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Hybridization has long been recognized as common in ferns, but the products of this arguably evolutionary important process have often been ignored in classifications. For example, the recently published Pteridophyte Phylogeny Group classification (PPG I) covered all hierarchical ranks from class to genus but did not include intergeneric hybrids (nothogenera). Here, we provide for the first time a comprehensive evaluation of previously proposed nothogenera in the context of a current phylogeny‐based pteridophyte classification (i.e., PPG I). We find that several nothogenera nested in the orders Osmundales and Polypodiales are supported in the framework of PPG I, but others are superfluous. Five new nothogenera are introduced here for the first time. We also explore the distribution of nothospecies across the pteridophyte phylogeny for the first time. We are unable to reject the hypothesis that species richness and nothospecies diversity are correlated, despite the finding that some temperate lineages contribute more nothospecies than expected whereas several tropical lineages lack them. This pattern could be the consequence of either fundamental differences in modes of speciation in temperate and tropical zones or unequal efforts to record nothospecies. In general, we emphasize the need to take nothogenera into account when proposing generic classifications, but the information provided by the existence of such hybrids needs to be carefully evaluated. Our results underscore the need to report and study hybrids in ferns and lycophytes, especially in biodiversity rich areas. [ABSTRACT FROM AUTHOR]

Recent studies investigating the evolution of genome size diversity in ferns have shown that they have a distinctive genome profile compared with other land plants. Ferns are typically characterized by possessing medium‐sized genomes, although a few lineages have evolved very large genomes. Ferns are different from other vascular plant lineages as they are the only group to show evidence for a correlation between genome size and chromosome number. In this study, we aim to explore whether the evolution of fern genome sizes is not only shaped by chromosome number changes arising from polyploidy but also by constraints on the average amount of DNA per chromosome. We selected the genus Asplenium L. as a model genus to study the question because of the unique combination of a highly conserved base chromosome number and a high frequency of polyploidy. New genome size data for Asplenium taxa were combined with existing data and analyzed within a phylogenetic framework. Genome size varied substantially between diploid species, resulting in overlapping genome sizes among diploid and tetraploid spleenworts. The observed additive pattern indicates the absence of genome downsizing following polyploidy. The genome size of diploids varied non‐randomly and we found evidence for clade‐specific trends towards larger or smaller genomes. The 578‐fold range of fern genome sizes have arisen not only from repeated cycles of polyploidy but also through clade‐specific constraints governing accumulation and/or elimination of DNA. [ABSTRACT FROM AUTHOR]

Sequencing the plastid genomes of land plants provides crucial improvements to our understanding of the plastome evolution of land plants. Although the number of available complete plastid genome sequences has rapidly increased in the recent years, only a few sequences have been yet released for the three bryophyte lineages, namely hornworts, liverworts, and mosses. Here, we explore the disparity of the plastome structure of liverworts by increasing the number of sequenced liverwort plastomes from five to 18. The expanded sampling included representatives of all major lineages of liverworts including the genus Haplomitrium. The disparity of the liverwort genomes was compared with other 2386 land plant plastomes with emphasis on genome size and GC‐content. We found evidence for structural conservatism of the plastid genomes in liverworts and a trend towards reduced plastome sequence length in liverworts and derived mosses compared to other land plants, including hornworts and basal lineages of mosses. Furthermore, Aneura and Haplomitrium were distinct from other liverworts by an increased GC content, with the one found in Haplomitrium only second to the lycophyte Selaginella. The results suggest the hypothesis that liverworts and other land plants inherited and conserved the plastome structure of their most recent algal ancestors. [ABSTRACT FROM AUTHOR]

