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Harald Schneider - One of the best experts on this subject based on the ideXlab platform.
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inferring the potential of plastid dna based identification of derived ferns a case study on the Asplenium trichomanes aggregate in europe
Plant Systematics and Evolution, 2018Co-Authors: Hongmei Liu, Harald Schneider, Johannes C Vogel, Stephen R RussellAbstract:The utility of three plastid DNA regions to identify fern species was explored with focus on the European representatives of the Asplenium trichomanes aggregate. The sampling included representatives of the three diploid and the four tetraploid taxa recognized in the European flora plus Macaronesia. Besides European samples, the compiled data set comprised specimens of a putative Hawaiian endemic and one species occurring in Southeast Asia. By combining the sequences of three non-coding plastid regions, 13 haplotypes were recovered of which four were found in more than one taxon. Evidences for four distinct diploid lineages were found that correspond to Asplenium anceps, A. inexpectans, A. trichomanes s.s., and A. tripteropus. The four tetraploids occurring in Europe shared haplotypes with A. inexpectans. Thus, DNA barcoding can successfully identify the diploids, but fail to separate the tetraploids from their diploid ancestors. As a consequence, barcoding analyses of ferns need to take into account the differences of ploidy level measured by evidence independent from the DNA barcode. Evidence for uneven accumulation of intra-species DNA variation was recovered by comparing all species. Furthermore, the study provided evidence that the current taxonomy of these ferns requires to be revised. The two European diploids form well-separated clades and need to be recognized as A. inexpectans and A. trichomanes s.s. To keep name consistency for all European tetraploids, a new name Asplenium jessenii is introduced to replace A. trichomanes subsp. hastatum.
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phylogenetic relationships of two cuban spleenworts with unusual morphology Asplenium schaffneria nigripes and Asplenium pumilum aspleniaceae leptosporangiate ferns
Plant Systematics and Evolution, 2017Co-Authors: Josmaily Loriga, Ledis Regalado, Carmen Prada, Harald Schneider, Jochen HeinrichsAbstract:The infrageneric classification of Asplenium, the most species-rich genus of ferns, is notoriously difficult as a result of extensive morphological homoplasy combined with exceptional morphological disparity. Besides a core Asplenium, 29 satellite genera have been described, but most of them have not been widely accepted. In recent years, molecular phylogenetic studies found most of these satellite genera to be nested in Asplenium, but several morphologically distinct taxa have not yet been included in such studies. One of these elements is the monospecific neotropical genus Schaffneria which is characterized by undivided suborbicular blades, lack of a costa, black stipes, netted veins and single or paired sori. Maximum likelihood and Bayesian phylogenetic inference based on the chloroplast DNA markers rbcL, rps4, rps4-trnS and trnL-trnF indicated a position of Schaffneria nigripes within Asplenium. We thus propose to treat Schaffneria as a synonym of Asplenium and adopt the name Asplenium nigripes. With the current sampling, Asplenium (Schaffneria) nigripes is placed sister to A. pumilum, the only species of Asplenium with whitish catenate hairs on its leaves. Despite considerable morphological differences, both species resemble each other in several features including filiform-lanceolate, mostly entire, brown-blackish rhizome scales with a dark-sclerotic center and some marginal projections, a striate, hairy epidermis, echinolophate spore ornamentation with slim microechinate folds forming small lacunae, and Aspidium-type gametophytes.
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species diversity and reticulate evolution in the Asplenium normale complex aspleniaceae in china and adjacent areas
Taxon, 2013Co-Authors: Yanfen Chang, Harald SchneiderAbstract:The Asplenium normale complex contains the widespread A. normale and several geographically restricted spe- cies: A. boreale, A. hobdyi, A. kiangsuense, A. oligophlebium and A. shimurae. The taxonomy of this group is unclear with some entities treated infraspecifically or as synonyms. Furthermore, the existence of diploids and tetraploids in this species complex is suggestive of reticulate evolution. In order to formulate a natural classification and to investigate the relationships in this complex, phylogenetic analyses of plastid and nuclear sequence data and inference of ploidy level were used to assess the distinctiveness of putative taxonomic units and their relationships. The Asplenium normale complex was recovered as a monophyletic group comprising six principal chloroplast lineages. The results support the hypothesis that A. normale s.l. contains several species. Based on our inferences, we outline an improved species classification recognizing three diploid and four tetraploid entities. Incongruence of chloroplast and nuclear phylogenies was interpreted to be a result of recurrent reticulation events in the A. normale complex.
