Phylogenetic Relationships in the Genus Paspalum (Poaceae: Panicoideae: Paniceae): An Assessment of the Quadrifaria and Virgata Informal Groups (original) (raw)

Phylogeny of Linearia and Notata groups of Paspalum L. (Poaceae, Panicoideae, Paniceae) and related species

Genetic Resources and Crop Evolution, 2007

Genus Paspalum L. comprises approximately 400 species worldwide and about 220 in Brazil. Paspalum is ecologically and economically important, and has been very useful as pasture. Traditionally, taxonomists use informal groups, most of which described by Agnes Chase in 1929. Some groups present a problematic circumscription, this is the case of the Linearia and Notata groups. This work uses a phylogenetic approach to study these groups and related species. DNA sequences from ITS of nuclear rRNA, from chloroplast intergenic spacer psbA-trnH and chloroplast trnL intron were used to perform the analyses. The informal groups studied were considered highly artificial, being the representatives from several informal groups splitted throughout the trees. Only a small core of species from Notata group could be accepted as a good formal clade.

Phylogeny of the Paniceae (Poaceae: Panicoideae): integrating plastid DNA sequences and morphology into a new classification

Cladistics, 2012

Included in the PACMAD clade of the family Poaceae (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, Danthonioideae), the tribe Paniceae s.l. is one of the largest tribes of the subfamily Panicoideae, with more than 2000 species. This tribe comprises a huge morphological, cytological, and physiological diversity represented by different inflorescence types, several basic chromosome numbers, and at least four major photosynthetic pathways. The tribe Paniceae has been the subject of molecular studies that have confirmed its paraphyly: two major clades were recognized based on their basic chromosome numbers (x =9 ,x = 10). The x = 10 Paniceae clade is sister to the Andropogoneae-Arundinelleae s.s. x =1 0c l a d ea n dt h ex = 9 clade with a subsample of Paniceae genera. As a result of a recent realignment within the tribe in terms of the phylogenetic position of minor and major Paniceae genera, a reanalysis of the whole sampling is performed and new underrepresented taxa are discussed. A total of 155 genera, currently considered within subfamily Panicoideae, are represented here by almost all genera of Paniceae s.l., representatives of Andropogoneae and Arundinelleae s.s., and the endemic and small tribe Steyermarkochloeae; we also included specimens of subfamily Micrairoideae, tribes Isachneae and Eriachneae. The sampling includes as outgroups 18 genera of the PACMAD clade (excluding Panicoideae) and four genera from the BEP clade (Bambusoideae, Ehrhartoideae, Pooideae), rooting with Bromus inermis. A matrix with 265 taxa based on the combined evidence from ndhF plastid sequences (2074 bp) and 57 morphological characters was subjected to parsimony analyses. Jackknife resampling was used to calculate group support. Most clades are characterized by morphological, cytological, anatomical, and ⁄ or physiological characters. Major tribal changes are based on the basic chromosome number; the pantropical x =9 clade is here recognized as Paniceae s.s., while the American x = 10 Paniceae s.l. is restricted to the reinstated tribe Paspaleae. The optimization of the photosynthetic pathway for the Paspaleae-Andropogoneae-Arundinelleae s.s. clade, including the monotypic Reynaudia, show a plesiomorphic C 4 state while the ancestral state for Paniceae s.s. is ambiguous. If Reynaudia were not included or placed elsewhere, the ancestral photosynthetic pathway for both the Paspaleae-Andropogoneae-Arundinelleae s.s. clade and the Paniceae s.s. would be unambiguously C 3 . In order to explore character evolution further, the morphological characters were mapped onto one of the most parsimonious trees. A relationship between photosynthetic pathways and inflorescence morphology is suggested here for the first time. Based on the optimization of morphological characters and additional data, we propose names for almost all inner clades at the rank of subtribe with a few groups as incertae sedis. With this extensive sampling, we resolved the phylogenetic relationships and the assignation of synapomorphies, and improved the support in subtribe sorting; consequently a robust circumscription of the tribe Paniceae s.l. is proposed.

Phylogenetics of Panicoideae (Poaceae) based on chloroplast and nuclear DNA sequences

