Cytogenetic Studies in the Genus Tribolium (Poaceae: Arundineae)

Spies, J. J.; Davidse, Gerrit; Plessis, H. du

doi:10.1002/j.1537-2197.1992.tb14610.x

Cited by 10 publications

(9 citation statements)

References 10 publications

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“…Topological conflict. -Despite cytological evidence for interspecific hybridization in Tribolium (Spies & al., 1992;Visser & Spies, 1994b-e), the plastid and nuclear topologies obtained in this study are largely congruent and combine to produce a well-resolved and strongly supported phylogenetic hypothesis. This is in contrast to studies in which extensive plastid-nuclear incongruence has been noted, and attributed to historical hybridization (e.g., Albach & Chase, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…Linder & Davidse (1997) suggest that the observed lack of character covariance may be a result either of widespread loss of traits gained at the base of the clade or, alternatively, that traits which initially arose independently have had their distributions randomised by subsequent hybridization. Support for the hybridization hypothesis is provided by studies of meiotic chromosomal behaviour and embryo sac development in Tribolium (Spies & al., 1992;Visser & Spies, 1994b-e). These reveal evidence of segmental allopolyploidy in a number of species, especially T. acutiflorum, T.…”

Section: Introductionmentioning

confidence: 90%

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Molecular phylogeny of African Rytidosperma–affiliated danthonioid grasses reveals generic polyphyly and convergent evolution in spikelet morphology

Verboom

Ntsohi

Barker

2006

TAXON

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Of the 90–95 species included in the Rytidosperma clade of grasses (Danthonioideae: Poaceae) about 20 are native to southern Africa, most of these belonging to the genera Karroochloa, Schismus and Tribolium. Whereas morphological data identify all three genera as being monophyletic, the robustness of this pattern is compromised by high levels of homoplasy. Here we use molecular data (plastid trnL–trnF and nuclear ITS sequences) to re–evaluate phylogenetic relationships within the Rytidosperma clade, with the specific aim of testing the monophyly of the African genera. Separate parsimony analyses of the two partitions reveal low levels of incongruence, which may be attributable to incomplete lineage sorting or past hybridization. Analyses of the combined data produce well resolved, strongly supported topologies that are virtually identical, regardless of the inference method used (parsimony or Bayesian inference) or whether or not "conflict" taxa are included. Our data support the monophyly of the Rytidosperma clade (synapomorphies include a punctate–ovate hilum, a large embryo, and lodicule microhairs) as well as the monophyly of the Australasian–South American Rytidosperma s.l. However, the monophyly of Karroochloa, Schismus and Tribolium is strongly contradicted, all three genera being polyphyletic as currently defined. Although not implemented here, a minimum of five new combinations would be required to rectify this situation. Character reconstructions reveal extensive convergence in a number of morphological features, especially those previously used to define genera. We suggest that the convergent pattern of evolution displayed by these traits, most of which describe spikelet/diaspore morphology, is linked to their functionality in seed dispersal and burial, and that this has compromised their utility as phylogenetic markers.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 90%

Molecular phylogeny of African Rytidosperma–affiliated danthonioid grasses reveals generic polyphyly and convergent evolution in spikelet morphology

Verboom

Ntsohi

Barker

2006

TAXON

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“…But how much of the species phylogeny is reflected by the plastid (bifurcating) tree? Considering that interspecific hybridisation is known to occur in this group of danthonioid grasses (Brock and Brown, 1961;Spies et al, 1992;Visser and Spies, 1994a, b, c, d;Waters, 2007) evolution is unlikely to have proceeded linearly. Furthermore, the plastid genome behaves like a single gene.…”