Polyploidy is widely considered as a major process in the evolution of plants but the accumulation of polyploid species diversity is still controversial. Some recent studies proposed increased extinction risk in neopolyploids compared with their diploid ancestors. The high proportion of polyploid ferns is expected to be formed mainly by neopolyploids, whereas paleopolyploid species are predicted to be clustered in clades founded by whole genome duplications. Here, we test this prediction by exploring the evolution of polyploidy in the derived fern family Aspleniaceae. The family has a global distribution and shows the highest frequency of polyploid taxa among all ferns. To test the hypothesis, we obtained a comprehensive phylogeny using chloroplast DNA sequences of 883 specimens representing 292 species. All published chromosome counts were mapped onto this phylogenetic framework in order to explore the evolution of polyploids. We recovered evidence for several whole genome duplications in the history of Aspleniaceae. Phylogenetic relationships of polyploids exceeding the tetraploid level suggest that tetraploid Asplenium species may have replaced their diploid ancestors as the main evolutionary players in some clades of this family. [ABSTRACT FROM AUTHOR]

In this review, we explore our current understanding of the fern and lycophyte diversity occurring in the Eastern Afromontane Biodiversity Hotspot (EABH). The review explores the species diversity of this region in the context of the Afromadagascan pteridophyte diversity based on an exhaustive species list assembled in the synopsis of Afromadagascan pteridophytes published by Roux in 2009. The list was updated by incorporating recent progress in our understanding of the taxonomy and phylogeny of these plants. Evidence for a distinct pteridophyte flora occurring in the East African mountain region was discovered using ordination and clustering analyses. This EABH floras shares links to other Afromadagascan pteridophyte floras such as the one in the tropical lowland forests of central and western Africa. These floras share the dominance of species that preferably occur in humid climates whereas other African pteridophyte floras tend to contain a higher proportion of xeric adapted ferns. The phylogenetic composition of the EABH pteridophyte flora was assessed by comparing global versus local proportion of orders, families, and genera. This analysis revealed distinct patterns that are partly caused by the radiation of Blotiella and Triplophyllum besides selective colonization of species pre-adapted to Afromadagascan climates. In situ speciation in the East African tropical mountains may have contributed to the global diversity of widespread genera such as Asplenium and Pteris. In summary, this is the first comprehensive attempt to assess the pteridophyte diversity of the East African mountains providing the framework for future studies on their conservation, ecology, and evolution. [ABSTRACT FROM AUTHOR]

The phylogenetic relationships of pteridophytes occurring in China were reconstructed using DNA sequences of the three plastid genes, atpA, atpB, and rbcL. The sampling comprised all genera of Chinese pteridophytes-including ferns and lycophytes-with the exception of four small genera. The effort to sample all recorded families and genera in a phylogenetic framework enabled the phylogenetic relationships of all Chinese pteridophytes to be addressed for the first time in a single phylogenetic hypothesis. The results provided strong evidence to support the continuing impact of Ren-Chang Ching's integrative classification of pteridophytes. Ten out of 11 orders accepted by Ching were consistent with the phylogeny, whereas four new orders were introduced to avoid paraphyletic taxa in the leptosporangiate ferns. Of the 63 families considered by Ching, 36 families were supported by molecular data, 22 of those had the same or nearly the same circumscription, and the remaining 14 families were supported but substantially revised. Twenty-eight small families were now accepted as synonyms. A consistent pattern was observed at the generic level. Among the 223 genera considered by Ching, 133 genera were recognized by the phylogeny, although some of them were substantially changed in the context of circumscription, and 90 were now accepted as synonyms. Three endemic genera were incorporated here for the first time in DNA-based phylogenetic analyses, namely Blechnidium, Saxiglossum, and Sinephropteris, which were shown to be nested in Blechnum, Pyrrosia, and Asplenium respectively. This paper tentatively accepts 40 families and 151 genera of ferns and lycophytes occurring in China; the importance of phylodiversity of Chinese pteridophytes is also briefly discussed. [ABSTRACT FROM AUTHOR]

