Five molecular markers reveal extensive morphological homoplasy and reticulate evolution in the Malva alliance (Malvaceae) Pedro Escobar García a,b, * , Peter Schönswetter a , Javier Fuertes Aguilar b , Gonzalo Nieto Feliner b , Gerald M. Schneeweiss a a Department of Biogeography and Botanical Garden, University of Vienna, Faculty Center Botany, Rennweg 14, 1030 Vienna, Austria b Department of Biodiversity and Conservation, Real Jardín Botánico de Madrid, CSIC, Plaza de Murillo, 2, 28014 Madrid, Spain article info Article history: Received 14 April 2008 Revised 26 September 2008 Accepted 20 October 2008 Available online 5 November 2008 Keywords: Malva alliance Althaea Alcea Lavatera Malva Malvalthaea Molecular phylogeny Character evolution Hybrid speciation Reticulate evolution abstract The Malva alliance is a well-defined group with extensive morphological homoplasy. As a result, the rela- tionships among the taxa as well as the evolution of morphological traits have remained elusive and the traditional classifications are highly artificial. Using five molecular markers (nuclear ITS, plastid matK plus trnK, ndhF, trnL-trnF, psbA-trnH), we arrived at a phylogenetic hypothesis of this group, the genera Alcea, Althaea and Malvalthaea being studied here for the first time with molecular data. Althaea and, in particular, Lavatera and Malva are highly polyphyletic as currently circumscribed, because their diag- nostic characters, the number and degree of fusion of the epicalyx bracts, evolve in a highly homoplasious manner. In contrast, fruit morphology largely agrees with the molecularly delimited groups. Hybrid ori- gins confirmed for the genus Malvalthaea and for Lavatera mauritanica and hybridization in the group of ruderal small-flowered mallows underline the importance of reticulate evolution in shaping the history of this group and complicating the interpretation of morphological evolution. Ó 2008 Elsevier Inc. All rights reserved. 1. Introduction Traditional classifications, from Linnean times to deep into the second half of the 20th century, have largely relied on the transla- tion of a suite of morphological characters into taxonomic ranks, without using any explicit method to treat taxonomic information. Notwithstanding conceptual and methodological progress in the second half of the 20th century allowing a more objective evalua- tion of the phylogenetic signal contained in the morphological characters, this signal may be distorted by a high level of homo- plasy (Nyffeler et al., 2005; Pfeil et al., 2002; Ranker et al., 2004; Scotland et al., 2003). Biologically meaningful causes of homoplasy include convergent/parallel evolution and reticulation (with or without polyploidization). These processes are not mutually exclu- sive and are amply known from angiosperms (Arnold, 1997; Grant, 1981; Otto and Whitton, 2000; Stebbins, 1950). Assessment of homoplasy, whether a morphological character is to be interpreted as symplesiomorphy or as a synapomorphy, requires an indepen- dently derived hypothesis on the phylogenetic relationships of the group of interest. Although not immune to homoplasy, molec- ular data provide the most important alternative. An excellent example for taxonomic problems caused by homo- plasy of morphological characters is provided by Malva and related genera (Malvaceae, tribe Malveae). This group includes mainly perennial herbs of Mediterranean to Southwestern Asian distribu- tion, with main centers of diversity in the Western Mediterranean Basin (Malva, Lavatera, Althaea) and the Middle East (Alcea). Based on morphology, the genera Malva, Lavatera, Althaea and Alcea have been grouped into the so-called Malva alliance (Bates, 1968). Molecular data suggest that Malope (Tate et al., 2005) and Kitaibela (former Malope alliance: Bates, 1968; Bates and Blanchard, 1970) are closely related to the Malva alliance, while a third genus, Malv- althaea, has been largely neglected. While the morphology-based circumscriptions of the small genera Malope (2–3 Mediterranean species: Cullen, 1966; Nogueira et al., 1993; Webb, 1968), Kitaibela (1 species in Southeast Europe: Webb, 1968) and Malvalthaea (1–3 lignified perennial species from the Caucasus and Northern Iran: Iljin, 1949; Riedl, 1976) are uncontroversial, those of Malva, Lava- tera, Althaea and Alcea are not. The reason is that different authors emphasized different (often single) characters as the differential ones, but, as in other malvaceous groups such as the Hibisceae (Pfeil et al., 2002), these are burdened with extensive homoplasy. 1055-7903/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2008.10.015 * Corresponding author. E-mail address: pedro.escobar.garcia@univie.ac.at (P. Escobar García). Molecular Phylogenetics and Evolution 50 (2009) 226–239 Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev