R J Bayer

The Commonwealth Scientific and Industrial Research Organisation, Canberra, Australian Capital Territory, Australia

Are you R J Bayer?

Claim your profile

Publications (21)34.02 Total impact

  • Source
    Randall J. Bayer, Gregory T. Chandler
    Regnum vegetabile. 01/2007; 147:317-336.
  • A. Aïnouche, R. J. Bayer, M.-T. Misset
    [Show abstract] [Hide abstract]
    ABSTRACT: Phylogenetic relationships within the complex genus Lupinus are estimated from internal transcribed spacer (ITS) sequences of the nuclear ribosomal DNA repeat. The molecular data supports Lupinus as a distinct monophyletic group within the tribe Genisteae. Different geographical lineages are revealed within Lupinus, which are each restricted to either the Old or the New World. In the New World, the ITS data support an eastern-western geographic disjunction of the lupines and the recognition of some well-supported clades. In the Old World, almost all the previously recognized taxa are taxonomically well differentiated. The homogeneous African rough-seeded lupines, Scabrispermae, are strongly supported as a monophyletic group, which is distinct from the diverse and heterogeneous circum-Mediterranean smooth-seeded ones. The latter appear to have evolved as two lineages, in which are revealed some intersectional relationships. Also ITS data allow the assessment of the phylogenetic position of the newly discovered species, L. anatolicus (in the Old World) and L. jaimehintoniana (the Mexican tree lupin). The ITS phylogeny suggests a rapid initial radiation of the lupines subsequent to their divergence from a common ancestor. Moreover, the results indicate that the annual and perennial habits have evolved many times in Lupinus and suggest a role for generation time in affecting the evolutionary history of lupines. Data on adaptive processes and character evolution are re-examined and discussed in the light of the ITS phylogeny.
    Plant Systematics and Evolution 01/2004; 246(3):211-222. · 1.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A molecular phylogeny of Oxylobium, Gastrolobium and related genera, including Brachysema, Jansonia, Nemcia and Podolobium, is presented. The study was conducted using five molecular regions and 48 taxa, utilizing chloroplast DNA (the trnK 5′ intron, psbA/trnH intergenic spacer, trnL intron and adjacent trnL/trnF intergenic spacer) and nuclear ribosomal DNA (ETS and ITS) markers. Oxylobium is shown to be polyphyletic, while Gastrolobium is paraphyletic, containing within it the genera Brachysema, Jansonia and Nemcia, as well as Oxylobium lineare. This concurs with a previous molecular analysis and the results of the two analyses are compared. Morphological traits, such as subtending bracts, ovule number and fluoroacetate content, are shown to be homoplastic and suites of characters for defining the different genera using different morphological characters are presented. Our results support a recent monograph that expands Gastrolobium to include Brachysema, Jansonia, Nemcia and Oxylobium lineare. This revision leaves Oxylobium and Podolobium occurring exclusively in eastern Australia, while Gastrolobium occurs almost exclusively in south-western Australia, with only two species, G. brevipes and G. grandiflorum, occurring outside this area.
    Plant Species Biology 11/2003; 18(2‐3):91 - 101. · 1.28 Impact Factor
  • Joseph T. Miller, Randall J. Bayer
    [Show abstract] [Hide abstract]
    ABSTRACT: The genus Acacia is subdivided into the following three subgenera: subg. Acacia, subg. Aculeiferum and the predominantly Australian subg. Phyllodineae. Morphological and molecular studies have suggested that the tribe Acacieae and genus Acacia are artificial and have a close affinity to the tribe Ingeae. Sequence analysis of the chloroplast trnK intron, including the matK coding region and flanking non-coding regions, were undertaken to examine taxon relationships within Acacia subgenera Acacia and Aculeiferum. Subgenus Acacia is monophyletic while subgenus Aculeiferum is paraphyletic. Within the subgenera, major divisions are found based on biogeography, New World versus African–Asian taxa. These data suggest that characters such as inflorescence and prickle and/or stipule type are polymorphic and homoplasious in cladistic analyses within the subgenera.
