2,142 research outputs found

    Collections-based systematics: Opportunities and outlook for 2050

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    Wen, Jun, Ickert-Bond, Stefanie M., Appelhans, Marc S., Dorr, Laurence J., Funk, Vicki A. (2015): Collections-based systematics: Opportunities and outlook for 2050. Journal of Systematics and Evolution 53 (6): 477-488, DOI: 10.1111/jse.12181, URL: http://dx.doi.org/10.1111/jse.1218

    Reduction of the Hawaiian genus Platydesma into Melicope section Pelea (Rutaceae) and notes on the monophyly of the section

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    Platydesma, an endemic genus to the Hawaiian Islands containing four species, has long been considered of obscure origin. Recent molecular phylogenetic studies have unequivocally placed Platydesma within the widespread genus Melicope as sister to the rest of the Hawaiian species of Melicope. This makes submerging Platydesma into Melicope necessary. We make the necessary new combinations: Melicope cornuta (Hillebr.) Appelhans, K.R. Wood & W.L. Wagner, M. cornuta var. decurrens (B.C.Stone) Appelhans, K.R. Wood & W.L. Wagner, M. remyi (Sherff) Appelhans, K.R. Wood & W.L. Wagner, and M. rostrata (Hillebr.) Appelhans, K.R. Wood & W.L. Wagner. An additional species that has been recognized within Platydesma should now be recognized under its original name M. spathulata A. Gray. All Hawaiian species belong to Melicope section Pelea. Our molecular phylogenetic studies also showed that in addition to merging Platydesma into section Pelea, five species described from New Caledonia need to be excluded from the section in order to achieve monophyly of section Pelea

    Melicope balgooyi Appelhans, W.L. Wagner & K.R. Wood, a new species and new record in Melicope section Melicope (Rutaceae) for the Austral Islands

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    Melicope balgooyi, a new species of Melicope (Rutaceae) is described. It is known only from the Austral Islands in the South Pacific (French Polynesia). However, it is not closely related to the other two species previously known from the Austral Islands, which are part of Melicope section Vitiflorae. The new species belongs to Melicope section Melicope and is most closely related to species from New Zealand, the Kermadec Islands, and the Society Islands. The new species has alternate to sub-opposite leaves, which is a very rare arrangement in Melicope and has only been described for two other species of the genus so far

    A molecular phylogeny of Acronychia, Euodia, Melicope and relatives (Rutaceae) reveals polyphyletic genera and key innovations for species richness

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    We present the first detailed phylogenetic study of the genus Melicope, the largest genus of the Citrus family (Rutaceae). The phylogenetic analysis sampled about 50% of the 235 accepted species of Melicope as well as representatives of 26 related genera, most notably Acronychia and Euodia. The results based on five plastid and nuclear markers have revealed that Acronychia, Euodia and Melicope are each not monophyletic in their current circumscriptions and that several small genera mainly from Australia and New Caledonia need to be merged with one of the three genera to ensure monophyly at the generic level. The phylogenetic position of the drupaceous Acronychia in relation to Melicope, which has capsular or follicular fruits, remains unclear and Acronychia might be a separate genus or a part of Melicope. The seed coats of Melicope, Acronychia and related genera show adaptations to bird-dispersal, which might be regarded as key innovations for species radiations. Euodia and its relatives, which lack these adaptations, include only about 20 species while the Melicope-Acronychia group consists of about 340 species. The drupaceous genera Comptonella, Dutaillyea, Picrella and Sarcomelicope are nested within Melicope and need to be merged with Melicope. The expanded genus is a prime example of the artificial classification system of Engler, who defined Rutaceous subfamilies mainly based on gynoecial and fruit characters. (C) 2014 Elsevier Inc. All rights reserved

    Figure 1 from: Appelhans MS, Wood KR, Wagner WL (2017) Reduction of the Hawaiian genus Platydesma into Melicope section Pelea (Rutaceae) and notes on the monophyly of the section. PhytoKeys 91: 125-137. https://doi.org/10.3897/phytokeys.91.21363