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apomixis and reticulate evolution in the Asplenium monanthes fern complex
Annals of Botany, 2012Co-Authors: Harald Schneider, Robert J Dyer, Vincent SavolainenAbstract:†Background and Aims Asexual reproduction is a prominent evolutionary process within land plant lineages and especially in ferns. Up to 10 % of the approx. 10 000 fern species are assumed to be obligate asexuals. In the Asplenium monanthes species complex, previous studies identified two triploid, apomictic species. The purpose of this study was to elucidate the phylogenetic relationships in the A. monanthes complex and to investigate the occurrence and evolution of apomixis within this group. †Methods DNA sequences of three plastid markers and one nuclear single copy gene were used for phylogenetic analyses. Reproductive modes were assessed by examining gametophytic and sporophyte development, while polyploidy was inferred from spore measurements. †Key Results Asplenium monanthes and A. resiliens are confirmed to be apomictic. Asplenium palmeri, A. hallbergii and specimens that are morphologically similar to A. heterochroum are also found to be apomictic. Apomixis is confined to two main clades of taxa related to A. monanthes and A. resiliens, respectively, and is associated with reticulate evolution. Two apomictic A. monanthes lineages, and two putative diploid sexual progenitor species are identified in the A. monanthes clade. †Conclusions Multiple origins of apomixis are inferred, in both alloploid and autoploid forms, within the A. resiliens and A. monanthes clades.
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genetic diversity and phylogeography in two diploid ferns Asplenium fontanum subsp fontanum and a petrarchae subsp bivalens in the western mediterranean
Molecular Ecology, 2009Co-Authors: Harald Schneider, Stephen J Russell, Harriet V Hunt, Stephen W Ansell, Johannes C VogelAbstract:Asplenium fontanum subsp. fontanum and A. petrarchae subsp. bivalens are diploid rock ferns of limestone outcrops of the western Mediterranean region. Asplenium fontanum subsp. fontanum occurs from Valencia through northeastern Spain to the Alpes-Maritimes and Swiss Jura. Asplenium petrarchae subsp. bivalens occurs only on Majorca, in Valencia and possibly in southern Spain. We analysed allozyme and chloroplast genetic marker diversity in 75 populations of A. fontanum subsp. fontanum and 12 populations of A. petrarchae subsp. bivalens sampled from across their respective ranges. The two species show similar levels of species and population genetic diversity to one another and to other diploid European Asplenium taxa. Both are predominantly outbreeding, as indicated by F(IS) = 0.108 and 0.167 respectively. Substantial between-population differentiation results largely from differentiation between regions. Isolation by distance operates over limited geographic ranges, up to 50 km. In A. fontanum subsp. fontanum, the major geographical differentiation between Valencia and the rest of the taxon range probably represents an ancient range fragmentation. A less pronounced differentiation divides populations in the SW from those in the NE of the range, with evidence for a biogeographic link between the eastern Pyrenees and southeastern France. High diversity in the Pyrenees may either represent ancient population differentiation, or a suture zone. In A. petrarchae subsp. bivalens, populations on Majorca exhibit a subset of the genetic diversity present in Valencia, although the two regions are strongly differentiated by differing allele frequencies. Dispersal from the mainland may have founded Majorcan populations, although a role for in situ island survival cannot be excluded.
Ronald L L Viane - One of the best experts on this subject based on the ideXlab platform.
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a global plastid phylogeny of the fern genus Asplenium aspleniaceae
Cladistics, 2020Co-Authors: Liang Zhang, Carl J Rothfels, Alan R Smith, Ronald L L Viane, David H Lorence, Kenneth R Wood, Chengwei Chen, Ralf Knapp, Lin Zhou, Xinmao ZhouAbstract:The infrageneric relationships and taxonomy of the largest fern genus, Asplenium (Aspleniaceae), have remained poorly understood. Previous studies have focused mainly on specific species complexes involving a few or dozens of species only, or have achieved a large taxon sampling but only one plastid marker was used. In the present study, DNA sequences from six plastid markers (atpB, rbcL, rps4, rps4-trnS, trnL and trnL-F) of 1030 accessions (616 of them newly sequenced here) representing c. 420 species of Asplenium (60% of estimated species diversity), 16 species of HymenAsplenium, three Diplaziopsidaceae, and four Rhachidosoraceae were used to produce the largest genus-level phylogeny yet for ferns. Our major results include: (i) Asplenium as broadly circumscribed is monophyletic based on our inclusion of representatives of 32 of 38 named segregate genera; (ii) 11 major clades in Asplenium are identified, and their relationships are mostly well-resolved and strongly supported; (iii) numerous species, unsampled in previous studies, suggest new relationships and numerous cryptic species and species complexes in Asplenium; and (iv) the accrued molecular evidence provides an essential foundation for further investigations of complex patterns of geographical diversification, speciation and reticulate evolution in this family.