    Australian Systematic Botany 03/2003; 16(1):27-33. · 1.47 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT:  Spartina alterniflora, a perennial grass native to the North American Atlantic coast, was introduced during the 19th century in western Europe (Southern England and western France) where it hybridized with the native Spartina maritima. In England, the sterile hybrid S. × townsendii gave rise by chromosome doubling to the highly fertile allopolyploid Spartina anglica, which has now invaded many salt marshes and estuaries in western Europe, and has been introduced in several continents. In South-West France, another sterile hybrid was discovered in 1892 in the Bidassoa Estuary, and named Spartina × neyrautii. According to their morphology, some authors suggested that S. × neyrautii and S. × townsendii result from reciprocal crosses. During the 20th century, the hybridization site was severely disturbed, and surviving of S. × neyrautii was questioned. In this paper, various Spartina populations are investigated in the Basque region (France and Spain), and compared to the hybrid taxa formed in England (S. × townsendii and S. anglica). The samples were analyzed using molecular fingerprinting (RAPD and ISSR) and Chloroplast DNA sequence (trnL-trnT spacer, trnL intron and trnL-trnF spacer). In the Bidassoa estuary, a hybrid isolated clone has been found, that displays additive species-specific nuclear markers of S. maritima and S. alterniflora, and that is subsequently considered as a surviving clone of S. × neyrautii. The molecular analyses indicate that S. × neyrautii and S. × townsendii share the same maternal (S. alterniflora), and paternal (S. maritima) parental species, but also that the two independent hybridization events have involved different parental (nuclear) genotypes in England and in South-West France.
    Plant Systematics and Evolution 02/2003; 237(1):87-97. · 1.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The mulga complex (Acacia aneura and closely related taxa) is a widespread group that is dominant in much of arid Australia. The group is taxonomically difficult, due to a complex interaction of sympatry and putative hybridisation between the major species, geographic variation within species and sympatric variation within A. aneura. Mulga is highly variable in a wide range of vegetative and reproductive characters and it is not unusual to find five or six distinct forms growing side by side. The aim of this project was to gain a better understanding of the relationships among mulga species and A. aneura varieties, as well as the maintenance of this variation. A single site in the Northern Territory, containing A. ayersiana, A. minyura and two varieties of A. aneura, was sampled intensively. Six morphotypes were observed in the field and five were strongly supported by morphometric analysis. Although the mulga complex is generally tetraploid (2n = 52), triploid (2n = 39) and pentaploid (2n = 65) seedlings were produced in the study population. Microsatellite primers developed for A. mangium (sect. Juliflorae) were amplified in individuals of each morphotype, resulting in genetic marker patterns consistent with polyploidy. Genetic and morphometric distances were correlated and differences between morphotypes account for 63% of the total genetic variation (φPT = 0.63, P < 0.001). Allele sequences confirmed the presence of genuine heterozygosity and clonality was suggested by the low genotypic diversity and the lack of allele segregation. Seedlings had identical genotypes to the maternal plants and polyembryony was observed in each taxon, consistent with apomictic reproduction. Both apomixis and ploidy level variation may restrict gene flow among morphotypes, playing a role in the maintenance of morphological diversity at the study site. The success of the group in arid and semi-arid Australia may also be due, in part, to these factors. SB01 043 Gene ti c, cyt og enet ic and m or phological var iat io n in m ulga
    Australian Systematic Botany - AUST SYSTEMATIC BOTANY. 01/2003; 16(1).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The largest monophyletic group within Acacia is subgenus Phyllodineae, with more than 950 predominately Australian species, the majority characterised by adult foliage consisting of phyllodes. Molecular sequence data from the internal transcribed spacers (ITS) of the nuclear ribosomal DNA repeat were used to investigate the monophyly of seven sections within the subgenus. A nested PCR approach was used to amplify the ITS region. Fifty-one species representative of all sections were sequenced together with one outgroup taxon Lysiloma divaricata (Ingeae).Phylogenetic parsimony analysis suggested that there are two main clades within Phyllodineae but that only one section, Lycopodiifoliae, is apparently monophyletic. In one of the main clades, Lycopodifoliae is related to some taxa in sections Alatae and Pulchellae and some members of section Phyllodineae. In the second main clade, sections Juliflorae, Plurinerves and Botrycephalae cluster with other members of section Phyllodineae. The two sections that are characterised by bipinnate foliage, Botrycephalae and Pulchellae, are nested within phyllodinous clades, indicating that at least two separate reversals to bipinnate leaves have occurred. Botrycephalae is paraphyletic with respect to taxa from section Phyllodineae that have single-nerved phyllodes and racemose inflorescences.
