A biosystematic study of &lt;i&gt;Pentameris&lt;/i&gt; (Arundineae, Poaceae)

Barker, Nigel P.

doi:10.4102/abc.v23i1.782

Cited by 16 publications

(21 citation statements)

References 22 publications

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“…We attempted to obtain complete species sampling for the Pentaschistis clade, based on the taxonomy of Davidse (1988), Linder and Ellis (1990), and Barker (1993), as well as recently described species and taxonomic changes (Phillips 1994, 1995; Galley and Linder 2006). Seventy‐three of 82 species were obtained, representing 80 of 90 taxa, including the four varieties of Pentaschistis pictigluma and both subspecies of P. airoides and P. aurea .…”

Section: Methodsmentioning

confidence: 99%

“…The cytology of many species has been investigated, all three genera have a basic chromosome number of x = 7 (Davidse 1988; du Plessis and Spies 1992; Spies and Roodt 2001). Comprehensive investigation of the leaf anatomy of almost all species in the clade has been carried out (Ellis 1989; Ellis and Linder 1992; Barker 1993) allowing a broad classification of the species into two types, those with orthophyllous leaves and those with sclerophyllous leaves (Ellis and Linder 1992). Micro‐morphological characteristics used to define these leaf types are shown in Table 1 and illustrated in Figures 1B and 1C.…”

Section: Characteristics Of Sclerophylls and Orthophylls Adjusted Frmentioning

confidence: 99%

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The Phylogeny of the Pentaschistis Clade (Danthonioideae, Poaceae) Based on Chloroplast Dna, and the Evolution and Loss of Complex Characters

Galley

Linder

2007

Evolution

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We construct a species-level phylogeny for the Pentaschistis clade based on chloroplast DNA, from the following regions: trnL-F, trnT-L, atpB-rbcL, rpL16, and trnD-psbA. The clade comprises 82 species in three genera, Pentaschistis, Pentameris, and Prionanthium.We demonstrate that Prionanthium is nested in Pentaschistis and that this clade is sister to a clade of Pentameris plus Pentaschistis tysonii. Forty-three of the species in the Pentaschistis clade have multicellular glands and we use ancestral character state reconstruction to show that they have been gained twice or possibly once, and lost several times. We suggest that the maintenance, absence, loss, and gain of glands are correlated with leaf anatomy type, and additionally that there is a difference in the degree of diversification of lineages that have these different character combinations. We propose that both glands and sclerophyllous leaves act as defense systems against herbivory, and build a cost/benefit model in which multicellular glands or sclerophyllous leaves are lost when the alternative defense system evolves. We also investigate the association between leaf anatomy type and soil nutrient type on which species grow. There is little phylogenetic constraint in soil nutrient type on members of the Pentaschistis clade, with numerous transitions between oligotrophic and eutrophic soils. However, only orthophyllous-leaved species diversify on eutrophic soils. We suggest that the presence of these glands enables the persistence of orthophyllous lineages and therefore diversification of the Pentaschistis clade on eutrophic as well as oligotrophic soils.KEY WORDS: Ancestral, correlated evolution, Danthonioideae, gland evolution, Pentaschistis, phylogeny, Poaceae.Interest in the evolution of complex structures and their influence upon the success of organisms has a long history. Classic examples include orchid flowers (Darwin 1862) and the evolution of eyes (Fernald 2004). Part of their fascination lies in the very low probability that such structures should evolve at all (Dawkins 1986). However, their (often) unique evolution makes it difficult to tease apart the adaptive aspects from other factors, including chance. In contrast, the loss of such complex structures presents us with an opportunity to explore their function. Losses tend to be more numerous than gains in many complex structures or traits (e.g., heterostyly [Kohn et al. 1996;Schoen et al. 1997]; secondary xylem in aquatic plants [Sculthorpe 1967]; wings in insects [Whiting et al. 2003]; or the chlorophyll producing function of chloroplasts, in holoparasites [Judd et al. 2002;APG 2003;Bungard 2004]; Nickrent et al. 2004]). This makes them more tractable to investigation than gains. For example, if the losses of a particular structure within a clade are nonrandom with respect to other morphological characters or habitat, these losses can be used to investigate Peculiar multicellular glands (see Fig. 1A, B) exist on the inflorescences and/or leaves in 43 species of Pentaschistis and of P...

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Section: Methodsmentioning

confidence: 99%

Section: Characteristics Of Sclerophylls and Orthophylls Adjusted Frmentioning

confidence: 99%

The Phylogeny of the Pentaschistis Clade (Danthonioideae, Poaceae) Based on Chloroplast Dna, and the Evolution and Loss of Complex Characters

Galley

Linder

2007

Evolution

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“…• • Pentaschistis ampla (NW, KM, SE) sister to P. exserta (DAC endemic); • Pentaschistis basutorum (DAC) basal to most of Pentaschistis (a predominantly CFR genus; Linder and Ellis 1990); • Pentaschistis tysonii (DAC) basal to Pentameris (an endemic CFR genus; Barker 1993 …”

Section: Connectivity Analysis Based On Phylogenetic Relationshipsmentioning

confidence: 99%

Taking the scenic route – the southern Great Escarpment (South Africa) as part of the Cape to Cairo floristic highway

Clark

Barker

Mucina

2011

Plant Ecology & Diversity

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Background: Numerous Cape Floristic Region (CFR) clades are found in the Afromontane region of Africa, causing speculation on the source of their distribution. The southern Escarpment has been postulated as a key link in the movement of Cape species between the CFR and these Afromontane areas. Aims: The strengths of three purported connections (the north-west, Matjiesfontein and south-east) between the CFR and the southern Escarpment are considered, and of the southern Escarpment track itself. Methods: A comprehensive database was compiled from which floristic comparisons and multivariate analyses were undertaken. Palaeo-connectivity was assessed from phylogenetic relationships determined from 19 phylogenies. Results: There is evidence of both palaeo-and current connectivity between the Escarpment and the CFR, most strongly for the SE connection. Current connectivity along the southern Escarpment track is relatively well supported between the eastern Nuweveldberge and Main Drakensberg but not between the Hantam-Roggeveld and Nuweveldberge. Palaeo-connectivity along the southern Escarpment track is well supported by the phylogenies. Conclusions: Climate regime may be a more important factor in floristic connectivity than geomorphological continuity. Historical connectivity along the southern Escarpment track suggests cyclical connectivity, probably in response to glacial-interglacial cycles and associated shifts in rainfall regimes along the southern Escarpment.

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“…contains nine species and is endemic to Western Cape, South Africa (Barker 1993). In his revision of Pentameris, Barker (1993) described chromosome numbers for P. distichophylla (Lehm.) Nees (2n = 6x = 36) and P thuarii Beauv.…”

Section: Poaceae the Basic Chromosome Number Of The Genus Pentameris mentioning

confidence: 99%

Poaceae

Spies

Roodt

2001

Bothalia

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A biosystematic study of <i>Pentameris</i> (Arundineae, Poaceae)

Cited by 16 publications

References 22 publications

The Phylogeny of the Pentaschistis Clade (Danthonioideae, Poaceae) Based on Chloroplast Dna, and the Evolution and Loss of Complex Characters

The Phylogeny of the Pentaschistis Clade (Danthonioideae, Poaceae) Based on Chloroplast Dna, and the Evolution and Loss of Complex Characters

Taking the scenic route – the southern Great Escarpment (South Africa) as part of the Cape to Cairo floristic highway

Poaceae

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