Arequipa, Peru)
    5 ( Department of Botany, MRC-166, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington DC 20013-7012, USA) * Author for correspondence. E-mail: wenj@si.edu
  • Received:2009-04-08 Published:2009-09-24

Abstract: The present paper reconstructs the biogeographic diversification for Nolana L.f. (Solanaceae), a genus of 89 endemic species largely restricted to fog-dependent desert lomas formations of coastal Peru and Chile. Previous efforts have reconstructed a phylogenetic estimate for Nolana using a combination of molecular markers. Herein, we expand on those results to examine hypotheses of biogeographic origins and diversification patterns. Nolana occupies 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 one Nolana species 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 galapagensis is 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 in Nolana, in one of the driest habitats on Earth, suggest rapid adaptive radiation in several clades. Success in Nolana may 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 to Nolana. The processes affecting or shaping the biota of western South America are discussed.

Key words: Atacama Desert, biogeography, chloroplast DNA, LEAFY second intron, Nolana, Peruvian Desert, Solanaceae, South America