    Australian Systematic Botany - AUST SYSTEMATIC BOTANY. 01/2003; 16(1).
  • Source
    Joseph T. Miller, Rose Andrew, Randall J. Bayer
    [Show abstract] [Hide abstract]
    ABSTRACT: With over 960 species, Acacia is the largest genus of plants in Australia with all but nine of these species classified as subgenus Phyllodineae. DNA sequences for the chloroplast trnK region were sequenced for over 100 species to test sectional classification and survey species relationships within this subgenus. Only one of the seven recognised sections was found to be monophyletic; however, the close relationship of sect. Botrycephalae to certain racemose, uninerved species of sect. Phyllodineae is confirmed. Support is found for an expanded version of Vassal's Pulchelloidea, with the addition of sect. Lycopodiifoliae and several members of sect. Phyllodineae. These species, while morphologically distinct in adult foliage, possess similar seedling characteristics. The multinerved species are unresolved, indicating a rapid morphological radiation with little chloroplast sequence divergence among these species. The low levels of sequence divergence, large numbers of morphological species groups and the adaptive radiation of the group are discussed.
    Australian Journal of Botany - AUST J BOT. 01/2003; 51(2).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Interspecific hybridization events have been reported in the genus Spartina Schreb. (Poaceae), involving the east American species Spartina alterniflora, and including either introgression (e.g., with the western American Spartina foliosa) or allopolyploid speciation (e.g., with the Euro-African Spartina maritima). Molecular phylogenetic analysis of the genus has been undertaken in order to understand phylogenetic relationships and genetic divergence among these hybridizing species. Twelve Spartina species have been sequenced for two nuclear DNA regions (ITS of ribosomal DNA, and part of the Waxy gene) and one chloroplast DNA spacer (trnT-trnL). Separate and conditional combined phylogenetic analyses using Cynodon dactylon as the outgroup have been conducted. Spartina is composed of two lineages. The first clade includes all hexaploid species: the Euro-African S. maritima (2n = 60), the East-American S. alterniflora (2n = 62) and the West-American S. foliosa (2n = 60). Spartina alterniflora appears as a closely related sister species to S. foliosa. Although belonging to the same lineage, Spartina maritima appears consistently more genetically differentiated from S. alterniflora than S. foliosa. The tetraploid species S. argentinensis (2n = 40) is placed at the base of this first clade according to the Waxy data, but its position is not well resolved by the other sequences. The second well-supported main lineage within genus Spartina includes the other tetraploid American species. Significant incongruence has been encountered between the waxy based tree and both the ITS and trnT-trnL trees concerning the position of S. densiflora, suggesting a possible reticulate evolution for this species. The results agree with hybridization patterns occurring in Spartina: introgression involving closely related species (S. alterniflora and S. foliosa) on one hand, and alloploid speciation involving more differentiated species (S. alterniflora and S. maritima) on the other hand.
