Phylogenetic reconstruction of the genus Helianthemum (Cistaceae) using plastid and nuclear DNA‐sequences: Systematic and evolutionary inferences

Abstract

Helianthemum is the largest, most widely distributed and most taxonomically complex genus of the Cistaceae. To examine the intrageneric phylogenetic relationships in Helianthemum, we used sequence data from plastid DNA (ndhF, psbA-trnH, trnL-trnF) and the nuclear ITS region. The ingroup consisted of 95 species and subspecies (2 subgenera, 10 sections) from throughout the range of Helianthemum, while the outgroup was composed of 30 species representing all the genera in the Cistaceae (Cistus Crocanthemum, Fumana, Halimium, Hudsonia, Lechea, Tuberaria) plus Anisoptera thurifera subsp. polyandra (Dipterocarpaceae). To infer phylogenetic relationships, we analysed three different matrices (cpDNA, nrDNA, cpDNA + nrDNA concatenated) using maximum likelihood and Bayesian inference, and performed molecular dating to estimate the ages of origin of the main clades using a Bayesian approach. The cpDNA + nrDNA concatenated dataset provided the highest Bayesian posterior probabilities and bootstrap support values, and the results supported the monophyly of the genus Helianthemum and its sister relationship to a clade consisting of all species of Cistus, Crocanthemum, Halimium, Hudsonia and Tuberaria. This result means that we did not retrieve the sister relationship between Helianthemum and Crocanthemum (plus Hudsonia) that could be expected according to previous published studies. Despite their different statistical support, the topology of the inner branches of all the consensus trees showed that Helianthemum is characterized by the emergence of three major clades in agreement with above-species taxonomy, although unresolved polytomies still remain towards the tips of the trees (species and subspecies). Clade I (mainly distributed in Mediterranean and alpine environments in European and western Asiatic mountain chains) fully coincided with subg. Plectolobum, whereas subg. Helianthemum was retrieved in clade II (arid and semi-arid environments from Macaronesia, the Mediterranean, subtropical northern Africa, Anatolia and central Asia) and clade III (Mediterranean ecosystems around the Mediterranean Basin). The burst of diversification during the Plio-Pleistocene detected in the three main clades of Helianthemum is concomitant with the Messinian salinity crisis, the onset of Mediterranean climatic conditions, and Quaternary glaciations, as found in many other groups of Mediterranean plants. Thus, the general lack of resolution in the trees can be attributed to rapid species diversification and events of reticulate evolution. A series of further taxonomic and evolutionary inferences can be drawn from our analyses: (i) no species occupied an early-diverging position with regard the rest of the species; (ii) a close relationship between H. caput-felis and subg. Plectolobum; (iii) an unexpected close relationship between H. squamatum/ H. syriacum (and H. motae), H. lunulatum/ H. pomeridianum and among H. songaricum/ H. antitauricum/ H. germanicopolitanum; (iv) a close relationship between incertae sedis species and sect. Eri...

Inheritance of a hair character in Helianthemum oelandicum var. canescens and allele frequencies in natural populations

“…The genus Helianthemum contains several young species complexes (Guzmán and Vargas 2009;Aparicio et al 2017) with a wide Mediterranean and/or temperate/alpine distribution (e.g. H. apenninum Mill, H. cinereum Pers., H. nummularium, H. marifolium Mill.…”

“…and H. marifolium that did not show any significant terminal resolution in the trees of a recent phylogenetic reconstruction. The poor resolution was ascribed to Pleistocene radiation and events of reticulate evolution (Aparicio et al 2017). The taxonomic treatment of these species complexes in both traditional and recent botanical literature has partly been based on diagnostic traits related to the presence and type of indumentum (e.g.…”

“…Malvaceae, Cistaceae (Janchen 1907;Bayer and Kubitzki 2003). Helianthemum is a young genus (Guzmán and Vargas 2009;Aparicio et al 2017) with a number of variable species complexes that have not yet reached reproductive isolation (cf. Widén 1986Widén , 2015.…”

Genetic diversity and differentiation in narrow versus widespread taxa ofHelianthemum(Cistaceae) in a hotspot: The role of geographic range, habitat, and reproductive traits

“…Originated in the Miocene, the genus diversified during the Pliocene and Pleistocene giving rise to three large radiating lineages, one diversified across the Saharo‐Arabian and Irano‐Turanian regions (sect. Eriocarpum ), the other two diversified around the Mediterranean Basin and the Eurosiberian mountains (sections Helianthemum and Pseudocistus , respectively; Aparicio et al., ; Martín‐Hernanz et al, unpublished). Within these lineages, it is remarkable that currently most species have restricted ranges or are endemic to very small regions (cf., López‐González, ; Proctor & Heywood, ), whereas only some species have large geographic distribution areas (e.g., H. apenninum , H. cinereum , H. kahiricum , H. ledifolium , H. lippii , H. nummularium , H. oelandicum , H. salicifolium, or H. stipulatum ).…”

“…This study focuses on four taxa of Helianthemum from Sierra Nevada (southern Spain) that are two pairs of relatives with disparate distribution area (two local endemics vs. two widespread) and soil preferences (two dolomite specialists vs. two soil generalist), which moreover represent two different lineages (subgenera) within Helianthemum (Aparicio et al., ). The aim of this study was to unravel the effect of environmental, reproductive, and phylogenetic factors on the patterns of genetic diversity and differentiation in our precise case study.…”