Contrasting nuclear‐plastidial phylogenetic patterns in the recently diverged IberianPhlomis crinitaandP. lychnitislineages (Lamiaceae)

Abstract

Systematic and evolutionary relationships within the diploid Western Mediterranean Phlomis crinita/lychnitis complex remain controversial apparently due to hybridization and introgression. This study examines patterns of sequence variation in the nuclear ribosomal DNA (ITS region) and three non‐coding plastid DNA regions (trnH‐psbA, trnT‐trnL and atpB‐rbcL) in this complex in an aim to clarify whether hybridization, introgression or lineage sorting resulting from recent diversification is mainly responsible for poorly understood relationships. Information recovered from nuclear and chloroplast markers was found to be strongly incongruent. Phylogenetic analysis of inferred nuclear ITS ribotypes is consistent with previous morphometric and taxonomic results in distinguishing two sister lineages, P. crinita s.l. and P. lychnitis. In addition, the high number of additive polymorphisms detected in ITS sequences suggests the sharing of ancestral variability and local patterns of gene flow within the complex. In contrast, the pattern of chloroplast haplotype variation is geographic rather than taxonomic, which might be caused by low mutation rates combined with frequent instances of interspecific hybridization. To integrate the apparently discordant plastid and nuclear evidence, we suggest that both lineage sorting and horizontal transfer have been involved. Even though pinpointing cases due to either phenomenon is difficult, the available data provide evidence of two sister lineages where hybridization events can be identified despite the inheritance of ancestral polymorphisms.

A plastid tree can bring order to the chaotic generic taxonomy of Rytidosperma Steud. s.l. (Poaceae)

“…The existence of a geographical structure to the cpDNA data, such that samples show affinity according to geographical area of origin rather than to morphology and thus traditional systematic arrangement, could confuse patterns at morphological and ecological levels (Fuertes Aguilar et al, 1999a;Feliner et al, 2004). Geographical patterning in cpDNA markers has been reported for the Tasmanian eucalypts (McKinnon et al, 2001(McKinnon et al, , 2004, for Iberian species of Phlomis (Albaladejo et al, 2005) and for white oaks in Europe (Dumolin-Lapé-gue et al, 1997;Petit et al, 2002). In these plant groups there is mounting evidence for the presence of several haplotypes within a single species, shared among species within geographical regions, with introgression and hybridisation being invoked as the most likely cause (Dumolin-Lapégue et al, 1997;Steane et al, 1998;Fuertes Aguilar et al, 1999a;Jackson et al, 1999;McKinnon et al, 2001;Petit et al, 2002).…”

Circumscription and phylogenetic relationship of Prostanthera densa and P. marifolia (Lamiaceae)

“…The psbA-trnH regions have been used at the interspecific level in the Lamiaceae (Albaladejo et al 2005;Gobert et al 2006). Similarly, the ETS region of nuclear ribosomal DNA has been found to evolve faster and consequently have greater variability than the internal transcribed spacer (ITS) region, which is more frequently used, making ETS particularly useful for studies below the generic level (Baldwin and Markos 1998;Linder et al 2000;Stappen et al 2003;Wilson et al 2012).…”

Estimation of phylogenetic relationships of Phlomis species based on seed protein polymorphism

“…The genus Phlomis L. contains over 100 species that have been divided into two main sections: Phlomoides and Phlomis (Moench, 1794;Albaladejo et al 2005). Section Phlomis was further subdivided into three subsections, Dendrophlomis, Gymnophlomis and Oxyphlomis (Bentham, 1834).…”

“…Morever, differentiation of P. carica from P. armeniaca, and of P. nissoli from P. syriaca within this complex is based on indimentum of calyces and leaves; hovewer, this character shows high variation among individuals of a population and among populations of these species (Huber-Morath, 1982). Also, hybridization is a common incident in this genus, leading to the formation of many interspecific hybrids that increase the taxonomic complexity (Albaladejo et al 2004;Albaladejo et al 2005;Albaladejo and Aparicio, 2007;Yuzbasioglu et al 2008b). Seed storage protein markers have been sucessfully used to resolve taxonomic relationships and characterize cultivated varieties in a number of crop plant species (Igrejas et al 1999;Vladova et al 2000;Jha and Ohri, 2002;Karihaloo et al 2002;Syros et al 2003;Bhargava et al 2005;Cherdouh et al 2005;Alvarez et al 2006;Stoilova et al 2006;Mirali et al 2007;Rout and Chrungoo, 2007;Yuzbasioglu et al 2008a) because they are stable, uniform, reliable, reproducible and largely independent of environmental fluctuations (Ghafoor et al 2002;Panigrahi et al 2007).…”