Davalliaceae is a small family of derived ferns that grow epiphytic or occasionally epilithic in the tropics and subtropics of the Old World. Despite recent taxonomic and phylogenetic achievements, some aspects of its classification remain controversial. In this study, we provided new spore observations on Davalliaceae by using scanning electron microscopy. The newly generated data were integrated together with previously reported spore evidence of this group. The evolution of spore ornamentation and taxonomic implications of spore characters was optimized onto a phylogenetic tree based on plastid sequences. Verrucate colliculate spore ornamentation was identified as plesiomorphic character state within Davalliaceae. The Humata clade was characterized by the transition from verrucate colliculate to fused verrucate ornamentation. Several species complexes subject to taxonomic controversy were found to show informative variation in the spore ornamentation. In conclusion, our observations support the utility of spores as a morphological taxonomic trait in ferns, as long as the evolution of spore morphology is considered. [ABSTRACT FROM AUTHOR]

The phylogenetic relationships of the two derived fern genera Pleocnemia and Pteridrys were considered ambiguous even with molecular evidence from previous studies. In the present study we determined the phylogenetic position based on five plastid DNA regions, namely atpA, atpB, rbcL, the rps4 + rps4-trnS intergenic spacer, and the trnL-F region, and an expanded taxonomic coverage including several accessions of each of the two genera. Our results showed that the monophyletic genus Pleocnemia belonged to the Dryopteridaceae and was not related to the Tectariaceae, as it had been in the past. Pleocnemia was found to be closely related to the bolbitidoid and lastreopsioid ferns. The monophyletic genus Pteridrys was found to be sister to a clade comprising Triplophyllum and Tectaria s.l. Thus, the placement of this genus into Tectariaceae was confirmed. The sinus teeth, the unique similarity shared by Pleocnemia and Pteridrys, evolved independently in the two genera. Both genera appeared to have diverged from their closest extant relatives at least since the Eocene, whereas the crown group ages indicated radiation events in the Late Miocene for both genera. [ABSTRACT FROM AUTHOR]

Obtaining reliable species identification of the legume genus Caragana has been challenging. Until now, species identification was mostly carried out utilizing diagnostic morphological characteristics, in addition to some successful applications of secondary chemical compounds. This study was designed to establish a DNA barcoding protocol enabling unambiguous identification of 238 accessions belonging to 67 species of Caragana. The performance of four DNA barcoding regions nrITS, trnH‐psbA, matK, and rbcL was explored using three analytical approaches, Pairwise Genetic Distance, Sequence Similarity and Phylogenetic Tree method. The chloroplast regions rbcL and matK showed lower discriminatory power compared with the nuclear region internal transcribed spacer (ITS) and the chloroplast region trnH‐psbA. The nrITS outperformed the other regions in the resolution rate. The present study brings forth an efficient barcode locus for Caragana. A barcode based either on a single‐locus nrITS or the combination of nrITS and trnH‐psbA was found to be most suitable for species discrimination with distinctive barcoding gaps. An attempt has also been made to resolve taxonomic issues in the Caragana opulens complex. DNA barcoding tools when complemented with alpha taxonomic evidence can aid in solving complex systematic problems, especially when taxa are characterized by overlapping traits, such as species belonging to the Fabaceae family. [ABSTRACT FROM AUTHOR]

We reconstructed a phylogenetic tree of Chinese vascular plants (Tracheophyta) using sequences of the chloroplast genes atpB, matK, ndhF, and rbcL and mitochondrial matR. We produced a matrix comprising 6098 species and including 13 695 DNA sequences, of which 1803 were newly generated. Our taxonomic sampling spanned 3114 genera representing 323 families of Chinese vascular plants, covering more than 93% of all genera known from China. The comprehensive large phylogeny supports most relationships among and within families recognized by recent molecular phylogenetic studies for lycophytes, ferns (monilophytes), gymnosperms, and angiosperms. For angiosperms, most families in Angiosperm Phylogeny Group IV are supported as monophyletic, except for a paraphyletic Dipterocarpaceae and Santalaceae. The infrafamilial relationships of several large families and monophyly of some large genera are well supported by our dense taxonomic sampling. Our results showed that two species of Eberhardtia are sister to a clade formed by all other taxa of Sapotaceae, except Sarcosperma. We have made our phylogeny of Chinese vascular plants publically available for the creation of subtrees via SoTree (), an automated phylogeny assembly tool for ecologists. [ABSTRACT FROM AUTHOR]