    Molecular Phylogenetics and Evolution 03/2002; 22(2):303-14. · 4.07 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A taxonomic revision with full descriptions and key are presented for the 109 known species of Gastrolobium, including 29 new species described here for the first time. Brachysema, Jansonia and Nemcia are formally placed into Gastrolobium and new combinations have been made where necessary. Included in the revision are full taxonomic descriptions for all species, full synonymies, literature references for original publications, typification, including selection of lectotypes where necessary, distributions complete with maps, and taxonomic and nomenclatural notes. New taxa described herein are G. acrocaroli, G. aculeatum, G. alternifolium, G. congestum, G. crispatum, G. cruciatum, G. cyanophyllum, G. diabolophyllum, G. discolor, G. elegans, G. euryphyllum, G. ferrugineum, G. glabratum, G. hians, G. humile, G. involutum, G. melanopetalum, G. mondurup, G. musaceum, G. nudum, G. nutans, G. reflexum, G. rhombifolium, G. semiteres, G. tenue, G. tergiversum, G. venulosum, G. whicherensis and G. wonganensis.
    Australian Systematic Botany - AUST SYSTEMATIC BOTANY. 01/2002; 15(5).
  • Source
    G T Chandler, R J Bayer, M D Crisp
    [Show abstract] [Hide abstract]
    ABSTRACT: Gastrolobium (Fabaceae: Mirbelieae) is an endemic Australian genus that produces toxic sodium monofluoroacetate. A phylogenetic reconstruction of Gastrolobium and the related genera Brachysema, Callistachys, Jansonia, Nemcia, Oxylobium, and Podolobium is presented, using sequence data from three regions-the psbA-trnH intergenic spacer and the trnK 5' intron from chloroplast DNA and the 3' end of the external transcribed spacer (ETS) from nuclear ribosomal DNA. Gastrolobium is shown to be paraphyletic, with Brachysema, Jansonia, Nemcia, and Oxylobium lineare nesting within it, and Nemcia is shown to be polyphyletic within Gastrolobium. Past key morphological characters, such as fluoroacetate content and characters associated with pollination syndrome, are shown to be homoplastic, with fluoroacetate possibly a plesiomorphic condition lost in more derived species. Podolobium is also shown to be polyphyletic, with the P. ilicifolium group sister to Gastrolobium and the P. alpestre group sister to Callistachys, a member of the Oxylobium group. It is recommended that Gastrolobium be expanded to include Brachysema, Jansonia, Nemcia, and Oxylobium lineare, while further work is required to test the sister-group relationship between Podolobium s.s. (sensu stricto) and Gastrolobium.
    American Journal of Botany 09/2001; 88(9):1675-87. · 2.59 Impact Factor
  • Source
    J T Miller, R J Bayer
    [Show abstract] [Hide abstract]
    ABSTRACT: The tribe Acacieae (Fabaceae: Mimosoideae) contains two genera, the monotypic African Faidherbia and the pantropical Acacia, which comprise about 1200 species with over 950 confined to Australia. As currently recognized, the genus Acacia is subdivided into three subgenera: subg. Acacia, subg. Aculeiferum, and the predominantly Australian subg. Phyllodineae. Morphological studies have suggested the tribe Acacieae and genus Acacia are artificial and have a close affinity to the tribe Ingeae. Based on available data there is no consensus on whether Acacia should be subdivided. Sequence analysis of the chloroplast trnK intron, including the matK coding region and flanking noncoding regions, indicate that neither the tribe Acacieae nor the genus Acacia are monophyletic. Two subgenera are monophyletic; section Filicinae of subgenus Aculeiferum does not group with taxa of the subgenus. Section Filicinae, eight Ingeae genera, and Faidherbia form a weakly supported paraphyletic grade with respect to subg. Phyllodineae. Acacia subg. Aculeiferum (s. s.) is sister to the grade. These data suggest that characters currently used to differentiate taxa at the tribal, generic, and subgeneric levels are polymorphic and homoplasious in cladistic analyses.