Section: A Chloroplast Tree Of the Rytidosperma Cladementioning

confidence: 99%

“…In these plant groups there is mounting evidence for the presence of several haplotypes within a single species, shared among species within geographical regions, with introgression and hybridisation being invoked as the most likely cause (Dumolin-Lapégue et al, 1997;Steane et al, 1998;Fuertes Aguilar et al, 1999a;Jackson et al, 1999;McKinnon et al, 2001;Petit et al, 2002). Given that the species in the present analysis hybridise in nature (Brock and Brown, 1961;Spies et al, 1992;Visser and Spies, 1994a, b, c, d;Waters, 2007), the occurrence of several ploidy forms within a single species, haplotype sharing among species from the same area (Waters, 2007;Waters et al, 2008) and continuous variation in morphological characters among several species, geographical patterning could offer an explanation to some of the patterns evident in the plastid tree presented here (Fig. 3B, Table 5).…”

Section: Fit With Ecology and Distributionmentioning

confidence: 99%

A plastid tree can bring order to the chaotic generic taxonomy of Rytidosperma Steud. s.l. (Poaceae)

Humphreys¹,

Pirie²,

Linder³

2010

Molecular Phylogenetics and Evolution

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Rytidosperma s.l., wallaby grasses and allies, is in dire need of a single, unanimously accepted generic taxonomy. Motivated by the desire to establish a generic classification that complies with phylogeny, we investigated how much phylogenetic signal is contained within a plastid (cpDNA) tree, given that the nrDNA tree (ITS) was uninformative and that a phylogenetic hypothesis based on a single genome may not be reliable. We find that the plastid tree is significantly different from a morphological cladogram and show that this is the result of homoplasy in the morphological dataset. Treated individually, several morphological characters fit the plastid tree very well. Similarly, we find a good fit of the plastid tree with ecological and distribution characters and with biogeographical patterns in the Southern Hemisphere. We conclude that a significant level of the species phylogeny is resolved by the plastid tree and are confident it can form a sound basis for a reconsideration of generic limits. None of the currently recognised seven genera in the Rytidosperma clade is monophyletic. Therefore, we propose combining the segregate genera in Australasia within a broadly construed Rytidosperma, including all the species from Australia, New Guinea, New Zealand and South America.

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“…This is based on the chromosome counts of Brock and Brown (1961), Bowden and Senn (1962), Gould (1958), Calder (1937 and Spies et al (1992). All numbers are based on x = 6.…”

Section: Formal Taxonomymentioning

confidence: 99%

Generic limits in the Rytidosperma (Danthonieae, Poaceae) complex

Linder¹,

Verboom²

1996

Telopea

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597Linder, H. Peter and Verboom, G. Anthony (Bolus Herbarium, University of Cape Town, Rondebosch 7700, South Africa) 1996. Generic limits in the Rytidosperma (Danthonieae, Poaceae) complex. Telopea 6(4): 597-627. The generic limits of the Australasian danthonioid grasses are re-assessed using morphological and anatomical data from virtually all danthonioid species. These data, encoded in the DELTA system, were analysed using parsimony. The position of these genera within the Poaceae, and the broad structure of the relationships between them, has been assessed previously using both embryological information and molecular analyses. The results of the present study support the recognition of Plinthanthesis, Notochloe and Schismus, as well as corroborating the distinction between Danthonia and Rytidosperma. Rytidosperma sensu Zotov is segregated into three genera: Rytidosperma s.s. with 35 species, which includes Monostachya, Erythranthera and Pyrrhanthera; Notodanthonia with 28 species; and two new genera, Thonandia (5 species) and Joycea (3 species). These genera are characterised morphologically and ecologically, and the species included in each genus listed. The relevant new combinations are made.

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Cytogenetic Studies in the Genus Tribolium (Poaceae: Arundineae)

Cited by 10 publications

References 10 publications

Molecular phylogeny of African Rytidosperma–affiliated danthonioid grasses reveals generic polyphyly and convergent evolution in spikelet morphology

Molecular phylogeny of African Rytidosperma–affiliated danthonioid grasses reveals generic polyphyly and convergent evolution in spikelet morphology

A plastid tree can bring order to the chaotic generic taxonomy of Rytidosperma Steud. s.l. (Poaceae)

Generic limits in the Rytidosperma (Danthonieae, Poaceae) complex

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