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Phylogeny of Salix subgenus Salix s.l. (Salicaceae): delimitation, biogeography, and reticulate evolution.

ABSTRACT: BACKGROUND:The taxonomy and systematics of Salix subgenus Salix s.l. is difficult. The reliability and evolutionary implications of two important morphological characters (number of stamens, and morphology of bud scales) used in subgeneric classification within Salix remain untested, and a disjunct Old-New World distribution pattern of a main clade of subgenus Salix s.l., revealed by a previous study, lacks a reasonable explanation. To study these questions, we conducted phylogenetic analyses based on 4,688 bp of sequence data from four plastid (rbcL, trnD-T, matK, and atpB-rbcL) and two nuclear markers (ETS and ITS) covering all subgenera of Salix, and all sections of subgenus Salix s.l. RESULTS:Subgenus Salix came out as para- or polyphyletic in both nrDNA and plastid trees. The plastid phylogeny successfully resolved relationships among the major clades of Salix, but resolution within subgenus Salix s.l. remained low. Nevertheless, three monophyletic groups were identifiable in subgenus Salix s.l.: the 'main clade' of subgenus Salix s.l., with New and Old World species being reciprocally monophyletic; the section Triandroides clade; and the subgenus Pleuradenia clade. While nrDNA regions showed higher resolution within subgenus Salix s.l., they failed to resolve subgeneric relationships. Extensive, statistically significant gene-tree incongruence was detected across nrDNA-plastid as well as nrDNA ETS-ITS phylogenies, suggesting reticulate evolution or hybridization within the group. The results were supported by network analyses. Ancestral-state reconstructions indicated that multiple stamens and free bud scales represent the plesiomorphic states within Salix, and that several significant shifts in stamen number and bud scale morphology have occurred. CONCLUSIONS:Subgenus Salix s.l. is not monophyletic, and the evolutionary history of the subgenus has involved multiple reticulation events that may mainly be due to hybridization. The delimitation of subgenus Salix s.l. should be redefined by excluding section Triandrae and subgenus Pleuradenia from it. The evolutionary lability of bud-scale morphology and stamen number means that these characters are unreliable bases for classification. The disjunct Old-New World distribution of subgenus Salix s.l. appears to be linked to the profound climatic cooling during the Tertiary, which cut off gene exchange between New and Old World lineages.

SUBMITTER: Wu J

PROVIDER: S-EPMC4357182 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Project description:Nolanea is a well-known and long-established subgenus of the genus Entoloma traditionally defined mainly by the mycenoid basidiocarps of the included species. Until now, revisions of this subgenus including molecular data exist only on a regional scale. In this study, the phylogeny of species of Nolanea is analysed based on multi-gene DNA sequences including data of specimens from all continents. New primers are designed for the mitochondrial small subunit and RPB2. The performance of the DNA loci in reconstructing the phylogeny in subg. Nolanea is evaluated. An ancestral state reconstruction is used to infer the character state evolution as well as the importance and reliability of morphological characters used to define subclades below subgeneric rank. Based on the results, seven sections are recognised in Nolanea: the sections Holoconiota, Infularia, Mammosa, Nolanea, Papillata, Staurospora, and the newly described sect. Elegantissima. A large phylogeny based on the fungal barcode rDNA ITS with numerous type sequences is used to evaluate current species concepts. Several names are revealed to be synonyms of older names. Four species new to science are described, namely E. altaicum, E. argillaceum, E. cornicolor, and E. incognitum. Lectotypes, epitypes or neotypes are designated for E. cetratum, E. clandestinum, E. conferendum, E. cuspidiferum, E. hebes, E. minutum, E. nitens, and E. rhodocylix. The re-evaluation of the limits of subg. Nolanea leads to an altered concept excluding species with distinct, lageniform cheilocystidia. The section Ameides is placed in subg. Leptonia. For several species formerly accommodated in Nolanea, but excluded now, viz., E. lepiotoides, E. rhombisporum, E. subelegans, and E. velenovskyi the taxonomic position remains unclear, because of the yet unresolved phylogeny of the whole genus Entoloma. Citation: Reschke K, Morozova OV, Dima B, et al. 2022. Phylogeny, taxonomy, and character evolution in Entoloma subgenus Nolanea. Persoonia 49: 136-170. https://doi.org/10.3767/persoonia.2022.49.04.

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Phylogeny of Salix subgenus Salix s.l. (Salicaceae): delimitation, biogeography, and reticulate evolution.

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