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the base number of loxoscaphoid Asplenium species and its implication for cytoevolution in aspleniaceae
Annals of Botany, 2010Co-Authors: Elke Bellefroid, Khadijah S Rambe, Olivier Leroux, Ronald L L VianeAbstract:† Background and Aims ‘Loxoscaphoid’ Asplenium species are morphologically a remarkably distinct group of Aspleniaceae. Except for two preliminary chromosome counts of Asplenium theciferum, the cytology of this group of species has, however, been largely unstudied. † Methods Chromosome counts were obtained by acetocarmine squash preparations of one mitotic cell and several meiotic cells. Relative DNA content of gametophytic and sporophytic cells was determined by flow cytometry. The phylogenetic placement of A. loxoscaphoides, A. rutifolium s.l. and A. theciferum s.l. was investigated through an analysis of rbcL sequences. † Key Results The dysploid base number is reported to be x ¼ 35 in Asplenium centrafricanum, A. loxoscaphoides, A. sertularioides and A. theciferum. Analysis of rbcL sequences confirms that ‘loxoscaphoids’ nest robustly within Asplenium. Several high ploidy levels exceeding the tetraploid level were found in A. theciferum s.l. and A. rutifolium s.l. All taxa proved to be sexual. † Conclusions Four base numbers are known at present for Aspleniaceae: x ¼ 39, 38, 36 and 35. The dysploid base number x ¼ 35 found in the ‘loxoscaphoid’ Asplenium spp. sheds a novel light on the cytoevolution of the whole family. We postulate a recurrent descending dysploid evolution within Aspleniaceae, leading to speciation at the (sub)generic and species/group level.
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phylogenetic analysis of Asplenium subgenus ceterach pteridophyta aspleniaceae based on plastid and nuclear ribosomal its dna sequences
American Journal of Botany, 2003Co-Authors: Caroline J Van Den Heede, Ronald L L Viane, Mark W ChaseAbstract:Phylogenetic relationships among 20 taxa of the fern genus Asplenium subgenus Ceterach (Filicopsida, represented by 73 accessions) were investigated using DNA sequence data from the nuclear ribosomal internal transcribed spacers (ITS nDNA) and plastid trnL-F intergenic spacer. In addition, a single sample per taxon was used in an analysis of the plastid rbcL gene. Chromosome counts were determined for all the samples, and these demonstrated a range from diploid to octoploid. Analyses of the DNA sequence data indicated that Asplenium subgenus Ceterach is polyphyletic, implicating homoplasy in the characters previously used to circumscribe this taxon. Plastid trnL-F and rbcL analyses resulted in identical tree topologies. The trees produced from the separate plastid and nuclear matrices agree in (1) the recognition of identical groups of accessions corresponding to A. dalhousiae, A. ceterach, A. aureum, A. cordatum, A. phillipsianum, and A. haughtonii; (2) the division of A. subg. Ceterach into two subclades, a Eurasian-Macaronesian and a strictly African alliance; (3) the position of A. dalhousiae as a member of the former subclade; (4) the lack of genetic variation in A. cordatum despite its morphological variability; and (5) the clustering of each autopolyploid with their diploid ancestor. However, the plastid and nuclear trees differ in their placement of A. haughtonii and A. dalhousiae, which might be due to different evolutionary histories of nuclear and plastid genomes, and is possibly an indication of ancient hybridization. The analyses confirm the existence of several strictly African taxa. Asplenium phillipsianum and A. cordatum each form species complexes of diploid and autopolyploid taxa, from which a third, morphologically intermediate, allotetraploid species has originated. Asplenium haughtonii is a distinct endemic species from Saint Helena. The maternally inherited plastid sequences support the hypothesis that A. aureum is an ancestor of A. lolegnamense and of A. octoploideum. Because gene conversion did not eliminate divergent ITS alleles in the allopolyploids, their reticulate ancestry could be demonstrated. Biparentally inherited nrITS sequences support the allopolyploid status of A. aureum, A. lolegnamense, and A. punjabense, indicating they share the ancestral A. javorkeanum genome.
Yanfen Chang - One of the best experts on this subject based on the ideXlab platform.