    American Journal of Botany 05/2001; 88(4):697-705. · 2.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Gnaphalieae are a group of sunflowers that have their greatest diversity in South America, Southern Africa, and Australia. The objective of this study was to reconstruct a phylogeny of the South African Gnaphalieae using sequence data from two noncoding chloroplast DNA sequences, the trnL intron and trnL/trnF intergenic spacer. Included in this investigation are the genera of the Gnaphalieae from the African basal groups, members of the subtribes Cassiniinae, Gnaphaliinae, and Relhaniinae, and African representatives from the large Old World genus Helichrysum. Results indicate that two Gnaphaloid genera, Printzia and Callilepis, should be excluded from the Gnaphalieae. In most trees the Relhaniinae s.s. (sensu stricto) and some of the basal taxa comprise a clade that is sister to the remainder of the tribe Gnaphalieae. The Relhaniinae, which are restricted to Africa, are not a monophyletic group as presently circumscribed, nor are the South African members of Helichrysum, the Cassiniinae and Gnaphaliinae. There is general agreement between our molecular analysis and that of morphology, particularly in the terminal branches of the trees.
    American Journal of Botany 03/2000; 87(2):259-72. · 2.59 Impact Factor
  • Source
    G.T. Chandler, R.J. Bayer
    [Show abstract] [Hide abstract]
    ABSTRACT: Assignment of the enigmatic Australian genus Emblingia to a particular family or order has been difficult. Informative morphological characters have not as yet been found to place Emblingia conclusively into a family, though it does share a number of attributes with the Capparaceae and Resedaceae. As a result, in the past it has been put in various families (Capparaceae, Sapindaceae, Goodeniaceae and Polygalaceae), representing a number of orders, as well as in its own family, the Emblingiaceae. The current molecular study, using rbcL, shows strong support for the placement of Emblingia within the Brassicales, and possibly sister to the Resedaceae. Further morphological and molecular studies within the Brassicales are needed before finalizing the familial placement of this genus. At this time, we consider treatment of Emblingia as a monotypic family, Emblingiaceae, within the order Brassicales the most satisfactory solution.
    Plant Species Biology 01/2000; 15(1). · 1.28 Impact Factor
  • Source
    Gregory T. Chandler, Randall J. Bayer
    [Show abstract] [Hide abstract]
    ABSTRACT: Assignment of the enigmatic Australian genus Emblingia to a particular family or order has been difficult. Informative morphological characters have not as yet been found to place Emblingia conclusively into a family, though it does share a number of attributes with the Capparaceae and Resedaceae. As a result, in the past it has been put in various families (Capparaceae, Sapindaceae, Goodeniaceae and Polygalaceae), representing a number of orders, as well as in its own family, the Emblingiaceae. The current molecular study, using rbcL, shows strong support for the placement of Emblingia within the Brassicales, and possibly sister to the Resedaceae. Further morphological and molecular studies within the Brassicales are needed before finalizing the familial placement of this genus. At this time, we consider treatment of Emblingia as a monotypic family, Emblingiaceae, within the order Brassicales the most satisfactory solution.
    Plant Species Biology 01/2000; 15(1):67-72. · 1.28 Impact Factor
  • Source
    A K Ainouche, R J Bayer
    [Show abstract] [Hide abstract]
    ABSTRACT: Internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA from 44 taxa of the genus Lupinus and five outgroup taxa were used for phylogenetic analysis. Lupinus appears as a strongly supported monophyletic genus, which is unambiguously part of the Genisteae. The lupines are distributed into five main clades in general accordance with their geographical origin. In the Old World, almost all the recognized taxonomic units are well resolved. The ITS data reveal an unexpectedly close relationship between the diverse sections Angustifoli and Lutei. The ITS results suggest a geographical division between the western New World lupines and the eastern ones. They also indicate the presence of some moderately to strongly supported groups of taxa, such as the Microcarpi-Pusilli group, the L. spariflorus-L. arizonicus group, the L. mexicanus-L. elegans group in the western New World, and the notable L. multiflorus-L. paraguariensis group in the eastern New World. The latter group strongly suggests that the eastern South American compound- and simple-leaved perennial lupines derive from a common ancestor. However, apart from some exceptions, relationships within the genus still remain largely unresolved based on ITS data. The lack of resolution at the base of the genus is suggestive of a rapid initial radiation of the lupines subsequent to the dispersal of their common ancestor. Relative rate tests demonstrate the presence of rate heterogeneity of ITS sequences within Lupinus. In many pairwise comparisons between taxa, substitution rate inequalities are correlated with the habit (annual, perennial), suggesting some role for the generation time effects in the evolutionary history of lupines.
