74 Systematic Botany (2002), 27(1): pp. 74–83  Copyright 2002 by the American Society of Plant Taxonomists Molecular Evidence from Chloroplast and Nuclear Markers for Multiple Colonizations of Lavatera (Malvaceae) in the Canary Islands JAVIER FUERTES-AGUILAR, 1 MARTIN F. RAY, 2 JAVIER FRANCISCO-ORTEGA, 3,6 ARNOLDO SANTOS-GUERRA, 4 and ROBERT K. JANSEN 5 1 Real Jardin Bota ´nico, C.S.I.C., Plaza de Murillo 2, Madrid E-28014, Spain; 2 Department of Ocean Sciences, University of California-Santa Cruz, Santa Cruz, California 95064; 3 Department of Biological Sciences and Fairchild Tropical Garden, Florida International University, University Park, Miami, Florida 33199; 4 Jardı ´n de Aclimatacio ´n de la Orotava, c/ Retama, 2, E-38400 Puerto de la Cruz, Tenerife, Islas Canarias, Spain; 5 Section of Integrative Biology, Plant Resources Center, and Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712 6 Author for correspondence (ortegaj@fiu.edu) Communicating Editor: James R. Manhart ABSTRACT. A molecular phylogenetic study based on chloroplast DNA restriction site and ITS sequence data shows that the two Macaronesian endemics, Lavatera phoenicea and Lavatera acerifolia, represent two independent introductions into the Canary Islands. The molecular phylogenies, combined with morphological, ecological, and biogeographical data, indicate that Lavatera phoenicea may be a bird-pollinated relict of an ancient laurel forest. Lavatera acerifolia, however, is nested in a derived clade of the Lavatera-Malva taxa from the Mediterranean region, suggesting a more recent introduction into the Canary Islands. Incongruence between chloroplast and nuclear phylogenies suggests that hybridization may have played a role in the evolution of L. acerifolia. Several features of L. phoenicea, such as corolla color and high nectar production, appear to be plesiomorphic and are still present because of historical constraints. In contrast, woodiness is a derived feature that originated as an adaptation to insular conditions. Two major hypotheses have been proposed for the origin of the unusual characters often associated with insular endemics. These include changes in reproduc- tive biology, loss of dispersal ability, and modifications in size with a trend towards woodiness in plants (Wil- liamson 1981; Grant 1998). The first hypothesis sug- gests that many of these unique characters are relictual and therefore, that much of the insular biota represents ancient lineages which found refuge on the islands fol- lowing major geologic and climatic changes in conti- nental areas (Axelrod 1975; Sunding 1979; Cronk 1992). The second hypothesis argues that the distinc- tive features of island endemics originated subsequent to long distance dispersal from the continent (Carlqu- ist 1965, 1974, 1995). Once there, several selective pres- sures of insular environments may have caused in- creased woodiness (Bo ¨hle et al. 1996), loss of dispersal ability (Cody et al. 1996; Grant 1998), and changes in reproductive biology (Williamson 1981; Barrett 1998). The first hypothesis has not received much support, mainly because of the young, post-Miocene ages of most emergent oceanic islands (Menard 1986; Francis- co-Ortega et al. 2000). Furthermore, molecular phylog- enies indicate a recent origin for taxa from Pacific ar- chipelagos (Carlquist 1995; Baldwin and Sanderson 1998). This is not the case for the Canary Islands be- cause some of the islands are up to 20 million years (Myr) old (Carracedo 1994) and macrofossils of the flo- ra are known from 14 myr (Garcia-Talavera et al. 1996). The Canary Islands are situated in the Atlantic Ocean only 100 km from the western Sahara coast. They have been considered to harbor many relicts of a subtropical flora that existed in the Mediterranean region before the Quaternary and the progressive de- sertification of northern Africa (Engler 1879; Axelrod 1975; Sunding 1979; Berry 1992; Cronk 1992). Disjunct distributions of species between the Canaries and east Africa and the existence in southern Europe of Tertiary fossil floras of genera currently restricted to the Ca- naries have been used as arguments to support the relictual nature of a portion of the Canarian flora (Sunding 1979; Follieri 1984; Francisco-Ortega et al. 1997a). Lavatera L. (Malvaceae) is a genus of about 18 spe- cies, which was segregated from Malva L. on the basis of a fused epicalyx. This traditional view, although highly unsatisfactory (Fernandes 1968a,b), has been followed until recent molecular studies (Ray 1994, 1995, 1998) have shown that a re-assessment of the morphological characters defining each genus is need- ed. Thus, we prefer to refer to the monophyletic group of species that includes both genera as the Lavatera- Malva complex. The group has a predominantly Med- iterranean distribution, with several species reaching the holarctic region and east Africa as well as western and central temperate Asia. Disjunct species occur in the California Islands, Baja California Islands, and Australia.