Diplarche and Menziesia transferred to Rhododendron (Ericaceae)

Craven, Lyn A.

doi:10.3767/000651911x568594

Cited by 9 publications

(13 citation statements)

References 6 publications

(11 reference statements)

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“…Our results agree in a well-supported monophyly of Rhododendron (Figs. 1-2), which is in line with previous studies e.g., Shrestha et al, 2018;and Schwery et al, 2015), and when species of Ledum and Menziesia are included (Craven (2011), Goetsch et al (2005), Kron and Judd (1990) and Kurashige et al (2001). Rhododendron camtschaticum, representing R. subgen.…”

Section: Discussionsupporting

confidence: 89%

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Incongruent phylogenies and its implications for the study of diversification, taxonomy and genome size evolution ofRhododendron(Ericaceae)

Khan

Nolzen

Schepker³

et al. 2020

Preprint

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PREMISERhododendron L. (Ericaceae Juss.), is the most species-rich genus of woody flowering plants with > 1000 species. Despite the interest in the genus and numerous previous phylogenetic analysis, the infrageneric classification for the genus is still debated, partly due to its huge diversity, partly due to homoplasy in key characters and partly due to incongruence between phylogenetic markers. Here, we provide a broad coverage of representative species of all Rhododendron subgenera, sections, and most subsections to resolve its infrageneric phylogeny or highlight areas of incongruence, support previous analyses of diversification patterns and establish a relationship between genome size evolution and its diversification.METHODSWe generated sequences of two plastid (trnK and trnL-F) and two nuclear (ITS and rpb2-i) markers for a total of 259 Rhododendron species, and used likelihood and Bayesian statistics to analyze the data. We analyzed the markers separately to discuss and understand incongruence among the data sets and among previous studies.RESULTSWe found that the larger a subgenus, the more strongly it is supported as monophyletic. However, the smaller subgenera pose several problems, e.g., R. subgen. Azaleastrum consists of two sections inferred to be polyphyletic. The main shift to higher diversification in the genus occurred in the Himalayan/SE Asian clade of R. subgen. Hymenanthes. We found that polyploidy occurs in almost all subgenera but most polyploid species are within R. subgen. Rhododendron sections Rhododendron and Schistanthe.CONCLUSIONWhereas previous reports stated that genome sizes of tropical plants are lower than those of colder and temperate regions in angiosperms in general, our study provides evidence for such a shift to small genome-tropical species within a genus. Taken together, we see the merit in the recognition of the five major clades at the sub generic level but given the amount of incongruence a large amount of species cannot be confidently assigned to one of these five clades. Further, genome-wide data will be necessary to assess whether these currently unassignable taxa are independent taxa, assignable to one of the five major clades or whether they are inter-subgeneric hybrids.

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Section: Discussionsupporting

confidence: 89%

“…& Thomson and Menziesia Sm. (Craven, 2011). With respect to the intrageneric classification, Goetsch et al (2005), based on DNA-based phylogenetic analyses, suggested a reduction to five subgenera, R. subgen.…”

mentioning

confidence: 99%

Incongruent phylogenies and its implications for the study of diversification, taxonomy and genome size evolution ofRhododendron(Ericaceae)

Khan

Nolzen

Schepker³

et al. 2020

Preprint

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“…Our results show a strongly supported monophyletic Rhododendron (Figures 1 and 2; Appendices S12-S18), which is in line with previous studies (e.g., Schwery et al, 2015;Shrestha et al, 2018), and, after inclusion of Ledum and Menziesia, also in line with Craven (2011), Goetsch et al (2005), Kron and Judd (1990), and Kurashige et al (2001). Rhododendron camtschaticum, representing R. subg.…”

Section: Phylogeny Of Rhododendronsupporting

confidence: 92%

Incongruent phylogenies and their implications for the study of diversification, taxonomy, and genome size evolution of Rhododendron