    American Journal of Botany 05/1999; 86(4):590-607. · 2.59 Impact Factor
  • Source
    J R Starr, R J Bayer, B A Ford
    [Show abstract] [Hide abstract]
    ABSTRACT: Wide speculation surrounds the origin and phylogenetic relationships of the most highly reduced sections in the genus Carex. In order to gain a better understanding of phylogeny in Carex, the relationship of the reduced sect. Phyllostachys to 12 putatively related sections, representing all four subgenera (Primocarex, Indocarex, Carex, Vignea), was inferred from sequences of the ITS (internal transcribed spacer) region of nrDNA. Phylogenetic reconstructions identified two main clades: (1) a "compound" clade composed of sections from subg. Indocarex, Primocarex, and a portion of subg. Carex, and (2) a "reduced" clade consisting of sections from subg. Carex (Phyllostachys) and Primocarex (Filifoliae and Firmiculmes). Subgenus Indocarex was paraphyletic within the "compound" clade supporting classifications that have merged it within a wider subg. Indocarex/Carex/Primocarex line. Subgenus Primocarex was polyphyletic. This result was consistent with theories that extreme reduction has occurred along several different evolutionary lines in Carex. Phylogenetic theories inferred from the presence or abnormal growth of the rachilla were not supported by tree topologies. Difficult sectional circumscriptions, such as the separation of sections Laxiflorae and Careyanae, were strongly upheld by sequence data. The ITS region is an effective tool for defining sectional limits and for estimating relationships among sections in Carex, but does not provide enough phylogenetic information to fully resolve relationships below the sectional level.
    American Journal of Botany 05/1999; 86(4):563-77. · 2.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bromus hordeaceus (sectionBromus, Poaceae), a predominantly self-fertilizing tetraploid (2n=28), is an annual weed native to the Mediterranean Basin, which now has a world-wide distribution. High morphological variation led to the recognition of four subspecies, three of which correlated with habitat-type. We examined genetic diversity at enzyme loci in 15 populations from the Mediterranean and the Atlantic region. Although sampled over a larger range of ecological and geographical conditions, the North-African populations appeared less genetically differentiated than populations from Brittany, suggesting higher levels of gene flow among the first ones (Nm=3.756 and 1.066 respectively). No genetic differentiation was encountered among the four subspecies. The populations were homozygous at homologous loci, suggesting high rates of selfing, but they frequently exhibited fixed intergenomic heterozygosity. The meiotic chromosome behaviour and disomic inheritance encountered are in accordance with the previously proposed allopolyploid origin of the species. The diploidsB. arvensis andB. scoparius have been previously implicated in the parentage ofB. hordeaceus on the basis of morphology and serology. We comparedB. hordeaceus with related diploid species belonging to the same section (sectionBromus) using different sources of data (flow cytometry, karyotypes, RAPD and DNA sequences). Molecular phylogeny based on internal transcribed spacer sequences of nuclear ribosomal genes provided the first clear scheme of relationships among monogenomic species of the section. A new hypothesis is proposed concerning the origin ofB. hordeaceus: We found that it diverged earlier than all other species of sectionBromus excluding the diploidB. caroli-henrici which is basal in this group. The 13 autapomorphies accumulated byB. hordeaceus, and the absence of intra-individual sequence heterogeneity are also consistent with the relatively ancient origin of the species within the section.