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    Figure 1 Phylogenetic affinities of Hawaiian Melicope section Pelea (incl. Platydesma) based on five plastid and nuclear markers (modified from Appelhans et al. 2014a). "Subsections" Apocarpa, Megacarpa and Pelea contain exclusively Hawaiian and Marquesan species and "subsection" Platydesma includes the former Hawaiian genus Platydesma. The New Caledonian species of Melicope section Pelea are part of the "mixed clade" and we therefore propose to exclude them from section Pelea

    Phylogenetic placement of Psilopeganum, a rare monotypic genus of Rutaceae (the citrus family) endemic to China

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    Psilopeganum (Rutaceae) is a rare monotypic genus endemic to the vicinity of the Yangtze River valley in Chongqing, Hubei, Sichuan and Guizhou provinces in China. It differs from most Rutaceae taxa by its herbaceous habit and has been treated as a member of the tribe Ruteae. Our study is the first attempt to place Psilopeganum in a phylogenetic context and our results show that the genus belongs to a clade with Boenninghausenia, Ruta and Thamnosma, which are part of Ruteae. Within this group, the position of Psilopeganum remains unclear because the Boenninghausenia-Thamnosma clade, Psilopeganum and Ruta form a trichotomy in most analyses. The ITS dataset placed Psilopeganum as sister to the Mediterranean and Canarian genus Ruta, which is corroborated by morphological similarities. Our studies support that Ruteae is paraphyletic with respect to Aurantioideae and that Dictamnus does not belong to Ruteae. The Indian, Sri Lankan, and Malagasy genus Chloroxylon is sister to the Boenninghausenia-Psilopeganum-Ruta-Thamnosma clade, despite its traditional placement in the subfamily Flindersioideae. The placement of Chloroxylon is consistent with an origin of the group of Chloroxylon, Boenninghausenia, Psilopeganum, Ruta and Thamnosma in southern Asia. The rapid uplifts of the Himalayas could account for one or two vicariance events splitting the lineages of the Boenninghausenia-Psilopeganum-Ruta-Thamnosma clade, and may explain the short branch length and low support for the relationships among Psilopeganum, Ruta, and the Boenninghausenia-Thamnosma clade

    Target enrichment improves phylogenetic resolution in the genus Zanthoxylum (Rutaceae) and indicates both incomplete lineage sorting and hybridization events

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    BACKGROUND AND AIMS: Zanthoxylum is the only pantropical genus within Rutaceae, with a few species native to temperate eastern Asia and North America. Efforts using Sanger sequencing failed to resolve the backbone phylogeny of Zanthoxylum. In this study, we employed target-enrichment high-throughput sequencing to improve resolution. Gene trees were examined for concordance and sectional classifications of Zanthoxylum were evaluated. Off-target reads were investigated to identify putative single-copy markers for bait refinement, and low-copy markers for evidence of putative hybridization events. METHODS: A custom bait set targeting 354 genes, with a median of 321 bp, was designed for Zanthoxylum and applied to 44 Zanthoxylum species and one Tetradium species as the outgroup. Illumina reads were processed via the HybPhyloMaker pipeline. Phylogenetic inferences were conducted using coalescent and maximum likelihood methods based on concatenated datasets. Concordance was assessed using quartet sampling. Additional phylogenetic analyses were performed on putative single and low-copy genes extracted from off-target reads. KEY RESULTS: Four major clades are supported within Zanthoxylum: the African clade, the Z. asiaticum clade, the Asian–Pacific–Australian clade and the American–eastern Asian clade. While overall support has improved, regions of conflict are similar to those previously observed. Gene tree discordances indicate a hybridization event in the ancestor of the Hawaiian lineage, and incomplete lineage sorting in the American backbone. Off-target putative single-copy genes largely confirm on-target results, and putative low-copy genes provide additional evidence for hybridization in the Hawaiian lineage. Only two of the five sections of Zanthoxylum are resolved as monophyletic. CONCLUSIONS: Target enrichment is suitable for assessing phylogenetic relationships in Zanthoxylum. Our phylogenetic analyses reveal that current sectional classifications need revision. Quartet tree concordance indicates several instances of reticulate evolution. Off-target reads are proven useful to identify additional phylogenetically informative regions for bait refinement or gene tree based approaches
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