Khan

Nolzen

Schepker³

et al. 2021

American J of Botany

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Premise: Classification of taxa depends on the quality of inferred phylogenies. Rhododendron, a highly species-rich genus (>1156 species) of woody plants, has a highly debated infrageneric classification, due to its huge diversity, homoplasy in key characters, and incongruence among data sets. We provide a broad coverage of representative species to resolve Rhododendron infrageneric phylogeny and highlight the areas of incongruence. We further investigate the effect of polyploidy and genome size evolution on diversification of Rhododendron. Methods: We generated two plastid and two nuclear loci for 260 Rhododendron species. We analyzed the loci separately as well as concatenated, utilizing both likelihood and Bayesian methods. We tested incongruence both among the data sets and with previous studies. We estimated genome sizes for 125 species through flow cytometry. Results: Our results suggest stronger support for larger subgenera; however, the smaller subgenera pose several problems; for example, R. tomentosum (former genus Ledum) occupies incongruent positions based on different DNA regions. The main shift to higher diversification in the genus occurs in the Himalayan/Southeast Asian clade of R. subg. Hymenanthes. We found that polyploidy occurs in almost all subgenera but most frequently within R. subg. Rhododendron sections Rhododendron and Schistanthe. Conclusions: We endorse the recognition of five major clades at the subgeneric level, but a number of species cannot be confidently assigned to these clades due to incongruency. With regard to genome size evolution, results support previous reports that genome sizes of tropical plants are lower than those of colder and temperate regions and that genome downsizing promotes diversification.

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“…Generic delimitation of the tribe Rhodoreae is a subject of dispute until now (Gillespie and Kron, 2010). The phylogenetic analyses of Rhododendron based on molecular data did not support the individual generic status of Menziesia and Therorhodion, or even Diplarche (Craven, 2011), but suggested their inclusion within the genus Rhododendron (Kurashige et al, 2001;Goetsch et al, 2005). The results of this palynological study added some new points of disagreement within the present generic alignment of this tribe (Gillespie and Kron, 2010).…”

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confidence: 56%

Pollen morphology of Rhododendron L. and related genera and its taxonomic significance

Sarwar

Takahashi

2013

Bangladesh J. Plant Taxon

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Pollen grains of 40 taxa of Rhododendron L. and its closely related genera, Therorhodion L. and Menziesia Sm., were examined by means of light microscopy and scanning electron microscopy (SEM), or SEM alone. Pollen tetrads of R. japonicum, R. schlippenbachii, R. tsusiophyllum and M. pentandra were examined also withtransmission electron microscopy. In all the genera studied, 3-colporate, oblate tosuboblate pollen grains are arranged in tetrahedral tetrads. The apocolpial pollen wall is composed of the exine - well developed tectum, columellae, foot layer and endexine, and the intine. On the contrary, the septal exine is composed of fragmentary tectum, and the two foot layers of adjacent grains are sometimes connected by columellae and endexine. Among different infrageneric taxa only the subsect. Ledum (sect. & subgen. Rhododendron) was characterized by small sized pollen tetrads, higher 2f/D value and rugulate exine sculpture. The pollen morphological characteristics overlapped each other in all other taxa. Thus palynological features showed little usefulness in the infrageneric classification of Rhododendron, however, they gave additional support to the individualgeneric status of Menziesia and Tsusiophyllum, and the sister relationship between Rhododendron and Therorhodion.DOI: http://dx.doi.org/10.3329/bjpt.v20i2.17393Bangladesh J. Plant Taxon. 20(2): 185-199, 2013

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Diplarche and Menziesia transferred to Rhododendron (Ericaceae)

Cited by 9 publications

References 6 publications

Incongruent phylogenies and its implications for the study of diversification, taxonomy and genome size evolution ofRhododendron(Ericaceae)

Incongruent phylogenies and its implications for the study of diversification, taxonomy and genome size evolution ofRhododendron(Ericaceae)

Incongruent phylogenies and their implications for the study of diversification, taxonomy, and genome size evolution of Rhododendron

Pollen morphology of <i>Rhododendron</i> L. and related genera and its taxonomic significance

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