Phylogeny of the Dorotheantheae (Aizoaceae), a tribe of succulent annuals

Abstract

Dorotheantheae (Aizoaceae) is a small tribe of succulent annual herbs with flat leaves belonging to the generaAethephyllum, Cleretum and Dorotheanthus, which are endemic to the winter–rainfall region of South Africa. Several species are well–known for their conspicuous and striking flowers but others possess very inconspicuous flowers. Analysis of molecular data from combined plastid and nuclear sequences shows that Dorotheanthus is monophyletic while Cleretum is diphyletic, since the two species of Cleretum with lyrate leaves are most closely related to the vegetatively similar, monotypic Aethephyl–lum. In the absence of clear, diagnostic characteristics for separating Cleretum and Dorotheanthus, a revised classification for the Dorotheantheae is proposed in which the tribe consists of a single genus, Cleretum. Within Cleretum, we recognize 14 species, by raising/re–instating two subspecies to species rank and including two that are still undescribed. The major clades occupy distinct climatic and edaphic niches. Repeated shifting from large to small flowers may indicate changes in the breeding system. Since succulence in annuals is rare in the winter–rainfall region of southern Africa, we compare patterns of distribution between Dorotheantheae and the other leaf–succulent annuals in the region, namely in Mesembryanthemum (Aizoaceae) and in Crassula (Crassulaceae). We find that similar to the non–succulent annuals of the Poaceae and the Brassicaceae in this region, the annual species of Mesembryanthemum show a preference for arid areas. In contrast, in Dorotheantheae and in Crassula the hot–spots of diversity lie mainly in the wetter parts of the winter–rainfall area, with a decrease in the number of annual species northwards to the arid, winter–rainfall areas of the Richtersveld and the southern Namib.

Biodiversity hotspots and Ocbil theory

“…x Myobatrachid frog Crinia georgiana Edwards et al (2007) x Banksia (Proteaceae) phylogenetic clustering Merwin et al (2012) x Rix et al (2014) Plant Soil x A u s t Acacia (Mimosaceae) Miller et al (2013) x A u s t S a l t -t o l e r a n t Acacia (Mimosaceae) Bui et al (2014a) x A u s t S a l t -t o l e r a n t Acacia ( x Above and below ground mutualisms affect oil-secreting orchids (Coryciinae) speciation Waterman et al (2011) x Marine climate-driven rampant speciation Namaqualand fossil pollen floras Dupont et al (2011) x Succulent annuals Dorotheantheae (Aizoaceae) Klak and Bruyns (2012) x Pelargonium (Geraniaceae) Martınez-Cabrera and Peres-Neto (2013) x Evolution of stapeliads (ApocynaceaeAsclepiadoideae) Bruyns et al (2014) x Ecology limits the diversity of sedges Tetraria (Cyperaceae) Slingsby et al (2014) x Oxalis (Oxalidaceae), especially vernal pool species Oberlander et al (2014) x Painted petal irises (Lapeirousia: Iridaceae). Forest et al (2014) x Speciation, extinction -Greater Cape flora Ellis et al (2014) x Topography as a driver of diversification x x AtRf Bromeliaceae adaptive radiation species diversification Givnish et al (2014) x Whole flora of tepui highlands and Gran Sabana uplands Rull et al (2013) 5.…”

Repeated evolution of endoscopic peripheral vascular bundles in succulent leaves of Aizoaceae (Caryophyllales)

“…-Several phylogenies have already been published for the Aizoaceae and for individual clades within the family, which showed high statistical support for the major clades (Klak & al., 2003(Klak & al., , 2007Klak & Bruyns, 2012), but moderate support in many parts of the tree within Ruschieae . In order to map the ancestral reconstruction of the orientation and presence of PVB, we generated a tree which retrieved the same well-supported nodes found previously (Klak & al., 2003(Klak & al., , 2007Klak & Bruyns, 2012). Since no transitions were found for the venation pattern in tribe Ruschieae, lack of resolution in this part of the tree would not have influenced our interpretation of the evolution of the PVB in Aizoaceae.…”

A phylogeny and revised classification for the Apatesieae (Aizoaceae: Ruschioideae) with a comparison of centres of diversity

“…Mesembryanthemum haeckelia num A.Berger was selected arbitrarily from the Mesembry anthemoideae to root the tree. In addition, two species from the Ruschieae and six species from the Dorotheantheae were chosen as outgroups (Klak & al., 2003;Klak & Bruyns, 2012). The material sampled is listed with GenBank accession num bers in Appendix 1.…”

“…Except for Mesembryanthemum haeckelianum (Mesembryan themoideae), Cleretum bruynsii Klak, C. lyratifolium Ihlenf. & Struck and C. patersonjonesii Klak, sequences of the psbA trnH, trnStrnG, trnQ UUG rps16 and the ITS regions for all other outgroups were obtained from GenBank (Klak & al., 2003Klak & Bruyns, 2012).…”

“…For this it was established that the highest level of generic diversity for the Ruschioideae as well as the Mesembryanthemoideae lies in the arid, winterrainfall areas of southern Africa (Bittrich, 1986;Jürgens, 1986;Hartmann, 1991), with centres in both the Succulent Karoo Region (SKR) and the Cape Floristic Region (CFR). However, this appears to mask a more complex situation since analysis of data for the Dorotheantheae (a tribe within Ruschioideae) showed that the highest concentration of species is in the wetter parts of the winterrainfall area in the CFR (Klak & Bruyns, 2012). The Aizooideae, which is sister to the Mesembryanthemoideae + Ruschioideae (Klak & al., 2003), shares the slightly succulent, flattened or subcylindrical leaves with a mesomorphic epider mis (Hartmann, 2001) with the Apatesieae, Dorotheantheae and Mesembryanthemoideae.…”