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species diversity and reticulate evolution in the Asplenium normale complex aspleniaceae in china and adjacent areas
Taxon, 2013Co-Authors: Yanfen Chang, Harald SchneiderAbstract:The Asplenium normale complex contains the widespread A. normale and several geographically restricted spe- cies: A. boreale, A. hobdyi, A. kiangsuense, A. oligophlebium and A. shimurae. The taxonomy of this group is unclear with some entities treated infraspecifically or as synonyms. Furthermore, the existence of diploids and tetraploids in this species complex is suggestive of reticulate evolution. In order to formulate a natural classification and to investigate the relationships in this complex, phylogenetic analyses of plastid and nuclear sequence data and inference of ploidy level were used to assess the distinctiveness of putative taxonomic units and their relationships. The Asplenium normale complex was recovered as a monophyletic group comprising six principal chloroplast lineages. The results support the hypothesis that A. normale s.l. contains several species. Based on our inferences, we outline an improved species classification recognizing three diploid and four tetraploid entities. Incongruence of chloroplast and nuclear phylogenies was interpreted to be a result of recurrent reticulation events in the A. normale complex.
Shiyong Dong - One of the best experts on this subject based on the ideXlab platform.
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taxonomic studies on Asplenium sect thamnopteris aspleniaceae ii spore morphology
Nordic Journal of Botany, 2012Co-Authors: Lingling Wei, Shiyong DongAbstract:Asplenium sect. Thamnopteris is a morphologically distinct group within Asplenium, however, the species delimitation within the section is difficult. To evaluate the utility of spore morphology in the taxonomy of Asplenium sect. Thamnopteris, we examined 64 samples representing ca 25 species using scanning electron microscopy. The results show that the spores are monolete and ellipsoidal in shape, and range between 35.7–50.1 × 24.1–32.4 µm in size. The perispore is morphologically very diverse but relatively stable within species. Based on the morphology of spores, we discuss the species concept of A. nidus L. and A. phyllitidis D. Don, propose a new combination (A. latibasis) for Neottopteris latibasis Ching, and treat A. phyllitidis subsp. malesicum Holttum, N. latibasis, N. latipes Ching ex S. H. Wu, and N. subantiqua Ching ex S. H. Wu as new synonyms. A key to all known species of sect. Thamnopteris is provided using characters of spore morphology.
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taxonomic studies on Asplenium sect thamnopteris aspleniaceae i cytological observations
American Fern Journal, 2011Co-Authors: Shiyong DongAbstract:The section Thamnopteris is morphologically distinct among the large fern genus Asplenium, but the species recognition within this section is very difficult. To understand the species concept of this section from a cytological view, I examined chromosome numbers of fifteen samples representing eight taxa (species and intraspecific taxa). As result, seven taxa were determin ed to be sexual tetraploids with chromosome number 2n = 144 and Asplenium humbertii is a sexual hexaploid with 2n = 216. Along with the chromosome numbers reported, notes on nomenclature, diagnostic characters, and geographical distribution for the eight taxa are given. Cytological data available so far indicate that Asplenium sect. Thamnopter is not a monophyletic group.
Robert J Dyer - One of the best experts on this subject based on the ideXlab platform.
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apomixis and reticulate evolution in the Asplenium monanthes fern complex
Annals of Botany, 2012Co-Authors: Harald Schneider, Robert J Dyer, Vincent SavolainenAbstract:†Background and Aims Asexual reproduction is a prominent evolutionary process within land plant lineages and especially in ferns. Up to 10 % of the approx. 10 000 fern species are assumed to be obligate asexuals. In the Asplenium monanthes species complex, previous studies identified two triploid, apomictic species. The purpose of this study was to elucidate the phylogenetic relationships in the A. monanthes complex and to investigate the occurrence and evolution of apomixis within this group. †Methods DNA sequences of three plastid markers and one nuclear single copy gene were used for phylogenetic analyses. Reproductive modes were assessed by examining gametophytic and sporophyte development, while polyploidy was inferred from spore measurements. †Key Results Asplenium monanthes and A. resiliens are confirmed to be apomictic. Asplenium palmeri, A. hallbergii and specimens that are morphologically similar to A. heterochroum are also found to be apomictic. Apomixis is confined to two main clades of taxa related to A. monanthes and A. resiliens, respectively, and is associated with reticulate evolution. Two apomictic A. monanthes lineages, and two putative diploid sexual progenitor species are identified in the A. monanthes clade. †Conclusions Multiple origins of apomixis are inferred, in both alloploid and autoploid forms, within the A. resiliens and A. monanthes clades.
