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

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.

Dispersals of Hyoscyameae and Mandragoreae (Solanaceae) from the New World to Eurasia in the early Miocene and their biogeographic diversification within Eurasia

“…Clarkson et al (2005) dated the age of the split between Nicotiana and its sister, Symonanthus, at 15.3 mya by using ITS sequence data and one calibration point. The split between Nolana and Lycium inferred by our data is at 10.20 mya, which is very similar to the results of Dillon et al (2009), who dated it at 10.39 mya by using three plastid DNA regions and two fossil calibration points. The ages of Nicotiana and Nolana estimated in different studies suggest that our data are generally comparable with previous findings.…”

“…Six plastid markers including the atpB gene, the ndhF gene, the rps16-trnK and the psbA-trnH intergenic spacer, the rbcL gene and the trnC-psbM region, were used to infer a phylogeny. The six markers were newly sequenced in this study or obtained from our recent study (Dillon et al, 2009). Two Nicotiana species (N. sylvestris Speg.…”

“…Vouchers or sources GenBank accession Tu et al (2008) and Dillon et al (2009). The amplification was performed in 25 ll reaction-mixture volumes using the Bioline Taq polymerase and associated reagents at 2.0 mM MgCl 2 concentration except for trnC-psbM, which used 4.0 mM MgCl 2 .…”

“…The lognormal distribution prior here represents a ''hard" minimum constraint for this calibration point. The calibration procedure in this study is similar to Dillon et al (2009) in dating the Nolana L. f., in which a fossil from Convolvulaceae instead of from Solanum and a data matrix of three genes rather than six genes used here.…”

Phylogenetic insights into Andean plant diversification

“…The effect of the cold Humboldt current on aridity in western South America may have also been intensified or reinforced by Andean uplift (Sepulchre et al, 2009). No comparable paleobotanical evidence is available for the onset of aridity in the Peruvian and Atacama deserts, but phylogenetic studies in Atacama endemic taxa tend to indicate a rather recent (MiocenePliocene) origin of diversification of these lineages in response to aridity (e.g., Luebert and Wen, 2008;Dillon et al, 2009;Heibl and Renner, 2012), falling into the range of estimates for onset of present-day hyperaridity of the Atacama Desert (Alpers and Brimhall, 1988;Hartley, 2003;Hartley and Rice, 2005;Arancibia et al, 2006;Reich et al, 2009). These climatic changes exerted feedbacks on Andean uplift.…”