Molecular phylogenetic analysis of Hawaiian Rutaceae (Melicope,PlatydesmaandZanthoxylum) and their different colonization patterns

Abstract

Melicope (Rutaceae) is one of the largest plant genera on the Hawaiian Islands. We present here a detailed molecular phylogenetic analysis of the Hawaiian species of this genus and compare the results with the other genera of Hawaiian Rutaceae, Platydesma and Zanthoxylum. Four nuclear and two plastid markers were sequenced, with the goals of untangling phylogenetic relationships, inferring biogeographic events and comparing patterns of distribution among the three genera. Our results show that there were two colonization events (Melicope + Platydesma, and Zanthoxylum) to the Hawaiian Islands, that Hawaiian Rutaceae have an Asian, Australian or Pacific origin and that there were two independent colonization events of Hawaiian Melicope lineages to the Marquesas Islands. The two most widely distributed Hawaiian Melicope spp. are not monophyletic and the current subgeneric classification of Hawaiian Melicope is highly artificial. On the Hawaiian Islands, Melicope and Zanthoxylum show contrasting biogeographic patterns, suggesting different patterns of dispersal. Melicope has a high percentage of single‐island endemics suggesting low dispersal ability, whereas Zanthoxylum taxa tend to occur across multiple islands. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 425–448.

The quest to resolve recent radiations: Plastid phylogenomics of extinct and endangered Hawaiian endemic mints (Lamiaceae)

“…Phylogenies of the Hawaiian mints have been reconstructed from datasets composed of commonly used DNA sequence markers, including cpDNA and nuclear ribosomal 5S non-transcribed spacer and external transcribed spacer regions (Lindqvist and Albert, 2002;Roy et al, 2013), which are rapidly evolving in many other species (Baldwin and Markos, 1998;Shaw et al, 2005;Small et al, 1998), but they fail to resolve relationships among the Hawaiian mints. A similar pattern of low genetic diversity has been noted in other recent radiations of Hawaiian plants (Appelhans et al, 2014;Baldwin and Sanderson, 1998;Cronk et al, 2005;Givnish et al, 2009;Givnish et al, 2013). Given this low diversity in recent radiations, large amounts of data are clearly required to increase resolution.…”

Reduction of the Hawaiian genus Platydesma into Melicope section Pelea (Rutaceae) and notes on the monophyly of the section

“…Sakai et al (1995) hypothesized that Hawaiian Melicope and Platydesma both arose from separate colonizations; the Melicope colonist was dimorphic while the ancestor of Platydesma was monomorphic. The results of molecular phylogenetic analyses (Harbaugh et al 2009, Appelhans et al 2014a,b) demonstrate that Hawaiian Melicope and Platydesma most likely arose from a single ancestor. The ancestor of Hawaiian Melicope + Platydesma was likely dioecious, because the closest relatives of the Hawaiian species (=the remainder of Melicope section Pelea excluding species from New Caledonia) are almost exclusively dioecious (Hartley 2001).…”

“…Recent molecular phylogenetic studies provided unequivocal evidence for the placement of Platydesma within Melicope , as sister to the Hawaiian taxa in Melicope section Pelea (Harbaugh et al 2009, Appelhans et al 2014a, 2014b; Fig. 1).…”

Continuous existence of Zanthoxylum (Rutaceae) in Southwest China since the Miocene

“…Today, Zanthoxylum is distributed in tropical, subtropical to temperate zones Kubitzki et al, 2011), with a wide habitat preference ranging from wet to arid conditions (Tiffney, 1980;Appelhans et al, 2014). The genus is capable of adapting to various sorts of climatic conditions or niches.…”