    Folia Geobotanica 01/1999; 34(4):405-419. · 1.57 Impact Factor
  • Source
    B Goffinet, R J Bayer, D H Vitt
    [Show abstract] [Hide abstract]
    ABSTRACT: The affinities as well as the circumscription of the Orthotrichaceae (Bryopsida), one of the most diverse families of mosses, have been the focus of a controversy for much of the last century. We obtained rbcL sequences for 37 arthrodontous mosses, including 27 taxa of the Orthotrichales. The sequences were analyzed using maximum parsimony and neighbor joining in order to (1) test the monophyly of the Orthotrichales and the Orthotrichaceae; (2) determine their phylogenetic relationships; and (3) test the current subfamilial classification within the Orthotrichaceae. Both analyses suggest that the Orthotrichales are polyphyletic. The Erpodiaceae and the Rhachitheciaceae as well as Amphidium and Drummondia, two genera of the Orthotrichaceae, are shown to be of haplolepideous affinity. The Splachnales, the Bryales sensu lato, and the Orthotrichales form a monophyletic clade sister to the Haplolepideae. Both neighbor joining and maximum parsimony also suggest that the Orthotrichaceae are composed of two major lineages dominated either by acrocarpous or cladocarpous taxa. The monophyly of the family is, however, only well supported by Tamura's distances. The genera Macrocoma, Macromitrium, Orthotrichum, Ulota, and Zygodon all appear to be artificial assemblages. This study illustrates the contribution of rbcL sequence data to bryophyte systematics and, particularly, in determining the affinities of taxa lacking a peristome, whose characters are central to the classification of mosses.
    American Journal of Botany 09/1998; 85(9):1324-37. · 2.59 Impact Factor
  • M L Ainouche, R J Bayer
    [Show abstract] [Hide abstract]
    ABSTRACT: The internal transcribed spacer (ITS) region of nuclear ribosomal DNA from 22 diploid and tetraploid annual Bromus species of section Bromus (Poaceae) and three species belonging to other Bromus sections, Bromus catharticus (section Ceratochloa), Bromus anomalus (section Pnigma), and Bromus sterilis (section Genea), were investigated by PCR amplification and direct sequencing. The length of the ITS-1 region varied from 215 to 218 bp, and that of the ITS-2 region from 215 to 216 bp, in the species analyzed. ITS-1 was more variable and provided more informative sites (49) than ITS-2 (32). No variation was encountered within species. In pairwise comparison among species of section Bromus, sequence divergence ranged from 0.0 to 8.0% for the combined ITS-1 and ITS-2 regions. Parsimony analysis using Avena longiglumis and Hordeum vulgare as outgroups resulted in well-resolved phylogenetic trees and showed that section Bromus is monophyletic according to the species analyzed outside of the section. The analysis clarified the phylogenetic relationships among monogenomic (diploid) species. Introduction of the allotetraploid species did not change the general topology of the trees obtained using only the diploid species. Although some tetraploid-diploid species relationships will have to be clarified with faster evolving markers, the ITS sequences are shown to be useful for assessing evolutionary relationships among closely related Bromus species, as well as for clarifying taxonomic problems in previously controversial cases (e.g., Bromus alopecuros and Bromus caroli-henrici). New hypotheses are proposed concerning the origin of several allotetraploid species. For example, it is shown that the tetraploid Bromus hordeaceus diverged earlier than all other species of section Bromus, excluding the diploid B. caroli-henrici, which is found to be basal in this group. The tetraploid Bromus arenarius, which was considered a hybrid between sections Bromus and Genea, and the tetraploid Bromus adoensis are sister taxa within section Bromus; they belong in a weakly differentiated clade with the diploids Bromus brachystachys, Bromus japonicus, Bromus squarrosus, Bromus arvensis, and Bromus intermedius.
    Genome 11/1997; 40(5):730-43. · 1.67 Impact Factor

Publication Stats

498 Citations
34.02 Total Impact Points

Institutions

  • 2000
    • The Commonwealth Scientific and Industrial Research Organisation
      • Division of Plant Industry
      Canberra, Australian Capital Territory, Australia
  • 1997–1999
    • University of Alberta
      • Department of Biological Sciences
      Edmonton, Alberta, Canada