Phylogenetic relationships among major subfamilies in Poaceae and among major tribes within Panicoideae were evaluated using parsimony and Bayesian analyses of chloroplast trnL-F and atpβ-rbcL DNA sequences and a nuclear ribosomal DNA sequence, ITS1-ITS2. The Panicoideae-Aristidoideae-Chloridoideae-Micrairoideae-Arundinoideae-Danthonioideae (PACMAD) clade was well resolved. A close relationship between Aristidoideae and Chloridoideae was found. The monophyly of Micrairoideae was resolved but the relationships of three tribes (Eriachneae, Isachneae, Micraireae) within Micrairoideae were unclear, only Eriachne and Isachne were monophyletic. Panicoideae sensu stricto were supported as monophyletic and sister to a clade of Danthoniopsis and Tristachya. Within Panicoideae, only a clade of Andropogoneae + Arundinella + Garnotia was supported. None of the analyses supported the monophyletic status of Paniceae. Within Paniceae, the bristle clade (excluding Cenchrus) + Alexfloydia, and the forest shade clade sensu , were found, but their circumscription remains ambiguous. A sister relationship between the endemic and rare Australian grasses Homopholis and Walwhalleya was also resolved. Arundinelleae were found to be polyphyletic. This study supported the separation of Arundinella and Garnotia from the remaining Arundinelleae and the inclusion of both genera in their own subtribes (Arundinellinae Honda sensu stricto and Garnotiinae Pilger) within the Andropogoneae. Arundinelleae should be abandoned as a taxonomic tribe within the Centothecoid + Panicoid clade. Within Andropogoneae, five out of a total of 11 subtribes (Chionachninae, Coicinae, Dimeriinae, Germainiinae, and Tripsacinae) were monophyletic.

A molecular phylogeny of Panicum (Poaceae: Paniceae): tests of monophyly and phylogenetic placement within the Panicoideae

American Journal of Botany, 2003

Panicum L. is a cosmopolitan genus with approximately 450 species. Although the genus has been considerably reduced in species number with the segregation of many taxa to independent genera in the last two centuries, Panicum remains a heterogeneous assemblage, as has been demonstrated in recent years. The genus is remarkably uniform in its floral characters but exhibits considerable variation in anatomical, physiological, and cytological features. As a result, several classifications, and criteria of what the genus should really include, have been postulated in modern literature. The purpose of this research, based on molecular data of the chloroplast ndhF gene, is to test the monophyly of Panicum, to evaluate infrageneric classifications, and to propose a robust phylogenetic hypothesis. Based on the present results, previous morphological and molecular phylogenetic studies, and inferred diagnostic morphological characters, we restrict Panicum sensu stricto (s.s.) to the former subgenus Panicum and support recognition of Dichanthelium, Phanopyrum, and Steinchisma as distinct genera. We have transfered other species of Panicum to other genera of the Paniceae. Most of the necessary combinations have been made previously, so few nomenclatural changes have been required. The remaining species of Panicum sensu lato (s.l.) are included within Panicum incertae sedis representing isolated species or species grouped within monophyletic clades. Additionally, we explore the performance of the three codon position characters in producing the supported phylogeny.

Erratum to: A phylogenetic study of subtribe Otachyriinae (Poaceae, Panicoideae, Paspaleae)

Plant Systematics and Evolution

The subtribe Otachyriinae was established, within tribe Paniceae, by Butzin in 1970, originally including 18 genera. Recent phylogenetic studies, based on molecular data, indicated that Otachyriinae belongs to tribe Paspaleae and is represented by the genera Anthaenantia, Hymenachne, Dallwatsonia, Otachyrium, species of Panicum sect. Laxa, Plagiantha, and Steinchisma. These taxa show a peculiar diversity in photosynthetic types, including C4 species, C3–C4 intermediates and C3 species. The internal evolutionary relationships among members of Otachyriinae have not yet been explored in detail. With the aim of providing new evidence to understand phylogenetic relationships of taxa included in Otachyriinae, 21 new sequences of the ndhF gene from 34 species were generated and analyzed using Bayesian inference and maximum parsimony (MP). The evolution of photosynthetic pathway was studied employing MP, Markov chain Monte Carlo, and maximum likelihood methods. Our results confirm that subt...

The inflorescences of Paspalum ( Poaceae, Paniceae ): The Quadrifaria group and the evolutionary pathway towards the fully homogenized, truncated common type

Plant Systematics and Evolution, 1996

The inflorescences ofPaspalum are composed of a main axis and 1 to more than 100 raceme-like lateral branches arranged along it. Each branch bears two rows of homogeneous subunits composed either of one or two consecutive-ordered axes, each one ending with a spikelet. In terms ofTroll's descriptive and typological system, such lateral branches were regarded as long paracladia which bear homogeneous bi-axial short paracladia. The structural pattern of these long paracladia is considered to be a recapitulation of the distal main-axis structure which was lost by evolutionary truncation. — The occurrence of a main florescence (= terminal spikelet) and a short paracladia-bearing zone at the distal portion of the main axis in several species of the genusPaspalum, as it is exemplified by species belonging to the so-called ‘Quadrifaria group’, seems to support the hypothesis that the usual inflorescence ofPaspalum actually derived from a paniculate structure by evolutionary homogenization and truncation processes. This ‘Quadrifaria-type inflorescences’ would be regarded as an intermediate step in the evolutionary pathway. Nevertheless, the phylogenetic implications of this interpretation remains obscure because at the present time there is not any hypothesis about the phylogeny of the genus available.